JPH0772308A - Imaging device - Google Patents

Abstract

(57) [Summary] [Purpose] A monocular lens is mounted with high accuracy to obtain a monocular lens array that is less affected by temperature and humidity. [Structure] The monocular lenses 50 are closely stacked in two rows and stacked in a bale, and the mounting accuracy is improved by the alignment action between the lenses. As the lens 50, an unnecessary lens 54 is applied with a paint by an inkjet printer or the like to shield light, and only the necessary lens is separated and used to form the array 10 of monocular lenses. The side surface of the lens 50 is roughened to prevent reflection of light inside the lens, and the permeation prevention layer 52 contains a pigment for absorbing LED light on the outer periphery thereof.
Is provided to prevent the movement of light to the adjacent lens.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image device such as an LED head, an EL head and an image sensor, and more particularly to a monocular lens array used. The present invention also relates to improving the resolution of the image device by reducing the light from the light emitting array onto the image forming surface to form an image, or by expanding the light from the document surface onto the light receiving array and projecting the light.

[0002]

The use of an array of monocular lenses in an imaging device has been known for a long time. However, if the mounting accuracy of the monocular lens is low, image connection between the lenses fails and white or black lines occur. For example, if the images formed by the first lens and the second lens are overlapped with each other, black streaks occur in the images, and if there is a gap in the formed images, white streaks occur.

Next, the effect of temperature and humidity on the monocular lens is great,
The image forming position changes due to the change of the curved surface shape due to the temperature change and the swelling or contraction of the surface due to the humidity change. The change in the image forming position causes white streaks or black streaks, which significantly deteriorates the image quality. The influence of temperature and humidity is great because a curved lens is used as the monocular lens.

The purpose of using a monocular lens is often to change the resolution by using an enlarged image or a reduced image.
The image device has a resolution of 300 DPI (dots / inch)
Many are 400 DPI, and when the resolution is 600 DPI, the array pitch of the light-receiving and emitting bodies is 84 at 300 DPI.
It is from 7 μm to 42.4 μm. When the width of each light receiving / emitting body is set to 30 μm corresponding to the resolution of 600 DPI, the gap between the light receiving / emitting bodies becomes about 10 μm. Also, with respect to electrodes, bonding pads, etc. connected to the respective light receiving and emitting bodies, the minimum distance between them is about 10 μm, and the line width of the electrodes is also about 10 μm. These means that the light emitting / receiving body, electrodes, bonding pads, etc. must be manufactured according to the rule of 10 μm. Assuming that the arrangement pitch of the light-receiving and emitting bodies is 600 DPI, as a result of miniaturization, defects of the light-receiving and emitting bodies due to pattern etching defects and the like increase, and output variations also increase. Further, if the electrode line width is reduced and the distance between the electrodes is reduced, a short circuit, disconnection, wiring resistance, etc. increase. As a result, the yield of the light emitting / receiving array is reduced and the variation in output is increased.

The resolution of the light emitting / receiving array is, for example, 300DP
If I is doubled to 600 DPI, correspondingly, the wiring density is also doubled on the side of the substrate on which the light emitting / receiving array is mounted. For this reason, wiring on the substrate becomes difficult and the cost thereof increases. When the resolution of the light emitting / receiving array is further increased, the bonding area of the bonding pad is reduced to about 1/2, and defective bonding, short circuit between the bonded wire lines, and the like increase. In an imaging device, all light emitters / receivers must operate normally. Therefore, if the resolution is increased, the increase in the defective rate due to the miniaturization and the increase in the total number of the light receiving and emitting bodies are overlapped with each other, and the overall yield is extremely lowered. For example, in an image device of A4 size and 600 DPI, the total number of light receiving and emitting bodies reaches about 5000, and it is difficult to produce them all as good products and bond them without defects. Further, when the wiring density of the substrate is doubled, the number of accidents such as wiring resistance, short circuit between wirings, disconnection, etc. increases dramatically.

A fundamental problem of the image device is that miniaturization and high precision are required as the resolution increases, and the number of image elements increases as the resolution increases, and the total yield is the resolution 2.
There is a decrease in the power. Therefore, in order to realize a high-resolution image device, how to solve the problems associated with miniaturization and increase in the number of elements is important.

As a related prior art, Japanese Patent Laid-Open No. 56-28869 discloses a self-focusing lens array or the like after arranging LED arrays in two rows and aligning the light beams with a half mirror. It is proposed to form an image with a compound eye lens array. However, in the compound eye lens array, a plurality of lenses are involved in image formation of light from one light source, and only an erecting equal-magnification real image can be obtained. For this reason LE
The light from the D array cannot be reduced and projected,
This is because this is an upright real image. Since the image cannot be reduced, only the processing for the boundary between the LED arrays can be performed.

Next, the inventor uses two sets of rows of light emitting / receiving arrays and a monocular lens array, combines lights from these arrays with a half mirror, and linearly forms an image on an image forming surface. Proposed (Japanese Patent Application No. 5-92,187). For example, in this image device, two light emitting arrays with a resolution of 300 DPI are
A row is used, and a monocular lens array reduces the image size by half to form an image. As a result, 600D with a light emitting and receiving array of 300DPI
Image processing of PI is possible. However, even in this image device, there is a problem that the characteristics of the monocular lens change depending on the ambient temperature and humidity, and it becomes difficult to synthesize the two sets of images.

[0009]

It is an object of the present invention to provide an image device having a high image-forming performance, in which a monocular lens is precisely mounted to prevent occurrence of white streaks and black streaks due to variations in lens mounting position. , 2) An object of the present invention is to provide an image device in which image quality is not deteriorated due to temperature and humidity fluctuations, and in particular, white lines and black lines are not generated. In addition to 1) and 2), 3) an object of the invention is to improve the resolution without reducing the arrangement pitch of the light receiving and emitting bodies, and to facilitate the realization of a high resolution image device. .

[0010]

According to the present invention, in an image device using a monocular lens array and a light emitting / receiving array, the monocular lens array has distributed refractive index type rod lenses arranged in two rows and in close contact with each other, and It is characterized in that lenses other than the predetermined lens are shielded from light. The present invention also provides an image device using such a monocular lens array, in which the light emitting / receiving arrays are three-dimensionally arranged in two or more rows, and
A feature is that a monocular lens array is provided for each row of the light emitting / receiving array, and a half mirror for further combining or splitting the light of the light emitting / receiving array of two or more rows is provided. In addition to the LED head shown in the embodiment, an image device using an array of monocular lenses such as an EL head and a contact image sensor and a light emitting / receiving array is used as the image device.

[0011]

According to the present invention, the distributed index type rod-shaped lenses are closely contacted in two rows and stacked in a bag, and unnecessary lenses are shielded from light to form an array of monocular lenses. When the lenses are stacked in close contact in two rows, the forces between the lenses will naturally align them in the correct position. Then, by shielding the unnecessary lenses from light, an array of monocular lenses with precision mounted lenses is obtained. Since the rod-shaped lens uses the internal refractive index distribution and is not a curved lens, the influence of temperature change is small. Also, swelling due to humidity is a phenomenon only on the lens surface and does not affect the internal refractive index distribution. As a result, an array of monocular lenses in which the mounting position of the lens is accurate and the influence of temperature and humidity is small can be obtained (claim 1).

According to the present invention, a plurality of light emitting / receiving arrays are three-dimensionally provided, and a monocular lens forms a reduced image on the photosensitive drum or the like, or an enlarged image is formed on the light receiving array.
For example, if the array has two columns, it is reduced / enlarged to 1/2, and if it is three columns, it is reduced / enlarged to 1/3. For example, the light from the light-emitting array of n rows is reduced to 1 / n, and the light of n rows is combined by a half mirror to form an image in one row. Similarly, the light from the document surface is divided into n beams by the half mirror, enlarged by n times by the monocular lens, and focused on the light receiving array. As a result, the resolution of the image device can be increased n times.

[0013]

EXAMPLE FIG. 1 shows the structure of a monocular lens array 10.
In the monocular lens array 10, rod-shaped distributed refractive index type monocular lenses 50 are closely arranged in two rows in a bale stack, and unnecessary lenses are shielded to form a shading lens 54. The monocular lens 50 that does not block light has a roughened side surface to prevent reflection inside the lens 50, and a transmission prevention layer 5 on the side surface of the lens 50.
It is preferable to provide 2 to block the movement of light between the adjacent lenses. Reference numeral 56 is a resin mixed with a pigment that absorbs LED light, which is used for bonding the lens 50, and 58 is a side plate, for example, plastic which is mixed with a pigment that absorbs LED light, and the main surface of the mounting side of the lens 50 is flat. Flat surface 59
To provide.

The monocular lenses 50 are mounted in two rows, and one row (lower row in FIG. 1) is completely shielded from light, and all the light-shielding lenses 54 are mounted.
In the other one column, one to three light-shielding lenses 54 are arranged between the lenses that do not shield light. As a result, it becomes the same as arranging the non-light-shielding lenses in one row with a space therebetween, and an array of monocular lenses 50 is formed. Considering the mounting accuracy of the monocular lens 50, the lenses in the first row are arranged on a flat surface 59, and the lenses 50 are closely contacted to each other, so that the lenses 50 are arranged in parallel at the same pitch and on the same surface.
Can be arranged. The lenses in the second row are arranged on the irregularities made by the lenses in the first row and ride on the concaves in the first row,
Apply pressure so that the lenses come into close contact with each other.
When fixed with, each lens sticks to each other and maintains accuracy,
It is arranged with high precision. This action is called a self-alignment action.

To shield the unnecessary lens from light, an ink jet printer or the like is used, and a paint that absorbs the LED light is applied only to the unnecessary lens. Further, in order to shield the light between the lenses 50, 50, a resin 56 is used in addition to the roughening of the lens side surface and the transmission preventing layer 52, and the LED light is absorbed by the pigment in the resin.

FIG. 2 shows a rod-shaped distributed index type monocular lens 5.
The principle of 0 is shown. In general, light tends to select a portion having a high refractive index to proceed, and if the refractive index distribution in the lens 50 is defined by, for example, the equation (1), (the left side of FIG.
The optical path is bent to the center of the lens 50, as shown by the solid line in the figure. n = n0 (1-ar ² ) (1) (n: refractive index distribution of lens, n0: refractive index at lens center axis, r: radial distance from lens center a: positive constant) Equation (1) Is a formula of the refractive index distribution for the self-focusing lens, and if the length of the lens 50 is selected, an image such as an inverted reduced image, an inverted enlarged image, an erect reduced image or an erect enlarged image can be obtained. A 2 × inverted magnified image and a 1/2 inverted reduced image (Example 2) are formed. An erect image may be used instead of the inverted image. In this way, a monocular lens 50 that can be reduced / enlarged with a rod-shaped lens is obtained. The material of the monocular lens 50 is glass or plastic.

The characteristics of the rod-shaped distributed index type monocular lens 50 are that 1) it is not a curved lens and therefore can be easily manufactured, and 2) that the image-forming position is not affected by changes in temperature and humidity. Explaining the influence of temperature and humidity, since the lens 50 does not use a curved lens but uses the internal refractive index distribution, even if the lens 50 expands / contracts due to a temperature change, the refractive index distribution itself does not substantially change. Position is largely unaffected. Similarly, even if the ambient humidity changes, water vapor hardly enters the inside of the rod lens 50, and the influence of humidity is small. Therefore, it is possible to prevent deterioration of image quality due to temperature and humidity fluctuations.

The structure of each monocular lens 50 will be described with reference to FIG. The diameter of the lens 50 is, for example, about 1 to 5 mm, more generally about 0.5 to 10 mm, and the side peripheral surface is ground to have irregularities of about 1 to 10 μm to provide the irregular reflection layer 60, and to provide a reflection angle other than a normal opening angle. The light incident at an angle is diffusely reflected to prevent the light from advancing to the emission side in the lens 50.
Further, the diffused reflection layer 60 is covered with a transmission prevention layer 52 to which a pigment that absorbs LED light is added to optically separate the surrounding lenses from each other.

In FIG. 4, L using the monocular lens array 10 is shown.
The principle of the ED head will be described. The LED arrays 6 are arranged at intervals, and the monocular lens 50 is arranged for each LED array 6,
The LED light is doubled to form an image on the image forming surface of the photosensitive drum 02 or the like.

[0020]

Embodiment 2 FIGS. 5 to 8 show an embodiment in which the monocular lens array 10 is used to form a 1/2 reduced image. In the embodiment, an LED head having a resolution of 600 DPI is manufactured by using an LED array having a resolution of 300 DPI.
An EL array, a CCD array, or the like may be used instead of the ED array. In FIG. 5, reference numeral 02 denotes a photosensitive drum,
Reference numerals 2 and 4 are substrates, and 6 and 8 are LED arrays, each of which has a resolution of 300 DPI, and each light emitter is arranged at a pitch of 84.7 μm. Substrate wiring having a density corresponding to a resolution of 300 DPI is provided on the substrates 2 and 4. 10 is the above-mentioned monocular lens array,
Reference numeral 12 is a similar monocular lens array. Reference numeral 14 denotes a half mirror that forms an image of the transmitted light from the lens array 10 on the photosensitive drum 02 and an image of the reflected light of the light from the lens array 12. Therefore, the substrates 2 and 4 are arranged so as to be inclined by 90 degrees, and the half mirror 14 is arranged at an inclination of 45 degrees in the middle, so that the light from the two rows of the LED array is formed on a straight line on the photosensitive drum 02. Let

FIG. 6 shows details of the LED head. 16
Is a correction lens array using an array of cylindrical lenses or an array of toric lenses. Here, an array of cylindrical lenses is used. An array of lenses having a uniform surface in the plane of FIG. 6 and a curvature along a direction perpendicular to FIG. is there. The role of the correction lens array 16 is to form an image by bringing the optical path close to a parallel light beam to form an image and the photosensitive drum 0.
2 is to widen the tolerance to the interval variation. The correction lens array 16 may not be provided.

20 is a housing made of plastic or the like,
Substrate 2, 4, Monocular lens array 10, 12, Half mirror 1
4. The correction lens array 16 is assembled and fixed with an adhesive or the like. The optical elements in the embodiment are the LED arrays 6 and 8, the monocular lens arrays 10 and 12, the half mirror 14, and the correction lens array 16, which accurately position them. LED
The rows of the array 6 are fixed and positioned on the substrate 2, and the rows of the LED array 8 are fixed and positioned on the substrate 4. The upper surface (main surface on the LED array 6 side) of the board 2 is positioned by the reference surfaces 22 and 23 of the housing 20, and both side surfaces of the board 2 are positioned by the reference surfaces 24 and 25 of the housing 20. Similarly, the upper surface of the substrate 4 is positioned by the reference surfaces 26 and 27, and both side surfaces are positioned by the reference surfaces 28 and 29. Monocular lens array 1
The reference numeral 0 indicates that the lower surface (the surface on the LED array 6 side) is positioned by the reference surfaces 30 and 31 of the housing 20, and both side surfaces are located on the housing 2
Positioning is performed with reference planes 32 and 33 of 0. Similarly, the lower surface of the monocular lens array 12 is positioned by the reference surfaces 34, 35, and both side surfaces are positioned by the reference surfaces 36, 37.

The half mirror 14 holds both side surfaces in the longitudinal direction by the grooves 38, 39 provided in the housing 20, and the grooves 38, 3 are held.
Position with 9. The bottom surface of the correction lens array 16 is positioned by the reference surfaces 40 and 41 of the housing 20, and the correction lens array 16 is pressed by the pressing pieces 42 and 43 of the housing 20 from the front side.
The pressing pieces 42 and 43 are positioned so as to have a shape corresponding to the unevenness of the surface of the correction lens array 16.

Reference numeral 44 is a reinforcing portion for preventing the housing 20 from being deformed. Since the first set consisting of the LED array 6 and the monocular lens array 10 and the second set consisting of the LED array 8 and the monocular lens array 12 are arranged at an angle of 90 degrees at a right angle, the housing 20 has an L shape,
The two L-shaped pieces may be deformed. Therefore, in order to prevent this, the reinforcing portion 44 is provided.

7 and 8 show the principle of image formation in the embodiment.
In the embodiment, the LED arrays 6 and 8 have a resolution of 300 DPI.
Are arranged in two columns, and the optical images are reduced to 1/2 by the monocular lens arrays 10 and 12, and are formed on the photoconductor drum 02. Then, in order to align the directions of the light beams with different directions of 90 degrees,
The half mirror 14 is used. For example, the lower left LED in Figure 7
The light from the array 6 is reduced to 1/2 by the monocular lens 50,
An image is formed on the shaded portion of the photosensitive drum 02. Similarly, the light from the LED array 8 on the upper left is reduced to 1/2 by the monocular lens 50 to form an image. From the formed image, the LED arrays 6 on the substrate 2 and the LEs on the substrate 4 are alternately arranged for each LED array.
The D array 8 will be used.

In the embodiment, it is shown that the resolution is improved while the resolution of the LED arrays 6 and 8 is fixed at 300 DPI. Other than this, for example, resolution 600DP
It is also possible to use two columns of the LED array of I, reduce each of them by half with two monocular lens arrays, and form an image on a straight line with a half mirror, so that the image device has a total resolution of 1200 DPI.

[0027]

According to the invention of claim 1, 1) an array in which a monocular lens is precisely mounted is realized by using a self-alignment function of a rod-shaped lens and light shielding to an unnecessary lens, and a white stripe or a black stripe is formed. It is possible to obtain an imaging device with high image forming performance without any occurrence. 2) By using a rod-shaped distributed index monocular lens, deterioration of image quality due to temperature and humidity fluctuations, especially the occurrence of white streaks and black streaks, can be prevented. Can be prevented. According to the invention of claim 2,
In addition to 1) and 2), 3) the resolution can be improved without reducing the arrangement pitch of the light receiving and emitting bodies, and the realization of a high-resolution image device can be facilitated.

[Brief description of drawings]

FIG. 1 is a cross-sectional view of essential parts of a monocular lens array according to an example.

FIG. 2 is a characteristic diagram showing a refractive index distribution and an optical path of a rod-shaped lens used in an example.

FIG. 3 is a perspective view of a rod-shaped lens used in Examples with a cutout portion.

FIG. 4 is a diagram showing a principle of image formation in the image device of the embodiment.

FIG. 5 is a diagram showing the principle of the image device according to the second embodiment.

FIG. 6 is a sectional view of an essential part of an image device according to a second embodiment.

FIG. 7 is a diagram showing image synthesis in the image device according to the second embodiment.

FIG. 8 is a diagram showing a principle of image formation in the image device according to the second embodiment.

[Explanation of symbols]

 02 Photosensitive drum 2,4 Substrate 6,8 LED array 10,12 Monocular lens array 14 Half mirror 16 Correction lens array 20 Housing 22-25 Reference plane 26-29 Reference plane 30-33 Reference plane 34-37 Reference plane 38, 39 Grooves 40, 41 Reference planes 42, 43 Holding pieces 44 Reinforcing section 50 Rod-shaped monocular lens 52 Anti-transmission layer 54 Light-shielding lens 56 Black adhesive 58 Side plate 59 Flat surface 60 Diffuse reflection layer

Claims (2)

[Claims] 1. An image device using a monocular lens array and a light emitting and receiving array, wherein the monocular lens array includes a distributed index type rod lens.
An image device characterized in that the lenses are arranged in rows and in close contact with each other, and lenses other than predetermined lenses are shielded from light. 2. The light emitting and receiving arrays are three-dimensionally arranged in two or more rows, the monocular lens array is provided for each row of the light receiving and emitting arrays, and light from the light receiving and emitting arrays of two or more rows is combined. Alternatively, a half mirror for splitting is provided,
The image device according to claim 1.