JPS617819A - Image exposing device - Google Patents

Abstract

PURPOSE:To uniform the image light quantity distribution on the surface of a photosensitive body in the image breadthwise direction by constituting more optical transmitters at end parts of a converging optical transmitter array than at the center part. CONSTITUTION:Converging optical transmitters 7 are arranged in two arrays at both end parts and in one array at the center part to form a converging optical transmitter 4. In this case, the array A of converging optical transmitters 7 in the center and arrays B and C at an end part are on different lines, but an array D of converging optical transmitters 7 may be extended to the end part and the 2nd array E may be added at the end part. Consequently, even if an original surface illuminance distribution decreases at original surface breadthwise end parts, the quantity of light at corresponding image parts on the photosensitive surface is increased relatively to correct the image light quantity distribution. Further, a light shield plate 8 may be arranged between both end parts of a lamp 1 and the original surface so as to make the image distribution on the photosensitive surface more uniform.

Description

[Detailed description of the invention] (Technical field) The present invention relates to an image exposure apparatus.

(Prior art and problems) A device that forms and exposes images using a large number of convergent light transmitters (product name: SELFOC) whose refractive index decreases parabolically from the center outward in the radial direction is This is well known in machines and document reading devices.

For example, FIG. 7 schematically shows a document image exposure device for an electrophotographic copying machine. A document illumination light source 1 is a halogen lamp, a light lamp, etc., which is elongated in the width direction of the document, that is, in a direction perpendicular to the document scanning direction, and is focused by a reflector plate 2 and moves in the direction of the arrow to scan the document. The document 0 on the document glass 3 is irradiated. The original image is formed via a convergent light transmitter array 4 onto the optical surface of an electrophotographic photoreceptor 5 rotating in the direction of the arrow.

Here, the illuminance distribution in the width direction of the document on the document glass 6 is generally as shown by the broken line in FIG. This is because the light intensity of the light source 1 decreases at the edges, and in any case, when the illuminance distribution on the document surface becomes like the broken line, the light is transmitted onto the photoreceptor through the convergent light transmitter array 4. The light intensity distribution of the formed image is similar to the broken line in Figure 8 in the direction perpendicular to the direction of photoreceptor movement, and as a result, both ends of the image are dark (
This causes the inconvenience of

Conventionally, attempts have been made to make the illuminance distribution uniform in the document width direction by (1) adding reflectors to both ends of the lamp, or (2) lowering the intensity at the center of the lamp than at both ends. However, in the case of ■, the reflector requires a sufficient area, and if the distance between the light source 1 and the glass B is short, a sufficient effect cannot be expected. In the case of (2), reducing the amount of light at the center is equivalent to reducing the efficiency of the light source. In any case, such problems become more apparent when a fluorescent lamp is used as a light source.

(Purpose and Structure Summary) An object of the present invention is to substantially improve the image light intensity distribution on the photosensitive surface in the image width direction when the illuminance distribution on the document surface is lower at the edges in the width direction of the document than in the center. The object of the present invention is to provide a reliable and simple means of construction that can be uniformly applied.

Therefore, in the present invention, the number of array rows of light transmitters at the ends of the convergent light transmitter array is greater than that at the center (Example) Figures 1 and 2 4 is a perspective view of an embodiment of the present invention, and FIGS. 1(B) and 2(B) are partial plan views thereof.

In both embodiments, the convergent optical transmitter array 4 has convergent optical transmitters 7 arranged in two rows at both ends and one row at the center. Figures 1 (GA) and (B) are those in which the array A of the convergent light transmitters 7 in the center and the arrays B and C of the end portions are on different lines, respectively, and Figures 2 (5) and (B). ) is one in which the array of convergent light transmitters 7 extends to the end, and a second array E is further added. In this way, even if the document surface illuminance distribution decreases at the edges in the width direction of the document surface, the light amount of the corresponding image portion on the photosensitive surface can be relatively increased, and the image light amount distribution can be changed as shown by the solid line in Figure 8. It can be corrected to 5.

In addition, in order to make the light intensity distribution of the image on the photosensitive surface more uniform, depending on the number of optical transmitters at the end of the playback or the intensity at the end of the lamp, as shown in Figure 5. Alternatively, a light shielding plate 8 may be disposed between both ends of the lamp 1 and the document surface, thereby adjusting the illuminance distribution on the document surface. FIG. 4 shows an example in which light shielding plates 8 as the light amount correcting member are fixed to both ends of the array 4. In FIG.

Alternatively, as shown in FIG. 5, at both ends of the array 4, part of the light transmitting body 7 is covered with a light shielding or neutral density filter member 10 to make the light intensity distribution of the image on the photosensitive surface more uniform. It may be made into At that time, the position of the member 10 may be adjusted as shown by the arrow in FIG. 6 using a screw-elongated hole mechanism or an eccentric cam, and the amount of coverage of the light transmitting body 7 by the member 10 may be adjusted. .

In the above example, the array has one row of optical transmitters in the center,
Although there are two rows at the ends, two or more rows may be arranged at the center and more rows at the ends.

In any case, the array is used as shown in FIG. 7, but it can also be applied to an image reading device that forms a document image on a photoelectric conversion type image sensor and converts the image into an electrical signal.

(Effects) As described above, according to the present invention, the number of convergent light transmitters is increased at the edges than at the center (by doing so, it is possible to improve the efficiency of general light sources, especially fluorescent lights, where the light intensity decreases at the edges). In an image exposure device that uses a lamp as a light source, it is now possible to make the light amount distribution of an image uniform, and even in a system where the effect of an end reflector plate cannot be fully exerted, it is now possible to make the light amount distribution of an image uniform. In addition, since a sufficient amount of light can be secured at the edges of the image, it is possible to make the length of the lamp shorter than before, making it possible to further downsize the device.

[Brief explanation of the drawing]

Figure 1 (13), Figure 2 (B) is an embodiment of the present invention, Figure 3 is an example of edge light amount correction, Figures 4 and 5. FIG. 6 is a diagram for explaining another embodiment of the present invention, FIG. 7 is an electrophotographic copying machine to which the present invention can be applied, and FIG. 8 is a diagram for explaining the light amount distribution, the array, and the positional relationship of the lamps. 1: Lamp, 4-piece array, 7: Focusing light transmitter, 8.1
0 is a light amount correction member. ″”7'3

Claims (3)

[Claims] (1) In an image exposure device that uses an array of a plurality of convergent light transmitters to expose an image of a document onto a photosensitive member, the number of rows of light transmitters at the ends of the array is greater than the number of rows in the center. An image exposure device characterized by: (2) The optical transmission bodies are arranged in a line in the center of the array,
The image exposure apparatus according to claim 1, wherein the arrangement at the end portion is two or more rows. (3) The image exposure apparatus according to claim 1 or 2, in which a light amount correction member is combined at the end of the array.