JPS5821227A - Imaging element using micro dach array - Google Patents

Abstract

PURPOSE:To obtain an imaging lens which is less affected by lens aberrations, has a wide angle of view and is of simple constitution by making the pitch of Dach mirror arrays disposed behind a multilens array sufficiently smaller than the diameter and pitch of the lens array. CONSTITUTION:Many Dach mirror arrays 7 are disposed behind a multilens array 1 consisting of many lenses 1', at the pitch P' sufficiently smaller than the diameter D and pitch P of the lenses 1'. The rays which emerge from the spot 5 on an object and pass through the lenses 1' are reflected twice by the Dach mirrors 7' and go backward in the extremely proximate positions. The incident rays and the reflected lays pass through roughly the same positions of the lenses 1' and form images in the original positions with virtually no influence by the aberrations and eccentricty of the lenses. Therefore the rays out from the respective parts of the object 10 form erecting images of equal magnifications in the same position as that of the object with the effect of the array 1 and the arrays 7. Thus the imaging element having a wide angle of view and simple constitution is obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an imaging element used in an imaging optical system. For example, in an electrophotographic copying machine, if a single imaging lens is used as the imaging element for slit exposure, a lens with a wide angle of view is required, the design of the optical system is difficult, and the optical path length becomes long, making the equipment difficult. It has the disadvantage of being large and bulky. As a means to solve this problem, conventional strip lens arrays in which lens systems consisting of multiple lenses are arranged in multiple rows, and
A roof mirror array consisting of a pair of mirrors that intersect at 0° is arranged in a row, and a lens array in which a large number of lenses are arranged in a row. Imaging elements such as roof mirror lens arrays are known.

However, when using a strip lens array as an imaging element, the distance is long, the device itself is large, and the multiple lenses that make up one lens system must be installed with their optical axes aligned. However, parts accuracy and assembly accuracy are strict.
Another disadvantage is that the lens has large aberrations.

The principle of the roof mirror lens array is that, as shown in FIG. 1', the parallel light beam is made into a parallel light beam, reflected twice by a roof mirror 2', and an image 4 is again formed at the original object position by a lens 1/.

In this case, as is clear from the figure, the light incident on the roof mirror 2' and the light exiting from the roof mirror 2-2' pass through different positions of the lens 1', so there is aberration and eccentricity in the lens 1'. In this case, as shown in FIG. 2, the imaging point 6 of the light beam emitted from the point 5 on the object shifts from its original position, and the imaging performance deteriorates. Furthermore, if there is a positional deviation d between the lens 1' and the mirror 2' as shown in FIG. 3, the effects of the aberrations and eccentricity of the lens described above will be further exacerbated.

Therefore, in the lens array and roof mirror array 2, each lens and roof mirror must be placed in positions that accurately correspond to each other, which requires high component precision and assembly precision, and has the disadvantage of being greatly affected by lens aberrations. .

Further, in common with strip lens arrays and roof mirror lens arrays, multiple light shielding plates having a shape that prevents light from leaking into the optical paths of mutually adjacent optical systems are required.

In view of the above-mentioned shortcomings of conventional strip lens arrays and roof mirror lens arrays, the present invention is less affected by lens aberrations, has a wide angle of view, does not require high-precision assembly, and has a complex shape for light shielding. It is an object of the present invention to provide an imaging element with a simple configuration that does not require a plate.

Hereinafter, the present invention will be explained in detail with reference to drawings showing embodiments thereof.

The imaging element according to the embodiment of the present invention shown in FIG. It is constructed by arranging a micro-roof mirror array 7 in which a large number of roof mirrors 7' are arranged in a row with a sufficiently large pitch P'. Also, the parts of the lens array l other than 1' are
A light shielding means 8 is provided on both the front and rear surfaces of the lens 1', with a portion other than the lens 1' protruding from the surface of the lens.

Furthermore, a right-angle mirror 9 is provided in front of the lens array l in parallel to the lens row direction.

Since the imaging element of the present invention is constructed as described above, as shown in FIG. Proceeding in opposite directions at a close position, the incident light and reflected light are passed through lens 1.
It passes through almost the same position as ', and is almost unaffected by aberrations and eccentricity of lens 1', and is imaged at the original position (when viewed in the direction of the ridgeline of the roof mirror as shown in Figure 5). . Furthermore, since the pitch P' of the roof mirror 7' is sufficiently smaller than the pitch P of the diameter D1 of the lens 1', the influence of positional deviation of the roof mirror can be ignored. Therefore, as shown in FIG. 6, the light rays emitted from each part of the object lO are
An image is formed at the original position by each lens 1' and lens array 7, and a real magnification image is obtained at the same position as the object 1O (when viewed in the direction of the ridgeline of the roof mirror).

However, as shown in FIG. 7, if the angle θ of the light incident on the lens l/side mirror 7' or the light reflected from the roof mirror 7' with respect to the lens optical axis exceeds 45°, the reflected light returns to the original lens. Since the light does not return, it is necessary to cut off the rays of at least 45° or more.

The light shielding means 8 of this embodiment is dimensioned to satisfy this requirement. As shown in FIG. 8, this light shielding means 8 is a flat plate 8α with a circular hole 8b having the same diameter as the lens 1', which is made in accordance with the pitch P of the lenses. The lens array l may be formed by sandwiching the integrally molded lens array l from both sides, or as shown in FIG. It can also be easily manufactured by integrally molding it into a thick piece.

Fig. 1θ is a diagram showing the range of light beams emitted from points 6α and 6b on the object and focused on the same point, for the lens array l equipped with the light shielding means 8 formed in this manner and the minute roof mirror 7. It is. Since the influence of lens aberrations is small, the angle of view can be widened to a maximum of 45 degrees, and therefore brightness and brightness unevenness are improved compared to the conventional method. Further, the distance between the lens array l and the roof mirror array 7 and the positional relationship in the column direction can be set freely, and the degree of parallelism can be rough.

Instead of the micro roof mirror array in the above embodiment, a micro roof prism array is used in which micro roof prisms are arranged in a row, each having two perpendicular surfaces and the outer surfaces of which are coated with silver, aluminum, or the like as a reflective surface. It's okay.

FIG. 11 shows an example in which the above-mentioned imaging element is used in an exposure optical system of an electrophotographic copying apparatus. In this example, the document table 1lFi moves in synchronization with the rotation of the photoreceptor drum 12, and the lighting device 13
, a right-angle mirror 9, and an imaging element 14 of the present invention, the exposure optical system is stationary. The slit-exposed original image light is reflected by the upper mirror surface of the right-angle mirror 9, enters the imaging element 14, is reflected by the minute roof array, exits from the imaging element 14, and is reflected by the lower mirror surface of the right-angle mirror 9. It is reflected and forms an equal-strength standing image on the photoreceptor 12. In addition to the above-mentioned right-angle mirror, a half mirror or the like may be used as a means for separating the light incident on the imaging element and the light emitted from the imaging element. This imaging optical system consists of a right-angle mirror, a roof mirror, and a
Since the optical path is bent four times by x=”z ′iI+, the straight-line distance between the document surface and the image formation surface on the photoreceptor drum is considerably shorter than when a strip lens array is used, and the device can be made smaller.

As described above, according to the present invention, the influence of lens aberrations, eccentricity, etc. is extremely small with a simple configuration in which the pitch of the roof mirror array A is made sufficiently small compared to the diameter and pitch of the lenses of the lens array. This provides an easy-to-assemble imaging element with a wide angle of view, improved brightness and uneven brightness.

[Brief explanation of the drawing]

Figure 1 is a schematic diagram explaining the function of a conventional roof mirror lens array, Figure 2 is a diagram explaining the effects of aberration and eccentricity of the lens of the imaging element, and Figure 3 is the lens of the imaging element. A schematic diagram explaining the influence of positional deviation of Dame 1 mirror,
FIG. 4 is a perspective view showing an embodiment of the present invention, FIG. 5 is a schematic diagram explaining the effects of aberration and eccentricity of the lens, and FIG. 6 is a schematic diagram explaining the imaging effect of the device of the present invention. Fig. 7 is a diagram showing the path of light rays whose direction of incidence and exit from the roof mirror is the optical axis of the lens, and whose angle is 45° or more. Cross-sectional view, 1st θ
11 is a schematic diagram showing the imaging light flux range of an imaging element equipped with the above-mentioned light shielding means, and FIG. 11 is a sectional view showing an example of an exposure optical system of a copying machine using the imaging element of the present invention. l...Multi-lens array 1'...Lens 7...
Micro-roof mirror array 7'...Micro-roof mirror 9...
・Right angle mirror Fig. 3 1

Claims (1)

[Claims] α゛) A multi-lens array in which a large number of lenses are arranged in a row, and behind the multi-lens array, a large number of roof mirrors or roof prisms are arranged in a row with a pitch sufficiently smaller than the diameter and pitch of the lenses. 2. The imaging element according to claim 1, wherein the imaging element is constructed by arranging a micro roof array, each of which is integrally molded from a material such as plastic. (3) A claim characterized in that a means for separating light incident on the imaging element and light emitted from the imaging element, such as a right-angle mirror or a half mirror, is provided in front of the imaging element. The imaging element according to item 1 or 2.