JPS60135927A - Adjusting device of quantity of light - Google Patents

Abstract

PURPOSE:To control the transmission quantity of light with respect to place and time by arranging a light quantity adjusting member in the optical path and changing selectively physical properties of this member with respect to place. CONSTITUTION:When a voltage is applied between a common terminal C connected to a transparent common electrode substrate 33 and lead wires l1-l7 connected to electrodes of individual liquid crystal units 27A, a liquid crystal 30 in the area interposed between parts, to which the voltage is applied, is made opaque. If individual members constituting a light quantity adjusting plate 27 such as lead wires l1-l7, the common electrode 33, etc. are made transparent, only the light in the part of the liquid crystal unit 27A connected to the lead wire l3 is intercepted, and the light in the other parts is transmitted. Then, when the light quantity adjusting plate 27 is provided in the optical path and the voltage applied to each electrode is selected, only the liquid crystal unit 27A to which the voltage is applied is made opaque to intercept optionally and partially the light passing this unit, and thus the transmission quantity of light is adjusted. Since this light quantity adjusting member can be operated by a control signal, the transmission quantity of light is controlled accurately and quickly.

Description

[Detailed description of the invention] 1. Industrial application field The present invention relates to a light amount adjusting device.

2. Prior Art First, the general structure of a scanning exposure type electrophotographic copying machine that requires a light amount adjustment device will be described.

When a copy document is placed on the document table and a copy button is pressed, an exposure lamp illuminates the document and travels in a predetermined direction together with an optical system including a reflecting mirror. Reflected light corresponding to the density of the original is irradiated onto a uniformly charged toner image carrier (for example, a photosensitive drum) via the optical system, and an electrostatic latent image is formed on the toner image carrier. Ru. Further, a toner image corresponding to the density of the document on the photoreceptor drum is formed by the developer.

On the other hand, a recording medium (for example, copy paper) is fed from the paper feeding device so as to match the position of the toner image on the toner image carrier, and comes into contact with the toner image carrier. Then, the toner image formed on the surface of the toner image carrier is transferred onto copy paper by the transfer pole. During this time, the toner image carrier continues to rotate in a predetermined direction, and the toner image is gradually transferred onto the copy paper.

Thereafter, the copy paper onto which the toner image has been transferred is separated from the toner image carrier, and the copy paper is sent to a roller fixing device.

The roller fixing device is composed of two rollers, at least one of which is a heated roller, in the case of a heat roller type, and heats and fixes the image formed by the developer onto the copy paper. Thereafter, the copy paper is discharged out of the main body of the copying machine. On the other hand, the toner image carrier is cleaned to remove excess toner powder after the visible toner image is transferred to copy paper, and this process is repeated every time recording is performed. The photosensitivity of the photosensitive layer that forms the surface of the photosensitive drum used in copying machines varies to some extent depending on the location on the photosensitive drum surface.
Even if the same amount of light is applied during exposure, the electrostatic potential of the electrostatic latent image formed on the surface of the photoreceptor drum may differ depending on the location.

Therefore, even if a toner image is formed on the photoreceptor drum by the developing device, density unevenness will eventually appear on the copy paper, making it difficult to see or read. In addition, halogen lamps and warning lights are used as light sources to expose documents, but there is always unevenness in the amount of light in the longitudinal direction, and they also deteriorate with use and the distribution of light in the longitudinal direction changes, causing what is called shading. The amount of exposure at both ends, called ``kabushi'', decreases, and the final image on the copy paper becomes blurred at both ends.

Therefore, in order to correct variations in the sensitivity of the photoreceptor drum and unevenness in the light amount of the exposure lamp, we have developed two methods: Prepare a plate with slits (such as wide slits) and place a slit plate of an appropriate shape in the optical path, or provide a light distribution adjustment plate equivalent to a camera aperture in the optical path, such as a photoreceptor drum. For parts of the surface with good photosensitivity, reduce the amount of light irradiated there by using a slit plate, etc. For parts with poor photosensitivity, increase the amount of light, or for example, the amount of light from an exposure lamp is insufficient. At the edges (longitudinal direction of the rung), where light from the exposure lamp tends to be distorted, a slit is formed so that the light from the exposure lamp passes through the center, resulting in a uniform exposure amount as a whole, making it possible to copy without density unevenness or shading. I was trying to recover. However, with the above-mentioned means (2), the light emitted from the exposure lamp changes uniformly, and it is not possible to correct shading of the exposure lamp or variations in sensitivity depending on the location of the photoreceptor drum. In addition, with method (2), even if a large number of slit plates with slit shapes that correspond to variations in the sensitivity of the photoreceptor drum and unevenness in the light amount of the exposure lamp are prepared, it is difficult to switch, and the slit shape of the selected slit plate is Since it is fixed, it is difficult to adjust free time. Furthermore, experience and skill are required to select a slit plate with an appropriate slit shape or to adjust a light distribution adjustment plate. The slit plate and the light distribution adjustment plate are each installed in the optical path inside the copying machine.In order to replace the slit plate or adjust the light distribution adjustment plate, the glass original plate etc. must be removed. In addition, the biggest drawback of the methods (-) and (2) is that both methods can only correct variations in sensitivity in the axial direction of the photoreceptor drum, and cannot correct the sensitivity in the circumferential direction. It is impossible to deal with variations. Even if the light t irradiated onto the photoreceptor drum is adjusted by selecting a slit plate with a certain slit shape or adjusting the light distribution adjustment plate,
The light reflected from the document exposes the photoreceptor drum, and the amount of light is not adjusted during the formation of the electrostatic latent image. In order to correct the sensitivity unevenness of a rotating photoreceptor drum, there must be a means for temporally controlling the light that exposes the photoreceptor drum, and conventional means have not been able to do this.

3. Purpose of the Invention The present invention has been made to solve the above problems, and its purpose is to provide a light amount adjustment device that can control the amount of light transmitted locally and temporally.

4. Structure of the Invention In other words, the present invention provides a light amount adjustment member disposed in the optical path, and the physical properties of this light amount adjustment member are selectively changed depending on the location. The present invention relates to a light amount adjusting device that is characterized in that it can be selectively changed.

5. Examples Hereinafter, the present invention will be explained in detail with reference to examples shown in the drawings.

FIG. 1 is an example of a schematic diagram of a copying machine using a light amount adjustment device based on the present invention.

The original 2 placed on the original placing table 3 is placed on the platen cover 4.
When the copy start button is operated in this state, the exposure lamp 5 starts exposure scanning in the direction of arrow A, and the image of the original is transferred to the first mirror unit 7 to which the exposure lamp 5 is attached.
An optical device comprising a second mirror unit rib, a lens 21, a mirror 8, etc. leads to a photoreceptor drum 9 having a photoconductive photosensitive layer.

This photosensitive drum 9 has a photoconductive layer made of selenium or the like provided on the outer peripheral surface of a grounded metal cylinder, and rotates in the direction of arrow B in conjunction with the exposure scanning of the exposure lamp 5.
Before being irradiated with the reflected light from the original 2, the photoconductive layer is charged uniformly, for example, by a charging electrode 10 to which a DC voltage of, for example, 5 KV is applied, and the exposure lamp 5 exposes and scans the original. When the photoreceptor drum 9 is irradiated with this reflected light, the conductivity of the part that receives the light increases, the electrical charge in that part escapes to the metal tube, and a positive charge is created in the part that is not hit by the reflected light. This forms an electrostatic latent image on the surface of the photoconductive layer corresponding to the image of the original document.

When the photosensitive drum 9 further rotates, negatively charged toner from the developing device 11 is attracted to the remaining positively charged portion by electrostatic force. As a result, the toner is attracted to the remaining positively charged portion, and a visible image is formed on the surface of the photoreceptor drum 9.

On the other hand, the copy paper 18 is transferred from the paper feeder 15 to the photosensitive drum 9.
In order to match the toner image above, the paper feed roller 17 is moved at a timing such that the leading edge of the toner image matches the copy paper 18.
The visible image on the photosensitive drum 9 is transferred onto the fed copy paper 18 by the transfer pole 12 to which a DC high voltage is applied.

Thereafter, for example, the copy paper 18 is separated from the photoreceptor drum 9 by the separation electrode 13 to which an alternating current voltage is applied, and the copy paper 18 is conveyed with the toner image transferred onto the upper surface by the conveyor belt 40.
The toner image is fused by a fusing device 19 having a heated fusing roller. Thereafter, the copy paper 18 is delivered to a paper ejection tray section by a paper ejection roller 29.

Even if the toner image on the surface of the photosensitive drum 9 is transferred to the copy paper 18 by the transfer pole 12, a small amount of toner may remain. Ru. Through the above cycle, the original is copied.

What should be noted in the copying machine configured as described above is that the optical path from the exposure lamp 5 to the photoreceptor drum 9 (
In this embodiment, a common terminal C connected to a transparent common electrode substrate 33 and a common terminal C connected to a transparent common electrode substrate 33 and each liquid crystal unit 27A are shown in FIG. When a voltage is applied between the lead wires 11 to t7 connected to the electrodes, the liquid crystal I in the area sandwiched between the electrodes becomes opaque. In FIG. 3, a voltage is applied between the lead wire t3 and the common terminal C. Here, if each member constituting the light amount adjusting plate 27, such as the lead wire, ~t7, and the common electrode 33, is transparent,
The light coming from the direction of the arrow E is placed in the light path of the liquid crystal unit (27A) connected to the lead wire t3, and if voltage is selectively applied to each electrode, the liquid crystal to which the voltage is applied is Since only the UNION 27A is opaque, the light passing through it can be partially blocked as desired, making it possible to adjust the amount of light transmission. Fig. 4 shows a method for correcting the sensitivity unevenness of the photosensitive drum 9, which controls the on/off of the voltage provided in the electrophotographic machine body with the electrode shown in Fig. 3. Let me explain the case. First, the sensitivity of the photosensitive drum 9 is measured.

This can be done by measuring the surface potential at each location on the photoreceptor drum 9 or by detecting the toner density at each location on the surface of the photoreceptor drum 9 after development. can be measured. Here, a means for measuring sensitivity unevenness of the photosensitive drum 9 by detecting the toner density after development will be explained using FIG. 1 as an example.

When a document 2 whose entire surface has a constant density is placed on the document table 3 and a copying operation is performed, an electrostatic latent image is formed on the photoreceptor drum 9 by light reflected from the document 2, which is then developed. When developed by the device 11, a visible image with a toner density corresponding to the density of the original document 2 is formed on the surface of the photoreceptor drum 9. At this time, if the copy paper 18 is not fed and voltage is not applied to the transfer pole 12 and separation pole 13, the visible image on the photosensitive drum 9 will remain in front of the image density detection section 35. will pass through. The image density detection section 35 is composed of, for example, a reflective sensor, and a plurality of reflective sensors are arranged in the axial direction of the photosensitive drum 9. If the output of each reflective sensor is sequentially measured when the visible image formed on the photoreceptor drum 9 passes in front of the image density detection section 35, the photoreceptor in the axial direction and rotational direction of the photoreceptor drum can be measured. Information on sensitivity unevenness of the body drum 9 can be obtained.

For each of the plurality of reflective sensors arranged in the axial direction of the photoconductor drum 9, if the output of the reflective sensor measured at a certain moment is not constant, there may be uneven sensitivity in the axial direction of the photoconductor drum 9, or When the output of each reflective sensor varies over time, this indicates that there is sensitivity unevenness in the circumferential direction of the photosensitive drum 9.

The density unevenness of the toner formed on the photoreceptor drum 9 appears as a difference in the output of each reflective sensor, and this becomes information regarding the sensitivity unevenness of the photoreceptor drum 9. RA the information
M (Random Access Memory)
or P-ROM (Programmable Read
The axial and circumferential sensitivity of the photoreceptor drum 9 can be adjusted by storing it in a storage device such as 0nly Memory) and selectively turning on and off the photoreceptor drum 27A depending on location and time. It becomes possible to completely correct unevenness. By rewriting the data in RAM every day, first thing in the morning, or as needed, highly accurate compensation becomes possible.

Conventional means for adjusting the amount of light include changing the voltage applied to the exposure lamp 5 to uniformly change the amount of light generated from the exposure lamp 5, or adjusting the amount of light using a slit plate or a light distribution adjustment plate. There was no. The means for changing the voltage applied to the exposure lamp 5 cannot correct the sensitivity unevenness in the axial direction of the photoreceptor drum 9, and the slit plate or light distribution adjustment plate cannot correct the sensitivity unevenness in the circumferential direction of the photoreceptor drum 9. Unevenness cannot be corrected. Moreover, even if the two are combined, it is not possible to finely correct the sensitivity unevenness of the photoreceptor drum 9.

However, as shown in this embodiment, by storing the information obtained by the image density detection device in a ROM or the like, it becomes possible to finely correct the sensitivity unevenness of any part of the surface of the image density sensor.

In the embodiment described above, the uneven sensitivity of the photosensitive drum 9 can be corrected by changing the sensitivity unevenness of the photosensitive drum 9. According to this means, a ROM or the like having a small storage capacity can be used, and the cost becomes low.

In addition, in the past, the toner density of the copy paper was checked, an appropriate slit plate was selected, or the light distribution adjustment plate was manually operated, and this was repeated several times to adjust the amount of light to an appropriate level. However, in this embodiment, the above-mentioned operation is completely unnecessary, and the efficiency of the adjustment work is significantly increased.

Figure 5 is a diagram showing when a voltage is selectively applied to the knit 2'7A.
The figure shows when correcting uneven exposure when the sensitivity is poor at approximately the center and the sensitivity is good toward both ends.
In order to irradiate a large amount of light to areas with poor sensitivity, no voltage is applied to the liquid crystal unit (27A), making them transparent, and to areas with good sensitivity, a voltage is applied to reduce the amount of light, making them opaque. . Figure 6 shows.

In the above embodiment, the light amount adjustment position n is provided in the optical path between the second mirror unit 2o and the lens 21, but as shown in FIG. The same effect as described above can be obtained by providing the lens 21 with an auxiliary frame 21 and incorporating it into the auxiliary frame 21 as shown in FIG. FIG. 9 shows a schematic cross-sectional view of a copying machine using a cathode ray tube 36 as an exposure light source.Under the direction of a drive circuit 37, an electron beam is scanned and generated from the cathode ray tube. An electrostatic latent image is formed on the photoreceptor drum 9 by the light. When using the cathode ray tube 36, Q F T (0ptical fib
If it is integrated by adhering it to the er surface, it will not only be possible to correct the uneven exposure of the photoreceptor drum 9, but also
Since it is possible to correct the fluorescence unevenness of the cathode ray tube, it can also be configured by arranging liquid crystal units 27A in a row as shown in FIG.

Note that the present invention can be further modified based on its technical idea. In the embodiment described above, the present invention can be used to obtain a photographic record by taking as an example a means for correcting sensitivity unevenness of the photosensitive drum 9. In addition, when emitting a constant amount of light from a light source with uneven light emission to an irradiated object, it is possible to adjust the amount of light 1z2 in the optical path.
By setting and controlling 7, it is also possible to correct uneven light emission from the light source.

However, even if other electrochromic materials are used, the same effect as described above can be obtained. Further, in the above description, emphasis has been placed on correction of sensitivity unevenness, but as described above, it is also possible to control the equalization of the light amount distribution from an exposure lamp or other light source.

6. Effects of the Invention By disposing a light intensity adjusting member in the optical path and selectively changing the physical properties of this light amount adjusting member depending on the location, the amount of light transmitted through this member can be freely adjusted. In this way, various obstacles caused by, for example, uneven sensitivity of not only the photoconductive photoreceptor but also semiconductor image sensors such as COD, various objects to be irradiated, and uneven brightness of the light emitting source can be eliminated. Also,
Since this light amount adjusting member can be operated in response to a control signal, for example, it becomes possible to accurately and quickly control the amount of light transmission without relying on experience or skill.

[Brief explanation of drawings]

The drawings show an embodiment of the present invention, and FIG. 1 is a schematic sectional view of a copying machine using a light transmission amount adjustment plate, FIG. 2 is a front view of a light transmission amount adjustment plate, and FIG. Figure 3 is a schematic cross-sectional view of the light bleeding amount adjusting plate, Figure 4 is a partially enlarged view of Figure 2, Figures 5 and 6 are front views of the light bleeding amount adjusting plate during operation, Figure 7 is a diagram showing when the optical adjustment plate and reflection mirror are integrated, Figure 2 is an exploded view of the optical adjustment plate integrated with the lens, and Figure 9 is an exposed view of the cathode ray tube. FIG. 10 is an exploded view of a light-4 amount adjustment plate integrated with an OFT, and FIG. 11 is a diagram showing another example of a light transmission amount adjustment plate. Regarding the symbols used in the drawings, please refer to 2.
- One document 4 -------Platen cover 5 ------- One exposure lamp 9, ---- One photosensitive drum 21 ---- Lens 27, ---- One light amount adjustment (27A-----1 liquid crystal unit 30--1 liquid crystal 33---m--common electrode 1---------Lead wire.

Claims (1)

[Claims] 1. A light amount adjusting member is disposed in the optical path, and the physical properties of this light amount adjusting member are selectively changed in places, so that the amount of light transmitted is selectively changed in places. A light amount adjusting device characterized in that: 2. The light amount adjusting device according to claim 1, wherein the light amount adjusting member is composed of a liquid crystal, and the light transmittance of the liquid crystal is locally changed by an external signal. 3. The light amount adjusting device according to claim 1 or 2, wherein a light amount adjusting member is provided in an optical path that guides reflected light from a document to an image carrier.