JP2002178555A - Optical unit, writing head and imaging unit - Google Patents

Abstract

PROBLEM TO BE SOLVED: To accurately form an image in the same magnification while miniaturizing an imaging optical system. SOLUTION: An optical system 3a comprises two convex lenses 32, 33 provided with a certain interval therebetween on one side of parallel surfaces of a transparent substrate 31, and a concave surface mirror 34 provided midway between the two convex lenses 32, 33 on the other side of the transparent substrate 31. A light from an object surface 1 incident on the convex lens 32 is collected so that the collected light is reflected by the concave surface mirror 34 so as to be collected on an image surface 2 by the convex lens 33. Thereby, the image on the object surface 1 is formed on the image surface 2 in the same magnification.

Description

DETAILED DESCRIPTION OF THE INVENTION

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an optical device and a write head used in a writing optical system for writing characters and images in an electrophotographic printer or a copying machine, and an image forming apparatus using the same. In particular, it relates to miniaturization of an optical device.

[0002] LE using light emitting diode (LED)
The D array is used for writing an image in an electrophotographic printer or copier. The printer using the LED array has a strong advantage against deformation of the optical system due to vibration and heat as compared with a laser raster printer. As shown in FIG. 14, the writing optical system of the printer using this LED array condenses the light emitted from the LED array 30 on the surface of the photoreceptor 19 by the imaging lens 61 to expose the photosensitive surface and expose the latent surface. Form an image.

In recent years, printers and copiers are required to be color-compatible and form high-definition images, and are also required to be reduced in size and cost. In order to cope with colorization, a tandem system using multiple photoconductors is often adopted, and a small-diameter drum photoconductor is used for miniaturization and cost reduction to form high-definition images. Also, the imaging optical system is being shortened. Therefore L
Since the writing head using the ED array is located close to the photoconductor, it is desired to reduce the thickness and size of the imaging optical system.

In order to reduce the thickness and size of the write head, for example, a write head disclosed in Japanese Patent Laid-Open No. 7-108709 has a housing 62 in which a plurality of rod lens arrays are arranged as shown in FIG. The LED array 30 is arranged so that the optical axis of the imaging lens array 63 attached to the LED coincides with the optical axis of each LED of the surface-emitting type LED array 30, and the imaging lens is provided on the incident side of the imaging lens array 63. An aperture member 64 having a plurality of holes having a diameter smaller than the diameter of the rod lens is arranged in the same arrangement as the arrangement of the rod lenses in the array 63, and only the direct light from each LED of the LED array 30 is irradiated on the photoconductor 19. Thus, a clear and accurate latent image is formed on the photoconductor 19.

When condensing light from the surface-emitting type LED array 30, the substrate surface of the LED array 30 is
It is common to paste them together. Therefore, the imaging lens array 63 is arranged in a direction perpendicular to the support substrate 65, and extracts light from the LED array 30 in a direction perpendicular to the support substrate 65. LED array 3 on support substrate 65
Since it is necessary to mount a driver LSI and peripheral circuits in addition to 0, there is a limit in reducing the width of the support substrate 65. When the housing 62 is brought close to the photoconductor 19, the occupied angle with respect to the photoconductor 19 is increased. However, it cannot be reduced due to the size of the support substrate 65, and there is a problem that the space required for other developing units and fixing units arranged around the photoconductor 19 is pressed.

On the other hand, Japanese Patent Application Laid-Open No. 8-32110 discloses a writing head in which the occupying angle with respect to a photoreceptor is reduced. As shown in FIG. 16, the write head uses an edge-emitting LED array 66, and the pn junction surface 67 of the edge-emitting LED array 66 and the optical axis of the imaging lens 61 using the rod lens array. The inner diameter of the cylindrical support 68 is made equal to the outer diameter of the imaging lens 61 so that light is emitted along the axis of the cylindrical support 68. In this writing head, the inner diameter of the cylindrical support 68 is formed equal to the outer diameter of the imaging lens 61,
Light is emitted along the axis of the support 68. In this write head, since the driver LSI and peripheral circuits are mounted on the edge emitting LED array 66, the thickness cannot be reduced in the longitudinal direction of the cylindrical support member 68, but the thickness can be reduced. Since the thickness can be reduced to about the thickness of the imaging lens 61, the space occupied by the photoconductor 19 can be reduced even when the cylindrical support 68 is brought close to the photoconductor 19.

Japanese Patent Application Laid-Open No. 8-79447 discloses an imaging optical system that does not use a rod lens array.
As shown in FIG. 17, the light of the object surface 70 is incident on the lens 72 of the first substrate 71, and the imaging optical system communicates with the opening 74 of the first substrate 71 provided with the spacer plate 73 interposed therebetween. The light is condensed by a lens 77 provided on the second substrate 75 via the opening 76 of the second substrate 75 and forms an image on an image plane 78. The oblique light incident on the lens 72 of the first substrate 71 is blocked by a light-shielding surface 79 between adjacent openings 74 of the first substrate 71.

[0008]

However, the edge-emitting LED array disclosed in Japanese Patent Application Laid-Open No. 8-32110 requires more time for manufacturing and mounting than the surface-emitting LED array. It causes cost increase.
For this reason, it is desirable to configure a write head using a surface-emitting type LED array. When an edge emitting LED array is used, the thickness of the imaging lens is about 3 mm at present, but further thinning cannot be expected in terms of handling and rigidity.

In order to obtain the same focal length and resolution as the optical system using a rod lens array in the optical system disclosed in Japanese Patent Application Laid-Open No. 8-79447, a plurality of lenses 72, an opening 74, and a light shielding surface 79 are required. Since the thickness of the first substrate 71 and the spacer 73 and the second substrate 74 having the plurality of openings 76 and the lenses 77 are substantially the same as those of the optical system using the rod lens array, the thickness of the entire optical system is reduced. It cannot be thinned. In addition, since the first substrate 71 and the second substrate 74 are stacked, it is necessary to strictly adjust the optical axis of each lens and the aperture during manufacturing. A lot of man-hours are required in the axis alignment process during assembly, which causes an increase in cost.

SUMMARY OF THE INVENTION It is an object of the present invention to provide an optical device, a writing head, and an image forming apparatus using the optical device capable of improving the disadvantages and reducing the size of the image forming optical system to accurately form a 1: 1 image. It is the purpose.

[0011]

An optical device according to the present invention has one or a plurality of optical elements arranged on both surfaces or one surface of a plate-shaped transparent substrate and a light incident on the transparent substrate from an object surface. Is emitted to the image plane via each optical element to form an equal-magnification image on the image plane.

Preferably, the optical element disposed on the transparent substrate includes a reflective element, and a non-reflective structure is disposed around the reflective element.

Preferably, the optical elements disposed on the transparent substrate include a light-collecting element on the incident side and a light-collecting element on the emitting side.

Further, it is preferable to have a roof prism in which a ridge is arranged at a position where the optical axis of the incident side light condensing element and the light exit side light condensing element cross each other.

The plate-shaped transparent substrate is a parallel plate,
All the optical elements on one side of the transparent substrate may be plane mirrors.

Further, an optical element may be provided on one surface of the transparent substrate, and the optical elements may be arranged such that the other surface of the transparent substrate is a total reflection surface.

It is desirable that one or both of the light incident surface and the light emitting surface of the transparent substrate be provided on the side surface of the transparent substrate.

Further, it is preferable to arrange the optical elements in an array of one row. Further, it is desirable to dispose a light shielding portion between the optical elements arranged in an array.

A writing head according to the present invention is characterized in that the above optical device is used in an imaging optical system for imaging light from a light source on a photosensitive surface.

An image forming apparatus according to the present invention is characterized in that an image is written on a photoreceptor by the write head.

[0021]

DETAILED DESCRIPTION OF THE INVENTION An optical system for forming an equal-magnification image from an object surface to an image surface according to the present invention comprises a first transparent substrate provided on the object surface side and an image surface side in contact with the first transparent substrate. The second provided in
And a transparent substrate. The first transparent substrate has a first convex lens provided on the object-side surface, and a second convex lens provided on the second transparent substrate-side surface with the optical axis of the first convex lens coincident with the first convex lens. . The second transparent substrate has a third convex lens provided on the surface on the first transparent substrate side, and a fourth convex lens provided on the image side surface with the optical axis coincident with the third convex lens. . The first transparent substrate and the second transparent substrate are the second transparent substrate.
The optical axes of the convex lens of the third lens and the third
And the third convex lens are in contact with each other.

In this optical system, the optical axes of the first convex lens and the second convex lens of the first transparent substrate are obliquely shifted with respect to the lens surface, and the curvatures of the first convex lens and the second convex lens are slightly changed. Similarly, the optical axes of the third convex lens and the fourth convex lens of the second transparent substrate are obliquely shifted with respect to the lens surface, and the curvatures of the third convex lens and the fourth convex lens are slightly changed. By optimizing, an image of the object surface can be formed on the image surface as a 1: 1 image. Therefore, the thickness of the optical system can be reduced, and the distance from the object surface to the first transparent substrate and the distance from the second transparent substrate to the image plane can be reduced.

[0023]

Embodiment 1 FIG. 1 is a configuration diagram of one embodiment of the present invention. As shown in the figure, the image of the object surface 1 is
An optical system 3 that forms an image at the same magnification as the first is provided with a first transparent substrate 4 provided on the object surface 1 side and a second transparent substrate 4 provided on the image surface 2 side in contact with the first transparent substrate 4. And a transparent substrate 5.
The first transparent substrate 4 has a first convex lens 6 provided on the surface on the object surface 1 side and a first convex lens 6 provided on the surface on the second transparent substrate 5 side.
And a second convex lens 7 provided with the optical axis coincident. The second transparent substrate 5 is provided with a third convex lens 8 provided on the surface on the first transparent substrate 4 side and a third convex lens 8 provided on the surface on the image plane 2 side with the third convex lens 8 aligned with the optical axis. 4 convex lens 9
Having. The first transparent substrate 4 and the second transparent substrate 5
Is arranged such that the optical axes of the second convex lens 7 and the third convex lens 8 are aligned with each other, and the second convex lens 7 and the third convex lens 8 are in contact with each other.

As shown in FIG. 2, for example, the optical system 3 condenses a light beam from the object surface 1 through the condenser lens 10, the relay lens 11, and the condenser lens 12 to condense it on the image surface 2. This is equivalent to a conventional erect imaging optical system 13 that forms an image of the surface 1 on the image surface 2 as an equal-magnification image. The lens 12 is replaced by convex lenses 6 to 9 of a first transparent substrate 4 and a second transparent substrate 5. Therefore, the image of the object surface 1 can be formed at the same magnification on the image surface 2 by the optical system 3 having the first transparent substrate 4 and the second transparent substrate 5.

As shown in FIG. 3, for example, the optical system 3 displaces the optical axes of the first convex lens 6 and the second convex lens 7 of the first transparent substrate 4 obliquely with respect to the lens surface. The curvature of the convex lens 6 and the second convex lens 7 is slightly changed to optimize, and similarly, the optical axes of the third convex lens 8 and the fourth convex lens 9 of the second transparent substrate 5 are inclined with respect to the lens surface. By shifting and optimizing the curvature of the third convex lens 8 and the fourth convex lens 9 by slightly changing them, the image of the object surface 1 can be formed on the image surface 2 as a 1: 1 image. Therefore, the thickness of the optical system 3 can be reduced, and
And the distance between the first transparent substrate 4 and the second transparent substrate 5
From the image plane 2 to the image plane 2 can be shortened.

FIG. 4 shows the configuration of an image forming apparatus such as a copying machine or a printer using the optical system 3 as a write head.
The image forming apparatus 14 includes an image forming unit 15, a primary transfer unit 16, a secondary transfer unit 17, and a fixing unit 1.
8 The image forming unit 15 includes a charging charger 20 and a writing head 21 disposed around the photoconductor 19, a color developing unit 22 including cyan (C), magenta (M), yellow (Y), and black (K). It has a drum cleaning unit 23 and irradiates a laser beam from the writing head 21 onto the photoreceptor 19 charged by the charging charger 20 to form an electrostatic latent image. The formed electrostatic latent image is visualized by the color developing unit 22. To form a toner image. The primary transfer unit 16 includes an intermediate transfer belt 24, a primary transfer unit 25, a tension roller 26, a secondary transfer roller 27, a cleaning unit 28, and a reference position sensor 29. When a color image is formed, the photosensitive member 19 is used. Are primarily transferred onto the intermediate transfer belt 24 and are superimposed. The intermediate transfer belt 24 is separated from the surface of the photoreceptor 19 by a contact / separation mechanism except when the toner image on the photoreceptor 19 is primarily transferred, and the surface of the photoreceptor 19 is only used when the image is primarily transferred to the intermediate transfer belt 24. Is pressed against. Secondary transfer unit 1
Reference numeral 7 secondary-transfers the toner image transferred to the intermediate transfer belt 24 to recording paper. The fixing unit 18 fixes the toner image transferred to the recording paper by heat and pressure.

The write head 21 is, as shown in FIG.
It has an LED array 30, a first transparent substrate 4 and a second transparent substrate 5, and a laser beam emitted from the LED array 30 is incident on the photoreceptor 19 through the optical system 3 and is magnified by an input image. Is formed on the photoconductor 19. The laser beam emitted from the LED array 30 in this manner is
Is obliquely incident on the transparent substrate 4 and the incident laser beam is obliquely emitted from the optical system 3 to write image information on the photosensitive member 19, so that the thickness of the write head 21 can be reduced and the size can be reduced. .

Further, a first transparent substrate 4 having a first convex lens 6 and a second convex lens 7 and a second transparent substrate 5 having a third convex lens 8 and a fourth convex lens 9 form an equal-magnification image. The case where the optical system 3 to be formed is configured has been described. However, as shown in FIG. 6, an optical system 3a that forms an equal-magnification image using one transparent substrate 31 can also be configured. In this case, the optical system 3a is provided between the two convex lenses 32 and 33 provided at a constant interval on one parallel surface of the transparent substrate 31 and the intermediate between the two convex lenses 32 and 33 on the other surface of the transparent substrate 31. Is formed by the concave mirror 34 provided in the first mirror. The optical system 3a receives the light from the object surface 1 into the convex lens 32 and condenses it, reflects the condensed light by the concave mirror 34, and condenses the light on the image surface 2 by the convex lens 33.
To form an image at the same magnification of the image of the object surface 1 on the object surface 2. Such an optical system that performs processing while transmitting light through the transparent substrate 31 is generally referred to as a folding optical system. In the folding optical system, a mirror can be arranged in the middle of the optical system, and the optical path can be bent at the mirror surface to fold the space, and the thickness can be reduced each time the space is folded. When this folding optical system is used, the optical elements arranged on the optical axis can be rearranged in the same plane, so that when manufacturing the optical system, the number of surfaces on which the optical system is arranged is reduced, and the number of parts can be reduced. be able to. Further, the manufacturing process can be simplified by collectively manufacturing optical elements in the same plane. ,
Further, the optical system can be manufactured by accurately arranging the optical system in the plane, and there is an advantage that a positioning step of aligning a plurality of components in accordance with the optical axis can be eliminated.

The two convex lenses 32 and 33 and the concave mirror 3
When the optical system 3a having the surface 4 is manufactured, since the surface to be processed is substantially two surfaces, the front surface and the back surface, the convex lens 3
2, 33 and the concave mirror 34 on the back surface can be manufactured at once. The optical axes of the convex lenses 32 and 33, which are optical elements, and the concave mirror 34 are aligned with the positional accuracy of the convex lenses 32 and 33 disposed on the front surface of the transparent substrate 31 and the positional accuracy of the concave mirror 34 disposed on the rear surface of the transparent substrate 31. So that
The accuracy of the mold and mask for forming the convex lenses 32 and 33 and the accuracy of the mold and mask for forming the concave mirror 34 can be uniquely determined. For example, when the convex lenses 32 and 33 are configured by micro lenses and the concave mirror 34 is configured by micro mirrors, the position designation by photolithography can be performed by, for example, 1 μm.
m or less, and the accuracy of optical axis alignment can be remarkably improved as compared with the case where a plurality of lenses are bonded. Further, the optical system 3a can be formed by one transparent substrate 31, the thickness of the optical system 3a can be reduced, and the optical system 3a can be reduced in size. By using this optical system 3a for the writing head 21 of the image forming apparatus, In addition, the write head 21 can be downsized.

In the above embodiment, the folding optical system 3a is constructed by reflecting the light with the concave mirror 34 in the middle of the optical path of the convex lenses 32 and 33. However, the reflecting surface is not required to be provided in the middle of the lens surface or in parallel with the lens surface. Is also good. The optical system arranged on the plate-shaped transparent substrate is not only a passive element such as a flat mirror, a curved mirror, a prism, a refractive lens, a grating lens, a wavelength filter, and a polarizing element, but also a liquid crystal cell that can dynamically switch an aperture. Alternatively, an active element such as a liquid crystal lens using a refractive index change due to a voltage or a movable micromirror using a micromachine technology may be used.

Embodiment 2 In the above embodiment, the case where the optical system 3a is constituted by the convex lenses 32 and 33 provided on one transparent substrate 31 and the concave mirror 43 has been described. An optical system to be formed may be configured. As shown in the configuration diagram of FIG. 7, the optical system 3b having a plurality of reflective elements includes an incident surface 36 formed on the side surface of the transparent substrate 35 at a constant incident angle, and one surface of the transparent substrate 35 The formed concave mirrors 37a and 37b, the grating lens 38, and the flat mirror 3 formed on the other surface of the transparent substrate 35
9a, 39b and 39c. The light incident on the optical system 3b is refracted on the incident surface 36, and the refracted light is converted into a plane mirror 39.
The reflected light is condensed by a convex mirror 37a, then reflected by a plane mirror 39b, a convex mirror 37b and a plane mirror 39c, sequentially condensed by a grating lens 38a, and emitted to form a 1: 1 image. In the case where light is reflected a plurality of times in the transparent substrate 35 as described above, when the transparent substrate 35 is thinned, the plane mirrors 39a, 39b, 39c and the convex mirrors 37a, 37c that reflect light are reduced.
7b approaches and is easily affected by unnecessary light such as flare light. Therefore, the plane mirrors 39a, 39b, 39c and the convex mirror 37
Non-reflective surfaces 40 and 41 are provided on surfaces other than the a and 37b and the grating lens 38a to limit the optical path of light passing through the transparent substrate 35 to reduce the influence of flare light.

When this optical system 3b is manufactured, FIG.
As shown in (a), one end of a flat transparent substrate 35 made of, for example, quartz glass is fixed at a certain angle α, for example, 8 °.
The incident surface 36 is formed by polishing at an angle of 0.1 degrees. next,
By ordinary photolithography and etching, FIG.
As shown in (b), a convex lens 42a for condensing incident light, a convex lens 42b serving as a relay lens, and a grating lens 38 for condensing outgoing light are formed on one surface of the transparent substrate 35. Thereafter, as shown in FIG. 7 (c), reflective films 43a and 43b are formed on the surfaces of the convex lenses 42a and 42b by vapor deposition and etching of aluminum to produce convex mirrors 37a and 37b. Further, the incident light is reflected by the other surface of the transparent substrate 35 and the convex mirror 42a
And the reflected light from the convex mirror 37a
5, reflection surfaces 44a, 44b, and 44c are formed at positions where the light is reflected by the other surface of the transparent substrate 35 and is incident on the grating lens 38 after being reflected by the other surface of the transparent substrate 35. And the plane mirrors 39a-3
9c is produced. As shown in the plan view of FIG. 9, when the grating lens 38, the convex mirrors 37a and 37b, and the plane mirrors 39a to 39c are manufactured on the transparent substrate 35, the optical elements such as the grating lens 38 are arranged in a plane. Since the alignment between the optical elements can be performed with the accuracy of photolithography for manufacturing the elements, the alignment accuracy is remarkably improved as compared with the case where a plurality of optical elements are aligned and bonded by the conventional method. be able to. Next, as shown in FIG. 7D, non-reflective surfaces 40 and 41 are formed by applying black resin on both surfaces of the transparent substrate 35 except for the grating lens 38, so that unnecessary flare light is not generated. Optical system 3b
Is prepared.

When the write head 21 is manufactured using the optical system 3b thus manufactured, as shown in FIG.
b and align the LED array 30 with the spacer 46
Is pasted on the printed circuit board 45 via the.

The write head 2 thus manufactured
1, when writing image information on the photoconductor 19, L
The light emitted from the ED array 30 is incident on the incident surface 36 of the optical system 3c, the light is refracted on the incident surface 36, the refracted light is reflected on a plane mirror 39a, and the reflected light is condensed on a convex mirror 37a and then condensed on a plane mirror. 39b, convex mirror 37b and plane mirror 39
Then, the light is sequentially reflected at c and condensed on the surface of the photoreceptor 19 by the grating lens 38a to form a 1: 1 image. When this light propagates through the transparent substrate 35 of the optical system 3c, the plane mirror 39a
Since the optical path is limited by .about.39c, aberration at the time of image formation can be improved. Further, since the thickness of the optical system 3b can be reduced, the size of the write head 21 can be reduced.

Third Embodiment In the second embodiment, the case where the optical system 3b and the LED array 30 are separately provided on the printed circuit board 45 to form the write head 21 has been described. The write head 21 may be configured integrally with the write head 21. FIG. 10 and FIG.
FIG. 10 is a side sectional view and FIG. 11 is a plan view showing a configuration of a write head 21 in which the array 30 is integrated with an optical system. As shown in the figure, the write head 21 has an optical system 3c.
And LE provided on the upper surface of the transparent substrate 50 of the optical system 3c.
It has a D array 30. The optical system 3 c includes a concave mirror 51 provided as an optical element on the incident-side upper surface of a transparent substrate 50 made of, for example, polycarbonate, a condenser lens 52 inclined at 45 degrees on the exit-side upper surface, and a concave mirror 51 and a condenser lens 52. As shown in the cross-sectional view of FIG.
It has a roof mirror 53 formed at an angle of degrees. Further, as shown in FIG. 12B, a light shielding groove 54 into which a black resin is injected is provided with an optical path between the LED array 30 and the concave mirror 51 interposed therebetween. The optical elements such as the LED array 30 and the concave mirror 51 are arranged such that the upper and lower surfaces of the transparent substrate 50 form a total reflection surface.

When manufacturing the write head 21,
As shown in FIG. 13A, a convex lens 55 for forming a transparent substrate 50 made of, for example, polycarbonate and a concave mirror 51, a condenser lens 52, a roof mirror 53, and a groove 56 for forming a light shielding groove 54 in a mold. To form Next, as shown in FIG. 13B, the reflecting surface 5 is formed on the upper surface of the convex lens 55 to form the concave mirror 51, and the black resin is injected into the groove 56 to form the light shielding groove 54, and the optical system 3c is formed. To form
Next, the LED array 3 is placed at a predetermined position on the upper surface of the transparent substrate 50.
The driving IC 58 for driving the LED array 30 and the LED array 30 is flip-mounted. In order to mount the LED array 30 and the driving IC 58, a wiring pattern is provided on the upper surface of the transparent substrate 50.

When a write latent image is formed on the photoreceptor 19 by the write head 21, of the light emitted from the LED array 30, the light flux radiated in the direction of approximately 45 degrees is the refractive index between the transparent substrate 50 and air. Is reflected by the total reflection surface on the front surface and the rear surface of the transparent substrate 50, enters the concave mirror 51, is reflected, and becomes a parallel light beam. This parallel light beam is reflected on the total reflection surface on the front and back surfaces of the transparent substrate 50, is inverted by the roof mirror 53 in the direction perpendicular to the surface of FIG. 10, and is reflected on the total reflection surface on the front and back surfaces of the transparent substrate 50. The image is formed on the photosensitive surface of the photoconductor 19 by the converging lens 53 inclined at an angle to form an image of the same magnification as the input image. When forming an equal-magnification image on the photoconductor 19, the light-shielding groove 54 blocks light between adjacent channels, thereby removing unnecessary flare light and suppressing deterioration of image formation. In addition, in order to realize an equal-magnification imaging system, a roof mirror 5 is provided.
Since the image inversion is performed by the method 3, a relatively bright optical system can be realized. Also, the transparent substrate 50 is
Since the D array 30 and the drive IC 58 are integrated, the write head 21 can be thin and small, and can be easily manufactured.

[0038]

As described above, according to the present invention, one or a plurality of optical elements are arranged on both sides or one side of the front and back surfaces of a plate-shaped transparent substrate, and light incident on the transparent substrate from the object surface is transmitted to each optical element. By constructing a so-called folding optical system so as to form a so-called folding optical system by emitting an image to the image plane via the element and forming an image on the image plane, the thickness of the optical device can be reduced and the size of the optical device can be reduced. .

Further, by arranging the non-reflection structure around the reflection element arranged on the transparent substrate, the optical path can be limited, and the influence of flare light can be reduced.

Further, since the optical elements disposed on the transparent substrate include the light-collecting element on the incident side and the light-collecting element on the output side, the unevenness of the optical device can be reduced to easily produce the same-magnification image forming optical system. Can be.

Further, by arranging a roof prism having a ridgeline at a position where the optical axis of the incident side light condensing element and the light exit side light condensing element cross each other, the incident light can be efficiently emitted, and a bright equal magnification is obtained. An imaging optics can be provided.

Further, the plate-shaped transparent substrate is formed of a parallel plate, and all the optical elements on one side of the transparent substrate are constituted by plane mirrors. It can be easily manufactured.

Further, the optical element is provided on one surface of the transparent substrate, and each optical element is arranged so that the other surface of the transparent substrate becomes a total reflection surface, so that a reflection film is laminated on one surface of the transparent substrate. It is not necessary and can be made flat, so that the same-magnification imaging optical system can be easily manufactured.

Further, by providing one or both of the light incident surface and the light emitting surface of the transparent substrate on the side surface of the transparent substrate, the light incident direction and the light emitting direction can be defined independently of the optical system disposed on the surface. Thus, a user-friendly optical device can be realized.

In addition, by arranging the optical elements in an array of one row, the optical device can be reduced in size and easily manufactured.

Further, by arranging the light shielding portion between the optical elements arranged in an array, the optical crosstalk between the respective optical systems can be reduced, and the imaging performance can be improved.

By using this optical device for an image forming optical system of a write head that forms an image of light from a light source on a photosensitive surface, the write head can be downsized.

Further, by using this write head in an image forming apparatus such as a printer or a copying machine, the area occupied by the write head with respect to the photoconductor can be reduced, and a high quality 1: 1 image can be formed on the photoconductor. can do.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of an embodiment of the present invention.

FIG. 2 is a configuration diagram of a conventional erect imaging optical system.

FIG. 3 is another layout diagram of the optical system of the embodiment.

FIG. 4 is a configuration diagram of an image forming apparatus.

FIG. 5 is a configuration diagram of a write head using the optical system of the embodiment.

FIG. 6 is a configuration diagram showing another configuration of the embodiment.

FIG. 7 is a configuration diagram of a write head according to a second embodiment.

FIG. 8 is a process chart showing a manufacturing process of the optical system of the second embodiment.

FIG. 9 is a plan view of an optical system according to a second embodiment.

FIG. 10 is a configuration diagram of a write head according to a third embodiment.

FIG. 11 is a plan view of a write head according to a third embodiment.

FIG. 12 is a sectional view of an optical system according to a third embodiment.

FIG. 13 is a process chart showing a manufacturing process of the optical system of the third embodiment.

FIG. 14 is a configuration diagram of a conventional write head.

FIG. 15 is a configuration diagram of a second conventional example of a write head.

FIG. 16 is a configuration diagram of a third conventional write head.

FIG. 17 is a configuration diagram of a fourth conventional write head.

[Explanation of symbols]

Reference Signs List 1; object surface, 2; image surface, 3; optical system, 4; first transparent substrate, 5; second transparent substrate, 6; first convex lens, 7; second convex lens, 8; Convex lens, 9; fourth convex lens, 31; transparent substrate, 32, 33; convex lens, 34; concave mirror.

Claims (11)

[Claims] 1. One or a plurality of optical elements are arranged on both surfaces or one surface of a plate-shaped transparent substrate, and light incident on the transparent substrate from the object surface is emitted to the image plane via each optical element. An optical device characterized by forming an equal-magnification image on an image plane. 2. The optical device according to claim 1, wherein the optical element disposed on the transparent substrate includes a reflection element, and a non-reflection structure is disposed around the reflection element. 3. The optical device according to claim 1, wherein the optical elements disposed on the transparent substrate include an incident-side light-collecting element and an output-side light-collecting element. 4. The optical device according to claim 3, wherein a roof prism having a ridge is disposed at a position where an optical axis of the incident side light-collecting element and an emission side light-collecting element intersect. 5. The plate-shaped transparent substrate is a parallel plate,
2. The optical device according to claim 1, wherein all the optical elements on one side of the transparent substrate are plane mirrors. 6. The optical device according to claim 1, wherein the optical element is provided on one surface of a transparent substrate, and the optical elements are arranged such that the other surface of the transparent substrate becomes a total reflection surface. apparatus. 7. The transparent substrate according to claim 1, wherein one or both of a light incident surface and a light emitting surface of the transparent substrate are provided on a side surface of the transparent substrate.
7. The optical device according to any one of claims 1 to 6. 8. The optical device according to claim 1, wherein the optical elements are arranged in an array of one row. 9. The optical device according to claim 8, wherein a light shielding portion is arranged between the optical elements arranged in the array. 10. A writing head, wherein the optical device according to claim 1 is used in an imaging optical system that forms light from a light source on a photosensitive surface. 11. An image forming apparatus comprising the write head according to claim 10.