JP2007276183A - Light emitting element array chip with microlens, and optical writing head - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a light emitting element array chip with a microlens, which can adjust a location of a light emitting point image on a photoconductor drum, to a predetermined location, and to provide an optical writing head. <P>SOLUTION: The plurality of light emitting array chips are provided for the optical writing head having an optical system which can form the light emitting point image on the photoconductor drum provided for a predetermined device, and have light emitting point arrays each formed of a plurality of linearly aligned light emitting points. Each light emitting array chip has the microlenses arranged on the respective light emitting points, and the light emitting point images corresponding to the light emitting points are formed via the optical system with rod lenses. Each combination between the light emitting point and the microlens corresponding to the light emitting point has an arrangement relationship between the light emitting point and the microlens corresponding to the light emitting point, and the arrangement relationship for each combination is determined such that all the light emitting point images corresponding to the light emitting points are almost equally spaced based on a circumcircle center of the light emitting point and the center of the gravity of the microlens corresponding to the light emitting point. Further at least one of the arrangement relationships of the combinations is inconsistent with a main scanning direction or a sub-scanning direction. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a light emitting element array chip and a writing head, and more particularly to a light emission point shift of a light emitting element array chip with a microlens.

  It is known that a light emitting element array and an optical writing head are used as a light source for exposing light to a photosensitive drum provided in an optical printer, a facsimile machine, or a copying machine (for example, Patent Document 1). FIG. 25 shows a principle diagram of an optical printer provided with an optical writing head. A photoconductive material (photosensitive member) such as amorphous Si is formed on the surface of the cylindrical photosensitive drum 102. This drum rotates at the speed of printing. The surface of the photosensitive drum of the rotating drum is uniformly charged by the charger 104. Then, the optical writing head 100 irradiates the photosensitive member with the light of the dot image to be printed, and neutralizes the charging where the light hits. Subsequently, toner is applied on the photosensitive member by the developing device 106 according to the charged state on the photosensitive member. Then, the toner is transferred onto the paper 112 sent from the cassette 110 by the transfer device 108. The sheet is heated and fixed by the fixing device 114 and sent to the stacker 116. On the other hand, the drum that has been transferred is neutralized by the erasing lamp 118 over the entire surface, and the remaining toner is removed by the cleaner 120.

  Further, FIG. 26 shows a principle diagram of a facsimile machine and a copying machine provided with an optical writing head. Components identical to those in FIG. 25 are denoted by the same reference numerals.

  Light is emitted from the light source 124 to the read original 122 conveyed by the paper feed roller 130, and is received by the image sensor 128 through the imaging lens 126 using the reflected light. The light emitting element array 132 of the optical writing head 100 is turned on by the printing or copying function of the facsimile or the copying function of the copying machine, and the photosensitive drum 102 is irradiated through the rod lens array 134. Printing on the paper 112 is as described for the optical printer. The light emitting element array 132 can be configured by arranging a plurality of light emitting element array chips.

  FIG. 24 shows a typical structural diagram of an optical writing head in the prior art. FIG. 24 is a cross-sectional view of a direction perpendicular to the main scanning direction (hereinafter referred to as sub-scanning direction) of the optical writing head mounted on the optical printer. A plurality of light emitting element array chips 61 in which light emitting elements are arranged in a row are mounted on the chip mounting substrate 60 in the main scanning direction, and the light emitting elements of the light emitting element array chip 61 are on the optical path of light emitted. Is arranged with an erecting equal-magnification rod lens array 74 that is long in the main scanning direction. The rod lens array 74 is fixed by a housing 63 having a function as an adjustment mechanism for adjusting the position in the optical axis direction. Light emitted from the light emitting element forms an image on the photosensitive drum 102 via the optical rod lens array 74. In addition, a heat sink 65 for releasing the heat of the light emitting element array chip 61 is provided on the base of the chip mounting substrate 60. The housing 63 and the heat sink 65 are secured by a fastener 66 with the chip mounting substrate 60 interposed therebetween. It is fixed. A typical structural diagram of such an optical writing head is disclosed as a prior art (for example, Patent Document 2).

  FIG. 19 is a plan view when a microlens is arranged on the light emitting element array chip. The light emitting element array chip 80 is provided with bonding pads 82 at both ends of the chip, and the light emitting points 84 of the light emitting element array chip are arranged linearly along the edge of the chip. FIG. 20 shows a state where microlenses 30m are connected and arranged on the light emitting elements with respect to the light emitting element array chip, and shows a partially enlarged view of the light emitting element array chip provided with the microlenses. Yes. This enlarged portion corresponds to the portion surrounded by the dotted line in FIG. FIG. 21 is a side view of FIG. Such a microlens and a light emitting element array chip are disclosed as prior art (for example, Patent Document 3).

  FIG. 22 shows an arrangement state of a conventional light emitting element array chip, FIG. 22 (a) is an explanatory view of a linear arrangement, and FIG. 22 (b) is an explanatory view of a conventional staggered arrangement. In FIG. 22 (a), a plurality of light emitting points 84 are linearly arranged on each light emitting element array chip 80. The plurality of light emitting element array chips 80 are connected so that the plurality of light emitting points 84 are connected in a straight line while maintaining the same arrangement interval.

  In the light emitting element array of the type arranged in a line on a substantially straight line shown in FIG. 22 (a), a plurality of light emitting element array chips are arranged in one direction on a printed wiring board. When an image is output by a printer or the like, the control signal is synchronized with predetermined image data at a predetermined control timing, the control signal is transferred to the corresponding light emitting element portion on the light emitting element array chip, and the light emitting element emits light. Let The printed wiring board 60 and the erecting equal-magnification lens array 74 are supported and fixed in a fixed positional relationship as an optical writing head as described above. An image (that is, irradiation light) corresponding to each light emitting point on the light emitting element array chip is projected onto the photosensitive drum 102 through the erecting equal-magnification lens array.

  In FIG. 22B, the length of the light emitting element array chip 81 is made longer than the length of the light emitting element array chip 80, and then the odd-numbered array chip 81-1 and the even-numbered array chip 81-2 are The orientation is changed 180 degrees, and the two ends are arranged in a zigzag state so that both ends are back to back.

  The light-emitting element array of the staggered type shown in FIG. 22 (b) has a plurality of light-emitting element array chips arranged in two lines (straight line a and straight line b) on a printed wiring board in a zigzag pattern. The light emitting point arrays (hereinafter also referred to as main scanning direction) are arranged at equal intervals. The printed wiring board and the erecting equal-magnification lens array are supported and fixed in a fixed positional relationship as an optical writing head as described above. An image (that is, irradiation light) corresponding to each light emitting point on the light emitting element array chip is projected onto the photosensitive drum through the erecting equal-magnification lens array. Here, a control signal corresponding to the image data is given to each light emitting element array chip so that the image on the photosensitive drum is correctly drawn.

  FIG. 23 shows a state in which the light emitting element array chips arranged in a staggered pattern are cut. FIG. 23 (a) is an explanatory diagram of dicing, and FIG. 23 (b) is an explanatory diagram of a staggered arrangement state. As shown in FIG. 23 (a), the light emitting element array chip 81 is cut into approximately rectangular pieces including the light emitting point 84 by the dicing blade 13, and then adjacent to each other as shown in FIG. 23 (b). The chips (81-1, 81-2) are arranged back to back. In dicing using the dicing blade 13, the array chip on the dicing tape 12 is cut at a predetermined angle. That is, the angle α of the long side edge on the side contacting the adjacent chip back to back with the chip surface 10a with respect to the cut end surface 10b on the light emitting point 84 side is an acute angle, and is lower than the perpendicular from the acute angle. Cut so that 10c does not protrude. As a result, the angle and cutting position of the cutting end face 10b are optimized, and stable staggered positioning can be achieved.

  As shown in FIG. 22 (b), by connecting a plurality of array chips 81 in a staggered arrangement, the centers of a plurality of light emitting points 84 arranged linearly on the chip surface of each array chip 81 are connected. The two straight lines a and b are parallel straight lines.

  The light emitting element arrays shown in FIGS. 22 and 23 are disclosed as prior art (for example, Patent Document 4).

  In addition, a method of obliquely cutting the light emitting element array chip in the main scanning direction with a high accuracy by dicing is disclosed as a prior art (Patent Document 5). In order to improve the connection accuracy of each light emitting element array chip, a dual dicer having a special structure for the oblique cutting method of each light emitting element array chip is used. The connection accuracy of each light emitting element array chip is improved using the dual dicer.

  By the way, when a self-scanning light-emitting element array is used as the light-emitting element array, it is known that the drive system needs to be devised due to the relationship between the light emission timing and the rotating photosensitive drum (for example, Patent Document 6). ). That is, the light emitting element corresponding to the first pixel of the light emitting element array chip is turned on, the light emitting element corresponding to the next pixel, the light emitting element corresponding to the next pixel, and so on are sequentially turned on. The timing for driving the last pixel and the first pixel of the adjacent chip is shifted by one scan. In order to solve this problem, in addition to a method in which recording elements are tilted in the opposite direction in a complementary manner, or in which the arranged chips are tilted in a complementary manner, a time-division driving method (Patent Document) 6) is disclosed.

  Note that the light utilization efficiency of the light emitting element is also an important factor for the optical writing head used in the above-described optical printer and the like. If the light utilization efficiency is good, the power consumption of the light emitting element array can be reduced accordingly. Therefore, it is generally known that the deterioration of heat generation of the light-emitting element can be reduced, and thus it is effective for extending the life. Therefore, in order to increase the light utilization efficiency, the directivity of LED light emission is improved by arranging a microlens array composed of an array of spherical microlenses (hereinafter also referred to as spherical lenses) immediately above the LED light emission point. Methods for improving are known. That is, the light incident on the aperture angle of the rod lens array can be increased by the microlens. Furthermore, in order to improve the light emission efficiency over the spherical lens, a lens (hereinafter, also referred to as a compound lens) that achieves an optimal shape of the microlens corresponding to the shape of the light emitting element and its manufacturing method are also disclosed. (For example, Patent Document 7).

FIG. 10 (a) is a diagram showing a configuration example of a light emitting element array in which light emitting points are arranged on a substantially straight line in the case of a conventional microlens (that is, a simple circular lens). FIG. 10 (b) is a diagram schematically showing a light emission point image formed on the imaging surface (photosensitive drum surface) when the photosensitive drum is stopped in FIG. 10 (a). As shown in FIG. 10 (a), the shape of each light emitting point 84 on the light emitting element array chip 80m is a shape in which a part of a substantially square (electrode portion) is notched (for example, Patent Document 6). In the light emitting element array chip 80m, a circular spherical microlens 30m (that is, a circular lens) is arranged immediately above each light emitting point 84. FIG. 11 is a view of the light emitting point 84 and the spherical microlens 30m shown in FIG. 10 as viewed from above. From FIG. 11, it can be seen that the center position (hereinafter also referred to as the center of the light emitting point circumscribed circle) Op of the circle circumscribing the shape of each light emitting point coincides with the gravity center position Omp of the microlens. . In the light emitting element array chip having such a configuration, as shown in FIG. 10, the light emitting points I _A1 and I _A2 on the end side of the light emitting element array chip are imaged on the photosensitive drum (hereinafter referred to as a light emitting point image). And emitted as emission point images I _A1 ′ and I _A2 ′. As can be seen from the light emission point image 80md shown in FIG. 10 (b), the light emission point images are irradiated at substantially equal intervals. Note that the width of the light emitting point 84 in the main scanning direction (a in the drawing) is shorter than the interval p between the respective light emitting points, and it can be seen that each light emitting point image is formed by the interval p between the respective light emitting points.

FIG. 12 (a) is a diagram showing a configuration example of a light emitting element array in which each light emitting element array chip is arranged in a staggered manner in the case of a microlens (that is, a compound lens) of the prior art. FIG. 12 (b) is a diagram schematically showing a light emission point image formed on the imaging surface (photosensitive drum surface) when the photosensitive drum is stopped in FIG. 12 (a). The shape of each light emitting point 84 of the light emitting element array chip 81s has a shape in which a part of the substantially square (electrode portion) is notched. In the light emitting element array chip 81s, the microlens 30 (that is, a composite lens) is disposed immediately above each light emitting point 84. FIG. 13 is a view of the light emitting point 84 and the compound lens 30 shown in FIG. 12 as viewed from above. From FIG. 13, it can be seen that the center position Op of the circle circumscribing the shape of each light emitting point coincides with the gravity center position Osp of the microlens. In the light emitting element array chip having such a configuration, as shown in FIG. 12, the light emitting points I _E1 and I _E2 on the end side of the light emitting element array chip have the light emitting point images I _E1 ′ and I _E1 on the photosensitive drum. _Imaged as _E2 '. As can be seen from the light emission point image 81sd shown in FIG. 12B, each light emission point image is irradiated at substantially equal intervals, including the joints between the light emitting element array chips. Note that the width in the main scanning direction of the light emitting point 84 (which is the same as that shown in FIG. 10a and is not shown) is shorter than the interval p between the light emitting points, and each light emission depends on the interval p between the light emitting points. It can be seen that a point image is formed.

  Further, the light emitting points 84 are arranged at equal intervals p in the main scanning direction, and the straight line (JJ ') and the straight line (KK') are maintained in parallel, and the straight line (LL ') and the straight line ( The same applies to MM ′). The distance between the straight line (L-L ') and the straight line (M-M') is a distance q in the sub-scanning direction, and the straight line (J-J '), straight line (K-K') and Is approximately the same as the distance between The straight line (J-J ') and the straight line (K-K') connect the circumscribed circle center Op of each light emitting point of each light emitting element array chip.

FIG. 14 (a) is a diagram showing a configuration example of a light emitting element array in which each light emitting element array chip is arranged in a staggered manner in the case of a conventional microlens (spherical lens). FIG. 14 (b) is a diagram schematically showing a light emission point image formed on the imaging surface (photosensitive drum surface) when the photosensitive drum is stopped in FIG. 14 (a). The shape of each light emitting point 84 of the light emitting element array chip 81m is a shape in which a part of a substantially square (electrode portion) is notched. In the light emitting element array chip 81m, a micro lens 30m is formed immediately above each light emitting point 84. The arrangement relationship between the light emitting point 84 and the spherical lens 30m shown in FIG. 14 is the same as the configuration shown in FIG. In the light emitting element array chip having such a configuration, as shown in FIG. 14, the light emitting points I _C1 and I _C2 on the end side of the light emitting element array chip have the light emitting point images I _C1 ′ and I _C1 on the photosensitive drum. _Imaged as _C2 '. As can be seen from the light emission point image 81md shown in FIG. 14B, each light emission point image is irradiated at substantially equal intervals, including the joints between the light emitting element array chips. The width of the light emitting point 84 in the main scanning direction (same as that shown in FIG. 10A) is shorter than the interval p between the respective light emitting points, and each light emitting point image is formed by the interval p between the respective light emitting points. I understand that.

Further, the light emitting points 84 are arranged at equal intervals p in the main scanning direction, and the straight line (BB ′) and the straight line (CC ′) are maintained in parallel, and the straight line (DD ′) and the straight line ( The same applies to E-E ′). The distance between the straight line (BB ') and the straight line (CC') is a distance q in the sub-scanning direction, and the distance between the straight line (DD ') and the straight line (EE') Is the same. Further, the straight line (BB ′) and the straight line (CC ′) connect the circumscribed circle center Op of each light emitting point of each light emitting element array chip. When using the erecting equal-magnification lens array 74 shown in FIG. 24 such as a SELFOC lens array, the line (B-B ') near the center line (L _A -L _A ') in the main scanning direction of the lens array A line (CC ') is placed.

  10 to 14 are diagrams for explaining important elements as a configuration of the prior art (for example, Patent Document 4).

  The center position Op of a circle circumscribing the shape of each light emitting point described in FIG. 11 (circle indicated by a broken line) and the gravity center position Omp of the microlens (spherical lens) are defined by a definition method described later. Further, the center-of-gravity position Osp of the microlens (compound lens) described in FIG. 13 is defined by a definition method described later.

JP 2003-170625 A JP 2004-209703 A JP 2005-311269 JP 2001-250981 A JP 2001-7054 JP 09-174937 A JP 2005-39195

  FIG. 15 shows a configuration example (hereinafter also referred to as a first configuration example) of a light emitting element array of a type in which a plurality of light emitting element array chips are arranged in a line on a substantially straight line. A light emitting element array chip 80 of a type arranged in a substantially straight line forms an image of a light emitting area of a plurality of light emitting points 34 (hereinafter also referred to as a light emitting area image) on a photosensitive drum via a rod lens array ( (Emission point image). It is clear to those skilled in the art that the light-emitting point images are preferably irradiated at regular intervals in a line, and should have such a configuration.

Therefore, in order to obtain light emission point images at equal intervals in a row, light emission points (In in the drawing) directly adjacent to the joints of the light emitting element array chips need to be arranged at substantially equal intervals p. For this purpose, as will high-definition (e.g., higher resolution), results in shortening the width of the gap of the light emitting points (i.e., the interval p is shortened), the cutting line of the seam S ₁ of the light emitting element array chip Then, the distance from the light emitting point In is shortened. Usually, the light emitting element array chip is formed on a compound semiconductor, and as described above, the light emitting element array chip is cut out by a dicing saw as a light emitting element array chip (for example, Patent Document 4).

However, since compound semiconductors are brittle and easily chipped during cutting, a margin of about several μm is required between the cutting line and the light emitting point. Further, when arranging the light emitting element array chips on the printed wiring board, a predetermined gap (S ₁ shown in FIG. 15) may be provided between the chips so that the chips are not damaged by the collision between the chips. I need it. Therefore, since the size of the light emitting points on the light emitting element array chip (that is, the light emitting point width a in the main scanning direction) needs to be smaller than the interval between the light emitting points (ie, p) by a certain value, As the definition becomes higher (that is, higher resolution), the emission point size becomes relatively smaller than the reduction of the emission point pitch. This causes a reduction in irradiation efficiency. That is, there arises a problem that the light output decreases relative to the high definition.

FIG. 16 shows a configuration example (hereinafter also referred to as a second configuration example) of a type of light emitting element array in which a plurality of light emitting element array chips are arranged in a staggered manner. The light emitting points 84 are arranged at equal intervals p in the main scanning direction, and the straight line (AA ′) and the straight line (BB ′) are maintained in parallel, and the straight line (A ₁ -A ₁ ′) and the straight line ( The distance between A _{2 and} A ₂ ′) is a distance q in the sub-scanning direction. The straight line (A ₁ -A ₁ ′) and the straight line (A ₂ -A ₂ ′) connect the circumscribed circle centers of the light emitting points of the light emitting element array chips. When using the erecting equal-magnification lens array 74 shown in FIG. 24, such as a SELFOC lens array, a straight line (A ₁ -A ₁ ′) near the center line (L _A -L _A ′) in the main scanning direction of the lens array. ) And a straight line (A ₂ -A ₂ ′). That is, in terms of resolution, light amount unevenness, and the like, the performance may decrease as the distance from the center line (L _A -L _A ′) in the main scanning direction of the lens array increases. For this reason, it is desirable that the distance q between the two light emitting point arrays in a staggered arrangement is, for example, within 100 μm.

Further, from the viewpoint of image signal processing, it is desirable that the distance q between the two light emitting point arrays is an integral multiple of the resolution in the sub-scanning direction. Under this condition, the deviation of the image data between the columns can be set to an integer line, so that the lighting timing for each chip can be matched (for example, Patent Document 6). Further, when the distance q between the columns increases, the amount of memory necessary for correcting the shift of the image data between the columns q in an optical printer or the like increases. As a result, the cost associated with an increase in memory can be increased, so the distance q between columns is preferably as small as possible. In the case of the second configuration example, unlike the first configuration example, the light emitting element array chips are not arranged in abutment in the main scanning direction. In other words, since each chip is alternately shifted from the straight line (A ₁ -A ₁ ′) and the straight line (A ₂ -A ₂ ′), the cutting accuracy in the main scanning direction is higher than that of the first configuration example. High accuracy is not required.

  However, when the light emitting element array of the second configuration example is used for the optical writing head, there is a demand for shortening the distance q between the two columns for the above-described reason, and therefore the distance between the cutting line and the light emitting point is made as short as possible. There is a problem to be done. In addition, there is a problem that high definition should be achieved according to the second configuration example while providing a margin of about several μm between the cutting line and the light emitting point in order to eliminate the influence of chipping.

Also in the second configuration example, when the light emitting element array chips are arranged in a staggered pattern on the printed wiring board, the chips are arranged with a predetermined gap so that the chips do not collide and are damaged. There is a need to. In addition, if the gap between the two chips is narrow, there is a risk that the adhesive for die bonding is sucked up by capillary action and the chip surface is soiled. Therefore, there is a problem that the cutting position in the sub-scanning direction of each chip should pass through a place more than a certain distance from the light emitting point to ensure a margin (S ₂ shown in FIG. 16) in the arrangement of each chip. .

Further, as a problem in the time-division driving described above, in common with the first configuration example and the second configuration example, as a light emitting element array, a self-scanning light emitting element array (hereinafter also referred to as SLED) is used. When the divided light emitting elements are used, there is a difference in lighting timing between the first light emitting point and the last light emitting point in the chip. FIG. 17 shows the relationship regarding the irradiation position on the photosensitive drum in the paper feeding direction when the lighting timing transfer direction is one direction (lighting direction of the arrow shown in the figure). FIG. 18 shows the relationship between the irradiation position on the photosensitive drum in the paper feed direction when the lighting timing transfer direction is alternately reversed for every odd-numbered and even-numbered chip (lighting direction of the arrow shown). In FIG. 17, as a first configuration example, the light emitting points of each light emitting element array chip 80 are arranged in a substantially straight line, and the light emitting points I _G1 and I _G2 at the end of each light emitting element array are represented by a light emitting point image 80d. FIG. 3 shows a state in which irradiation is performed without shifting on a straight line (illustrated I _G1 ′ and I _G2 ′). In FIG. 18, as a second configuration example, the light emitting element array chips 81 are arranged in a staggered arrangement, and the light emitting points I _H1 and I _H2 at the ends of the light emitting element array chips are straight in the light emitting point image 81d. It is shown that the irradiation is performed without shifting on the line (illustrated I _H1 ′ and I _H2 ′). In this way, the image data on the photosensitive drum, which must be a straight line, becomes a sawtooth shape (shown in FIG. 17) or a triangular wave shape (shown in FIG. 18) in units of chips in the paper feed direction. There is a point.

  Regarding this problem, in the first configuration example, the conventional technique deals with this problem by a technique in which the chip is inclined with respect to the main scanning direction (Patent Document 6). This method is not a sufficient method even for a light emitting element array chip whose resolution is increased. Furthermore, this method has a light emitting element array configuration that is maintained in parallel at a certain inclination, and cannot be handled for a staggered arrangement (second configuration example). Therefore, in the prior art, there is room for improvement in the method of correcting the blur of the light-emitting point image in the sub-scanning direction in the time-division driving method or the self-scanning light-emitting element array.

  An object of the present invention is to realize a high-definition optical writing head.

  The light-emitting element array chip of the present invention is provided in an optical writing head having an optical system for forming a light-emitting point image on a photosensitive drum provided in a predetermined apparatus, and includes a plurality of light-emitting points arranged in a straight line. A plurality of light emitting element array chips each having a light emitting point array, each including a microlens disposed on each light emitting point, and the light emitting point image corresponding to the light emitting point is provided via the optical system including a rod lens. For each combination that is imaged and configured by the light emitting point and the microlens corresponding to the light emitting point, the light emitting point and the microlens corresponding to the light emitting point have an arrangement relationship, The circumscribed circle center of the light emitting point and the lens of the microlens corresponding to the light emitting point so that the arrangement relationship is substantially equidistant for all of the light emitting point images corresponding to the light emitting point. Is defined on the basis of the heart, arrangement of at least one of the combinations is configured such that the mismatch in the main scanning direction or sub-scanning direction.

  In the light emitting element array chip of the present invention, the combinations that are inconsistent in the arrangement relationship are all the combinations provided in the light emitting element array chip, and are configured to be inconsistent only in the main scanning direction.

  Apart from that, in the light emitting element array chip of the present invention, the combinations that are inconsistent with respect to the arrangement relationship are all the combinations provided in the light emitting element array chip, and are configured to be inconsistent only in the sub-scanning direction. Yes.

  Furthermore, in the light emitting element array chip of the present invention, the light emitting element array chip is a self-scanning light emitting element array chip, and a line connecting positions of the center of gravity of the lens of all the microlenses and all of the light emitting points. A line connecting the positions of the circumscribed circle centers is defined at a predetermined angle that is not parallel. In particular, the predetermined angle is determined on the basis of the resolution of any one of an optical printer, a facsimile, and a copier using the light-emitting element array chip of the time-division driving method.

  In a high-definition light-emitting element array, it is possible to arrange light-emitting element array chips with a predetermined gap while satisfying manufacturing requirements between chips while suppressing a decrease in light output.

  In addition, the distance between the two light emitting point arrays is shortened, the distance between the cutting line in the main scanning direction or the sub scanning direction of the chip and the light emitting point is made as long as possible, and the chip main scanning direction is used to eliminate the influence of chipping. Alternatively, a margin of about several μm can be provided between the cutting line in the sub-scanning direction and the light emitting point. Furthermore, it can arrange | position with a predetermined gap between each chip | tip so that each chip | tip may not collide and may be damaged.

  That is, according to one embodiment of the present invention, the position of the light emitting point image on the photosensitive drum can be adjusted to a predetermined position by adjusting the position of the center of gravity of the lens array provided on the light emitting element array chip. Thereby, even if the light emitting point position on the chip is shifted, the light emitting point images can be arranged at substantially the same position on the photosensitive drum.

  Alternatively, the position of the light emitting point image can be shifted by shifting the center of gravity of the lens array without shifting the position of the light emitting point. Therefore, even when a time-division light emitting element is used, the light emitting element array chip can be configured so as to improve the difference in lighting timing between the first light emitting point and the final light emitting point in the chip.

  The present invention defines the positional relationship between the position of the light emitting point and the microlens. First, predetermined items are defined as described below.

  FIG. 8 (a) is a schematic diagram for explaining the center position of a circle circumscribing the shape of each light emitting point (hereinafter referred to as the circumscribed circle center position). In general, the light emitting points are often square or rectangular and have a shape such that a part thereof is cut out by an electrode. The circumscribed circle center means the center position (black dot at the center of the cross) indicated by a broken line in FIG.

  FIG. 8 (b) is a schematic diagram for explaining the centroid position of the microlens (hereinafter also referred to as the lens centroid position) on each light emitting point. For example, in the case of a simple circular spherical lens or aspherical lens, the lens centroid position refers to the center position (Omp in the drawing) of the circle. When the lens is a homogeneous medium, the “center of gravity position” is the position of the center of gravity determined by the shape, thickness of each part, etc. (Omp in the drawing). For example, the compound lens shown in FIG. 13 also refers to the position of the center of gravity determined by its shape, the thickness of each part, and the like (as distinguished from Osp for convenience as shown in FIG. 13).

In the embodiments described below, the light-emitting element array chips 80 arranged in a substantially straight line are represented by the subscripts (80 m, 80 m ₁ , 80 m ₂ ) corresponding to the respective embodiments as the same elements. Similarly, the staggered light emitting element array chip 81 is represented by the subscripts (81 m, 81 m ₁ , 80 _S1 ) corresponding to the respective examples, with the same elements.

  Embodiments of the present invention will be described below with reference to the accompanying drawings.

  First, an outline of an optical system constituting the optical writing head according to the present invention will be described.

  FIG. 9 (a) shows a schematic diagram of an optical system related to an optical writing head based on the prior art, and FIG. 9 (b) shows a schematic diagram example of an optical system related to the optical writing head based on the present invention. .

  Specifically, FIG. 9A shows an image of a light emitting point of a light emitting element array chip (eg, LED array) on a photosensitive drum via a rod lens array (eg, Selfoc lens array). It is a schematic diagram of an optical system. Such an optical system is used as an optical system of an optical printer having a so-called LED. As described with reference to FIG. 21, the LED array and the microlens array in FIG. 9A are formed integrally with the LED substrate as viewed from the side. In FIG. 21, a spherical lens is representatively illustrated, but an aspherical lens array or a compound lens array may be used.

  FIG. 9 (a) shows only the relationship between one LED light emitting point (In) and the image of the photosensitive drum 102 (light emitting point image In ′), and a microlens (in FIG. 9, spherical lens 30m). Is schematically illustrated with a thin lens. The optical system of FIG. 9 (a) uses a rod lens array 74 to convert a virtual image In '' (enlarged by a micro lens) of a light emitting point formed by a micro lens 30m provided immediately after the light emitting point In to a photosensitive drum. This is an optical system in which an erect life-size image is formed on the top. Therefore, as shown in FIG. 9 (a), the virtual image of the light emitting point is formed on the optical axis connecting the light emitting point and the microlens, and thus the light emitting point image on the photosensitive drum is also formed at the same position. The FIG. 9 (b) schematically shows a light emission point image formed on the imaging surface (photosensitive drum surface). As described above, the light emission point image on the imaging surface is formed at the same (conjugate) position as the original light emission point.

  Specifically, FIG. 9B shows another example of an optical system that forms an image of a light emitting point of a light emitting element array chip (LED array in the figure) on a photosensitive drum via a rod lens array 74. It is a schematic diagram. In order to be able to compare with FIG. 9 (a), description will be made assuming that the components such as the microlens are the same.

  FIG. 9B shows only the relationship between one LED emission point (In) and the image of the photosensitive drum 102 (emission point image In ′), and the microlens 30m is typically a thin lens. It is drawn in. The optical system of FIG. 9 (b) is a photosensitive drum using a Selfoc lens array to display a virtual image In '' (enlarged by a microlens) of a light emitting point formed by a microlens 30m provided immediately after the light emitting point In. This is an optical system in which an erect life-size image is formed on the top.

  The optical system shown in FIG. 9 (b) is different from the optical system shown in FIG. 9 (a), and the light emitting point is at a position shifted from the optical axis of the microlens, so as shown in FIG. 9 (b). The virtual image of the light emitting point is formed at a position shifted from the optical axis of the microlens. Therefore, the photosensitive light-emitting point image on the photosensitive drum 102 is also formed at a shifted position conjugate with this. Further, since the virtual image is enlarged, the deviation amount of the virtual image position from the microlens optical axis is enlarged by this enlargement magnification rather than the deviation amount of the light emitting point. Therefore, the light emission point image is enlarged in the same manner as the displacement amount of the light emission point image.

  For example, means for adjusting spot light on a target object by providing an objective lens capable of moving in main scanning and sub scanning in a conjugate optical system at infinity or finite is generally known. However, there is no prior art in which a microlens as a condensing function is provided with such an optical axis adjustment function, and the present invention makes use of this effect to solve the problems of the prior art. To do.

  That is, the optical system shown in FIG. 9 (a) is based on the prior art. As described above, this configuration has a problem that the light output decreases relative to the high definition. In addition, there is a problem of providing a margin of about several μm between the cutting line and the light emitting point in order to eliminate the influence of chipping, and further, there is a problem of high definition according to the second configuration example. In addition, when the light emitting element array chips are arranged on the printed circuit board, there is a problem that the chips should be arranged with a predetermined gap so that the chips do not collide with each other and are not damaged. In addition, in order to avoid the risk of soiling the chip surface, there is a problem that the cutting position must be passed a certain distance away from the light emitting point. When the time-division driving, the image data on the photosensitive drum, which must be a straight line, is sawtooth-shaped (shown in FIG. 17) or triangular wave shape (shown in FIG. 18) in units of chips in the paper feed direction. It has the problem of becoming.

  According to the present invention, the optical system shown in FIG. 9B can be embodied to solve all the above problems.

  In other words, according to the first configuration example, the optical printer or the like can be designed without reducing the light emitting point size by intentionally shifting the positional relationship between the center of gravity of the microlens lens and the center of the light emitting point circumscribed circle in the main scanning direction. It is possible to configure so that light emission point images with a resolution (that is, higher definition) that meets the requirements and on the photosensitive drum are equally spaced. Therefore, it is possible to solve the problem that the light output decreases relative to the high definition.

  In addition, in order to achieve high definition according to the second configuration example, the positional relationship between the center of gravity of the microlens and the center of the light emitting point circumscribed circle is intentionally shifted in the sub-scanning direction without being affected by chipping, A margin of about several μm can be provided between the cutting line and the light emitting point.

  Further, in the first and second configuration examples, when the light emitting element array chips are arranged on the printed wiring board, the lens center of gravity of the microlens and the light emitting point circumscribing are provided so that the chips do not collide and are damaged. By intentionally shifting the positional relationship with the center of the circle in the main scanning direction or the sub-scanning direction, a predetermined gap can be secured between the chips. By the same method, in the second configuration example, if the gap between the two chips is narrow, the adhesive for die bonding is sucked up by capillary action, so as to avoid the risk of soiling the chip surface. The cutting position can be passed a certain distance away from the light emitting point.

  In addition, when using a self-scanning light-emitting element array, in a time-division drive, with a resolution that matches the design requirements of an optical printer, etc., a constant between the paper feed speed of the optical printer and the time required to transfer one chip. In order to obtain a light emitting point image on the photosensitive drum having the relationship, the positional relationship between the center of gravity of the microlens lens and the center of the circumscribed circle of the light emitting point is intentionally shifted in the main scanning direction or the sub-scanning direction. In addition, the problem of a sawtooth shape (shown in FIG. 17) or a triangular wave shape (shown in FIG. 18) can be solved.

  In addition, in order to solve the above-described plurality of problems or problems, one or more of the above-described problems or problems can be combined and solved by combining various microlens arrangements or light emission point arrangements.

Example 1
Next, specific Example 1 will be described based on the contents of the above outlined invention. Example 1 uses the method described in FIG. 9 to intentionally shift the center position of the microlens 30m and the light emitting point In in the main scanning direction, without reducing the light emitting point size, such as an optical printer. This is a more specific embodiment that is configured so as to obtain light emission point images with a resolution (that is, higher definition) that meets the design requirements of FIG.

FIG. 1 (a) is a diagram showing a configuration example which is an embodiment according to the present invention for a light emitting element array chip having a first configuration. FIG. 2 shows a cross-sectional structure of the light emitting point (particularly, the rightmost light emitting point I _B1 ) of the left chip of FIG. 1 (a). When viewed from the side, the LED array and the microlens array in FIG. 1 (a) are integrally formed with the LED substrate as shown in FIG. The shape of the light emitting element array the light emitting points 84 of the chip 80 m ₁ has a shape that contains notched in a part of the substantially square (electrode portion). Only the light emitting points at both ends of the chip are arranged inside the chip in the main scanning direction at a pitch different from the pitch p of the other light emitting points, and the center of gravity Omp of the spherical microlens 30m immediately above the light emitting point (I _B1 or I _B2 ) The center position Op of the circle circumscribing the light emitting spot shape is shifted outward in the main scanning direction (δ in the figure). Note that the width of the light emitting point 84 in the main scanning direction (a in the drawing) is shorter than the interval p between the respective light emitting points, and it can be seen that each light emitting point image is formed by the interval p between the respective light emitting points.

In FIG. 2, the distance between the lens centers is 42.3 μm apart from the end of the light emitting element array chip, and the distance between the centers of the light emitting points is 42.3 μm apart from the end of the light emitting element array chip. The light emitting element array chip edge is disposed on the microlens gravity line Bm and the light emitting point centerline Am both the main scanning direction chips inside, the rightmost light emitting point centerline Am and lens gravity line Bm of the light emitting point I _B1 is 4 um It's off. The main scanning width of the light emitting points 84 is all 13 μm.

Further, FIG. 1B is a diagram schematically showing a light emission point image formed on the imaging surface (photosensitive drum surface) when the photosensitive drum is stopped. As shown in FIG. 1B, the light emitting points I _B1 and I _{B2 at} both ends of the chip that are shifted inward by δ are formed at positions equidistant from the other light emitting points on the photosensitive drum 80m ₁ d. (I _B1 ′ and I _B2 ′ shown).

  In the configuration shown in FIG. 2, more specific numerical values which are one embodiment of the present invention are shown. The light emitting point width was set to 13 μm, the microlens was made of an ultraviolet curable epoxy resin material having a refractive index n = 1.52, a diameter of 30 μm, a radius of curvature r = 16 μm, and a light emitting point surface-to-lens vertex distance of 20 μm. However, the light emitting points at both ends of the chip are closer to the inside of the chip 11 μm than the light emitting point pitch p (42.3 μm = 600 dpi (600 points per inch)) other than both ends, and the spherical surface is more spherical than the circumscribed circle center of both ends The center of gravity of the lens was shifted to the outside of the 4 μm chip.

  Here, the magnification of this lens is 2.75 times. Therefore, the light emitting point image on the photosensitive drum can be shifted by 2.75 times the amount of deviation between the light emitting point circumscribed circle center and the lens center of gravity. When the light emitting element array substrate and the rod lens array 74 were combined and drawn on the photosensitive drum, the light emitting point images could be arranged on the photosensitive drum at equal intervals of 42.3 μm. According to this example, the distance between the light emitting points at both ends of the chip and the cutting line (in the main scanning direction) could be secured by 7 μm as shown in FIG. For this reason, it is difficult to be affected by chipping, and productivity is improved. In this embodiment, only one light emitting point at each end of the chip is shifted, but a plurality of light emitting point positions can also be shifted.

  In other words, by intentionally shifting the center position of the microlens and the light emitting point in the main scanning direction, the resolution (that is, high definition) that meets the design requirements of an optical printer or the like without reducing the light emitting point size and Since the configuration is such that the light emission point images are equally spaced, it is possible to solve the problem that the light output decreases relative to the high definition.

  Further, when the light emitting element array chips are arranged on the printed wiring board, the chips can be arranged with a predetermined gap so that the chips do not collide with each other and are damaged. In the same way, if the gap between the two chips is narrow, the risk that the die bonding adhesive is sucked up by capillary action and the chip surface is soiled can be avoided.

(Example 2)
Next, specific Example 2 will be described based on the above-described outline of the invention. FIG. 3 is a diagram for explaining a staggered chip as a second configuration example, and the distance between the light emitting point and the cutting line (sub-scanning direction) can be secured by the same method as in the first embodiment.

FIG. 3 (a) is a diagram showing a configuration example which is an embodiment according to the present invention for the light emitting element array chip having the second configuration. The shape of the light emitting element array the light emitting points 84 of the chip 81m ₁ has a shape that contains notched in a part of the substantially square (electrode portion). Then, in one chip of the staggered chip, only the light emitting points at both ends of the chip, while maintaining the pitch p between the other light emitting points, each light emitting point 84 in the sub-scanning direction, and the lens of the microlens at each light emitting point The line F ₁ −F ₁ ′ connecting the center of gravity Omp is shifted by Δq (shifted in the sub-scanning direction) to the line G ₁ −G ₁ ′. Similarly, in the other chip of the staggered array chip, only the light emitting points at both ends of the chip are Δq up to the line G ₂ −G ₂ ′ with respect to the line F ₂ −F ₂ ′ connecting the lens center of gravity Omp of the microlens of each light emitting point. They are shifted by a minute (shifted in the sub-scanning direction). Therefore, as shown in FIG. 3 (a), on the light emitting element array of the staggered arrangement, the distance between the staggered arrangements of the light emitting element array chips is increased from P to P + 2Δq.

Further, FIG. 3B is a diagram schematically showing a light emission point image formed on the imaging surface (photosensitive drum surface) when the photosensitive drum is stopped in the configuration of FIG. 3A. In the light emitting element array configured as described above, the light emitting point image 81m ₁ d formed on the photosensitive drum is adjusted by adjusting the arrangement of the light emitting point and the microlens array on the light emitting element array. emission points corresponding to _D1 or I _D2) (I _D1 'or I _D2') is, in a state of maintaining the distance q between the line H-H 'and the line I-I', and is irradiated.

  Thereby, the distance between the light emitting point and the cutting line (sub-scanning direction) can be secured, and according to the second configuration example, the center position of the microlens and the light emitting point is intentionally shifted in the sub-scanning direction, A margin of about several μm can be provided between the cutting line in the sub-scanning direction and the light emitting point without being affected by chipping.

  Further, when the light emitting element array chips are arranged on the printed wiring board, the chips can be arranged with a predetermined gap so that the chips do not collide with each other and are damaged. In the same way, if the gap between the two chips is narrow, the risk that the die bonding adhesive is sucked up by capillary action and the chip surface is soiled can be avoided.

  In Embodiments 1 and 2, a simple spherical lens has been described, but a compound lens as shown in FIG. 13 may be used.

(Example 3)
For example, Example 3 will be described as a modification of Example 2. In Example 3, a case where a compound lens (shown in FIG. 13) is used instead of the spherical lens (shown in FIG. 11) will be described.

  FIG. 4 (a) is a diagram for explaining a staggered array chip that is a second configuration example using the compound lens 30, and FIG. 4 (b) is a diagram illustrating a photosensitive drum stop in the configuration of FIG. 4 (a). It is the figure which showed typically the light emission point image formed on the image formation surface (photosensitive drum surface) at the time. FIG. 5 is a diagram for explaining the arrangement relationship between the light emitting point and the compound lens according to the present embodiment. According to Example 3, even when a compound lens is used, the distance between the light emitting point and the cutting line (sub-scanning direction) can be ensured as in Example 2.

In FIG. 4 (a) and FIG. 5, the shape of the light emitting element array the light emitting points 84 of the chip 81s ₁ has a shape that contains notched in a part of the substantially square (electrode portion). All the light emitting points (for example, the light emitting point I _F1 ) on one chip in the staggered arrangement are arranged in the main scanning direction while maintaining the pitch p between the other light emitting points. In the direction, the line OO ′ connecting the lens center of gravity Osp of the microlens of each light emitting point is shifted by Δq (shifted in the sub-scanning direction) to the line NN ′. Emitting point I _F2 other on the chip all the staggered array, in the main scanning direction, are disposed in a state of maintaining the pitch p between other light emitting points, in the sub-scanning direction, of the light emitting points The line QQ ′ connecting the lens center of gravity Osp of the microlens is shifted by Δq (shifted in the sub-scanning direction) to the line PP ′. As a result, the center of gravity Osp of the compound lens 30 immediately above the light emitting point (I _F1 or I _F2 ) and the center Op of the light emitting point circumscribed circle are shifted by Δq in the sub-scanning direction. Therefore, as shown in FIG. 4 (a), on the light emitting element array of the staggered arrangement, the distance between the staggered arrangements of the light emitting points is increased from P to P + 2Δq.

The configured light emitting element array, as described above, emission points 81s ₁ d imaged on a photosensitive drum (shown in FIG. 4 (b)), the arrangement of the light-emitting point and the microlens array on the light emitting element array by adjusting, light emitting point emission points corresponding to (I _F1 or I _F2) (I _F1 'or I _F2') is maintained the distance q between lines R-R 'and the line S-S' Irradiated in the state.

  Thereby, the distance between the light emitting point and the cutting line (sub-scanning direction) can be secured, and the center position between the compound lens 30 and the light emitting point 84 is set in the sub-scanning direction in order to achieve high definition according to the second configuration example. By deliberately shifting to a certain distance, a margin of about several μm can be provided between the cutting line (in the sub-scanning direction) and the light emitting point without being affected by chipping.

(Example 4)
Next, a fourth application example of the present invention will be described. As described in FIG. 17, in the prior art as the first configuration example, the light emitting points of the respective light emitting element array chips 80 are arranged in a substantially straight line on the entire chips, and the end portions of the respective light emitting element array chips are arranged. The light emission points I _G1 and I _G2 are not aligned on the light emission point image 80d, but are shifted and irradiated. For this reason, there has been a problem that a sawtooth is formed in units of chips in the paper feed direction. In Example 4, a light emitting element array chip will be described in which the arrangement of light emitting points and spherical lenses on the light emitting element array chip is adjusted in order to eliminate the influence of the rotation of the photosensitive drum.

FIG. 6 is a diagram showing a configuration example of a self-scanning light-emitting element array to which the present invention is applied with respect to a first configuration example in the case where the light emission direction is one direction. FIG. 6A (light emitting element array chip surface view) shows that the light emitting element array chip 80m ₂ connects the center of gravity of each lens with respect to a line U ₁ -U ₁ 'connecting each light emitting point circumscribed circle center for each chip. A spherical lens array is formed at an angle θ ₁ by a line T ₁ −T ₁ ′. The light emitting element array chip 80 m ₂ is in the main scanning direction, are the interval between the light emitting points 84 is arranged by p. Therefore, in the light emitting element array chip 80m ₂ configured as described above, the light emitting points I _J1 and I _J2 at the end of each chip are configured to be shifted by a distance corresponding to the predetermined angle θ ₁ in the sub scanning direction. ing. Here, T ′ is the emission center point determined from the emission point circumscribed circle center Op and the spherical lens center of gravity Omp.

  FIG. 6 shows a light emission point image on the photosensitive drum when the photosensitive drum is stopped. FIG. 6B is a diagram when the photosensitive drum is rotating at a predetermined speed. 6 (c) (a diagram when the photosensitive drum is rotating). FIG. 6 (b) is an explanatory diagram for making the effects of the present embodiment easier to understand, and FIG. 6 (c) is a diagram showing the effects of the present embodiment.

In FIG. 6 (b), since the light emission point image is formed on the photosensitive drum so as to correspond to each chip, the light emission point image V ₁ corresponding to T ₁ ′ parallel to the line U ₁ −U ₁ ′. With respect to the line W ₁ -W ₁ 'passing through', a light emitting point image is formed at an angle θ ₁ 'by a line V ₁ -V ₁ ' connecting a light emitting point image corresponding to each light emitting center point for each chip. Imaged on top. Therefore, in the light emitting point image 80m ₂ d on the photosensitive drum by the light emitting element array chip 80m ₂ configured in this way, the light emitting points I _J1 ′ and I _J2 ′ at the end of each chip are predetermined in the sub-scanning direction. Are shifted by a distance corresponding to the angle θ ₁ ′.

The light emission point image as shown in FIG. 6B is a case where the rotation of the photosensitive drum is stopped. As shown in FIG. 6 (c), in order to arrange the emission point images on the line W ₁ −W ₁ ′ on a substantially straight line, the arrangement relationship between the emission point and the microlens arranged on the emission point is self- It is defined as an angle θ ₁ ′ for canceling out the difference in lighting time due to scanning light emission and the angle caused by the rotation of the photosensitive drum. Therefore, as shown in FIG. 6 (c), the light emission point images 80m ₂ d ′ on the photosensitive drum irradiated to the optical printer or the like are the light emission points I _J1 ′ ′ and I _J2 ′ ′ at the end of each chip. In the time-division driving using the self-scanning light emitting element array, the light is irradiated substantially in a straight line.

  That is, by configuring a self-scanning light emitting element array as shown in Example 4, the light emission on the photosensitive drum that is substantially in a straight line with the resolution that meets the design requirements of an optical printer or the like when time-division driving is performed. A point image can be obtained. Accordingly, it is possible to solve the problem that a sawtooth is formed in units of chips in the paper feed direction.

(Example 5)
Next, a fifth application example of the present invention will be described. As described with reference to FIG. 18, in the conventional technology as the second configuration example, the light emitting element array has the light emitting element array chips 81 arranged in a staggered pattern alternately in opposite directions, and each light emitting element array chip end portion. The light emission points I _H1 and I _H2 are not aligned with each other in the light emission point image 81d, but the light emission point images I _H1 ′ and I _H2 ′ are irradiated in a shifted manner. For this reason, there has been a problem that a triangular wave is formed in units of chips in the paper feed direction. In Example 5, a light emitting element array chip will be described in which the arrangement of light emitting points and spherical lenses on the light emitting element array chip is adjusted in order to eliminate the influence of the rotation of the photosensitive drum.

FIG. 7 is a diagram showing a configuration example of a self-scanning light-emitting element array to which the present invention is applied with respect to a second configuration example when the light emission direction is two directions (shown in FIG. 18). FIG. 7 (a) (surface diagram of the light emitting element array chip) shows that the light emitting element array chip 81m ₂ connects the center of gravity of each lens with respect to a line U ₂ −U ₂ ′ connecting each light emitting point circumscribed circle center for each chip. A spherical lens array is formed at an angle θ ₂ by the line T ₂ −T ₂ ′. The light emitting element array chip 81m ₂ is described as a combination of six light emitting points and microlenses in the main scanning direction for convenience, and the interval between the light emitting points 84 is arranged at p. Therefore, in the light emitting element array chip 81m ₂ configured as described above, the light emitting points I _N1 and I _N2 at the ends of the chips are configured with a predetermined distance q in the sub-scanning direction. Here, T ₂ ′ is a light emission center point determined from the light emission point circumscribed circle center Op and the spherical lens center of gravity Omp.

  FIG. 7 shows a light emission point image on the photosensitive drum when the photosensitive drum is stopped. FIG. 7B is a diagram when the photosensitive drum is rotating at a predetermined speed. 7 (c) (a diagram when the photosensitive drum is rotating). FIG. 7 (b) is an explanatory diagram for making the effects of the present embodiment easier to understand, and FIG. 7 (c) is a diagram showing the effects of the present embodiment.

In FIG. 7 (b), since the light emission point image is formed on the photosensitive drum so as to correspond to one chip in the staggered arrangement, the light emission point image corresponding to T2 ′ is parallel to the line U ₂ −U ₂ ′. With respect to the line W ₂ −W ₂ ′ passing through V ₂ ′, a light emission point image at an angle θ ₂ ′ is obtained by a line V ₂ −V ₂ ′ connecting the light emission point images corresponding to the respective light emission center points for each chip. An image is formed on the photosensitive drum. Since the light emitting point image is formed on the photosensitive drum to correspond to the other chip staggered, 'parallel to, emission points Y _2' line W ₂ -W ₂ line X ₂ -X ₂ through ' On the other hand, a light emission point image is formed on the photosensitive drum at an angle θ ₂ ′ by a line Y ₂ -Y ₂ ′ connecting the light emission point images corresponding to the light emission center points for each chip. Accordingly, the emission points 81Md ₂ on the photosensitive drum by the light emitting element array chip 81m ₂ configured as above, the light emitting point I _N1 'and I _N2' in the tip end is in the sub-scanning direction, a predetermined They are offset by a distance corresponding to the angle θ ₂ ′.

The light emission point image as shown in FIG. 7B is a case where the rotation of the photosensitive drum is stopped. As shown in FIG. 7 (c), substantially on a straight line to line W ₂ -W ₂ 'or line X-X', in a staggered arrangement interval q, in order to arrange the emission points, the emission point and its emission point The arrangement relationship with the microlens arranged in is defined as an angle θ ₁ ′ for canceling the lighting time difference due to self-scanning light emission and the angle caused by the rotation of the photosensitive drum. Therefore, as shown in FIG. 7 (c), the light emission point images 81m ₂ d ′ on the photosensitive drum irradiated to the optical printer or the like are the light emission points I _N1 ′ ′ and I _N2 ′ ′ at the end of each chip. In the time-division driving using the self-scanning light emitting element array, the light is irradiated substantially in a straight line.

  That is, by configuring a self-scanning light emitting element array as shown in Example 4, a light emitting point image that is substantially in a straight line is obtained with a resolution that meets the design requirements of an optical printer or the like when time-division driving is performed. be able to. Accordingly, it is possible to solve the problem that a sawtooth is formed in units of chips in the paper feed direction. In the case of Example 5, among the two rows of chips shown in FIG. 7 (a), for the upper row and for the lower row, chips having the same configuration are arranged in opposite directions, so the direction of shifting the spherical lens is reversed. become. Therefore, the lighting direction of the light emitting point is a direction for correcting the inclination of each chip as shown in FIG.

In the fourth and fifth embodiments, the spherical lens 30m has been described. Needless to say, this can also be realized by using the compound lens 30. The angle theta ₁ and theta ₂ to the corresponding theta ₁ 'and theta _2', the light emitting element array chip length, the resolution of such optical printer, or the paper feeding speed of such light-emitting rate and optical printer, other at the lighting rate or the like Needless to say, the angle is fixed.

  In Examples 1 to 5, a method for individually solving a plurality of problems has been described as a representative example, but many modifications and substitutions can be made by those skilled in the art within the spirit and scope of the present invention. it is obvious. For example, in order to solve the above-described plurality of problems, each microlens or each light emitting point is individually or continuously in the main scanning direction and / or the sub-scanning direction, in accordance with the requirements related to the design of the optical printer or the like. It can be adjusted accordingly. Accordingly, the invention should not be construed as limited by the embodiments described above, but only by the claims.

  According to the present invention, each light-emitting point and each microlens in the light-emitting element array chip can be adjusted individually or continuously in the main scanning direction and the sub-scanning direction according to the requirements related to the design of the optical printer or the like. Therefore, it is possible to provide a light emitting element array chip and an optical writing head of higher quality, which are useful for an optical printer, a facsimile machine, and a copying machine using the optical writing head.

(a) is a diagram showing a configuration example that is an embodiment according to the present invention for the light-emitting element array chip of the first configuration, (b) is an imaging surface (photosensitive drum surface) when the photosensitive drum is stopped It is the figure which showed typically the light emission point image formed on the top. The cross-sectional structure of the light emitting point at the right end of the left chip is shown for the light emitting element array chip having the first configuration. (a) is a diagram showing a configuration example according to an embodiment of the present invention for a staggered chip that is a second configuration example, (b) is an imaging surface (photosensitive drum surface when the photosensitive drum is stopped) It is the figure which showed typically the light emission point image formed on the top. (a) is a diagram for explaining a staggered array chip, which is a second configuration example using a compound lens, and (b) is formed on the imaging surface (photosensitive drum surface) when the photosensitive drum is stopped. It is the figure which showed the emitted light spot image typically. It is a figure explaining the example of a structure of the light emission point of an Example by this invention, and a compound lens. (a) is a surface view of a light emitting element array chip as a first configuration example, (b) is a light emission point image diagram on the photosensitive drum when the photosensitive drum is stopped, and (c) is a photosensitive drum. It is a light emission point image figure when is rotating at a predetermined speed. (a) is a surface view of a light emitting element array chip as a second configuration example, (b) is a light emission point image diagram on the photosensitive drum when the photosensitive drum is stopped, and (c) is a photosensitive drum. It is a light emission point image figure when is rotating at a predetermined speed. (a) is a schematic diagram explaining the center position of a circle circumscribing the shape of each light emitting point. (b) is a schematic diagram explaining the gravity center position of the microlens on each light emitting point. (a) is a schematic diagram of an optical system according to an optical writing head based on the prior art, and (b) is a schematic diagram of an optical system according to an optical writing head showing an embodiment based on the present invention. . (a) is a diagram showing a configuration example of a light emitting element array in which light emitting points are arranged on a substantially straight line in the case of a conventional microlens, and (b) is an imaging surface (photosensitive surface when a photosensitive drum is stopped). FIG. 3 is a diagram schematically showing a light emission point image formed on a drum surface. It is the figure which looked at the light emission point and spherical lens from the upper part in the case of the conventional microlens. (a) is a diagram showing a configuration example of a light emitting element array in which each light emitting element array chip is arranged in a staggered manner in the case of a compound lens of the prior art, (b) is an image formation when the photosensitive drum is stopped FIG. 3 is a diagram schematically showing a light emission point image formed on a surface (photosensitive drum surface). It is the figure which looked at the light emission point and compound lens from the upper part in the case of the compound lens of a prior art. (a) is a figure which shows the structural example of the light emitting element array arranged in zigzag form in the case of the microlens (spherical lens) of a prior art, (b) is an imaging surface at the time of a photosensitive drum stop ( FIG. 3 is a diagram schematically showing a light emission point image formed on a photosensitive drum surface. FIG. 3 is a diagram showing a configuration of a light emitting element array of a type in which a plurality of light emitting element array chips are arranged in a substantially straight line as a first configuration example. FIG. 6 is a diagram showing a configuration of a light emitting element array of a type in which a plurality of light emitting element array chips are arranged in a staggered manner as a second configuration example. It is a figure showing the relationship regarding the irradiation position on the photosensitive drum of a paper feed direction when the transfer direction of lighting timing is one direction. It is a figure showing the relationship about the irradiation position on the photosensitive drum of a paper feed direction in case the transfer direction of lighting timing is reversed reversely. It is a top view when a microlens is arrange | positioned to a light emitting element array chip. It is a figure which shows a mode that the compound lens is connected and arranged on the light emitting element with respect to the light emitting element array chip. It is a side view which shows a mode that the compound lens is connected and arranged on the light emitting element with respect to the light emitting element array chip. (a) is explanatory drawing of a linear arrangement | sequence, (b) is explanatory drawing of a staggered arrangement | sequence. (a) is explanatory drawing of dicing, (b) is explanatory drawing of the arrangement | sequence state of a light emitting element array chip. It is a typical structural diagram of an optical writing head. It is a principle diagram of an optical printer provided with an optical writing head. It is a principle diagram of a facsimile and a printer provided with an optical writing head.

Explanation of symbols

30 Compound lens
30m spherical lens
80 Linear array of light emitting device array chips
81 Staggered light emitting element array chip
74 Rod lens array
100 optical writing head
102 Photosensitive drum
Lens center of gravity of Osp compound lens
Lens center of gravity of Omp spherical lens
Op circumscribed circle center of luminous point

Claims (11)

A plurality of light emitting elements having a light emitting point array comprising a plurality of light emitting points arranged in a straight line, provided in an optical writing head having an optical system for forming a light emitting point image on a photosensitive drum provided in a predetermined apparatus. An array chip,
A microlens disposed on each light emitting point, and the light emitting point image corresponding to the light emitting point is imaged through the optical system;
For each combination composed of the light emitting point and the microlens arranged on the light emitting point, the light emitting point and the microlens arranged on the light emitting point have an arrangement relationship,
A microlens in which the arrangement relationship for each combination is arranged on the circumscribed circle center of the light emitting point and on the light emitting point so that all of the light emitting point images corresponding to the light emitting point are substantially equidistant in the main scanning direction. A light emitting element array chip that is defined based on the center of gravity of the lens and is configured such that the arrangement relationship of at least one of the combinations does not match in the main scanning direction or the sub-scanning direction.   2. The light emitting element array chip according to claim 1, wherein the combinations that are inconsistent with respect to the arrangement relationship are all the combinations provided in the light emitting element array chip, and are configured to be inconsistent only in the main scanning direction.   2. The combination that is inconsistent with respect to the arrangement relationship is only the combination closest to the end portion in the main scanning direction provided in the light emitting element array chip, and is configured to be inconsistent only in the main scanning direction. Light emitting element array chip.   2. The light emitting element array chip according to claim 1, wherein the combinations that are inconsistent with respect to the arrangement relationship are all the combinations provided in the light emitting element array chip, and are configured to be inconsistent only in the sub-scanning direction. The light emitting element array chip is a light emitting element array chip constituting a self-scanning light emitting element array,
For each light emitting element array chip, a line connecting the positions of the center of gravity of all the microlenses and a line connecting the positions of the circumscribed circle centers of all the light emitting points are defined at a predetermined non-parallel angle. 2. The light emitting element array chip according to claim 1.   6. The light emitting element array chip according to claim 5, wherein the predetermined angle is determined based on a resolution of the predetermined apparatus using the self-scanning light emitting element array of a time division driving method.   The light emitting element array chip according to claim 1, wherein the microlens is a spherical lens or a compound lens.   An optical writing head comprising the light emitting element array chip according to claim 1.   9. An optical printer comprising the optical writing head according to claim 8.   A facsimile comprising the optical writing head according to claim 8.   A copying machine comprising the optical writing head according to claim 8.

Images