JPH0823718B2 - Image forming apparatus having optical image memory - Google Patents

Description

The present invention relates to an image forming apparatus for forming an image by image information light such as reflected light of an original, and after the image information is temporarily stored in an optical image memory. The present invention relates to an image forming apparatus that reads out an image and forms an image.

(B) Conventional Technology In image forming apparatuses such as electrophotographic copying machines, the functions thereof have been diversified in recent years. For example, in the case of an electrophotographic copying machine, which has spread remarkably in recent years, it has various functions such as multi-copy, double-sided copy, and composite copy.

By the way, a general copying machine uses an original scanning type as an optical system, which includes a scanner that moves along an original placed on an original table, and the reflected light of the original reflects a mirror and a lens. And so on to the photoconductor. Therefore, according to this optical system, the original must be scanned to form one copy,
When performing multi-copy or the like, it is necessary to scan the originals for the number of copies, so that there is a problem that the copying process takes time. Further, in that case, the scanner return time is also required for every scanning of one document, which causes a problem that the processing time becomes longer.

For multi-copying, a sorter that sorts and discharges copied paper on multiple trays, or an automatic document feeder that circulates the original copy several times to make copies is used. Although it is designed to be ejected, there is a problem that the device becomes large in and a problem that the document is easily damaged in.

Therefore, conventionally, as shown in JP-A-54-140542,
The original image is once written in the optical image memory such as liquid crystal, electrochromy, PLZT (compound of Pb, La, Zr, Ti), and when the image is formed, the original image is read out from the optical image memory and recorded on the recording medium (photoconductor). An automatic document processor for recording (latent image formation) has been proposed. In addition, Japanese Utility Model Application Laid-Open No. 54-139852 discloses a method of forming an optical image memory on each surface of a regular polyhedron and irradiating the photoconductor with the reflected light of the image written in the optical image memory to form a latent image. Has been done.

(C) Problems to be Solved by the Invention By the way, the above-mentioned photoconductor has a latent image formed by a state change depending on the presence or absence of light irradiation. For example, when a photoconductor having a photoconductive layer is used, First, the surface of the photoconductor is uniformly charged and then exposed by the reflected light from the optical image memory. Then, the resistance of the photoconductive layer in the exposed portion is reduced, and the surface charge is canceled. As a result, an electrostatic latent image is formed on the photoconductor. In general, toner is attached to the area where the charge is not canceled, that is, the area where the light is not irradiated, and the latent image is developed.

However, when an image is formed using the optical image memory as described above, a toner adhering portion may be formed around the image forming portion. This is because the peripheral portion of the optical image memory is not irradiated with light, so that the surface charge is not canceled and the toner adheres to the periphery of the portion (image forming portion) corresponding to the optical image memory. If the paper to which the toner is transferred is approximately the same size as the optical image memory, this excess toner remains on the photoconductor as is and is discarded as waste toner, but if the size of the paper is large, it is transferred to the paper. There is a problem that a frame-shaped portion is formed around the image. In addition, since extra toner is used for each image formation as described above, there is a problem that the cost for image formation increases.

In view of the above-mentioned problems, the present invention prevents the toner from adhering to the periphery of the image forming unit by using the frame surface of the image storage memory as a light reflecting material, thereby forming an image having an optical image memory. The purpose is to provide a device.

(D) Means for Solving the Problems The present invention provides a frame with an optical image memory capable of image writing, reading and erasing, and irradiates light from the image reading side of the image written optical image memory. Then, in the image forming apparatus for forming a latent image on the photoconductor by exposing the photoconductor with the reflected light of the optical image memory, the surface of the frame on the image reading side of the optical image memory is made of a light reflecting material. The surface of the frame on the image writing side is made of a light absorbing material.

(E) Function In the present invention, when the optical image memory on which the image is written is irradiated with light from the image reading side, the light corresponding to the written image is reflected on the optical image memory portion to expose the photoconductor. To do. Further, in the peripheral portion of the optical image memory, that is, in the frame portion of the optical image memory, since the surface of the frame body is a light reflecting material, the irradiated light is almost totally reflected to expose the photoconductor. Therefore, for example, when a photoconductor having a photoconductive layer is used, a latent image corresponding to the image to be formed is formed in the region corresponding to the optical image memory on the photoconductor, and all the charges in the surrounding region are charged. In the canceled state, toner is not attached to the peripheral portion. Further, since the surface of the frame body on the image writing side is made of a light absorbing material, no reflected light is generated when the image is written in the optical image memory. Therefore, the optical image memory is not exposed by the reflected light during image writing. Therefore, good image writing can be performed in the optical image memory.

(F) Example <Description of Image Forming Method Using Optical Image Memory> Description of Configuration FIG. 5 is a diagram showing a sectional configuration of the optical image memory.

The optical image memory 1 includes an upper substrate 1a composed of a glass 11 that transmits light, a transparent electrode 12 made of ITO or the like, a photoconductive layer 13 and a reflective layer 14, and a lower substrate 1b composed of glass 11 and a transparent electrode 12.
And a liquid crystal layer 15 between them. Transparent electrode 12,1
A write power supply 16 or an erase power supply 17 is selectively connected between the two by a switch 18. In this embodiment, the writing power source 16 is a DC power source and the erasing power source 17 is an AC power source, but these power sources vary depending on the type of liquid crystal and the layer thicknesses of the photoconductive layer and the liquid crystal layer.

The photoconductive layer 13 is formed, for example, by light irradiation of an inorganic photoconductive material such as CdS, CdSe, As2Se3, SeTe, amorphous silicon or amorphous germanium, or an organic photoconductive material such as polyvinylcarbazole or trinitrofluorenone. It is a material whose resistance decreases. Further, the liquid crystal layer 15 is a ferroelectric liquid crystal, and even if the electric field is removed, the state in which the dielectric polarization occurs is stable and the direction is reversed by the external electric field. Specifically, there are smectic C phase, nematic cholesteric mixed liquid crystal and the like. In this embodiment, cholesteric liquid crystal 5 is used.
% -Nematic liquid crystal 95% mixed liquid crystal is used. Further, the reflection layer 14 blocks light so that the light emitted from above does not pass through to the lower side, reflects the read light from the lower side, and prevents the photoconductive layer 13 and the liquid crystal layer 15 from coming into contact with each other. It prevents chemical reaction between both layers.

 Description of Operation FIG. 6 is an equivalent circuit of the optical image memory.

In the figure, 13R and 13C are the resistance and capacitance of the photoconductive layer 13, 15
R and 15C represent the resistance and capacitance of the liquid crystal layer, respectively.

When light having image information such as document reflected light is irradiated from the photoconductive layer 13 side (writing side) while the writing power supply 16 is applied between the transparent electrodes 12 of the optical image memory 1, the light is emitted. The resistance of the photoconductive layer in the region is lowered, the electric field applied to the liquid crystal layer corresponding to this region is increased, and dielectric polarization occurs in the liquid crystal layer. This lowers the light transmittance of the liquid crystal layer in this region (light is scattered). Further, the resistance of the region of the photoconductive layer which is not irradiated with light does not change, and the liquid crystal layer corresponding to that region does not undergo dielectric polarization, so the light transmittance does not change. In this way, the liquid crystal layer 13 is partially changed by the light irradiation, and an image is written in the optical image memory 1.

When the optical image memory 1 is irradiated with light from the liquid crystal layer 15 side (readout side), the irradiated light is reflected by the reflective layer 14 because the light transmittance is high in the region where the liquid crystal layer has not changed in the above-described process. The light is scattered in the area where the liquid crystal layer has not changed. This becomes image information light, and this light forms an image on the electrophotographic photosensitive member or the like.

When erasing the image information written in the optical image memory 1, when the erasing power supply 17 is applied between the transparent electrodes 12 and 12, the entire surface of the optical image memory is irradiated with light from the writing side. An erasing power source is applied to the liquid crystal layer 15 to increase the transparency of the liquid crystal layer 15 and erase the written image.

Since the liquid crystal layer 13 is a memory type, the written image is not erased even if the application of the writing power supply 16 is released after the image is written, and the written image is stored for a long time. Can be set. Therefore, a power source for storing the image information on the optical image memory is unnecessary. As the optical image memory, other than the above-mentioned ones, an electrochromic material having an image storage effect, PLZT, or the like may be used.

<Description of Copying Machine Using Optical Image Memory> Configuration of Copying Machine FIG. 3 is a schematic front view of a copying machine to which the above optical image memory is applied.

An automatic document feeder (ADF) 2 is provided on the upper surface of the copying machine body. The ADF 2 has a document tray 21, a supply roller 22, a conveyor belt 23, a paper discharge tray 24, and the like. The originals to be copied are placed on the original tray 21 with the image surface facing downward, and are supplied one by one from the top by the supply roller 22. The original supplied by the supply roller 22 is further supplied and conveyed by the conveying belt 23, temporarily stopped on the original table 25, exposed by an optical system described later, and its reflected light (original reflected light) is guided to the optical image memory. . Then, the exposed document is discharged onto the paper discharge tray 24 by the conveyor belt 23.

An image storage device 3 having an optical image memory is provided in the central portion of the main body of the copying machine. The image storage device 3 is provided with a memory plate having a plurality of optical image memories, and a holding portion for holding the memory plate detachably and moving it in the directions of arrows A and B in the drawing. At the bottom of the platen 25,
An image writing optical system including 6, 26 and a lens 27 is provided, the document set on the document table 25 is exposed, and the reflected light is guided to the memory plate. Reference numeral 28 is an erasing lamp used when erasing an image in the optical image memory.

FIG. 1A is an external perspective view of the memory plate,
FIG. 1B is an external perspective view of the holding portion of the memory plate.

The memory plate 31 includes a plurality of optical image memories 3 in a frame 31a.
1-1 to 31-n are filled. In the figure, the upper surface of the frame 31a is on the image writing side, that is, the photoconductive layer side, and the lower surface is on the image reading side. The upper surface of the frame 31a is configured to absorb light, and the lower surface is configured to reflect light. For example, the frame body 31a is made of a metal such as Al that is mirror-reflected, and only its upper surface is painted black. Therefore, it is possible to prevent light from being absorbed on the upper surface of the frame body 31a and reflected light by the frame body 31a from entering the optical image memory as stray light.
Further, since the light is totally totally reflected on the lower surface of the frame 31a, the charges around the optical image memory are almost completely canceled when a latent image is formed on the photoconductor by the reflected light of the optical image memory. The width of the frame body 31a is substantially the same as the width of the photoconductor described later, the photoconductor can be exposed almost completely in the width direction, and the reflected light may stray into other parts of the image forming apparatus as stray light. Absent. Further, as the frame body 31a, another one may be used as long as the upper surface absorbs light and the lower surface reflects light. For example, the frame body may be resin-molded and the upper surface may be black-painted or bonded with a black resin, or the lower surface may be metal-plated or a mirror-reflecting Al sheet may be bonded. The light reflectance of the lower surface of the frame 31a may be substantially the same as that of the reflective layer 14 of the optical image memory.

As described above, the optical image memories 31-1 to 31-n each include the photoconductive layer and the liquid crystal layer, and the light transmittance of the area illuminated by the reflected light of the document is reduced to form an image. Each of the optical image memories 31-1 to 31-n is made in accordance with the maximum size of a document placed on the document table 25.
The image writing optical system is also arranged accordingly.
For example, in the copying machine of this embodiment, the maximum size of the document placed on the document table 25 is A3 size, and the reflected light of the document guided by the image writing optical system is the optical image memories 31-1 to 31-1.
An image of maximum A3 size is written in each of 31-n. The memory plate 31 is moved in the directions of arrows A and B in FIG. 3 by a holding portion described later, whereby the optical image memory 31-1.
Any one of 31 to 31-n faces the image forming position of the image writing optical system and the exposure position of the reading optical system, which will be described later, and an image is written in or read from the optical image memory. An electrode 32 is provided at the end of the memory plate 31. This electrode 32 is a transparent electrode (12,1) of each of the optical image memories.
2), and the write power supply or erase power supply is connected.

The memory plate 31 is mounted on the holding portion shown in FIG. 4 (B). The holding portion has a window frame-shaped holding member 33, and the memory plate 31 is fitted into the holding member 33. This fitting may be, for example, meshing, and may be any mechanism as long as the memory plate 31 can be locked at a predetermined position of the holding member 33. An electrode 34 forming a pair with the electrode 32 is provided at an end of the holding member 33, and power is supplied from a writing power source and an erasing power source via a cord 35.

Under the holding member 33, driving rollers 33a, 33a are provided. An engaging portion (not shown) that engages with the rollers 33a, 33a is provided below the holding member 33.
By the rotation of 33a, 33a, they move in the directions of arrows A and B in the figure. The rollers 33a, 33a are connected by a shaft 33b, and the pulleys 33c,
The driving force of the motor 33f is transmitted via the belt 33d and the pulley 33e. Further, the holding member 33 has a detection piece 36 for position detection.
And an optical sensor 37 for detecting the detection piece 36. When the optical sensor 37 detects the detection piece 36, the first optical image memory 31-1 of the memory plate 31 faces the image writing optical system and the image reading optical system described later, which serves as a reference for the memory plate 31. The position.

The memory plate 31 is detachably attached to the holding member 33, and the electrode 32 of the memory plate 31 and the electrode of the holding member 33 are attached.
By connecting 34, power is supplied to the transparent electrode of the memory plate 31. Since the memory plate 31 is detachably attached to the holding member 33 (copier body) in this way, the memory plate 31 can be easily replaced when the characteristics of the optical image memory deteriorate. Further, it is possible to easily exchange the types of memory plates (those having different numbers of optical image memories on the memory plate surface, those having different sensitivity characteristics, etc.). The holding member 33 is coated with, for example, black so that the upper and lower surfaces thereof absorb light.

 FIG. 4 is an electric circuit diagram of the memory plate portion.

Depending on the selection of the switch 18, either the write power source (DC) 16 or the erase power source (AC) 17 is supplied to the transparent electrode of the memory plate 31. The switches 38-1 to 38-n are switches for supplying electric power to the transparent electrodes 12-1 to 12-n. The switch 18 is connected to the writing power supply 16 when the image is written in the memory plate 31, and is connected to the erasing power supply 17 when the image is erased. Also switch
38-1 to 38-n are optical image memories 31-1 to 31-
It is a switch connected when an image is written to or erased from n.

Further, the memory plate 31 is provided with a protective cover for protecting the optical image memory surface from dust and the like. FIG. 2 (A) is a view showing a cross section of the protective cover, and FIG. 2 (B) is an external perspective view thereof. An upper cover 39a and a lower cover 39b are provided on the upper and lower surfaces of the memory plate 31, respectively. The upper and lower covers 39a, 39b are substantially box-shaped and are made of a light transmissive member such as glass, resin film, or plastic. The transmitted light is in the wavelength range where the optical image memory is exposed. The upper and lower covers 39a and 39b are provided so as to protect the optical image memories 31-1 to 31-n of the memory plate 31, respectively, and the height thereof is equal to or more than the focal depth of the lens. That is, the height of the upper cover 39a is not less than the focal depth d1 of the lens 27 of the image writing optical system, and the height of the lower cover 39b is not less than the focal depth d2 of the lens of the image reading optical system described later. There is. Therefore, even if dust or the like adheres to the protective covers 39a and 39b, the dust does not affect the image formed on the optical image memory or the photoconductor. The d1 and d2 are usually about 2 to 30 mm.

A filter corresponding to the sensitivity characteristic of the photoconductive layer 13 may be used for the upper cover 39a, and a filter corresponding to the sensitivity characteristic of the photoconductor 4 may be used for the lower cover 39b. A heat ray absorption filter that absorbs the heat of the optical system may be used.
Further, if the side surfaces of the box-shaped upper and lower covers 39a and 93b are made of a member that does not transmit light, there is an advantage that the optical image memory can be prevented from being exposed to stray light.

In FIG. 3, a drum-shaped photosensitive member 4 is arranged below the main body of the copying machine. The photoconductor 4 has a photoconductive layer,
Surrounding charger 41, developing device 42, transfer charger 43
Etc. are provided. The surface of the photoconductor 4 is uniformly charged by the charging charger 41, and then exposed to the light guided by the image reading optical system. The image reading optical system has a light source 51, mirrors 52 and 53, and a lens 54 arranged below the memory plate device 3, and guides the reflected light of the memory plate 31 to the photoconductor 4. An electrostatic latent image is formed on the photoconductor 4 by the reflected light of the memory plate 31, and the electrostatic latent image is developed by the developing device.
Visualized with 42 toner. A sheet cassette 61 is provided on the left side surface of the main body of the copying machine, and a sheet to be subjected to toner transfer is fed to the transfer charger 43. The transfer charger 43 transfers the toner onto the sheet, and then the sheet is fixed by the fixing device 62 and discharged to the sheet discharge tray 63.

Continuous Copy Operation In the case of continuous copy (forming a plurality of copies of a large number of originals) by the copying machine configured as described above, first the memory plate 3
An image is written in the optical image memories 31-1 to 31-n (n is the number of originals) by the reflected light of the original, and then the reflected light of the memory plate 3 forms an image on the sheet.

When writing an image, the switch 18 is connected to the writing power supply 16, and the switches 38-1 to 38-n are sequentially turned on. For example, first, an image is written in the optical image memory 31-1 of the memory plate 31 by the reflected light of the first original.
At this time, only the switch 38-1 is turned on and the others are turned off. When the image is written in the optical image memory 31-1, the holding member 33 is moved in the direction of arrow A by one optical image memory, and the reflected light of the second original causes the optical image memory.
Image is written to 31-2. At this time, switch 38
Only -2 is turned on. In this way, the images are sequentially written from the optical image memory 31-1 while sequentially replacing the original and the memory plate, and when the image writing of the nth original is completed, the writing process is completed. During the writing process, the upper surface of the frame body 31a of the memory plate 31 is configured to absorb light, so that the reflected light of the frame body 31a does not expose the optical image memory as stray light. It is possible to write various images.

Next, in order to read the image information written in the memory plate 31 and form an image on the sheet, the holding member 33 is moved to the arrow B direction.
The optical image memory 31
Image reading is performed in order from -1 to form an image. This reading is performed by moving the holding member 33 in the direction of arrow A to scan the image information in the optical image memory and guiding the reflected light to the photoconductor 4, and the moving speed of the holding member 33 in the direction of arrow A. Is set according to the rotation speed of the photoconductor 4 and the copy magnification. When copying a plurality of originals, the holding member 33 continues to move in the direction of arrow A, during which the images of the optical image memories 31-1 to 31-n are read (scanned) by the image reading optical system. Images are sequentially formed. When copying multiple copies, the optical image memory 31-
After the holding member 33 has moved to n, the holding member 33 returns to the reference position (moves in the direction of arrow B), and image formation is performed while moving in the direction of arrow A again.

When the latent image is formed on the photoconductor 4 by the reflected light from the optical image memory, the frame body 31a of the memory plate 31 is configured to reflect the light.
The charge of the portion corresponding to 31a) is canceled and the toner does not adhere to the portion.

By continuously moving the holding member 33 in the direction of the arrow A in this manner, a plurality of originals can be continuously image-formed, so that the processing time can be shortened. In addition, even when images are formed on multiple copies, the images are formed for each copy and discharged onto one tray, so there is no need to install a sorter, etc., and the size of the device can be prevented. Since it does not occur, the document can be prevented from being damaged.

When erasing the images in the optical image memories 31-1 to 31-n, the erasing power source 17 is applied and the switches 38-1 to 38-n are applied.
The image information written in the optical image memories 31-1 to 31-n is erased by turning on the switch and turning on the erasing lamp 28.

As described above, image formation is performed using the optical image memory. In this embodiment, an electrophotographic photosensitive member having a photoconductive layer is used as the photosensitive member, but other photosensitive members such as a photocuring material and a media sheet coated with microcapsules containing a colorless dye are used. Good.
In this media sheet, the microcapsules in the area exposed to light cure, so if an image receiving sheet coated with a developing material is overlaid and pressure is applied using a pressure roller, etc., the uncured microcapsules are destroyed and the colorless flow out. The dye is developed by the developing material of the image receiving sheet to form a colored image. Therefore, in this case, the microcapsules around the image forming portion (the portion corresponding to the optical image memory) of the media sheet are hardened by the light reflected by the frame body, so that unnecessary destruction of the microcapsules is prevented and the formed image is formed. It is possible to prevent the inside of the main body of the image forming apparatus from being soiled or soiled.

When forming a negative image, for example, when forming an image using a photoconductor having a photoconductive layer, it is possible to obtain a negative image in which black and white are reversed by attaching toner to a region where charge is canceled. However, in that case, the surface of the frame body of the optical image memory is made of a light absorbing material to prevent the adhesion of toner to the peripheral portion of the image forming area.

(G) Effect of the Invention As described above, according to the present invention, since the image reading side surface of the frame body around the optical image memory is made of the light reflecting material,
The photoconductor is exposed by the light reflected by the frame, and the periphery of the image forming portion (the portion corresponding to the optical image memory) can be made in the same state as the white portion of the document. Therefore, for example, when a photoconductor having a photoconductive layer is used, there is an advantage that waste of toner can be prevented, the cost of image formation can be reduced, and image stain can be prevented. Further, since the surface of the frame body on the image writing side is made of a light absorbing material, no reflected light is generated when the image is written in the optical image memory. For this reason, since the optical image memory is not exposed by the reflected light during image writing, a good image can be written in the optical image memory. Further, when a media sheet coated with photosensitive microcapsules is used, there is an advantage that stains on a formed image and stains inside the image forming apparatus, especially stains on the pressure roller can be prevented.

[Brief description of drawings]

1 (A) and 1 (B) are an external perspective view of an image memory plate and an external perspective view of a holding portion thereof, and FIG. 2 (A) and FIG.
(B) is a cross-sectional view and a perspective view of the protective cover of the memory plate, FIG. 3 is a schematic configuration diagram of a copying machine having the memory plate, and FIG. 4 is a circuit diagram of the memory plate. FIG. 5 is a diagram showing a cross-sectional structure of the optical image memory, and FIG. 6 is an equivalent circuit diagram of the optical image memory. 3 ... Image storage device, 31 ... Memory plate, 31a ...
Frame, 31-1 to 31-n ... Optical image memory, 33 ... Holding member.

 ─────────────────────────────────────────────────── ─── Continuation of front page (56) References JP-A 1-243078 (JP, A) JP-A 57-13458 (JP, A) JP-A 50-122241 (JP, A) JP-A 62- 14638 (JP, A) JP 56-32161 (JP, A) JP 53-143329 (JP, A) JP 61-149977 (JP, A) JP 60-252336 (JP, A) JP-A-54-140542 (JP, A) Actually opened 54-139852 (JP, U) JP-B-3-3220 (JP, B2)

Claims (1)

[Claims] 1. An optical image memory capable of image writing, reading and erasing is provided in a frame, and light is emitted from the image reading side of the image written optical image memory to reflect light from the optical image memory. An image forming apparatus for forming a latent image on a photoconductor by exposing the photoconductor with light, wherein the frame surface on the image reading side of the optical image memory is a light reflecting material, and the frame body on the image writing side is used. An image forming apparatus having an optical image memory, the surface of which is a light absorbing material.