JP4895242B2 - Optical scanning apparatus and image forming apparatus - Google Patents

Description

  The present invention relates to an optical scanning apparatus and an image forming apparatus, and more particularly to an optical scanning apparatus that scans a surface to be scanned with a light beam and an image forming apparatus that forms an image on a recording medium based on image information.

  Conventionally, as an image forming apparatus that forms a multicolor image using the Carlson process, for example, a latent image corresponding to a black, yellow, magenta, and cyan component image is formed on the surface of four photosensitive drums by an optical scanning device. Image forming apparatus for forming a multicolor image by forming toner images obtained by visualizing these latent images with corresponding color toners and fixing them on a sheet as a recording medium. It has been known.

  In recent years, this type of image forming apparatus is often used for simple printing as an on-demand printing system, and demands for improving productivity and improving image quality are increasing. One means for improving productivity is to increase the printing speed by increasing the rotational speed R (rpm) of the polygon mirror for deflecting the light beam and the speed V (m / s) of the transfer body. It is done.

In general, the relationship between the speed V of the transfer body and the rotation speed R of the polygon mirror can be expressed as follows.
m ≧ (60 / R · N) × (D / 25.4) × V
Here, m represents the number of light beams, N represents the number of deflection surfaces of the polygon mirror, and D represents the recording density (dpi).

  However, if the number of revolutions of the polygon mirror is increased, the amount of heat generated from the drive system also increases, and changes in the scanning position over time due to distortions in the housing, etc., such as resist misalignment and scan line tilt, etc. And color misregistration occurs.

  For this reason, in order to increase the number of light beams and decrease the rotational speed of the polygon mirror within the range satisfying the above formula, a surface emitting semiconductor laser array in which a plurality of light emitting sources emitting light beams are arranged is often used. Has come to be. In such a multi-beam type optical scanning device using a laser array having a plurality of light emitting sources, if the light amounts of the respective light emitting sources are not accurately matched, density unevenness will occur in the printed image, especially in many cases. In a color image, the color changes and becomes a factor that degrades the image quality.

  Therefore, when a surface emitting semiconductor laser array is used as a light source, as disclosed in Patent Document 1 and Patent Document 2, a light beam from the light source is branched, and the branched light beam is used as a light detection sensor. An image forming apparatus capable of avoiding deterioration in image quality by aligning the output of the light beam from each light emitting source while monitoring the image quality via the monitor is proposed.

  However, when a branching optical system and a light detection sensor are newly provided, the number of parts increases, the time required for the adjustment increases, and there is a problem that the production cost increases.

  The present invention has been made under such circumstances, and a first object thereof is to provide an optical scanning device capable of reducing the number of parts of the device and reducing the production cost while maintaining scanning accuracy. It is to provide.

  A second object of the present invention is to provide an image forming apparatus capable of reducing the number of parts of the apparatus and reducing the production cost while maintaining the quality of image quality.

The invention according to claim 1 is an optical scanning device that scans a surface to be scanned with a light beam, and includes a plurality of light emitting sources that are two-dimensionally arranged at equal intervals, and the row direction of the plurality of light emitting sources is A light source that forms a predetermined angle with respect to a main scanning direction, a deflecting unit that collectively deflects a plurality of light beams respectively emitted from the plurality of light emitting sources, and the plurality of deflected light beams to be scanned An image forming optical system that forms an image on a surface, a light guide unit that guides at least a part of each of the plurality of light beams in a predetermined direction without passing through the deflecting unit, and a substrate that is shared with the light source. Receiving the plurality of guided light beams, and directly receiving the deflected plurality of light beams without passing through the imaging optical system, and receiving a signal based on the received light beams. An output light detection system ;
After the light emitting sources are sequentially driven and the deflecting unit starts deflecting, the light beam guided by the light detection system is received until the light detection system receives the light beam deflected by the deflecting unit. The light amount of each of the plurality of light emitting sources is set based on the output signal of the light detection system that has received the light, and the driving of the light emitting source for which the setting has been made last is maintained. A control device for determining a write timing by each of the plurality of light emitting sources based on a signal output from the light detection system when the light detection system receives the emitted light beam deflected by the deflecting unit. This is an optical scanning device.

  According to this, at least a part of the light beam emitted from each light source of the light source is guided in a predetermined direction by the light guide unit, and the rest is deflected through the deflection unit. The guided light beam and the deflected light beam are received by a common light detection system.

  Therefore, the light detection system for monitoring the light quantity of the light beam and the light detection system for detecting the deflected light beam and generating the synchronization signal can be shared. For this reason, the number of parts of the apparatus can be reduced while maintaining the scanning accuracy, and as a result, the production cost can be reduced.

  2. The optical scanning device according to claim 1, wherein the imaging optical system is an optical in which a diffractive surface for diffracting the light beam deflected by the deflecting unit is formed, as in the optical scanning device according to claim 2. The diffractive surface includes an element, and has a power in a direction that corrects a focus movement related to a deflection direction of the plurality of light beams, which depends on a wavelength difference between the plurality of light beams. it can.

  3. The optical scanning device according to claim 1, wherein the light guiding unit branches the plurality of light beams in a direction toward the deflecting unit and in the predetermined direction, as in the optical scanning device according to claim 3. It can be a means to do.

  The optical scanning device according to any one of claims 1 to 3, wherein the plurality of light emitting sources are aligned in a polarization direction, and the light guiding means is the plurality of light guiding units, as in the optical scanning device according to claim 4. Any one of the S-polarized component and the P-polarized component of each of the light beams can be guided.

  According to a fifth aspect of the present invention, there is provided an image forming apparatus for forming an image by fixing a toner image formed based on a latent image obtained from image information on a recording medium. An image forming apparatus comprising: the optical scanning device according to claim 1; and a photosensitive member having a scanned surface on which a latent image is formed by the optical scanning device.

  According to this, since the image forming apparatus includes the optical scanning device according to any one of claims 1 to 4, it is possible to reduce the number of parts while maintaining the quality of the image quality. Production costs can be reduced.

  The invention according to claim 6 is an image that forms a multicolor image by superimposing and fixing a toner image formed on the basis of a latent image for each color obtained from information about the multicolor image on a recording medium. A forming apparatus comprising: the optical scanning device according to any one of claims 1 to 4; and a plurality of photoconductors on which latent images corresponding to respective colors are formed by the optical scanning device, A plurality of light emitting sources respectively correspond to the plurality of photoconductors, and an imaging optical system of the optical scanning device forms an image of the light beam from the plurality of light emitting sources on the corresponding scanned surface of the photoconductor. An image forming apparatus characterized by the above.

  According to this, since the image forming apparatus includes the optical scanning device according to any one of claims 1 to 4, it is possible to reduce the number of parts while maintaining the quality of the image quality. Production costs can be reduced.

1 is a diagram illustrating a printer 10 according to an embodiment of the present invention. FIG. 2 is a perspective view showing an optical scanning device 100 of the printer 10 in FIG. 1. FIG. 3 is a diagram (No. 1) for describing a displacement detection method by the displacement detection device 45 in FIG. 1. FIGS. 4A, 4B, and 4C are diagrams (No. 2, No. 3, and No. 4) for explaining a positional deviation detection method by the positional deviation detection device 45 in FIG. . FIG. 2 is a side view showing an optical scanning device 100 of the printer 10 in FIG. 1. It is a perspective view which shows the mode of the vicinity of the light source unit 130 in FIG. It is a top view which shows the laser array 131 in FIG. It is a figure for demonstrating the diffraction surface of toroidal lens 107A. 9A and 9B are diagrams showing an optical layout of the optical scanning apparatus 100. FIG. 2 is a block diagram of a control circuit 200 of the optical scanning device 100. FIG. 11A and 11B are diagrams for explaining a method of generating a pixel clock signal. It is a figure for demonstrating the function of the binarization circuit 215 in FIG. It is a block diagram of the light source drive circuit 213 in FIG. It is a timing chart of the 1st light emission mode and the 2nd light emission mode. FIG. 10 is a diagram for explaining a modification of the arrangement of the light receiving elements 142.

  Hereinafter, an embodiment of the present invention will be described with reference to FIGS. FIG. 1 shows a schematic configuration of a printer 10 as an image forming apparatus according to an embodiment.

  The printer 10 is a tandem type color printer that prints a multicolor image by superimposing and transferring black, yellow, magenta, and cyan toner images on plain paper (paper) using the Carlson process. is there. As shown in FIG. 1, the printer 10 includes an optical scanning device 100, four photosensitive drums 30A, 30B, 30C, and 30D, a transfer belt 40, a misregistration detection device 45, a paper feed tray 60, and a paper feed roller 54. , A first registration roller pair 56, a second registration roller pair 52, a fixing roller 50, a paper discharge roller 58, and a substantially rectangular parallelepiped housing 12 for housing the above components.

  The housing 12 is formed with a paper discharge tray 12a on which the printed paper is discharged on the upper surface, and the optical scanning device 100 is disposed below the paper discharge tray 12a.

  The optical scanning device 100 scans the photosensitive drum 30A with a light beam of a black image component modulated based on image information supplied from a host device (such as a personal computer), and cyan for the photosensitive drum 30B. The light beam of the image component is scanned, the light beam of the magenta image component is scanned on the photosensitive drum 30C, and the light beam of the yellow image component is scanned on the photosensitive drum 30D. The configuration of the optical scanning device 100 will be described later.

  The four photosensitive drums 30A, 30B, 30C, and 30D are cylindrical members each having a photosensitive layer having a property that becomes conductive when irradiated with a light beam. Below the scanning device 100 are arranged at equal intervals along the X-axis direction.

  The photosensitive drum 30A is disposed at the −X side end inside the housing 12 with the Y-axis direction as the longitudinal direction, and is rotated clockwise in FIG. 1 (the direction indicated by the arrow in FIG. 1) by a rotation mechanism (not shown). It is like that. In the vicinity thereof, a charging charger 32A is arranged at the 12 o'clock (upper) position in FIG. 1, a toner cartridge 33A is arranged at the 2 o'clock position, and a cleaning case 31A is arranged at the 10 o'clock position. .

  The charging charger 32A is arranged with a predetermined clearance with respect to the surface of the photosensitive drum 30A with the longitudinal direction as the Y-axis direction, and charges the surface of the photosensitive drum 30A with a predetermined voltage.

  The toner cartridge 33A includes a cartridge body filled with toner of a black image component, a developing roller charged with a voltage having a polarity opposite to that of the photosensitive drum 32A, and the toner filled in the cartridge body is passed through the developing roller. The toner is supplied to the surface of the photosensitive drum 30A.

  The cleaning case 31A includes a rectangular cleaning blade whose longitudinal direction is the Y-axis direction, and is disposed so that one end of the cleaning blade is in contact with the surface of the photosensitive drum 30A. The toner adsorbed on the surface of the photosensitive drum 30A is peeled off by the cleaning blade as the photosensitive drum 30A rotates, and is collected in the cleaning case 31A.

  The photosensitive drum 30B is arranged at a predetermined interval on the + X side of the photosensitive drum 30A, and is rotated clockwise (in the direction indicated by the arrow) in FIG. 1 by a rotating mechanism (not shown). A charging charger 32B, a toner cartridge 33B, and a cleaning case 31B are arranged around the photosensitive drum 30A in the same positional relationship as the above-described photosensitive drum 30A.

  The charging charger 32B is configured in the same manner as the above-described charging charger 32A, and charges the surface of the photosensitive drum 30B with a predetermined voltage.

  The toner cartridge 33B includes a cartridge main body filled with toner of cyan image component, a developing roller charged with a voltage having a polarity opposite to that of the photosensitive drum 32B, and the toner filled in the cartridge main body is passed through the developing roller. The toner is supplied to the surface of the photosensitive drum 30B.

  The cleaning case 31B is configured similarly to the cleaning case 31A and functions in the same manner.

  The photosensitive drum 30C is arranged at a predetermined interval on the + X side of the photosensitive drum 30B, and is rotated clockwise (in the direction indicated by the arrow) in FIG. 1 via a rotation mechanism (not shown). Around the periphery, a charging charger 32C, a toner cartridge 33C, and a cleaning case 31C are arranged in the same positional relationship as the photosensitive drum 30A.

  The charging charger 32C is configured similarly to the above-described charging charger 32A, and charges the surface of the photosensitive drum 30C with a predetermined voltage.

  The toner cartridge 33C includes a cartridge main body filled with magenta image component toner, a developing roller charged with a voltage having a polarity opposite to that of the photosensitive drum 32C, and the toner filled in the cartridge main body passes through the developing roller. The toner is supplied to the surface of the photosensitive drum 30C.

  The cleaning case 31C is configured similarly to the cleaning case 31A and functions in the same manner.

  The photosensitive drum 30D is arranged at a predetermined interval on the + X side of the photosensitive drum 30C, and is rotated clockwise (in the direction indicated by the arrow) in FIG. 1 by a rotating mechanism (not shown). Around the periphery, a charging charger 32D, a toner cartridge 33D, and a cleaning case 31D are arranged in the same positional relationship as the above-described photosensitive drum 30A.

  The charging charger 32D is configured in the same manner as the charging charger 32A described above, and charges the surface of the photosensitive drum 30D with a predetermined voltage.

  The toner cartridge 33D includes a cartridge body filled with yellow image component toner, a developing roller charged by a voltage having a polarity opposite to that of the photosensitive drum 32D, and the toner filled in the cartridge body is passed through the developing roller. The toner is supplied to the surface of the photosensitive drum 30D.

  The cleaning case 31D is configured similarly to the cleaning case 31A and functions in the same manner.

  Hereinafter, the photosensitive drum 30A, the charging charger 32A, the toner cartridge 33A, and the cleaning case 31A are collectively referred to as a first station, and the photosensitive drum 30B, the charging charger 32B, the toner cartridge 33B, and the cleaning case 31B are collectively referred to as a second station, The photosensitive drum 30C, the charging charger 32C, the toner cartridge 33C, and the cleaning case 31C are collectively referred to as a third station, and the photosensitive drum 30D, the charging charger 32D, the toner cartridge 33D, and the cleaning case 31D are collectively referred to as a fourth station. .

  The transfer belt 40 is an endless annular member, a driven roller 40a disposed below the photosensitive drum 30A, a driven roller 40c disposed below the photosensitive drum 30D, and a position slightly lower than these driven rollers 40a and 40c. The upper end surface is wound around the driving roller 40b disposed in the contact roller 40b so as to be in contact with the lower end surfaces of the photosensitive drums 30A, 30B, 30C, and 30D. The drive roller 40b rotates counterclockwise (in the direction indicated by the arrow in FIG. 1) by rotating counterclockwise in FIG. A transfer charger 48 to which a voltage having a polarity opposite to that of the above-described charging chargers 32A, 32B, 32C, and 32D is applied is disposed near the + X side end of the transfer belt 40.

  The misregistration detection device 45 is disposed on the −X side of the transfer belt 40 and receives the LED 42a that illuminates the −Y side end of the transfer belt 40 and its reflected light, as can be understood from FIGS. 1 and 2. A photo sensor 41a, an LED 42b that illuminates the central portion of the transfer belt 40, a photo sensor 41b that receives the reflected light, an LED 42c that illuminates the −Y side end of the transfer belt 40, and a photo sensor 41c that receives the reflected light. ing.

  Then, as shown in FIG. 2, the toner image detection patterns 43A, 43B, and 43C formed on the transfer belt 40 along the Y-axis direction are illuminated by the LEDs 42a, 42b, and 42c, respectively. Based on the time difference of detection signals obtained by receiving light by the photosensors 41a, 41b, and 41c, respectively, the resist and magnification in the Y-axis direction and the resist and inclination in the X-axis direction are measured at the first station as described later. It is detected as a relative displacement based on the pattern of the formed toner image. The relative positional deviation from the first station is detected when the toner image formed at each station is overlapped with the toner image formed at the other station. This is to control the optical scanning device 100 described later so as to overlap.

Hereinafter, a method for detecting the resist and magnification in the Y-axis direction and the resist and inclination in the X-axis direction will be briefly described with reference to FIG. FIG. 3 is a plan view of the transfer belt. In FIG. 3, t _y , t ₁ , t ₂ , t _{3, and the} like are detection time differences when line patterns to be described later are detected by the photosensors 41a, 41b, and 41c. .

  Each of the detection patterns 43A, 43B, and 43C has an angle of 45 degrees with the four line patterns Y, M, C, and K parallel to the Y axis and the Y axis, as representatively shown for the detection pattern 43C. It is composed of four line patterns Y ′, M ′, C ′, and K ′. The line patterns Y and Y ′ were transferred at the fourth station, the line patterns M and M ′ were transferred at the third station, and the line patterns C and C ′ were transferred at the second station. The line patterns K and K ′ are transferred at the first station.

  When each of the detection patterns 43A, 43B, and 43C is formed on the transfer belt 40, the detection patterns 43A, 43B, and 43C move in the −X direction as the transfer belt 40 is driven. The LEDs 42a, 42b, and 42c are illuminated, and the reflected light is received by the photosensors 41a, 41b, and 41c, respectively.

Here, as shown in FIG. 3, assuming that the detection pattern 43A and the detection pattern 43C are misaligned in the X-axis direction, for example, the time when the line pattern Y of the detection pattern 43A is detected, and the detection pattern in the time of detecting the line pattern Y of 43C there is a difference in time t _y. Therefore, the inclination of the toner image formed at the fourth station can be detected based on the time _ty and the speed of the transfer belt. Similarly, if the same processing is performed for the other line patterns M, C, and K of the detection pattern 43A and the detection pattern 43C, the inclination of the toner image formed at the first to fourth stations can be detected. Information regarding the inclination of each pattern is supplied to the optical scanning device 100 described later, and correction is performed based on the pattern formed in the first station.

Further, by measuring the times t ₁ , t ₂ , and t ₃ from the time when the line pattern Y of the detection pattern 43B is detected to the time when the other line patterns M, C, and K are detected, the first station The positional deviation in the X-axis direction of the line patterns Y, M, and C with reference to the line pattern K can be detected. For example, when there is no displacement in the X-axis direction, t ₂ is twice t ₁ and t ₃ is three times t ₁ . However, since the above relationship does not hold when a positional deviation occurs, each of the line patterns Y, M, and C based on the line pattern K is determined from the relationship between the time t ₁ , t _2, and t _3. The positional deviation in the X-axis direction can be detected. Information on the positional deviation in the X-axis direction detected here is supplied to the optical scanning device 100 described later, and correction based on the information on the positional deviation is performed.

Further, in the detection pattern 43A, the time from the detection of the line pattern Y to the detection of the line pattern Y ′, the time from the detection of the line pattern M to the detection of the line pattern M ′, and the line The time from the detection of the pattern C to the detection of the line pattern C ′ and the time from the detection of the line pattern K to the detection of the line pattern K ′ are the line patterns Y, M, C, If K, Y ′, M ′, C ′, and K ′ are not displaced in the Y-axis direction, they are the same. However, as shown in FIG. 4A, when the line patterns Y and Y ′ are shifted in the −Y direction with respect to the line patterns K and K ′, the detection times related to the line patterns K and K ′. When t ₀ is compared with the detection time t ₁ related to the line patterns Y and Y ′, the time t ₁ becomes smaller than the time t ₀ . On the other hand, when the line patterns Y and Y ′ are shifted in the + Y direction, the time t ₁ becomes longer than the time t ₀ . Therefore, by comparing the time t ₀ and the time t ₁ , the relative Y-axis direction of the line patterns Y and Y ′ formed at the fourth station with respect to the line patterns K and K ′ formed at the first station is determined. Misalignment can be detected. Further, by performing the same processing for the line patterns M and M ′ and the line patterns C and C ′, the lines formed at the second station and the third station for the line patterns K and K ′ formed at the first station. The relative displacement in the Y-axis direction of the patterns M and M ′ and the line patterns C and C ′ can be detected.

  Similarly, for the detection patterns 43B and 43C, the line patterns M and M ′, the line patterns C and C ′, and the lines formed in the first to third stations respectively with respect to the line patterns K and K ′ formed in the first station. The relative displacement in the Y-axis direction of the patterns Y and Y ′ can be detected.

Further, as shown in FIG. 4B, the position of the photosensor 41a in the Y-axis direction is set as a reference position, and the detection according to the line patterns K and K ′ when the reference position and the position of the detection pattern 43A coincide with each other. If the time is t ₀ , for example, as shown in FIG. 4C, the detection time t ₀ ′ for the line patterns K and K ′ when the detection pattern 43A is shifted in the + Y direction is from t ₀ . Also grows. On the other hand, the detection time t ₀ ′ related to the line patterns K and K ′ when shifted in the −Y direction is smaller than t ₀ . Therefore, by comparing the detection times t ₀ and t ₁ , it is possible to detect an absolute displacement in the Y-axis direction of the detection pattern 43A. Further, by performing the same processing on the detection pattern 43C, it is possible to detect an absolute positional deviation of the detection pattern 43C in the Y-axis direction.

  Information on the positional deviation in the Y-axis direction described above is supplied to the optical scanning device 100 described later, and correction based on the line patterns K and K ′ is performed under the control of the optical scanning device 100.

  Note that the configuration of the misregistration detection device 45 is disclosed in Japanese Patent No. 3644923, and is well known, so the description thereof is omitted here.

  Returning to FIG. 1, the paper feed tray 60 is disposed below the transfer belt 40. The paper feed tray 60 is a substantially rectangular parallelepiped tray, and a plurality of sheets 61 to be printed are stacked and stored therein. A rectangular paper feed port is formed near the + X side end of the upper surface of the paper feed tray 60.

  The sheet feeding roller 54 takes out the sheets 61 one by one from the sheet feeding tray 60 and leads them to a gap formed by the transfer belt 40 and the transfer charger 48 through a registration roller pair 56 composed of a pair of rotating rollers. .

  The fixing roller 50 is composed of a pair of rotating rollers. The fixing roller 50 overheats and pressurizes the paper 61 and guides it to the paper discharge roller 58 via the registration roller pair 52.

  The paper discharge roller 58 includes a pair of rotating rollers, and sequentially stacks the derived paper 61 on the paper discharge tray 12a.

  Next, the configuration of the optical scanning device 100 will be described. 2 and 5, the optical scanning device 100 includes a polygon mirror 104, an fθ lens 105, a reflection mirror 106B and a reflection mirror 106A, which are sequentially arranged in the −X direction of the polygon mirror 104, and a reflection mirror. Toroidal lens 107A disposed below mirror 106A, toroidal lens 107B and reflecting mirror 109B sequentially disposed in the + X direction of toroidal lens 107A, reflecting mirror 109A disposed below toroidal lens 107A, and reflecting mirror 109A The reflection mirror 108A and the reflection mirror 108B are sequentially arranged in the + X direction of the lens, the fθ lens 305, the reflection mirror 306C and the reflection mirror 306D are sequentially arranged in the + X direction of the polygon mirror 104, and the reflection mirror 306D is disposed below the reflection mirror 306D. T A toroidal lens 307D, a toroidal lens 307C and a reflecting mirror 309C sequentially arranged in the −X direction of the toroidal lens 307D, a reflecting mirror 309D arranged below the toroidal lens 307D, and sequentially arranged in the + X direction of the reflecting mirror 309D. A pair of light source units 130, 330 and cylinder lenses 102, 302, which are provided with a reflection mirror 308D and a reflection mirror 308C, and are arranged so as to sandwich the polygon mirror 104 on a straight line forming a predetermined angle θ with the X axis. A condensing lens 110 disposed near the cylinder lens 102, a condensing lens 310 disposed near the cylinder lens 302, a half mirror 101, a reflecting mirror 111, and a condensing lens 112 disposed near the light source unit 130. And light receiving element 142 and light Disposed in the vicinity of the unit 330, a half mirror 301, a reflecting mirror 311, and a like condensing lens 312 and the light receiving element 142.

  Here, a coordinate system determined by rotating the XY coordinates around the Z axis by an angle θ is referred to as an xy coordinate system, and hereinafter this coordinate system is used as appropriate.

  FIG. 6 shows a state near the light source unit 130. As shown in FIG. 6, the light source unit 130 is mounted in the vicinity of the + x side end of the −y side surface of the rectangular plate-like substrate 140 whose longitudinal direction is the x-axis direction, and is a rectangular parallelepiped casing 130 b, A laser array 131 and a coupling lens 130a are provided.

  The casing 130b has a rectangular parallelepiped shape, and a circular opening is formed on the surface on the -y side, and the coupling lens 130a is fitted into the opening without a gap.

  The laser array 131 is a surface-emitting type semiconductor laser array in which light sources are two-dimensionally arranged, and the y axis is centered on the inner wall surface on the + y side inside the casing 130b so that the optical axis coincides with the coupling lens 130a. It is fixed in a state where it is rotated by an inclination angle α (clockwise as viewed from the front). As shown in FIG. 7, the laser array 131 has 32 light emitting sources arranged in a matrix of 8 rows and 4 columns with d1 between rows and columns on the surface at the -y side. And the polarization direction of each light emission source is arrange | positioned in the direction (row direction) of the arrow in FIG. 7 as an example. In the present embodiment, a multi-beam light source that drives the light emission sources arranged in the first and second rows, and the seventh and eighth rows indicated by black circles among the 32 light emission sources is realized. The others are dummy light sources.

Here, the inclination angle α is expressed by the following equation (1), where Ms is the magnification in the sub-scanning direction of the optical system described later.
α = sin ⁻¹ (2 · d1 · Ms) (1)
The laser array 131 is fixed at the inclination angle α determined by the above equation (1), thereby allowing eight light sources in the first and second rows and eight light sources in the seventh and eighth rows. The sources are arranged with the pitch in the sub-scanning direction as d2, respectively, and the pitch of the light beam spot in the sub-scanning direction of the photosensitive drums 30A and 30B matches the scanning line pitch corresponding to the recording density.

The eight light emitting sources arranged in the first and second rows are called the first light emitting source group G1, and the eight light emitting sources arranged in the seventh and eighth rows are called the second light emitting source group G2. The light emission sources constituting the first light emission source group G1 are called the light emission source G1 ₁₁ , the light emission source G1 ₁₂ , the light emission source G1 ₁₃ , and the light emission source G1 _{14 in} order from the first column of the first row. The light emission sources G1 ₂₁ , G1 ₂₂ , G1 ₂₃ , and G1 ₂₄ are called light emission sources in order from the first column, and the light emission sources constituting the second light emission source group G2 emit light in order from the first column of the seventh row. The light source G2 ₁₁ , the light source G2 ₁₂ , the light source G2 ₁₃ , and the light source G2 ₁₄ are called the light source G2 ₂₁ , the light source G2 ₂₂ , the light source G2 ₂₃ , and the light source G2 _{24 in} order from the first column of the eighth row. Shall be called.

  Instead of fixing the laser array 131 at the inclination α as described above, the row direction of the light emission source forms an angle α with respect to the main scanning direction and the column direction is the secondary direction at the stage of the processing process of the laser array 131. Each light source may be formed so as to coincide with the scanning direction.

  Returning to FIG. 6, the light receiving element 142 is mounted in the vicinity of the −x side end of the −y side surface of the substrate 140 and outputs, for example, a voltage signal corresponding to the intensity of the received light beam.

  The half mirror 101 is disposed on the −y side of the light source unit 130, transmits a light beam emitted from the laser array 131 via the coupling lens 130 a, and branches a part thereof in the −x direction. As described above, since the laser array has the tilt angle α, the light beam has a P-polarized component and an S-polarized component with respect to the half mirror 101. Here, it is assumed that the half mirror 101 branches the P-polarized component of the light beam in the −x direction.

  The condensing lens 112 condenses the light beam branched by the half mirror 101 onto the light receiving element 142 via the reflection mirror 111.

  2 and 5, the cylinder lens 102 is fixed to the housing 12 of the printer 10 via a support member (not shown), and condenses the light beam emitted from the light source unit 130 onto the deflection surface of the polygon mirror 104. .

  The condensing lens 110 condenses the light beam from the polygon mirror 104 onto the light receiving element 142.

  The light source unit 330 is mounted in the vicinity of the + x side end of the −y side surface of the rectangular plate-like substrate 140 whose longitudinal direction is the x-axis direction, and has the same configuration as the light source unit 130.

  The light receiving element 142 is mounted in the vicinity of the + x side end portion of the + y side surface of the substrate 140 and outputs a signal corresponding to the intensity of the received light beam.

  The half mirror 301 is disposed on the + y side of the light source unit 330, transmits the light beam emitted from the light source unit 330, and branches a part thereof in the + x direction. Here, it is assumed that the half mirror 301 branches the P-polarized component of the light beam in the −x direction.

  The condensing lens 312 condenses the light beam branched by the half mirror 301 onto the light receiving element 142 via the reflection mirror 311.

  The cylinder lens 302 is fixed to the housing 12 of the printer 10 via a support member (not shown), and condenses the light beam emitted from the light source unit 330 onto the deflection surface of the polygon mirror 104.

  The condensing lens 310 condenses the light beam from the polygon mirror 104 onto the light receiving element 142.

  The polygon mirror 104 is formed of a regular hexagonal columnar member having a low height, and six deflection surfaces are formed on the side surface. Then, it is rotated at a constant angular velocity in the direction of the arrow shown in FIG. 2 by a rotating mechanism (not shown) around an axis P parallel to the Z axis. Therefore, the light beam emitted from the light source unit 130 and the light source unit 330 and condensed on the deflection surface of the polygon mirror 104 is deflected along the Y axis at a constant angular velocity by the rotation of the polygon mirror 104.

  The fθ lenses 105 and 305 have an image height proportional to the incident angle of the light beam, and move the image surface of the light beam deflected at a constant angular velocity by the polygon mirror 104 at a constant speed with respect to the Y axis.

  The reflection mirrors 106A, 106B, 306C, and 306D are arranged with the longitudinal direction as the Y-axis direction. The light beams that pass through the fθ lenses 105 and 305 are folded back and guided to the toroidal lenses 107A, 107B, 307C, and 307D.

  The toroidal lens 107A has a longitudinal direction as a Y-axis direction, is stably supported by a support plate 110A whose both ends are fixed to the housing 12, and a light beam folded back by the reflecting mirror 106A is converted into a Y-axis direction as a longitudinal direction. The image is formed on the surface of the photosensitive drum 30A through the reflecting mirrors 108A and 109A. As shown in FIGS. 8A and 8B, the toroidal lens 107A has a Fresnel diffraction surface formed of a sawtooth diffraction grating on the surface on which the light beam is incident. This diffractive surface has a power (refractive power) that corrects the focus change in the main scanning direction due to the wavelength difference of the light beam emitted from each light source, and the ratio of the power due to refraction to the power due to diffraction. Is configured to be constant from the optical axis to the outside of the optical axis. In the present embodiment, since the power of the scanning optical system is positive, as the wavelength becomes longer, the refractive power becomes weaker and the focus moves away. Therefore, a diffraction power is set on the diffraction surface so as to be in the direction opposite to the focus movement.

  The toroidal lenses 107B, 307C, and 307D are configured in the same manner as the toroidal lens 107A. The longitudinal direction is the Y-axis direction, one end (+ Y side) is fixed to the housing 12, and the other end (−Y side) is rotated, for example. These are stably supported by support plates 110B, 310C, and 310D supported by drive mechanisms 112B, 312C, and 310D (not shown in FIG. 2, refer to FIG. 5) each having a motor and a feed screw mechanism. The light beams folded back by the reflection mirrors 106B, 306C, and 306D are respectively connected to the surfaces of the photosensitive drums 30B, 30C, and 30D via the reflection mirrors 108B, 308C, and 308D having the Y-axis direction as the longitudinal direction. Image.

  The optical path of the light beam of the optical scanning device 100 configured as described above can be shown in an optical layout diagram as shown in FIGS. 9A and 9B.

  Hereinafter, the operation of the scanning optical system of the optical scanning apparatus 100 and the Carlson process will be described with reference to FIGS. 9A and 9B. As shown in FIG. 9A, the plurality of light beams emitted from the light emitting source groups G1 and G2 of the light source unit 130 are temporarily intersected by the coupling lens 130a and enter the cylinder lens 102. The cylinder lens 102 condenses the light beams from the incident light source groups G 1 and G 2 in the vicinity of the deflection surface of the polygon mirror 104. The light beams deflected by the polygon mirror 104 enter the fθ lens 105 while increasing the interval between the light beams.

  The light beam from the light source group G1 that has entered the fθ lens 105 is reflected by the reflection mirror 106B and enters the toroidal lens 107B. Then, the light is condensed on the surface of the photosensitive drum 30B by the toroidal lens 107B via the reflection mirror 108B and the reflection mirror 109B.

  The light beam from the light source group G2 that has entered the fθ lens 105 is reflected by the reflecting mirror 106A and enters the toroidal lens 107A. Then, the light is condensed on the surface of the photosensitive drum 30A by the toroidal lens 107A via the reflection mirror 108A and the reflection mirror 109A.

  On the other hand, as shown in FIG. 9B, the plurality of light beams emitted from the light emitting source groups G <b> 1 and G <b> 2 of the light source unit 330 are temporarily intersected by the coupling lens 130 a and enter the cylinder lens 302. The cylinder lens 302 condenses incident light beams from the light source groups G 1 and G 2 in the vicinity of the deflection surface of the polygon mirror 104. The light beams deflected by the polygon mirror 104 enter the fθ lens 305 while widening the interval between the light beams.

  The light beam from the light source group G1 that has entered the fθ lens 305 is reflected by the reflection mirror 306C and enters the toroidal lens 307C. Then, the light is condensed on the surface of the photosensitive drum 30C by the toroidal lens 307C via the reflection mirror 308C and the reflection mirror 309C.

  The light beam from the light source group G2 that has entered the fθ lens 305 is reflected by the reflection mirror 306D and enters the toroidal lens 307D. Then, the light is condensed on the surface of the photosensitive drum 30D by the toroidal lens 307D via the reflection mirror 308D and the reflection mirror 309D.

  The condensing points of the light beams from the light source groups G1 and G2 of the light source unit 130 formed on the photosensitive drums 30A and 30B in this way are indicated by an arrow B in FIG. 2 as the polygon mirror 104 rotates. Are moved (scanned) in a lump direction. Further, the light beam condensing points from the light source groups G1 and G2 of the light source unit 330 formed on the photosensitive drums 30C and 30D are rotated in the direction indicated by the arrow C in FIG. Are collectively moved (scanned).

  Here, as shown in FIG. 7, since the laser array 131 of the light source unit 130 is fixed by rotating by an angle α around the y axis, the eight light emitting sources constituting the light emitting source groups G1 and G2 are respectively This is equivalent to arranging the adjacent intervals at equal intervals in the sub-scanning direction as d2 (d1 · sin α). Similarly, since the laser array 131 of the light source unit 330 is fixed by rotating by an angle −α around the y axis, the eight light emitting sources constituting the light emitting source groups G1 and G2 are spaced apart from each other by d2 ( d1 · sin α) is equivalent to being arranged at equal intervals in the sub-scanning direction. Therefore, the photosensitive drums 30A, 30B, 30C, and 30D are subjected to 8-line scanning by eight light sources in one scanning.

  On the other hand, the photosensitive layer on the surface of each of the photosensitive drums 30A, 30B, 30C, and 30D is charged with a predetermined voltage by the charging chargers 32A, 32B, 32C, and 32D, so that charges are distributed at a constant charge density. . As described above, when each of the photosensitive drums 30A, 30B, 30C, and 30D is scanned, the photosensitive layer where the light beam is condensed becomes conductive, and charge transfer occurs in that portion, and the potential is increased. Becomes zero. Therefore, by scanning the photosensitive drums 30A, 30B, 30C, and 30D rotating in the directions of the arrows in FIG. 1 with the light beams modulated based on the image information, the respective photosensitive drums 30A, 30B, and 30C are scanned. , 30D can form an electrostatic latent image defined by the charge distribution.

  When electrostatic latent images are formed on the surfaces of the photosensitive drums 30A, 30B, 30C, and 30D, the developing rollers of the toner cartridges 33A, 33B, 33C, and 33D shown in FIG. Toner is supplied to each surface of 30D. At this time, since the developing rollers of the toner cartridges 33A, 33B, 33C, and 33D are charged by voltages having a polarity opposite to that of the photosensitive drums 30A, 30B, 30C, and 30D, the toner adhering to the developing rollers is the photosensitive drums 30A, 30B, and 30D. It is charged with the same polarity as 30C and 30D. Therefore, the toner does not adhere to the portions of the surfaces of the photosensitive drums 30A, 30B, 30C, and 30D where the electric charges are distributed, and the toner adheres only to the scanned portions, whereby the photosensitive drums 30A, 30B, and 30C. , A toner image in which the electrostatic latent image is visualized is formed on the surface of 30D. The toner image is transferred to the transfer belt 40.

Next, the control circuit of the light source unit 130 and the light source unit 330 of the optical scanning device 100 configured as described above will be described by taking the control circuit 200 of the light source unit 130 as a representative. The control circuit 200 is formed on the base 140 of the light source unit 130. As shown in FIG. 10, the high-frequency clock generation circuit 201, the toroidal lens control circuit 202, the counter 203, the comparison circuit 204, the pixel clock generation circuit 205, the image processing A circuit 207, a frame memory 208, line buffers 210 _{1 to} 210 ₁₆ , a write control circuit 211, a binarization circuit 215, a light source driving circuit 213, and the like are included.

  The high frequency clock generation circuit 201 generates the clock signal VCLK based on the information regarding the positional deviation in the main scanning direction supplied from the positional deviation detection device 45. Specifically, the magnification obtained on the basis of the reference magnification and the information on the absolute displacement from the reference position of the line patterns K and K ′ of the detection patterns 43A and 43C detected by the displacement detector 45. A clock signal VCLK that cancels the error is output.

  The toroidal lens control circuit 202 drives the toroidal lens 107B via the drive mechanism 112B based on the information regarding the inclination of each detection pattern supplied from the misalignment detection device 45, and the toner image transferred at the second station. Is made to coincide with the inclination of the toner image formed at the first station.

  The counter 203 counts the clock signal VCLK generated by the high frequency clock generation circuit 201 and supplies the count value to the comparison circuit 204.

The comparison circuit 204 uses the count value supplied from the counter 203, the preset value L set in advance based on the duty ratio stored in the memory 206, and the transition timing of the pixel clock as the scanning position and the scanning optical system. The design phase data H _N (N = 1, 2, 3,...) Determined from the characteristics is compared. When the count value matches L, the control signal sig_L is output. When the count value matches the phase data H _N , the control signal sig_H is output and a reset signal is supplied to the counter 203.

  The pixel clock generation circuit 205 outputs a pixel clock signal PCLK that becomes 1 when the control signal sig_L supplied from the comparison circuit 204 falls and becomes 0 when the control signal sig_H falls.

  Hereinafter, a method for generating the pixel clock signal will be described with reference to FIG. FIG. 11A shows a clock signal VCLK having a wavelength T generated by the high frequency clock generation circuit 201. The clock signal VCLK is counted by the counter 203 every cycle, and the count value cont is supplied to the comparison circuit. The comparison circuit 204 compares the count value cont with the set value L and phase data H stored in the memory 206. Here, assuming that the duty ratio is 50%, the value of the set value L is 3, and the phase data is 7, the comparison circuit 204 raises the control signal sig_H when the count value cont becomes 3, and the count value cont Changes from 3, the control signal sig_H falls. When the count value cont becomes 7, the control signal sig_L is raised, and when the count value cont changes from 7, the control signal sig_H is lowered. The pixel clock generation circuit 205 sets the pixel clock signal PCLK to 0 when the control signal sig_H falls, and sets the pixel clock signal PCLK to 1 when the control signal sig_L falls. By repeating the above operation, the pixel clock generation circuit 205 generates the pixel clock signal PCLK obtained by dividing the clock signal VCLK by 8. In this embodiment, a pixel clock signal divided by 8 is used as a basic pixel clock signal, and phase modulation can be performed with a resolution of 1/8 clock.

Next, as an example, a case where the phase of the clock signal VCLK is delayed by 1/8 clock will be described with reference to FIG. FIG. 11B shows a clock signal VCLK having a wavelength T generated by the high frequency clock generation circuit 201 and a count value cont from the counter 203. Here, when the phase data H _N is changed to 6, the comparison circuit 204 raises the control signal sig_H when the count value cont reaches 3, and lowers the control signal sig_H when the count value cont changes from 3. When the count value cont becomes 6, the control signal sig_L is raised, and when the count value cont changes from 6, the control signal sig_L is lowered. The pixel clock generation circuit 205 sets the pixel clock signal PCLK to 0 when the control signal sig_H falls, and sets the pixel clock signal PCLK to 1 when the control signal sig_L falls. By repeating the above operation, the phase of the pixel clock signal PCLK can be delayed by 1/8 clock. In other words, in the present embodiment, by arbitrarily setting the value of the phase data L, PCLK can be phase-modulated with a resolution of 1/8 clock.

  Returning to FIG. 10, the frame memory 208 temporarily stores raster-developed image data supplied from the host device 214.

The image processing circuit 207 reads the data stored in the frame memory 208, creates pixel data for each light emission source of the laser array 131, and supplies it to the line buffers 210 ₁ to 210 ₁₆ corresponding to the respective light emission sources. Here, pixel data corresponding to the light source of the first light source group G1 is stored in the line buffers 210 _{1 to} 210 _8, and pixels corresponding to the light source of the second light source group G2 are stored in the line buffers 210 _{9 to} 210 ₁₆ . Data shall be stored.

The binarization circuit 215 binarizes the signal output from the light receiving element 142 based on, for example, a predetermined threshold value. The method will be described below with reference to FIG. The light beam emitted from the light source 130 is branched by the half mirror 101 into a light beam of S polarization component and P polarization component. The light beam of the S-polarized component is incident on the light receiving element 142 intermittently by being deflected to the polygon mirror 104. On the other hand, the light beam of the P-polarized component is incident directly on the light receiving element 142. The light receiving element 142 receives the light beam of the S polarization component and the light beam of the P polarization component, and outputs a voltage signal V ₁₄₂ as shown in FIG. Binarizing circuit 215, the voltage signal V ₁₄₂ from the light receiving element 142 is input, and the threshold V _s which is set in advance, by comparing the voltage signal V _142, the voltage signal V ₁₄₂ below threshold V _s When the voltage signal V ₁₄₂ becomes equal to or greater than the threshold value V _s , the binary signal Tr that becomes 1 is generated and is output to the write control circuit 211. Here, as described above, the light emitting sources of the laser array 131 have the polarization directions aligned in the direction indicated by the arrows in FIG. 7 and the angle α is very small. It is remarkably larger than the amount of light of the P-polarized component. Therefore, the threshold value V _s can be sufficiently large with respect to the voltage V ₀ corresponding to the P-polarized component of the light beam.

  As shown in FIG. 13, the light source driving circuit 213 includes light source driving units 1 a, 1 b, 1 c, 1 d, 2 a, 1 b, 1 c, 2 d that drive the first light emitting source group G <b> 1 of the laser array 131, and second A light source driving unit 3a, 3b, 3c, 3d, 4a, 4b, 4c, and 4d for driving the light emitting source group G2 and a light amount setting circuit 213a are provided. Each of the light source driving units 1a to 1d, 2a to 2d, 3a to 3d, and 4a to 4d sets a light amount corresponding to a light emission source based on a driving signal modulated according to image information supplied from the writing control circuit 211. Each is driven with the power set by the circuit 213a.

  The light amount setting circuit 213a sequentially drives each light emitting source individually when scanning the non-image area, monitors the light amount via the light receiving element 142 of the light source unit 130, and a light source driving unit so as to obtain a predetermined light amount. The power output from each of 1a to 1d, 2a to 2d, 3a to 3d, and 4a to 4d is set. Hereinafter, this operation is referred to as a first light emission mode.

  The writing control circuit 211 reads out pixel data for each light source in synchronization with, for example, the falling edge of the binarized signal Tr from the binarizing circuit 215, and the pixel clock signal supplied from the pixel clock generating circuit 205 Superimposed on PCLK, independent modulation data is generated for each light source. Then, based on the positional deviation information in the X-axis direction (sub-scanning direction) from the positional deviation detection device 45, the driving units 1a to 1d and 2a to the light source driving circuit 213 that first supplies modulation data for each light source group. 2d, 3a to 3d, and 4a to 4d are selected, and modulation data is supplied while selecting the driving units 1a to 1d, 2a to 2d, 3a to 3d, and 4a to 4d in order based on this.

Specifically described first light-emitting source group G1, by performing the 8 scan lines by one scanning, in the case of forming a toner image on the transfer belt 40, the first line is scanned by the light emitting source G1 ₁₁ The For example, when it is desired to form a toner image by shifting by one line in the sub-scanning direction, G1 ₁₂ is selected as the light source for scanning the head line, and the light source G1 ₁₂ , G1 ₁₃ , G1 ₁₄ , Scanning is performed with 7 lines using G1 ₂₁ , G1 ₂₂ , G1 ₂₃ , G1 ₂₄ , and in the second and subsequent scans, scanning is performed with 8 lines using all the light emitting source groups of the first light emitting source group G1. Similarly, if G1 ₁₃ , G1 ₁₄ ,..., G1 ₂₄ are selected as light emission sources for scanning the first row, the toner image can be shifted in the sub-scanning direction by 2 to 7 lines. Therefore, if the above-described correction processing is performed when a positional deviation in the sub-scanning direction is detected by the positional deviation detection device 45, the toner image is finer than when the incident timing to the polygon mirror 104 that is normally performed is varied. Can be adjusted. Normally, the correction process is performed together with a process for changing the timing of incidence on the polygon mirror 104 in accordance with the position shift state.

  Further, when supplying the modulation data to the light source driving circuit 213, each modulation data is sent to the light source driving circuit 213 at the timing when the scanning start positions by the respective light emitting sources coincide in consideration of the regular arrangement of the respective light emitting sources. Supplied to. Thereby, each light emission source is driven based on the modulation data. Hereinafter, this operation is referred to as a second light emission mode.

FIG. 14 shows a timing chart of the first light emission mode and the second light emission mode. As shown in FIG. 14, the first light emission mode is started at the same time as the deflection surface of the polygon mirror 104 changes. Specifically, the light amount setting circuit 213a monitors the voltage signal from the light receiving element 142, and emits light sources G1 ₁₁ to G1 ₁₁ to the light source driving units 1a to 1d, 2a to 2d, 3a to 3d, and 4a to 4, respectively. By sequentially supplying the drive signal for G2 ₂₄ every t seconds, the light emission sources G1 _{11 to} G2 ₂₄ are caused to emit light sequentially, and the amount of light is set respectively. When the light amount setting of the last light source G2 ₂₄ is completed, the drive of the light source G2 ₂₄ is maintained as it is. Then, by the light beam from the light emitting source G2 _24, when the voltage signal Tr from the binarization circuit 215 is output second light emitting mode is started. The first light emission mode is performed so that the light beam is completed while scanning the non-image area.

  In the optical scanning device 200 configured as described above, when the image information from the host device 214 is received, the light source units 130 and 330 are driven by the modulation data based on the image information, and the first station, the second station, and the third station. At the station and the fourth station, toner images of the respective color image components are formed on the transfer belt 40 so as to overlap each other. Then, as shown in FIG. 1, the toner image is transferred to a sheet 61 taken out from the sheet feed tray 60 by a transfer charger 48 and fixed by a fixing roller 50. The paper 61 on which the image is formed in this manner is discharged by the paper discharge roller 58 and sequentially stacked on the paper discharge tray 12a.

  As described above, according to the optical scanning device 100 according to the present embodiment, the light beams emitted from the light source of the light source unit 130 and the light source unit 330 are branched by the half mirror 101, and the S polarization component of the light beam. Is intermittently incident on the light receiving element 142 via the polygon mirror 104, and the P-polarized component of the light beam is always incident on the light receiving element 142. Therefore, since the light detection system for monitoring the light amount of the light beam and the light detection system for detecting the deflected light beam and generating the synchronization signal (Tr) can be shared, the scanning accuracy is maintained. However, the number of parts of the apparatus can be reduced, and as a result, the production cost can be reduced.

  In addition, since the output of each light source of the laser array 131 is adjusted before scanning, it is possible to avoid density unevenness in the printed image. Particularly in a multicolor image, it is possible to effectively avoid the deterioration of the image quality due to the change in the color.

  In addition, since the light emitting sources of the laser array 131 have the same polarization direction, the reflection characteristics at the polygon mirror 104 and the reflecting mirrors in the scanning optical system are uniform between the light beams. Accordingly, the density between the scanning lines becomes uniform, image formation by high-quality multi-beam scanning can be performed, and the amount of light can be used efficiently.

  In the present embodiment, a monitor signal of the light emission source is generated from the signal before binarization of the light receiving element 142, and a synchronization signal that takes the writing timing is generated from the signal after binarization. Therefore, the signal processing circuit is shared and the number of parts is reduced, so that cost reduction is realized.

  Further, since the laser array 131, the light receiving element 142, and the control circuit 200 are mounted on the same substrate 140, the wiring from the light receiving element 142 to the laser array 131 can be shortened. For this reason, it is difficult to be influenced by noise, and even a weak signal has little attenuation, and the light source can be controlled and the light amount can be reliably and accurately set, so that a high quality image can be formed.

  The light beam deflected by the polygon mirror 104 is directly received by the light receiving element 142 without passing through the imaging optical system (toroidal lenses 107A, 107B, 307C, 307D). Therefore, even if there is a wavelength difference between each light source, the magnification shift in the main scanning direction by the imaging optical system is less likely to occur, and the timing of synchronization detection is aligned between each light source, so that there is no color misregistration. High-quality image formation can be performed.

  In addition, a sawtooth diffractive surface is formed on the incident surface of the toroidal lenses 107A, 107B, 307C, and 307D, and at least main scanning associated with the wavelength difference of the light beams emitted from the respective light emission sources is formed on the diffractive surface. The power is set so as to correct the focus movement in the direction. Therefore, even if there is a wavelength difference between the light beams, the magnification deviation in the main scanning direction can be corrected by the power set on the diffraction surface, so that the magnification in the main scanning direction of each scanning line is aligned and there is no color deviation. High-quality image formation can be performed.

  Further, since the light receiving element is made common to each light emitting source of the laser array 131, the output from each light emitting source can be adjusted without variation in sensitivity. Therefore, high-quality image formation without color change can be performed.

  The printer 10 according to the present embodiment includes the optical scanning device 100. Therefore, it is possible to reduce the number of parts of the apparatus and reduce the production cost while maintaining the quality of image quality.

  In the light source units 130 and 330 of this embodiment, the case where the light receiving element 142 is mounted on the substrate 140 has been described. However, the present invention is not limited to this, and as shown in FIG. It may be connected via.

  In the above embodiment, the case where the optical scanning device 100 of the present invention is used in a printer has been described. However, the image forming apparatus other than the printer, for example, a copier, a facsimile, or a multifunction machine in which these are integrated. Is preferred.

DESCRIPTION OF SYMBOLS 10 ... Printer, 12 ... Housing, 30A-30B ... Photosensitive drum, 40 ... Transfer belt, 50 ... Fixing roller, 45 ... Position shift detector, 100 ... Optical scanning device, 104 ... Polygon mirror, 105, 305 ... f (theta) lens, 106A, 106B, 108A, 108B, 109A, 109B, 306C, 306D, 308C, 308D, 309C, 309D ... reflective mirror, 107A, 107B, 307C, 307D ... toroidal lens, 130, 330 ... light source unit, 102, 302 ... cylinder Lens, 110, 310 ... Condensing lens, 101, 301 ... Half mirror, 111, 311 ... Reflecting mirror, 112, 312 ... Condensing lens, 142 ... Light receiving element, 131 ... Laser array, 200 ... Control circuit, 202 ... Toroidal Lens control circuit, 213 ... Light source drive Circuit, 213a ... light quantity setting circuit, 213 ... light source driving circuit, 215 ... binarizing circuit, G1, G2 ... luminous source _{group, G1 11, G1 12, G1} 13, G1 14, G1 21, G1 22, G1 23, G1 ₂₄ , G2 ₁₁ , G2 ₁₂ , G2 ₁₃ , G2 ₁₄ , G2 ₂₁ , G2 ₂₂ , G2 ₂₃ , G2 ₂₄ ...

Japanese Patent No. 2908852 JP 2002-40350 A

Claims (6)

An optical scanning device that scans a surface to be scanned with a light beam,
A plurality of light sources that are two-dimensionally arranged at equal intervals from each other, and a light source in which the row direction of the plurality of light sources forms a predetermined angle with respect to the main scanning direction
Deflecting means for collectively deflecting a plurality of light beams respectively emitted from the plurality of light emitting sources;
An imaging optical system for imaging the deflected light beams on the surface to be scanned;
A light guiding means for guiding at least a part of each of the plurality of light beams in a predetermined direction without passing through the deflecting means;
Mounted on the same substrate as the light source, and receives the plurality of guided light beams, and directly receives the deflected plurality of light beams without passing through the imaging optical system, A light detection system that outputs a signal based on the received light beam ;
After the light emitting sources are sequentially driven and the deflecting unit starts deflecting, the light beam guided by the light detection system is received until the light detection system receives the light beam deflected by the deflecting unit. The light amount of each of the plurality of light emitting sources is set based on the output signal of the light detection system that has received the light, and the driving of the light emitting source for which the setting has been made last is maintained. A control device for determining a write timing by each of the plurality of light emitting sources based on a signal output from the light detection system when the light detection system receives the emitted light beam deflected by the deflecting unit. Optical scanning device.   The imaging optical system includes an optical element formed with a diffraction surface that diffracts the light beam deflected by the deflecting unit, and the diffraction surface depends on a wavelength difference between the plurality of light beams. 2. The optical scanning device according to claim 1, wherein the optical scanning device has a power in a direction for correcting a focus movement with respect to a deflection direction of the plurality of light beams.   The optical scanning device according to claim 1, wherein the light guiding unit is a unit that branches the plurality of light beams in a direction toward the deflecting unit and in the predetermined direction.   The polarization direction of each of the plurality of light emitting sources is aligned, and the light guiding unit guides one of the S-polarized component and the P-polarized component of each of the plurality of light beams. The optical scanning device according to claim 1. An image forming apparatus that forms an image by fixing a toner image formed based on a latent image obtained from image information to a recording medium,
An optical scanning device according to any one of claims 1 to 4,
And a photoconductor having a scanned surface on which a latent image is formed by the optical scanning device. An image forming apparatus for forming a multicolor image by superimposing and fixing a toner image formed on the basis of a latent image for each color obtained from information on a multicolor image on a recording medium,
An optical scanning device according to any one of claims 1 to 4,
A plurality of photoconductors each forming a latent image corresponding to each color by the optical scanning device,
The plurality of light emitting sources respectively correspond to the plurality of photosensitive members, and the imaging optical system of the optical scanning device forms an image of the light beam from the plurality of light emitting sources on the corresponding scanned surface of the photosensitive member. An image forming apparatus.

Images