WO2010058462A1

WO2010058462A1 - Scanning type projector

Info

Publication number: WO2010058462A1
Application number: PCT/JP2008/071088
Authority: WO
Inventors: 幹生堀江; 祥平松岡
Original assignee: Hoya株式会社
Priority date: 2008-11-20
Filing date: 2008-11-20
Publication date: 2010-05-27
Also published as: JPWO2010058462A1; JP5226081B2

Abstract

In order to align writing start positions of respective scanning lines at high accuracy, a scanning type projector includes at least one light source unit which emits a light flux, a scan unit which scans a surface to be scanned with the emitted light flux in two directions, a main scanning direction and a sub scanning direction, a first reflection unit which is provided in an area outside an effective scanning area on the surface to be scanned and has a first reflection surface with a higher reflectance than the effective scanning area, a reflected light detection unit which detects a reflection light of the light flux with which the first reflection unit is scanned, and a light emission control unit which performs a light emission control to the at least one light source unit based on a projection image according to a timing at which reflected light detection means detects the reflected light.

Description

Scanning projector

The present invention relates to a scanning projection apparatus mounted on an image forming apparatus such as a projector, a laser printer, or an image scanner, and more specifically, scanning capable of aligning the writing position of each scanning line on a scanned surface with high accuracy. The present invention relates to a mold projection apparatus.

2. Description of the Related Art There is known a two-dimensional scanning projection device that two-dimensionally scans a light beam emitted from a light source and projects it on a scanned surface such as a screen. This type of scanning projection apparatus is suitable for use as a so-called rear projector that projects an image from behind the screen and observes the image from the front of the screen, for example.

An example of a scanning projection apparatus is disclosed in International Publication WO 2004/004167 (hereinafter referred to as “Patent Document 1”). The scanning projection apparatus described in Patent Document 1 has a linear detector disposed in an area outside the effective scanning between the screen and the scanning optical system. The scanning projection apparatus detects scanning light using a linear detector, and writes each scanning line after a predetermined delay time has elapsed. However, the writing position of each scanning line varies due to individual differences among components, mounting errors, aberrations, and the like, and causes a problem of distorting or color shifting an image projected on the screen. In order to avoid the occurrence of such a problem, in a general scanning projection apparatus, the writing position of each scanning line is electrically adjusted and aligned in the adjustment process before shipping the assembled product.

However, when the usage environment (for example, temperature) of the scanning projection apparatus changes, the dimensions of each component change due to the change, and as a result, the writing position of each scanning line may vary. . The larger the scanning projection device, the longer the optical (physical) distance between the screen and other parts, so the screen (more precisely, where each scan line should be written) The fluctuation of the relative position with each part appears remarkably. Such a change in relative position is one of the main factors that cause variations in the writing position of each scanning line during actual use, and is regarded as a problem.

Further, when sub-scanning (two-dimensional scanning) is to be performed based on the configuration of Patent Document 1, in order to detect signals by receiving laser light corresponding to all scanning lines in the scanning range, sub-scanning is performed. A linear detector having a light receiving area that is long in the scanning direction is indispensable. However, the linear detector that is long in the sub-scanning direction has the disadvantages that the mounting space is limited due to the large outer dimensions and the unit price is high.

The present invention has been made in view of the above circumstances, and its object is to be concerned when a temperature change or the like occurs while having a simple structure suitable for downsizing and excellent in cost. It is an object of the present invention to provide a scanning projection apparatus that can effectively suppress variations in the writing position of each scanning line.

A scanning projection apparatus according to an embodiment of the present invention that solves the above problem is an apparatus that scans a light beam on a surface to be scanned in two directions: a main scanning direction and a sub-scanning direction orthogonal to the main scanning direction. , Has the following characteristics. That is, such a scanning projection apparatus includes at least one light source unit that irradiates a light beam, a scanning unit that deflects the irradiated light beam and scans it in two directions on the surface to be scanned, and an effective scan on the surface to be scanned. A first reflecting portion that is disposed in the region and has a higher reflectance than the effective scanning region on the surface to be scanned; a light flux returning portion that returns the light beam reflected by the first reflecting portion and re-enters the scanning portion; Light emission control according to the projected image in at least one light source unit according to the reflected light detection unit that detects a part of the reflected light that is re-incident on the scanning unit and deflected, and the timing of detection of the reflected light by the reflected light detection unit And a light emission control unit for performing the above.

As described above, in the present invention, the light reflected from the first reflecting part is detected to control the light emission of the light source part. Since the first reflecting portion is directly arranged on the surface to be scanned, the position where each scanning line should be written on the surface to be scanned and the first reflection even when the usage environment such as temperature changes. Fluctuations in the relative position with respect to the part hardly occur. That is, since the writing of each scanning line is still complete even when the usage environment changes, a fine image without distortion or color misregistration is projected onto the surface to be scanned.

Further, the reflected light having no angle of view in the scanning direction, which is returned by the light flux returning unit, is incident on the reflected light detecting unit according to the present invention. Therefore, the reflected light detection unit does not need to be a detector having a light receiving area corresponding to the angle of view in the scanning direction, unlike the linear detector of Patent Document 1, for example, to reduce the size and cost of the scanning projection apparatus. Any suitable single cell small sensor may be used.

Here, by making the first reflecting portion a long reflecting portion that is substantially parallel to the sub-scanning direction and has a long side, the timing of detection of the reflected light becomes almost regular and control becomes easy. In addition, the reliability of timing detection can be improved by configuring the first reflecting portion to have a side longer than the length of the effective scanning region in the sub-scanning direction. A configuration in which the sides in the sub-scanning direction are shortened or interrupted (a configuration in which small-sized reflecting portions are intermittently arranged in the sub-scanning direction) may be employed.

The first reflecting portion is preferably a position where writing of the light beam in the main scanning direction is scheduled on the surface to be scanned, in order to further facilitate positioning of the first reflecting portion with respect to the design writing position of each scanning line. Is placed close to.

The light emission control unit is configured to perform light emission control on at least one light source unit, for example, after a predetermined time elapses after the reflected light is detected by the reflected light detection unit.

It is desirable that the scanning projection apparatus according to the present invention further includes a long second reflecting portion having a side forming a predetermined angle with respect to the side of the first reflecting portion. In this case, the reflected light detection unit detects the reflected light of each of the first reflection unit and the second reflection unit. The light emission control unit controls the writing position in the sub-scanning direction of the light beam on the surface to be scanned based on the detection time intervals of the reflected light from the first reflecting unit and the second reflecting unit. That is, according to such a configuration, it is possible to satisfactorily control not only the writing in the main scanning direction but also the writing position in the sub-scanning direction.

The first reflecting portion or the second reflecting portion may be a reflecting member attached to the effective scanning outside region, or is applied to the effective scanning outside region which is excellent in mass productivity and positional accuracy and advantageous in cost. Or it may be a printed reflective area.

The light flux returning part returns the light beam incident on the first reflecting part or the second reflecting part to the optical path substantially the same as the incident light, so that the light beam is incident on the first reflecting part or the second reflecting part substantially perpendicularly. It is good also as a structure which has the normal incidence lens to make. Here, the normal incidence lens is, for example, a Fresnel lens arranged close to the surface to be scanned. That is, the normal incidence lens does not need to be a dedicated product, and may be a Fresnel lens included in a general scanning projection apparatus, that is, a general-purpose lens.

The scanning projection apparatus further includes a reflected light deflecting unit that deflects at least a part of the reflected light that is returned to the substantially same optical path as that at the time of incidence and is deflected by the scanning unit, and guides the reflected light to the reflected light detecting unit. It may be.

Further, the scanning unit may include a deflector that deflects in the main scanning direction or the sub-scanning direction in order from the light source unit side, and a scanning optical system that scans the light beam deflected by the deflector on the surface to be scanned. . In such a case, the reflected light deflecting unit is preferably arranged in the vicinity of the deflector in order to efficiently guide the light beam deflected by the deflector to the reflected light detecting unit.

The scanning projection apparatus may further include a conjugate optical system in which the deflection surface of the deflector that deflects the light beam and the detection surface of the reflected light detection unit that detects the reflected light are conjugate to the pupil.

Here, the deflector is, for example, a two-dimensional scanning galvanometer mirror or a two-dimensional MEMS (Micro Electro Mechanical Systems) mirror that deflects a light beam in two directions, or a polygon mirror with surface tilt. The deflector may be a deflector that deflects the light beam in one direction. Such a one-dimensional deflector is used in combination with, for example, another deflector or a light source system that controls the incident angle of a light beam to the one-dimensional deflector.

The first reflection unit or the second reflection unit may be configured to reflect a light beam incident on the first reflection unit or the second reflection unit with a high divergence and increase a reflected light beam diameter. . In this case, the reflected light deflecting unit is configured to deflect light around the reflected light flux to the reflected light detecting unit.

Further, the first reflecting portion or the second reflecting portion may be configured by a single convex shape having a size equal to or larger than the spot size of the light beam incident on the first reflecting portion or the second reflecting portion, Or you may comprise by the some convex shape of the size smaller than this spot size.

It is an external appearance front view which shows the external appearance (front) of the two-dimensional scanning projector of 1st embodiment of this invention. 1 is a main scanning sectional view schematically showing a configuration of a two-dimensional scanning projection apparatus according to a first embodiment of the present invention. 1 is a sub-scan sectional view schematically showing a configuration of a two-dimensional scanning projection apparatus according to a first embodiment of the present invention. It is main scanning sectional drawing of the reflection member which the two-dimensional scanning projector of 1st embodiment of this invention has. It is a main scanning sectional view of a reflective member which a two-dimensional scanning projection device of another embodiment of the present invention has. It is a figure which shows the signal waveform which the light reception sensor which the two-dimensional scanning projection apparatus of 1st embodiment of this invention has has is output. It is an external appearance front view which shows the external appearance (front) of the two-dimensional scanning projector of 2nd embodiment of this invention. It is a figure for demonstrating the correction process of the writing position of the subscanning direction in 2nd embodiment of this invention. It is a figure which shows the structure of the polygon mirror with a surface tilt which the two-dimensional scanning projector of 3rd embodiment of this invention has. It is a main-scan sectional drawing which shows roughly the structure of the two-dimensional scanning type projector of 4th embodiment of this invention.

Hereinafter, a two-dimensional scanning projection apparatus according to an embodiment of the present invention will be described with reference to the drawings.

FIG. 1 is an external front view showing the external appearance (front) of the two-dimensional scanning projector 100 according to the first embodiment of the present invention. The two-dimensional scanning projection apparatus 100 is configured as a rear projector that projects an image from behind the screen so that a viewer can observe the image from the front of the screen, for example.

As shown in FIG. 1, a screen S on which an image is projected is provided in front of the two-dimensional scanning projector 100. The two-dimensional scanning projection apparatus 100 has a housing H that holds various components constituting the two-dimensional scanning projection apparatus 100 including the screen S. In this specification, a direction orthogonal to the screen S (direction orthogonal to the paper surface in FIG. 1) is defined as an “X direction”, and a first direction parallel to the screen S (left and right parallel to the paper surface in FIG. 1) is defined. (Direction) is defined as “Y direction”, and a second direction (vertical direction parallel to the paper surface in FIG. 1) parallel to the screen S and perpendicular to the first direction is defined as “Z direction”. That is, the X, Y, and Z directions are defined as directions orthogonal to each other. Further, the Y direction is defined as “main scanning direction”, and the Z direction is defined as “sub scanning direction”.

2 and 3 are diagrams schematically showing the arrangement of various components held inside the housing H of the two-dimensional scanning projection apparatus 100. FIG. 2 and 3, for convenience of explanation, optical components constituting the two-dimensional scanning projection apparatus 100 are mainly illustrated, and other components (for example, holding members, electric circuits, etc.) are not shown in principle. 2 and 3 is a central axis (optical axis) AX of the two-dimensional scanning projection apparatus 100. The point where the center axis AX of the two-dimensional scanning projection apparatus 100 and the screen S intersect with the central point S ₀ of the effective scanning area of the screen S (effective display area according to another expression). Match. In a state where the optical path of the two-dimensional scanning projection apparatus 100 is developed, a section including the central axis AX and the main scanning direction of the two-dimensional scanning projection apparatus 100 is defined as a “main scanning section”, and the central axis AX and the sub-axis A cross section including the scanning direction is defined as a “sub-scanning cross section”. 2 and 3 are a main scanning sectional view and a sub-scanning sectional view schematically showing the configuration of the two-dimensional scanning projection apparatus 100, respectively. However, in FIG. 3, a light beam separation mirror 8a, a sensor optical system 8b, and a light receiving sensor 8c, which will be described later, are shown for convenience, and are actually arranged at positions away from the sub-scan section.

As shown in FIG. 2 and FIG. 3, the two-dimensional scanning projection apparatus 100 has a plurality of light source units that emit laser light (parallel light) (here, a total of three

light source units

1a, 1b, and 1c). ing. Each light source unit has the same configuration, and is arranged so as to be aligned on the sub-scan section. Various optical components such as a two-dimensional deflector 4, a scanning optical system 5, and a Fresnel lens 6 are arranged in order from the light source unit side on the optical path of the two-dimensional scanning projector 100 from the light source unit to the screen S. In FIG. 2, a light beam traveling from the light source unit toward the screen S side is indicated by a dotted line, and a light beam traveling from the screen S toward the light source unit side is illustrated by a solid line. In FIG. 3, in order to clarify the drawing, the light beams emitted from the respective light source units are simply indicated by the solid line only with the principal ray.

The two-dimensional scanning projection apparatus 100 includes a system controller 10 that performs overall control of the entire apparatus, and an image processing unit 20 that generates image data (image data) to be projected onto the screen S. Yes. The image processing unit 20 generates a modulation signal corresponding to the image data under the control of the system controller 10 and outputs it to each light source unit. Each light source unit modulates and irradiates laser light in accordance with an input modulation signal. Each light source unit simultaneously irradiates modulated laser light to simultaneously scan the screen S with three scanning lines. The laser light emitted from each light source unit is incident on the deflection surface 4P of the two-dimensional deflector 4.

The two-dimensional deflector 4 is a deflector (for example, a well-known two-dimensional scanning galvanometer mirror or two-dimensional MEMS mirror) configured such that the deflection surface 4P vibrates at high speed on the sub-scanning section or the main scanning section, for example. Laser light incident on the deflection surface 4P from the light source unit is scanned with respect to the screen S in two directions, ie, a main scanning direction and a sub-scanning direction. The laser light incident on the deflection surface 4P is incident on the scanning optical system 5 while being continuously deflected by the deflection surface 4P at an angle corresponding to the vibration state.

The scanning optical system 5 is composed of a plurality of lenses and has, for example, an fθ characteristic as a whole. The laser light emitted from the scanning optical system 5 enters the Fresnel lens 6. The Fresnel lens 6 has a shape and dimensions that sufficiently cover the entire effective scanning area of the screen S. Here, the effective scanning area of the screen S is defined as a rectangular area formed by the effective scanning width Sm in the main scanning direction and the effective scanning height Sv in the sub-scanning direction shown in FIG. 1 (or FIGS. 2 and 3). Is done.

The laser light incident on the Fresnel lens 6 is deflected in a direction substantially perpendicular to the surface of the screen S by the optical action of the Fresnel lens 6 regardless of the incident angle. A lenticular lens (not shown) is arranged between the Fresnel lens 6 and the screen S. The laser light deflected by the Fresnel lens 6 is diffused left and right by the optical action of the lenticular lens and then incident on the screen S. The laser light incident on the screen S scans the screen S at a substantially constant speed in the main scanning direction by the fθ characteristic given by the scanning optical system 5. The two-dimensional scanning projection apparatus 100 ensures a wide viewing angle by the optical action of the Fresnel lens 6 and the lenticular lens.

In the two-dimensional scanning projection apparatus 100, the two-dimensional deflector 4 is configured to rotate by a predetermined angle in the sub-scanning direction for each scanning in the main scanning direction by the two-dimensional deflector 4. Here, the predetermined angle is equal to the number of laser beams (three in the first embodiment) arranged in the sub-scanning direction, which are simultaneously used for scanning the screen S, and the spot size formed on the screen S by the laser beams ( It is defined as the angle corresponding to the length multiplied by the spot diameter in the sub-scanning direction). A two-dimensional image is formed on the screen S by repeating the scanning in the main scanning direction and simultaneously performing the scanning in the sub-scanning direction.

The actual scanning range of the laser light on the screen S depends on individual differences of various parts constituting the two-dimensional scanning projection apparatus 100, variations in the external dimensions of various parts due to the use environment, or optical performance of the optical parts. Considering fluctuations and the like, it is set slightly wider than the effective scanning area of the screen S. Specifically, the scanning width of the laser light on the screen S in the main scanning direction is a scanning width S′m wider than the effective scanning width Sm. Further, the scanning height of the laser light on the screen S in the sub-scanning direction is a scanning height S′v wider than the effective scanning height Sv. That is, the actual scanning range of the laser beam on the screen S is defined as a rectangular region formed by the scanning width S′m and the scanning height S′v. Here, as shown in FIG. 1, a range obtained by excluding the effective scanning area of the screen S from the actual scanning range of the laser light on the screen S is defined as an “outside effective scanning area R”.

In the two-dimensional scanning projection apparatus 100 according to the first embodiment, in order to satisfactorily correct the deviation of the writing position of each scanning line, as shown in FIGS. A position on the non-effective scanning area R (a position close to the writing position) that is a predetermined distance away in the main scanning direction from the effective writing position (the right side of the effective scanning area in FIG. 1 or the upper end of the effective scanning width Sm in FIG. 2). In FIG. 1, the reflecting member 7 is disposed on the back side of the external frame. The reflecting member 7 is, for example, a resin molded product, and has a rectangular shape that is longer than the effective scanning height Sv when facing from the direction facing the screen S. The surface facing from this direction is the reflecting surface 7a, and a material having a high reflectance such as metal is deposited thereon. The reflective surface 7a has a rectangular shape that substantially matches the external dimension of the reflective member 7 when viewed from the direction, and the longitudinal direction is parallel to the sub-scanning direction. The front surface side (scanning optical system 5 side) of the reflecting member 7 is covered with a Fresnel lens 6. Therefore, the laser light emitted from the scanning optical system 5 is incident on the reflecting member 7 via the Fresnel lens 6.

The reflecting member 7 has a shape such that the cross section is always the same when cut by any plane parallel to the main scanning cross section. Here, FIG. 4 shows a main scanning sectional view of the reflecting member 7. As shown in FIG. 4, the reflecting surface 7a of the reflecting member 7 is formed in a convex shape. The width of the reflecting surface 7a (the length in the main scanning direction) is approximately the same as or larger than the spot size of the laser light incident through the Fresnel lens 6. Therefore, the laser light is incident on the reflection surface 7a without any deviation, and is slightly diverged and reflected only in the main scanning direction. That is, the laser beam reflected by the reflecting surface 7a has a diameter larger than that of the incident light in the main scanning direction, as is apparent when comparing the dotted line (incident light) and the solid line (reflected light) in FIG. .

Incidentally, the laser light is deflected by the optical action of the Fresnel lens 6 and is incident on the reflecting surface 7a substantially perpendicularly. Therefore, the laser beam reflected by the reflecting surface 7a returns the same optical path as that at the time of incidence. The laser light returning on the same optical path passes through the Fresnel lens 6 and the scanning optical system 5 in order, and is deflected by the deflection surface 4P of the two-dimensional deflector 4.

Various shapes are assumed for the reflecting surface 7a. FIG. 5A to FIG. 5C show three examples of the shape of the reflecting surface 7a. The reflecting surface 7a shown in FIG. 5A has a configuration having a plurality of convex shapes having a size smaller than the spot size of the laser light incident on the reflecting surface 7a. The reflective surface 7a shown in FIG. 5B has a configuration having a surface shape inclined with respect to the screen S. Such a surface shape can be regarded as a part of a convex shape having a very large curvature. The reflecting surface 7a shown in FIG. 5C has a concave shape. The end of the reflecting surface 7a in FIG. 5C is rounded. Any of the reflecting surfaces 7a shown in FIGS. 5A to 5C reflects the incident laser beam by slightly diverging in the main scanning direction, like the reflecting surface 7a of FIG.

The reflection surface 7a assumed here is a smooth surface, but may be a rough surface in another embodiment. The reflecting surface 7a is a surface having a fine uneven shape of a predetermined size, which is roughened by, for example, blasting or the like. In the case of a rough surface, the laser light incident on the reflecting surface 7a is reflected in various directions, becomes a slightly broadened light beam, returns to the optical path at the time of incidence, and the optical path from the Fresnel lens 6 to the sensor optical system 8b. The light is received by the light receiving sensor 8c.

As shown in FIG. 2, the two-dimensional scanning projector 100 has a light beam separation mirror 8 a at a position near the two-dimensional deflector 4 that faces the deflection surface 4 </ b> P of the two-dimensional deflector 4. The light beam separation mirror 8a has a reflection surface only on the surface facing the deflection surface 4P. The position where the light beam separation mirror 8a is disposed is outside the effective light beam diameter of the laser light (dotted line in FIG. 2) directed from the light source portion toward the deflection surface 4P. Therefore, the laser beam traveling from the light source unit toward the deflecting surface 4P is not shielded by the light beam separation mirror 8a. However, the position of the light beam separation mirror 8a is within the effective light beam diameter of the reflected light (solid line in FIG. 2) (the periphery of the effective light beam diameter). Therefore, a part of the reflected light is incident on the reflecting surface of the light beam separation mirror 8a and reflected. In addition, an optical isolator (not shown) is disposed in front of each light source unit, and return light to each light source unit is shielded.

The laser beam reflected by the reflecting surface of the light beam separation mirror 8a is collected by the sensor optical system 8b and received by the light receiving surface of the light receiving sensor 8c. The light receiving surface of the light receiving sensor 8c is disposed at a position conjugate with the optical pupil of the deflecting surface 4P of the two-dimensional deflector 4 by the sensor optical system 8b. Therefore, the reflected light is received at approximately one point on the light receiving surface. Therefore, the light receiving sensor 8c does not need to have a configuration having a plurality of cells like the linear detector described in Patent Document 1, for example, and may be a single small sensor having a single cell. Such a sensor is suitable for downsizing and cost reduction of the two-dimensional scanning projection apparatus. Note that the light beam separation mirror 8a is located outside the effective light beam diameter of the laser light (dotted line in FIG. 2) from the light source unit toward the deflection surface 4P and does not cause mechanical interference with the two-dimensional deflector 4. The closer to the two-dimensional deflector 4, the better. As the light beam separation mirror 8a is arranged in the vicinity of the two-dimensional deflector 4, the periphery of the effective light beam diameter of the reflected light (solid line in FIG. 2) is reflected more efficiently and guided to the light receiving sensor 8c. Because it can. According to another aspect, even when the light beam separation mirror 8a is downsized, if the light beam separation mirror 8a is disposed in the vicinity of the two-dimensional deflector 4, a sufficient amount of light for signal detection can be guided to the light receiving sensor 8c.

The light receiving sensor 8c generates a voltage corresponding to the received laser beam and outputs it to the system controller 10 as a detection signal for determining the writing position. FIG. 6 shows a signal waveform input to the system controller 10 from the light receiving sensor 8c. As shown in FIG. 6, the detection signal is repeatedly input from the light receiving sensor 8c to the system controller 10. When a predetermined time t elapses after the detection signal is input (in other words, the rising edge of the signal waveform is detected), the system controller 10 writes the laser light that scans the screen S at the writing position (FIG. 1). 2, or the upper end of the effective scanning width Sm in FIG. 2), and outputs an instruction to the image processing unit 20 to perform light emission control of each light source unit. When the image processing unit 20 performs light emission control of the light source unit according to the instruction for all the scanning lines, the writing position of each scanning line is aligned. As a result, an image having no distortion or color misregistration is projected on the screen S. It should be noted that when setting the predetermined time t, it is actually necessary to consider signal delay and the like. Further, the image processing unit 20 performs light emission control of the three light source units during the image drawing period of FIG. 6, but controls light emission of only one of the light source units in order to obtain a detection signal during other periods. Continuous light is irradiated during the latter period.

Thus, in the two-dimensional scanning projection apparatus 100 of the first embodiment, the reflecting member 7 is directly attached on the screen S. Therefore, the position of the reflecting member 7 with respect to the position where each scanning line is to be written does not vary substantially even when a temperature change or the like occurs during actual use. That is, even when a temperature change or the like occurs, the relative position between the position where each scanning line should be written and the reflecting member 7 does not substantially change. Therefore, the writing positions of the respective scanning lines are still aligned, and the image projected on the screen S is not substantially distorted or displaced. Further, as in Patent Document 1, when the relative position between the scanning line detection sensor and the screen is indirectly determined via another holding member, the sensor and the screen are caused by vibration during transportation. The attachment position such as may move slightly. The maximum amount of variation of the relative position that can occur in that case is not only the tolerance of the sensor, the screen itself, but also the stack of tolerances of all the parts that hold the sensor or screen directly or indirectly. Therefore, in Patent Document 1, the writing position of each scanning line may vary greatly after transportation. On the other hand, in the two-dimensional scanning projection apparatus 100 of the first embodiment, the reflecting member 7 is directly attached to the screen S. Therefore, the maximum fluctuation amount of the relative position is only the sum of the allowable tolerances of the reflecting member 7 and the screen S. That is, according to the two-dimensional scanning projection apparatus 100 of the first embodiment, variation in the writing position of each scanning line, which is a concern due to vibration during transportation, is effectively suppressed.

The mounting position of the reflecting member 7 is preferably immediately before the writing position of each scanning line as in the first embodiment. This is because when the reflecting member 7 is disposed immediately before the writing position, the reflecting member 7 can be easily positioned with respect to the writing position. However, in another embodiment, the reflecting member 7 may be attached to any location within the effective scanning outside region R.

According to the first embodiment described above, since the writing position of each scanning line is still aligned even when a temperature change or the like occurs, distortion or color misregistration in the main scanning direction appears on the image projected on the screen S. Will not occur. On the other hand, the writing position in the sub-scanning direction with respect to the effective scanning area of the screen S is determined by open control. Therefore, strictly speaking, the writing position in the sub-scanning direction can vary according to changes in the usage environment such as temperature. Therefore, it is desirable to correct the writing position in the sub-scanning direction in addition to the writing position of each scanning line. As a second embodiment, a configuration capable of correcting both the writing position of each scanning line and the writing position in the sub-scanning direction will be described. In the following, only the configuration and features unique to each embodiment will be described, and the same configurations and the like as those of the first embodiment will be referred to above.

FIG. 7 is an external front view showing the external appearance (front) of the two-dimensional scanning projection apparatus 100z of the second embodiment. As shown in FIG. 7, the two-dimensional scanning projection apparatus 100z further includes a reflecting member 7 'in addition to the reflecting member 7 on the back side of the appearance frame. The reflecting member 7 ′ is located on the non-effective scanning area R between the ideal writing position of each scanning line (the right side of the effective scanning area in FIG. 7 or the upper end of the effective scanning width Sm in FIG. 2) and the reflecting member 7. At a position, it is arranged obliquely with respect to the sub-scanning direction (in other words, the longitudinal direction of the reflecting member 7).

The reflecting member 7 ′ is different in length from the reflecting member 7 in the longitudinal direction. The front surface side (scanning optical system 5 side) of the reflecting member 7 ′ is also covered with the Fresnel lens 6 as with the reflecting member 7. The two-dimensional scanning projection apparatus 100z of the second embodiment corrects the writing position in the sub-scanning direction using the reflecting member 7 '.

FIG. 8 is a diagram for explaining the correction process of the writing position in the sub-scanning direction. FIG. 8A is a diagram when the screen S is viewed from the scanning optical system 5 side. In FIG. 8A, the arrows extending in the main scanning direction indicate the scanning lines A1 to A3. FIGS. 8B, 8C, and 8D show signal waveforms output from the light receiving sensor 8c when scanning the scanning lines A1, A2, and A3, respectively.

As shown in FIG. 8A, the scanning lines A1 to A3 scan on two reflecting surfaces (the reflecting surface 7a of the reflecting member 7 and the reflecting surface 7'a of the reflecting member 7 '). Therefore, the light receiving sensor 8c receives reflected light twice in a short time and outputs two detection signals as shown in FIGS. 8B to 8D. Here, the detection signal corresponding to the reflective surface 7a is defined as "first detection signal", and the detection signal corresponding to the reflective surface 7'a is defined as "second detection signal". Since the interval between the reflecting surface 7a and the reflecting surface 7'a on each scanning line is different, the time interval between the first detection signal and the second detection signal is also different for each scanning line.

The two-dimensional scanning projection apparatus 100z of the second embodiment has n light source units. That is, the two-dimensional scanning projection apparatus 100z is configured to simultaneously scan n rows of scanning lines. Here, a design time interval between the first detection signal and the second detection signal corresponding to the first light source unit is defined as “interval t0”, which corresponds to each of the i-th and (i + 1) -th light source units. The design time interval difference is defined as “interval difference Δt”, and the design time interval corresponding to the i-th light source unit is defined as “interval ti”. At this time, the interval ti is represented by t0 + (i−1) Δt. The i-th light source unit refers to a light source unit that scans the i-th scanning line from the top among n scanning lines that are scanned simultaneously.

In the second embodiment, in order to obtain a detection signal, only the a-th light source unit out of n emits continuous light during a period other than the image drawing period. The design time interval between the first detection signal and the second detection signal corresponding to the a-th light source unit is ta (= t0 + (a−1) Δt). The system controller 10 compares the actual time interval t'a between the first detection signal and the second detection signal input from the light receiving sensor 8c with the designed time interval ta.

The system controller 10 estimates the amount of deviation of the writing position in the sub-scanning direction based on the comparison result. The deviation amount of the writing position in the sub-scanning direction can be converted into the number of scanning lines by a predetermined formula f (f = (t′a−ta) / Δt). Consider a case where the amount of deviation in the writing position in the sub-scanning direction is, for example, two in terms of the number of scanning lines. In this case, the system controller 10 instructs the image processing unit 20 so that the (i-2) th light source unit outputs the modulated light to be output by the i th light source unit. By performing such correction, the writing position in the sub-scanning direction is always kept constant regardless of the use environment.

FIG. 9 shows a configuration of the two-dimensional deflector 14 included in the two-dimensional scanning projection apparatus 100y of the third embodiment. The two-dimensional scanning projection apparatus 100 y of the third embodiment has a two-dimensional deflector 14 as an alternative to the two-dimensional deflector 4. As shown in FIG. 9, the two-dimensional deflector 14 is, for example, a polygon mirror with surface tilt. The polygon mirror with surface tilt has a configuration in which each deflection surface is inclined by a predetermined angle in the sub-scanning direction with respect to the adjacent deflection surface. Here, a description will be given by taking as an example a polygon mirror with surface tilt having eight deflection surfaces (deflection surfaces P1 to P8).

FIG. 9A is a main scanning sectional view showing a schematic configuration of a polygon mirror with surface tilt. As shown in FIG. 9A, the deflection surface P1 is a surface parallel to the sub-scanning direction, while the other deflection surfaces P2 to P8 have an angle with respect to the sub-scanning direction. FIG. 9B is a diagram for explaining the surface tilt shape of the polygon mirror with surface tilt. For convenience of explaining such a shape, FIG. 9B shows only the deflection surfaces P1, P2, and P3. As shown in FIG. 9B, the adjacent deflection surfaces P1 and P2 or the deflection surfaces P2 and P3 are each configured to have a surface tilt angle α. As the subscript of the deflection surface P increases by 1, the angle between the deflection surface and the sub-scanning direction increases by α degrees. The deflection surface P8 is inclined at an angle 7α with respect to the deflection surface P1 (sub-scanning direction). Each deflection surface of the polygon mirror with surface tilt deflects incident laser light in the sub-scanning direction by an amount corresponding to the surface tilt angle. That is, the scanning width, scanning interval, etc. in the sub-scanning direction are defined by the surface tilt angle of each deflection surface.

Consider the case where the number of scanning lines in the entire range including the non-effective scanning region R is 560 and the deflection surface of the polygon mirror with surface tilt is 16 surfaces. In this case, an array light source in which, for example, 35 light sources are arranged in the sub-scanning direction as the light source unit is mounted on the two-dimensional scanning projection apparatus 100y. Then, 35 laser beams are simultaneously incident on the deflecting surfaces and deflected, and are simultaneously scanned on the screen S via the optical system at the subsequent stage. Since 35 scanning lines are scanned using each deflection surface, the total number of scanning lines reaches 540, which is obtained by multiplying the number of simultaneous scanning lines 35 by the number 16 of deflection surfaces.

The number of light sources to be mounted on the two-dimensional scanning projection apparatus 100y and the number of deflection surfaces of the polygon mirror with surface tilt are appropriately selected according to the required number of scanning lines, scanning speed, and the like. The details of the polygon mirror with surface tilt are disclosed in, for example, Japanese Patent Application Laid-Open No. 61-198208.

FIG. 10 is a main scanning sectional view schematically showing the configuration of the two-dimensional scanning projection apparatus 100x of the fourth embodiment. As shown in FIG. 10, the two-dimensional scanning projector 100x has a beam splitter 18 as an alternative to the light beam separation mirror 8a. The beam splitter 18 transmits the laser light emitted from the light source unit, and reflects the reflected light from the reflecting members 7 and 7 '. The reflected light reflected by the beam splitter 18 is collected by the sensor optical system 8b and received by the light receiving sensor 8c. According to the configuration of the fourth embodiment, a further amount of reflected light is guided to the light receiving sensor 8c. Since the light receiving sensor 8c can receive a lot of reflected light, it can output a detection signal at a stable level.

Incidentally, the beam splitter 18 is disposed at a position that intersects the central axis AX of the two-dimensional scanning projector 100x (in other words, the laser light emitted from the light source unit). Therefore, in the case of the configuration of the fourth embodiment, the laser light reflected by the reflecting member 7 is deflected by the beam splitter 18 and guided to the light receiving sensor 8c even when the width is not widened in the main scanning direction. Therefore, in 4th embodiment, the reflective surface 7a of the reflective member 7 does not need to be a convex surface, and may be comprised by the plane, for example.

The above is the embodiment of the present invention. The two-dimensional scanning projection apparatus according to the present invention is not limited to the above-described configuration, and various modifications are possible within the scope of the technical idea of the present invention. For example, the two-dimensional scanning projector according to the present invention is not limited to a multi-beam two-dimensional scanning projector, but may be a single-beam two-dimensional scanning projector.

In the two-dimensional scanning projection apparatus according to another embodiment, a region corresponding to the reflecting member 7 or 7 'on the screen S has reflectivity instead of an optical component such as the reflecting member 7 or 7'. The structure which apply | coated or printed the material may be sufficient. In such a case, the coating agent has the effect of increasing the divergence of the laser light incident on the reflecting surface 7a and reflecting it as a slightly broadened light beam. When the reflecting

member

7 or 7 ′ is manufactured by printing or the like, it is excellent in mass productivity and positional accuracy and advantageous in terms of cost.

Further, as a substitute for the beam splitter 18 of the fourth embodiment, a two-dimensional scanning projection apparatus having a diaphragm mirror is assumed. The diaphragm mirror also has a slit that is wider than the width of the laser light emitted from the light source unit and narrower than the width of the reflected light from the reflecting member 7 in the main scanning direction. Therefore, the laser light emitted from the light source unit passes through the slit of the diaphragm mirror. On the other hand, part of the reflected light from the reflecting member 7 enters the shielding part of the diaphragm mirror. Here, the shielding portion of the diaphragm mirror is configured as a reflection surface or a diffraction surface. Therefore, a part of the reflected light from the reflecting member 7 is deflected or diffracted by the shielding part, enters the sensor optical system 8b, and is guided to the light receiving sensor 8c.

The two-dimensional scanning projection apparatus according to the present invention is assumed to be mounted on a projector, but can be suitably used for other image forming apparatuses such as a laser printer and an image scanner.

Claims

In a scanning projection apparatus that scans a light beam on a surface to be scanned in two directions of a main scanning direction and a sub-scanning direction orthogonal to the main scanning direction,
At least one light source unit for irradiating the luminous flux;
A scanning unit that deflects the irradiated light beam and scans the scanned surface in the two directions;
A first reflecting portion disposed in an area outside the effective scan on the scanned surface and having a higher reflectance than the effective scanning area on the scanned surface;
A light flux returning section that returns the light flux reflected by the first reflecting section and re-enters the scanning section;
A reflected light detector that detects a part of reflected light that is re-incident on the scanning unit and deflected;
A light emission control unit that performs light emission control according to a projection image on the at least one light source unit according to the timing of detection of the reflected light by the reflected light detection unit;
A scanning projection apparatus comprising:
2. The scanning projection apparatus according to claim 1, wherein the first reflecting part is a long reflecting part having a long side in the sub-scanning direction.
3. The first reflecting portion according to claim 1, wherein the first reflecting portion is disposed in proximity to a position where writing of the light beam in the main scanning direction is scheduled on the surface to be scanned. A scanning projection apparatus according to claim 1.
The said light emission control part performs the said light emission control with respect to the said at least 1 light source part after progress for a predetermined time after the said reflected light is detected by the said reflected light detection part. Item 4. The scanning projection device according to any one of Items 3 to 4.
A second reflecting portion having a side that forms a predetermined angle with respect to the side of the first reflecting portion;
The reflected light detection unit detects reflected light of each of the first reflection unit and the second reflection unit,
The light emission control unit controls a writing position in the sub-scanning direction of the light beam on the scanned surface based on a detection time interval of reflected light of each of the first reflecting unit and the second reflecting unit. The scanning projection apparatus according to claim 3, wherein the scanning projection apparatus according to claim 3 is cited.
The first reflection part or the second reflection part is a reflection member attached to the area outside the effective scan, or a reflection area coated or printed on the area outside the effective scan. The scanning projection apparatus according to any one of claims 1 to 5.
The light flux returning section returns the light flux incident on the first reflecting section or the second reflecting section to the first reflecting section or the second reflecting section in order to return the light flux incident on the first reflecting section or the second reflecting section. The scanning projection apparatus according to any one of claims 1 to 6, further comprising a normal incidence optical element that makes incidence perpendicularly.
The scanning projection apparatus according to claim 7, wherein the normal incidence optical element is a Fresnel lens disposed close to the surface to be scanned.
It further includes a reflected light deflecting unit that deflects at least a part of the reflected light returned to the substantially same optical path and deflected by the scanning unit from the optical path and guides the reflected light to the reflected light detecting unit. The scanning projection apparatus according to claim 7 or 8.
The scanning unit is sequentially from the light source unit side,
A deflector for deflecting the light beam in the main scanning direction or the sub-scanning direction;
A scanning optical system for scanning the light beam deflected by the deflector on the surface to be scanned;
Have
The scanning projection apparatus according to claim 9, wherein the reflected light deflecting unit is disposed in the vicinity of the deflector.
The optical system further includes a conjugate optical system that conjugates an optical pupil between a deflection surface of the deflector that deflects the light beam and a detection surface of the reflected light detection unit that detects the reflected light. Item 11. A scanning projection apparatus according to Item 10.
The deflector is a two-dimensional scanning galvanometer mirror, a two-dimensional MEMS (Micro Electro Mechanical Systems) mirror, or a polygon mirror with surface tilt, which deflects the light beam in the two directions. The scanning projection apparatus according to claim 11.
The first reflecting part or the second reflecting part is configured to reflect the light beam incident on the first reflecting part or the second reflecting part with a large divergence, and the reflected light deflecting part is The scanning projection apparatus according to claim 9, wherein light around the reflected light beam is deflected to the reflected light detection unit.
The first reflecting portion or the second reflecting portion is configured by a single convex shape having a size equal to or larger than the spot size of the light beam incident on the first reflecting portion or the second reflecting portion, or The scanning projection apparatus according to claim 13, wherein the scanning projection apparatus includes a plurality of convex shapes having a size smaller than a spot size.