JPH0664375B2 - Image forming device - Google Patents

Description

TECHNICAL FIELD The present invention relates to an image forming apparatus capable of high-definition and large-sized display.

[Conventional technology]

Conventionally, as this type, there is a type using a CRT (cathode ray tube), a flat display using a liquid crystal, or a type using an electrophotographic process.

[Problems to be solved by the invention]

Among them, the one using the CRT has a large CRT, which makes it difficult to construct a small apparatus. In addition, the flat display using liquid crystal has a drawback that the driving circuit has a complicated structure and is expensive. For example, the pixel is 500 × 50
When configuring a display of 0, it is necessary to control ON / OFF (color) of each pixel independently at the same time,
Conventionally, it was necessary to control ON / OFF of each pixel by the number of pixels, that is, 250,000 driving circuits. Although measures are taken such as integrating dozens of drive circuits, a large number of drive circuit ICs and complicated wiring have been an obstacle to cost reduction.

Further, in many conventional display devices such as CRTs and liquid crystals, when the power is turned off, the displayed contents are erased, so that it is necessary to supply electric power during the displaying period.

In addition, it is also conceivable to use an electrophotographic process as described in JP-A-58-153957. A display device using a similar process is disclosed in Japanese Patent Laid-Open No. 58-58.
It is also described in Japanese Patent Publication No. 98746.

These processes are carried out between a counter electrode arranged to face the photoconductor layer of a photoconductor having a transparent conductive layer and a photoconductor layer provided on a transparent support, and between the photoconductor layer and the counter electrode. Means for supplying toner to the transparent conductive layer, means for applying an electric field between the transparent conductive layer and the counter electrode to perform light image exposure from the transparent support side, and a force for attracting the toner to the counter electrode side. Means for selectively adhering the toner onto the photoconductor to form a visible image, and does not require a charger or cleaning device for uniformly charging at high voltage. Although there are certain advantages, there are drawbacks such as the need to apply a voltage of 100 V or more and the difficulty of obtaining a stable image.

Further, as described in Japanese Patent Laid-Open No. 58-98746, a structure in which the means for performing the light image exposure and the toner supply means are fixed and the photosensitive member is moved is inevitably large in size. There were no drawbacks.

An object of the present invention is to provide a relatively compact image forming apparatus which uses a small number of drive circuits, has a relatively simple structure, and can use a low voltage of several tens of volts or less to perform high-definition and large-sized display. To provide in form.

Another object of the present invention is to provide a high-definition and large-sized image forming apparatus capable of continuously displaying even after the power is turned off.

[Means for solving problems]

A first aspect of the image forming apparatus according to the present invention includes a photoconductor, a counter electrode, a means for supplying toner, an optical exposure system, and a means for applying a force to attract the toner to the counter electrode side. The image forming apparatus has a means for moving the counter electrode and a means for electrically sequentially switching the light image exposure positions in synchronization with the movement of the counter electrode.

The second invention of the image forming apparatus according to the present invention is a means for irradiating uniform irradiation light as an optical exposure system, and an electronic shutter means for controlling the passage of this uniform irradiation light in synchronization with the movement of the counter electrode. And are provided.

[Action]

According to a first aspect of the present invention, while moving the counter electrode, the light image exposure position is sequentially switched in synchronism with this movement, and toner is selectively adhered onto the photoconductor to form a visible image.

A second aspect of the present invention is that the exposure light is selectively passed by an electronic shutter during exposure to sequentially switch the optical image exposure position to selectively attach toner onto the photoconductor. It is a visible image.

〔Example〕

FIG. 1 and FIG. 2 are views for explaining one embodiment of the first invention of the present invention, and show the case where the pixels are 10 × 10 pixels. Reference numeral 1 is a photoconductive layer, 2 is a transparent conductive layer, 3 is a transparent support, and 1, 2, 3 constitute a photoreceptor 4. Reference numeral 5 is an optical image exposure system, and 6 is a magnetic brush means. The magnetic brush means 6 comprises a magnet roller 7, a rotatable sleeve 8 concentric with the magnet roller 7, and a conductive toner 9 disposed on the sleeve surface and attracted by the magnetic attraction force of the magnet roller 7. To be done.

As shown in FIG. 2, the light image exposure system 5 has a two-dimensionally arranged exposure light source group 10 which will be described later and whose light irradiation position can be independently controlled for each pixel by a driving unit (not shown).

A voltage 13 is applied between the sleeve 8 of the magnetic brush means 6 and the transparent conductive layer 2 of the photoconductor 4.

To operate this, the magnetic brush means 6 is moved in the direction of arrow 12 while rotating the sleeve 8 in the direction of arrow 11. Here, if the gap 14 between the sleeve 8 and the photoconductor layer 1 of the photoconductor 4 is set appropriately, the resistance when the toner 9 on the sleeve surface passes through the gap 14 is large, so that the magnetic brush means 6 advances. A toner pool 15 is generated in the direction. Since the voltage 13 is applied to the toner 9 through the sleeve 8, the surface of the photoconductor in contact with the toner 9 is
The polarity of the voltage 13 is uniformly charged. On the other hand, the photoconductive layer 1 is exposed to light through the transparent conductive layer 2 and the transparent support 3 by the optical image exposure system 5 as follows.

The exposure light source group 10 shown in FIG. 2 is composed of light source rows 10-1, 10-2, 10-3, ... 10-10 corresponding to the scanning lines, and is synchronized with the movement of the magnetic brush means 6. Optical image exposure is sequentially performed.

That is, when the magnetic brush means 6 comes over the light source array 10-1, ten light source elements 10-1-1, 10- on the light source array 10-1.
1-2, …… 10-1-10 is activated according to the image signal. When the light source element emits light, this light passes through the transparent support 3 and the transparent conductive layer 2 to expose the photoconductive layer 1. As a result, the photoconductor layer 1 is brought into a conductive state in the portion where the light irradiation is performed, and the electric charge charged on the surface is removed.

For example, when the light source elements 10-1-2 and 10-1-3 emit light, only the surface of the photoconductor layer 1 corresponding to this portion is discharged.

Then, when the magnetic bra means 6 comes over the light source array 10-2,
The light source elements 10-2-1, 10-2-2, ... 10-2-10 are caused to emit light in accordance with an image signal.

In this way, in synchronization with the movement of the magnetic brush means 6,
When the light source elements on the light source arrays 10-1, 10-2, 10-3, ... 10-10 are sequentially made to emit light in accordance with the image signal, an electrostatic latent image corresponding to the successive image signal is formed on the photoconductor 4. An image is formed. Then, when the surface of the photoconductor 4 separates from the toner 9 as the magnetic brush means 6 moves, the toner adheres only to the portion where the charge is removed. This is for the following reason.

In FIG. 3, since a voltage 13 is applied between the sleeve 8 and the transparent conductive layer 2, an electric field is generated in the layer of the toner 9. However, the electric field E ₁ is small in the portion where the charged electric charges 16 are present, and the electric field E ₂ is large in the removed portion. Therefore, in the portion where the charge is removed, a current flows through the toner 9 due to the electric field E ₂ , and the toner 17 in the portion that contacts the photoconductor 4 is charged as shown in FIG. Since the toner 17 is attracted toward the photoconductor 4 by the electrostatic attraction between the toner 17 and the induced charge 18 on the transparent conductive layer 2, the toner 17 remains even after the magnetic brush means 6 is separated. On the other hand, in the portion where the charge is not removed, the electric field E ₁ is small, so that the toner 17 is difficult to be charged. Even if the charged toner 17 is present, a repulsive force due to the same-polarity charge acts on the charged charge 16 on the photoconductor 4 and the toner 9 does not adhere. Actually, the charge removal by exposure and the toner 9 after the charge removal
However, in any case, as the magnetic brush means 6 moves, a toner image is formed on the upper surface of the photoconductor 4 according to the exposure light image by the optical image exposure system 5.

It should be noted that the toner 9 is not exposed after the light image exposure.
The contact time between the surface of the photoconductor 4 and the surface of the photoconductor 4 should not be too long. That is, if the time period during which the charged toner 17 is in contact with the photoconductor 4 is too long, the surface of the photoconductor 4 after the charge removal is again cut off, so that the toner suction force becomes weak and an image is not formed. Further, since the optical image of the light source element is directly guided to the photoconductor layer 1 through the transparent support 3 and the transparent conductive layer 2 without passing through the lens, the thickness of the transparent support 3 and the transparent conductive layer 2 is equal to the optical image. It is desirable to make it thin to prevent the diffusion of

The exposure light source group 10 includes an electroluminescent plate (EL) made of a phosphor.
Various materials such as a plate), a light emitting diode, and a liquid crystal shutter can be used.

An example of the configuration of the exposure light source group 10 based on electroluminescence (EL) will be described with reference to the plan views of FIGS. The optical image exposure system 5 includes an insulating support 19,
The line selection electrode group 20, the reflection layer 21, the phosphor layer 22, the pixel selection electrode group 24, and the transparent protective film 23. Reference numeral 25 denotes a drive circuit for selecting a specific electrode from the line selection electrode group 20. The selected electrode outputs an AC potential of amplitude V, and the unselected electrode outputs a 0 potential. Reference numeral 26 is a drive circuit for selecting a specific electrode from the pixel selection electrode group 24.
As in the case of 5, the AC voltage having an amplitude V _O of a phase opposite to that of the line selection electrode is output only to the selected pixel selection electrode. When the line selection electrode and the pixel selection electrode are selected, an AC voltage having an amplitude of 2V _O is applied to the phosphor layer 22 at the pixel position at the intersection, so that the phosphor layer 22 emits light with high brightness. Whether only one of the line selection electrode and pixel selection electrode is selected,
At a pixel position where neither of them is selected, the amplitude of the AC voltage is V _O or 0, so that the emission brightness is small or does not emit light. Therefore, the pixel selection electrodes 24-1, 24-2, line by line are selected while sequentially selecting the line selection electrodes 20-1, 20-2, 20-3, ... According to the movement of the magnetic brush means 6.
The exposure light source group 10 as described with reference to FIG. 2 can be realized by selecting only the pixels to be blackened.

An embodiment using the electronic shutter of the second invention of the image forming apparatus of the present invention will be described. In this embodiment, a liquid crystal shutter is used as the electronic shutter. When a liquid crystal shutter is used, a shutter for controlling the passage of uniform light may be constructed by a matrix electrode similar to that of the embodiment shown in FIG.

6 (a), (b), and (c) are examples of the configuration of the optical image exposure system 5 using the liquid crystal shutter. FIG. 6 (a) is a plan view, and FIGS. 6 (b) and (c) are FIG. 3 is a sectional view of a main part. The light image exposure system 5 is a uniform irradiation light source 2 including light sources 27-1 to 27-4.
7, a transparent support 28, 30, a liquid crystal layer 29, a line selection electrode group 20, and a pixel selection electrode group 24.

The selection electrode groups 20 and 24 are driven in the same manner as in the case of FIG. 5, and at the pixel position where both the line selection electrode and the pixel selection electrode are selected, a voltage having an amplitude of 2V _O is applied to the liquid crystal layer 29 and the other voltage is applied. In this case, a voltage of V _O or 0 is applied. The characteristic of liquid crystal is that when a voltage of 2V _O is applied, light passes through and V
Is _O following voltage is set to a very translucent deteriorates. Therefore, the passage of the light emitted from the uniform illumination light source 27 is controlled by the liquid crystal, and the photoconductor 4 is selectively exposed. Light source 27 for uniform illumination
May emit light, but may emit light only in the vicinity where the liquid crystal shutter is operated.

For example, when the line selection electrode 20-1 is selected, the uniform illumination light source 27 causes the light source 27-1 to emit light, and when 20-2 is also selected, both 27-1 and 27-2 are selected. , 20-3 or 20-4 is selected, only 27-2 is selected, and 20-5 is selected, 27-2 and 27-3 are selected.

In the above description, the case where the photoconductor 4 and the light image exposure system 5 are separately configured has been described, but it goes without saying that the photoconductor 4 and the light image exposure system 5 may be integrally configured. In the case of the integral configuration, the transparent support 3 and the like are not necessarily required. Alternatively, the transparent conductive layer 2 may be provided directly on the insulating transparent protective film 23.

FIG. 7 is a sectional view showing a specific example of the image forming apparatus according to the present invention. The surfaces of the magnetic brush means 6 and the photoconductor 4 are protected by a transparent cover 31. Further, in the magnetic brush means 6 of FIG. 7, a toner layer thickness control plate (doctor) 32 for controlling the thickness of the layer of the toner 9 on the surface of the sleeve 8.
It shows the case where is attached. By controlling the gap 14 between the doctor 32 and the sleeve 8, the contact condition between the toner 9 and the surface of the photoconductor 4 can be changed. In order to form a visible image, the magnetic brush means 6 is moved from the upper side to the lower side in synchronization with the movement of the magnetic brush means 6 from the back side of the photoconductor 4 as described above.
Further exposure is performed to form a visible image with the toner 9 on the surface of the photoconductor 4. By viewing this from the outside of the transparent cover 31, it can be used as a display device. To form a visible image again, the magnetic brush means 6 is moved up and moved downward while being exposed again, so that the old toner image is erased and a new toner image is formed.

According to the image forming apparatus of the present invention, in the case of displaying m × m pixels, as described above, it is possible to drive the matrix configuration, so that it is sufficient to have 2m drive circuits, and the configuration is simple. There are advantages. Further, by miniaturizing the magnetic brush means 6, high-definition display is possible with a relatively compact structure. In terms of ease of handling, the applied voltage is 13
Is preferably low voltage. We have found that the applied voltage can be made extremely small by making the thickness of the photoconductor 4 extremely smaller than the conventionally used thickness of 20 to 50 μm.

For example, when a selenium-based photoreceptor having a photoconductor layer 1 with a thickness of 1 μm was used, a clear visible image with high contrast was obtained at an applied voltage of −20 V.

Using a 2 μm thick As ₂ Se ₃ photoconductor of the photoconductor layer 1 −
With an applied voltage of 25 V, a high contrast and clear visible image was obtained with an applied voltage of -25 V using an amorphous silicon photoreceptor having a photoconductor layer 1 with a thickness of 5 μm.
These visible images were also obtained by changing the polarity of the voltage.

By the way, when a selenium-based photoconductor having a thickness of 5 μm of the photoconductor layer 1 was used, a toner image free of background fog was obtained at an applied voltage of −40 V. occured. The thickness of the photoconductor layer 1 is 5 μm.
When the amorphous silicon photoconductor of No. 3 was used, ground fog occurred at an applied voltage of -30 V.

When the thickness of the photoconductor layer 1 is reduced to 5 μm or less, the absolute value of the applied voltage is preferably 50 V or less in order to obtain a toner image without background fog.

Although each of the above-described embodiments has a horizontal shape, it goes without saying that a vertical shape can also be used. In particular, in the case of the display device shown in FIG. 7, it is convenient because the display device can be formed in the vertical shape as it is.

〔The invention's effect〕

As described above, the first and second aspects of the present invention can realize a high-definition large-screen display with a relatively compact structure. Further, since the image is displayed as a visible image by a toner image, the image is retained even after the power is turned off. Further, by reducing the thickness of the photoconductor layer of the photoconductor, there is an advantage that a visible image can be obtained at a low voltage which cannot be considered by the conventional electrophotographic method.

[Brief description of drawings]

FIG. 1 is a block diagram showing an embodiment of the first invention according to the present invention, and FIG. 2 is a plan view showing a structure example of an optical image exposure system in the embodiment of FIG. 1, FIGS. FIG. 5 is an explanatory view of a visible image forming process in the embodiment of FIG. 1, FIG. 5 (a),
FIG. 6B is a plan view showing a configuration example of a light image exposure system and a sectional view of an essential part. FIGS. 6A, 6B, and 6C are plan views of a liquid crystal shutter and a sectional view of an essential part, respectively. FIG. 7 is a side view showing an example of the display device according to the present invention. In the figure, 1 is a photoconductive layer, 2 is a transparent conductive layer, 3 is a transparent support, 4 is a photoconductor, 6 is a magnetic brush means, 7 is a magnet roller, 8 is a sleeve, 9 is toner, and 10 is an exposure light source. A group, 20 is a line selection electrode group, 22 is a phosphor layer, 24 is a pixel selection electrode group, 29 is a liquid crystal layer, and 31 is a transparent cover.

Claims (4)

[Claims] 1. A fixed photosensitive member comprising a transparent support and a transparent conductive layer and a photoconductive layer provided on the transparent support, a counter electrode arranged to face the photoconductive layer of the photosensitive member, and the photosensor. A means for supplying toner between the conductor layer and the counter electrode, and a fixed optical exposure system for applying a voltage between the transparent conductive layer and the counter electrode to perform light image exposure from the transparent support side. An image forming apparatus having a means for applying a force to attract the toner to the side of the counter electrode, a means for fixing the photoconductor and the optical exposure system, and a means for moving the counter electrode, and the counter electrode. And a means for sequentially electrically switching the light image exposure position in synchronization with the movement of the image forming apparatus. 2. The image forming apparatus according to claim 1, wherein the thickness of the photoconductor layer is 5 μm or less and the magnitude of the applied voltage is 50 V or less. 3. A fixed photosensitive member comprising a transparent support and a transparent conductive layer and a photoconductive layer provided on the transparent support, a counter electrode arranged to face the photoconductive layer of the photosensitive member, and the photosensor. A means for supplying toner between the conductor layer and the counter electrode, and a fixed optical exposure system for applying a voltage between the transparent conductive layer and the counter electrode to perform light image exposure from the transparent support side. An image forming apparatus having a means for applying a force to attract the toner to the counter electrode side, a means for moving the counter electrode while fixing the photoconductor, and a uniform irradiation as the optical exposure system. An image forming apparatus comprising: a means for irradiating light and an electronic shutter means for controlling passage of the uniformly irradiated light in synchronization with movement of the counter electrode. 4. The image forming apparatus according to claim 3, wherein the size of the photoconductor layer is 5 μm or less and the size of the applied voltage is 50 V or less.