JPH02549A - Optical scanner - Google Patents

Abstract

PURPOSE:To prevent an image from laterally deviating at a joint and to sufficiently read an original by altering the optical axis plane of a second optical element array on a mirror, and superposing it from a first optical element array on the optical axis plane up to an image forming surface or an original surface. CONSTITUTION:A light radiated from a first LED array 10 is not interrupted by a mirror 9 but passed over an optical axis plane X, and focused on a linear line O of an image forming surface 3 by a focusing lens 8. On the other hand, a light radiated from a second LED array 12 is reflected on the mirror 9, and focused on the linear line O on the surface 3 by the lens 8. The line O on the surface 3 is optically scanned by flashing the arrays 10, 12 in response to an input image signal to form an electrostatic latent image. Since the light from the arrays 10, 12 is located in the plane X after passing the lens, even if the focus of the lens 8 is deviated from the surface 3, the images of the arrays 10, 12 are held in the linear state to be incident to the surface 3 so that no lateral deviation of the image occurs.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to an optical scanning device for forming an electrostatic latent image on an image forming surface of a photoconductor or the like or for reading an original, and in particular, relates to an optical scanning device for forming an electrostatic latent image on an image forming surface such as a photoreceptor or for reading an original. A light emitting element array formed by arranging in a row a number of light emitting elements that emit light according to the image signal, a light amount control element array formed by arranging a number of light amount control elements in a row that control the amount of light according to an image signal, or a light receiving device A light-receiving element array formed by arranging a large number of light-receiving elements in a row that output electrical signals according to the amount of light (in this specification, these light-emitting element arrays, light quantity control element arrays, and light-receiving element arrays are collectively referred to as optical elements) The present invention relates to an optical scanning device using an array (referred to as an array).

2. Description of the Related Art A conventional optical scanning device for image recording using a light emitting element array, as shown in FIG. The LED array 1 formed by lining up the LED array 1 of
It has an imaging lens 2 such as a single rod lens array that forms an image at the same magnification on the top, and the light emitting elements of the LED array 1 blink selectively in accordance with the image signal, thereby forming an image. One straight line 0 on the formation surface 3 was optically scanned to form an electrostatic latent image.

However, according to such a configuration, when recording a wide width, for example, in the case of an AO version, the extremely long LED array 1 is used.
Not only is it extremely expensive, but the accuracy is also degraded due to the effects of deflection, etc.
If there is a defective light emitting section, the entire device must be replaced, which is extremely uneconomical.

In order to solve this problem, it is conceivable to use multiple small LED arrays, but since it is impossible to form a light emitting part up to the very edge at both longitudinal ends of the LED array, multiple LED arrays can be used. cannot be used simply by arranging them in one straight line. Therefore, as shown in FIG. 12, small LED arrays 4, 6, imaging lenses 5,
A plurality of sets of 7 and 7 are arranged in a staggered manner and inclined with respect to the image forming surface 3, and the plurality of LED arrays 4 and 6 are configured to optically scan one straight line O of the image forming surface 3. is known (for example, see Japanese Unexamined Patent Publication No. 57-203370).

Problems to be Solved by the Invention However, with this configuration, new problems as described below arise. The apparatus shown in FIG. 12 will be described below with reference to FIG. 13, which is a side view of the device shown in FIG.

Generally, the LED arrays 4, 6, the imaging lens 5.7, etc. are mounted on a common base and treated as a unit.
are tilted relative to each other by 2θ and are positioned so that the images are formed on a common straight line 0, and then the unit is attached to the apparatus so that the image forming point 0 coincides with the image forming surface 3.

However, in reality, the mounting position of the unit may shift slightly due to processing errors, assembly errors, etc. Now, set the imaging point O to the image forming surface 3
Suppose that the position relative to the image forming surface deviates by a distance OH when it should match the image forming surface. Therefore, the position of the image forming surface with respect to the LED arrays 4 and 6 is the position indicated by 3A. At this time, the image of the LED array 4 is focused on point B, and the image of the LED array 6 is focused on point A, so that the images are shifted laterally by a distance AB. Here, the allowable value of deviation is Xμm, θ=1
If it is 5°, then the following formula holds true.

OHtanθ=AH≦15X10 (w)OH≦0.
If you try to keep the image deviation within about 1/2 dot with an image density of 9.400 dpi, the deviation of the imaging point 0 from the image forming surface must be kept within 0.056111. I understand. Considering misalignment between unit assembly and installation, warpage due to temperature difference inside the unit, etc., it is difficult to maintain the center joint at a precision of 0.0561 or less, resulting in misalignment of both images.

Such a problem occurs not only when an LED array is used, but also in an optical scanning device for image recording using a light amount control element.

The above description relates to an optical scanning device for image recording using an optical element array, but an optical scanning device for reading an original using a light receiving element array has also been known. That is,
In FIG. 11, a document surface to be read is placed at the position of the image forming surface 3, a light receiving element array (image sensor) is placed at the position of the LED array 1, and the document surface is irradiated with a light source (not shown). 2. Description of the Related Art There has been known an optical scanning device for reading a document, which is configured to form a 1-magnification image of reflected light from a main scanning straight line 0 on a light-receiving element array, and perform photoelectric conversion to obtain an image signal.

However, in this case as well, there is a problem in that a long and expensive image sensor is required when reading a wide document. Therefore, as in the case of image recording, it is conceivable to read the document by arranging a plurality of short image sensors in a staggered manner similar to the LED array shown in FIG. If a deviation occurs, the 13th
Points A and B in the diagram are read, resulting in a poor read image. Furthermore, when reading a document, there is a problem in that it is difficult to illuminate the document.

The present invention has been made in view of the above problems, and when recording an image on an image forming surface using an optical element array such as a light emitting element array or a light amount control element array, a plurality of light beams are used. When using an optical element array, there is little chance of image shift at the joints of the optical element array, and when reading originals using an optical element array such as a light-receiving element array, there is no problem with document illumination. An object of the present invention is to provide an optical scanning device that can perform good document reading using a plurality of optical element arrays.

Means for Solving the Problems In order to solve the above-mentioned problems, the present invention divides a plurality of optical element arrays into at least a first optical element array and a second optical element array, and divides them into an image forming surface or a document surface. A mirror is arranged at a position that does not block the optical path between the first optical element array and the image forming surface or the document surface, and this mirror allows the light of the second optical element array to be arranged in a staggered manner. It has a configuration in which the axial plane is changed and superimposed on the optical axis plane extending from the first optical element array to the image forming surface or the document surface.

Effect of the present invention With the above-described configuration, in the case of image recording,
The mirror changes the optical path of the light from the second optical element array and superimposes it on the same optical axis plane as the light incident on the image forming surface from the first optical element array. The light incident on the image forming surface from the array will be located on the same plane, and even if the image forming point and the position of the image forming surface are shifted, an image will be formed on a straight line on the image forming surface, unlike the conventional method. This prevents the image from shifting horizontally at the seam.

In addition, in the case of document reading, among the reflected light that is reflected from the document surface and passes through the same optical axis plane, only the light corresponding to the second optical element array is changed in optical path by a mirror, and the optical path is changed to the second optical element array. Since the remaining light enters the first optical element array without being affected by the mirror, good reading by the staggered arrangement of the first and second optical element arrays is possible. By arranging the light sources beside the same optical axis plane, the entire document width can be uniformly illuminated.

Embodiment FIG. 1 is a perspective view showing a schematic configuration of an optical scanning device according to an embodiment in which the present invention is applied to image recording, and FIG. 2 is a side view thereof. In FIGS. 1 and 2, 3 is an image forming surface such as a photoreceptor, 8 is an imaging lens such as a rod lens array, 9 is a mirror, and 10 is a tower on which a plurality of LED chips 11 are mounted in a straight line. a second LED array, 12 is a plurality of LEDs;
This is a second LED array in which chips 13 are arranged in a straight line. The imaging lens 8 includes the -th LED array 10 and the second L
The entire width of the ED array 12 is imaged at the same magnification on the image forming surface 3, and the optical axis plane X is arranged to be perpendicular to the image forming surface 3. The -th LED array 10 and the second LED array 12 are arranged in a staggered manner, one LED array IO is on the optical axis plane X of the imaging lens 8, and the other LED array 12 is on the optical axis plane It is arranged next to the optical axis plane X so as to face the optical axis plane X.

The mirror 9 is located on the optical axis plane X of the imaging lens 8, and the -th LED
The arrangement is such that the light entering the imaging lens 8 from the array 10 is not blocked, but the light from the second LED array 12 is reflected and entering the imaging lens 8. Further, the mounting position and angle of the mirror 9 are set so that the light from the second LED array 12 is reflected and superimposed on the optical axis plane X extending from the -th LED array IO to the image forming surface 3, As a result, the -th LED array 10. Second LED array 1
2 is imaged onto a straight line O on the image forming surface 3. In addition, in order to adjust so that the image of the -th LED array 10 and the image of the second LED array 12 on the image forming surface 3 are accurately aligned in one straight line (that is, adjust the horizontal deviation of the images) ), No.-
The LED array lO or the second LED array 12 is indicated by arrow A,
Just move it towards your mouth. When adjusting the second LED array 12 by moving it in the direction of the arrow, depending on the inclination angle of the mirror 9, the second LED array 12 may be moved to the imaging lens 8.
The optical path length may change and the focus may shift. In order to prevent this, it is preferable that the inclination angle of the mirror 90 with respect to the optical axis X is 45 degrees and that the second LED array 12 is moved parallel to the optical axis X, as shown in FIG.

In FIG. 1, the -th LED array IO and the second LED array 12 are such that their respective images formed on the image forming surface 3 are spaced apart from each other by a predetermined distance on the straight line O. They are arranged consecutively at intervals corresponding to the interval). This adjustment is possible by moving either the -th LED array 10 or the second LED array 12 in the direction of the arrow.

Usually, these imaging lens 8, mirror 9, image LED array 10, second LED array 12, etc. are mounted on a single base and handled as a unit.

The operation of the optical scanning device configured as described above will be described below. The light emitted from the image LED array 10 passes on the optical axis plane X without being blocked by the mirror 9, and forms an image on the straight line O of the image forming surface 3 by the lens 8. On the other hand, the light emitted from the second LED array 12 is reflected by the mirror 9 and focused on the straight line 0 on the image forming surface 3 by the imaging lens 8 . Thus, by blinking the image LED array 10 and the second LED array 12 in accordance with the input image signal, one straight line 0 on the image forming surface 3 is optically scanned, and an electrostatic latent image is formed.

Here, the light from these LED arrays 10.12 is
After passing through the imaging lens, it is within the same optical axis plane X, so for example,
The position of the unit including the imaging lens 8, the mirror 9, the image-LED array 10, the second LED array 12, etc. relative to the image forming surface 3 is shifted, and the imaging point of the imaging lens 8 is shifted from the image forming surface 3. Even if the image-LED array 10 and the second LED
The image of the array 12 enters the image forming surface 3 while maintaining a straight line, and a good image is formed without causing the horizontal deviation of the image as described in FIG. 13. In other words, the allowable range of mounting accuracy of the unit including the imaging lens 8, the mirror 9, the image-LED array 10°, the second LED array I2, etc. becomes wider than in the past.

Note that in the above embodiment, only two LED arrays in total are used, one LED array 10 and one second LED array I2, but the present invention is not limited to this case.
It is also possible to use more than one LED array. In that case, three or more LED arrays are arranged in a staggered manner so that the light from one row of LED arrays (the -th LED array) travels without being obstructed by the mirror, and the light from the other row of LED arrays travels unobstructed by the mirror.
By configuring the array so that the light from the array (second LED array) is reflected by a mirror and incident on the image forming surface through the same optical axis plane, it is possible to use a general-purpose LED array about the size of an A4 sheet. , it becomes possible to record extremely wide widths without causing image shift, and for example, it becomes possible to record sizes of AI, AO1, and even larger sizes. Further, in the above embodiment, a single imaging lens 8 is used and a mirror is arranged between this imaging lens 8 and the LED array, but instead of this, each LE
An imaging lens may be arranged corresponding to the D array, and the light exiting the imaging lens may be superimposed on the same optical axis plane using a mirror.

Next, the joint between the LED array 10 and the second LED array 12 will be described. In the above embodiment, the
A portion of the light emitted from the light emitting elements at the end of the LED array 1O is reflected by the end surface 9A of the mirror 9, becoming a ghost image or a noise component, which may reduce image contrast. For this reason, it is desirable to make the thickness of the mirror 9 as thin as possible or to make the end face of the mirror 9 sharp like a knife to reduce the amount of light reflected at the end face.

In addition, as shown in the above embodiment, when the light from one LED array is made to travel straight and the light from the other LED array is reflected by a mirror and connected in a straight line on the image forming surface, the light emitting element near the joint The maximum amount of light will be about 1/20th. The explanation and countermeasures will be explained below.

Figure 3 is a diagram for explaining the loss of light quantity of the light emitting elements near the end of the LED array, and is an enlarged view of the joint area in the device of Figure 1, and the narrow optical surface of the imaging lens is viewed in the direction of the arrow ■. FIG. 14 represents a light emitting element at the end of the LED array IO, and 15 and 16 represent light emitting elements located a predetermined distance apart.

14', 15', and 16' are light emitting elements 14.
It is a statue of 15.16. C-C is LED array IO and 1
2, that is, the joint C-C.

Generally, light from each light emitting element of the LED array 10 is focused on the image forming surface 3 within a solid angle θ determined by the numerical aperture of the imaging lens 8 . However, near C-C, the mirror 9 extends to the C-C position, so even if the light is within the solid angle θ, the light passing to the right of the joint C-C will be vignetted by the mirror 9. It does not reach the imaging lens 8. The light emitting element 14 at the end can be considered to be located very close to the joint C-C and on the back joint C-C, so the light from this light emitting element 14 is theoretically 1
/2 is vignetted. In the light emitting element 15, the amount of vignetting of the light is less than 1/2, but some loss of light amount occurs. This loss is shown in FIG. 3 by a hatched area α and a dotted area β. The amount of vignetting is determined by the position of the mirror 9 placed between the imaging lens and the LED array and the numerical aperture of the imaging lens 8. Above, we have described the light amount loss on the image-LED array 10 side, that is, on the transmitted light side.
The light amount loss at the end on the second side, that is, on the reflected light side, can be considered in the same way. In other words, the loss due to vignetting caused by the mirror 9 can be replaced with the loss due to non-reflection caused by the absence of the mirror 9. When the brightness of the image on the image forming surface is shown in a graph in combination with the above, it becomes a seven-figure shape in which the brightness decreases to 1/2 at the joint C--C as shown in FIG. In addition, in FIG. 4, the vicinity of C-C is enlarged. Furthermore, it was assumed that there was no unevenness in brightness due to each light emitting element or imaging lens.

In this way, a plurality of LED arrays 10. 12, the brightness of the image decreases at the joint, as shown in FIG. However, such a decrease in the brightness of the image at the seam can be corrected by controlling the light emission time of each light emitting element, and specifically, for example,
The method described in 4P16 of the 1986 National Conference of the Institute of Image Electronics Engineers, a high-intensity diode printer, or Japanese Patent Application No. 175953/1988 previously filed by the present applicant may be used.

By the way, the characteristics shown in FIG. 4 apply to the LED array 10. as shown in FIG. This figure is for the case where the end of the mirror 9 is accurately positioned at the boundary C-C of 12, but in reality it is extremely difficult to position the mirror 9 accurately as shown in FIG. , Due to installation errors during assembly, differences in expansion coefficient due to temperature changes, etc., there may be some deviation. now,
Assuming that the end of the mirror 9 is shifted by a distance d toward the LED array IO side from the CC position, the brightness distribution of the image formed at that time will be as shown by the solid line in FIG. That is, L.E.
The range in which the light from the D array 10 is affected by vignetting by the mirror 9 expands, and the amount of light further decreases by a in the vicinity of C-C. For this reason, even if the above-mentioned correction is made by controlling the light emission time of the light emitting element based on the characteristics when the mirror is not shifted (characteristics shown by the two-dot chain line in Figure 5), the amount of light will be insufficient and the image quality will deteriorate. Sometimes.

In order to prevent this deterioration in image quality, as shown in FIG. 6, the brightness of the image near the joint C--C should be reduced gradually. That is, if the curve of decrease in image brightness is made gentler, the amount of decrease in light amount becomes smaller than the amount of decrease in light amount a shown in FIG. 5 for the same amount of deviation d of mirror 9, and it is possible to improve the image quality. can. Therefore, it is preferable to position the partial mirror 9 close to the imaging lens 8 side so that the brightness of the image gradually decreases. Further, as another method, it is more effective to provide a part of the -7 mirror in which the light reflectance (transmittance) gradually changes at the end of the mirror 9 on the joint CC side.

The light reflectance (transmittance) distribution of the nof mirror formed at the end of the mirror 9 will be described below.

FIG. 7 is a graph showing an example of the light reflectance distribution of a part of the mirror formed at the end of the mirror 9.

In Figure 7, 9a is a part of the mirror with constant reflectance, 9b
9c is a part of the half mirror, and 9c is a part without the mirror 9 (referred to as a transparent part). In this embodiment, the reflectance decreases linearly as it approaches the transparent part 9c from the mirror part 9a,
In addition, a half mirror 9b whose reflectance is 1/2 is formed at the joint C--C. With this configuration, when the light from the light emitting element located on the dovetail joint C-C at the end of the LED array 10 travels to the image forming surface, a portion of the half mirror is placed in the area to the left of the C-C position. 9b, the amount of light is reduced compared to that in Figure 3, but C-C
In the area to the right of the position, light transmission occurs due to the No.-7 mirror formation, which compensates for the decrease in the amount of transmitted light at the left side of the C-C position, and in the end, the amount of light transmitted is reduced to 1/2 as in the one in Fig. 3. Light will pass through. The light from the light emitting element that is υ away from the extreme end is
By forming the half-mirror portion 9b, the amount of transmitted light is reduced compared to the one shown in FIG. On the other hand, the LED array 12
The light from the light emitting element near the C-C position at the extreme end of the screen is reflected by the mirror 9 and formed into an image, but at this time, the amount of reflected light is reduced due to the half-mirroring in the area to the right of the C-C position. On the other hand, in the region to the left of the C-C position, some light is reflected due to the provision of the half mirror part 9b, and the decrease in the region to the right of the C-C position Supplement. Thus, in this case as well, 1/2 of the light will be reflected as in the case of FIG. The light from the light emitting element closer to the center than that light emitting element is...
3, the amount of reflected light is reduced compared to the one shown in FIG. For this reason, as shown by the two-dot chain line in Figure 6,
Although the brightness of the image decreases to 1/2 at the joint C-0, a characteristic in which the decrease changes gradually is obtained.

Fig. 8 shows the formation at the end of the mirror 9... - Humira part 9
This shows another example of the light reflectance of b. In this example, on the right side of the joint C-C, the reflectance increases at a constant rate from the reflectance (1-n) larger than 0.5 at the joint. However, on the left side of the joint C--C, the reflectance changes from n to decrease at a constant rate. In this example as well, the characteristics shown in FIG. 6 can be obtained. Note that the half-mirror part 9b having a reflectance distribution as shown in FIG. 7 is easier to manufacture and is therefore preferable. Also, the light reflection weight distribution of a part of Humira does not necessarily have to be a straight line as shown in Figures 7 and 8.
A curved line may be used as long as the rate of increase in reflectance on the right side and the rate of decrease in reflectance on the left side from joint C-C are the same rate.

Even when using a mirror equipped with a mirror 95 like the one shown in FIGS. 7 and 8, the generation time of the light emitting element near the joint depends on the brightness reduction characteristics near the joint. control and compensate for reductions in brightness. in this case,
Even if the position of the mirror 9 shifts, the amount of decrease in light amount due to the shift is relatively small, so that no deterioration in image quality occurs and a good image can be obtained.

FIG. 9 is a perspective view showing another embodiment of the present invention, and FIG. is a side view.

In this embodiment, a long image -L is placed on the optical axis plane of the imaging lens 8.
ED arrays 10-1 and 10-2 are arranged at intervals,
Next to the optical axis plane, a short second LED array 12 is arranged, and furthermore, a short mirror is arranged at a position opposite to the second LED array 12 on the optical axis plane of the imaging lens 8. 2L
The configuration is such that the light from the ED array 12 is superimposed on the optical axis plane of the imaging lens 8. Here, as shown in FIG. 10, the mirror is polished by polishing the mirror surface 21.
, and the end faces η on both sides thereof have sharp edges. Aluminum is usually used for the metal base, and the polygon mirror processing technology used in laser beam printers and the like can be used as is to form the mirror surface.

In this embodiment as well, the LED array 10-1, 10-2
The light from the second LED array 12 passes on the same optical axis plane and enters the image forming surface 3, so that good image recording can be performed.

Here, the LED array 10-1.1O-2 is made longer,
For example, since it is made in A4 size and the second LED array 12 is made short, for example, about 40 m1 in length, it is easy to manufacture and operate the assembly adjustment jig. i.e. a long mirror or LED
Although it is difficult to move the array with fine precision because it is easily affected by warping, in this embodiment, the second LED array 12 and the mirror length are short, so the operation is easy. Furthermore, as a result of shortening the second LED array 12, the length of the mirror can also be shortened, and the manufacturing cost of the mirror m can be reduced. As described above, the mirror 20 is made of a metal base material.
Since the surface is polished to a mirror surface to form the mirror surface 21, the polishing is performed extremely slowly (for example, 1
(cutting amount per cycle is approximately several microns). The cost required for this processing accounts for most of the total cost of Mirror 4. Therefore, since the cost of adding a mirror is proportional to the length, if a short mirror can be used as in this embodiment, it will be advantageous in terms of manufacturing cost of the device.

Furthermore, if a metal mirror is used, the following advantages can be obtained. That is, if the materials of the mirror 20 and the base (not shown) that holds the mirror, LED array, etc. are different, the coefficient of thermal expansion will be different, and therefore, when there is a temperature change, the mirror 20 will warp or change its position. This may cause misalignment or loss of focus.

Since aluminum is usually used for the base, such problems do not occur if aluminum mirror marks are used.

Further, the end face n of the mirror is connected to the -th LED array 10-1.
．． The light from 10-2 is reflected and scattered, disturbing the imaging state.

Therefore, it is desirable that the end face n be as sharp as possible, and in the case of metal, the end face can be made extremely sharp. In a mirror made of glass, if the end face is made sharp, chipping or the like will occur, and it is virtually impossible to make the end face sharp, so reflected and scattered light cannot be reduced.

Although the above embodiments have been described using an LED array as an optical element array, the present invention is not limited to this, and may also be an optical element array using a laser diode, EL, etc. as a light emitting element. Well, furthermore, liquid crystal, P
The same effect can be obtained even with an optical element array using a light amount control element such as LZT.

Further, the present invention is also applicable when a light receiving element such as an image sensor is used as the optical element array. That is, in FIG. 1, a document to be read is placed at the position of the image forming surface 3, image sensors are placed at the positions of the LED arrays 10 and 12, and a light source that illuminates the straight line O is placed beside the imaging lens 8. By arranging them, the straight line O can be read satisfactorily by a plurality of image sensors.

Effects of the Invention As is clear from the above description, the present invention divides a plurality of optical element arrays into at least a first optical element array and a second optical element array, and mutually aligns the plurality of optical element arrays with respect to an image forming surface or a document surface. The second optical element array is arranged in a staggered manner, and the optical axis plane of the second optical element array is changed using a mirror so that the second optical element array is superimposed on the optical axis plane extending from the first optical element array to the image forming surface or document surface. In the case of image recording using an optical element array such as a light emitting element or a light quantity control element array, the optical path of the light from the second optical element array is changed by a mirror, and the light is incident on the image forming surface from the first optical element array. The light from the first optical element array and the second optical element array can be made incident on the image forming surface through the same optical axis plane, and the imaging point and image of each optical element array can be overlapped. This has the effect that even if the position of the image forming surface is shifted, an image can be formed on one straight line on the image forming surface, and recording without image shift is possible. In addition, in the case of document reading using an optical element array such as an image sensor, among the light reflected from the document surface and passing through the same optical axis plane, the part of the light corresponding to the second optical element array is mirrored. is reflected and incident on the second optical element array, and the remaining light is incident on the first optical element array without being obstructed by the mirror. This has the effect that the entire width can be uniformly illuminated, and therefore a wide document can be read satisfactorily using a plurality of short optical element arrays.

[Brief explanation of the drawing]

FIG. 1 is a schematic perspective view showing an optical scanning device according to an embodiment of the present invention, FIG. 2 is a side view thereof, and FIG. 3 is an enlarged view of the vicinity of the joint in the device of FIG. FIG. 4 is a graph showing the brightness distribution of the image on the image forming surface in the above embodiment. FIG. A graph showing the brightness distribution. Figure 6 is a graph similar to Figure 5 showing another example of the image brightness distribution near the joint. Figure 7 is a graph showing the light reflection of a part of the half mirror formed at one end of the mirror. FIG. 8 is a graph showing another example of the light reflectance distribution of a part of the half mirror formed at one end of the mirror. FIG. 9 is an optical scanning device according to another embodiment of the present invention. FIG. 10 shows a mirror used in the example, (a) is a perspective view, (b) is a plan view, (C) is a side view,
FIG. 11 is a schematic perspective view showing an example of a conventional optical scanning device;
FIG. 12 is a schematic perspective view showing another example of a conventional optical scanning device, and FIG. 13 is a side view illustrating the positional relationship among the LED array, imaging lens, and image forming surface in the device. 3... Image forming surface, 8... Imaging lens, 9... Mirror 9A... Mirror one end surface, 9a... Mirror part, 9b...
...half mirror part, 9 c-transparent part, 10. 10-
1. 10-2...-th LED array, 11...L
ED chip, 12... Second LED array, 13... IJil: D chip, Add... Mirror 21... Mirror surface, n... End surface.

Claims (1)

[Claims] An optical element array consisting of a large number of light emitting elements, light quantity control elements, or light receiving elements arranged in a row, the first optical element array and the second optical element array being arranged in a staggered manner with respect to an image forming surface or a document surface. an optical element array, an imaging lens disposed between these optical element arrays and the image forming surface or document surface, and blocking an optical path between the first optical device array and the image forming surface or document surface; an optical scanning device, the optical scanning device having a mirror that is placed in a position where the second optical element array is not aligned, and that changes the optical axis plane of the second optical element array so as to overlap the optical axis plane from the first optical element array to an image forming surface or a document surface.