JPH0525091B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an electrostatic latent image visualization device suitable for visualizing electrostatic latent images.

Image information output directly from an image reading device, computer, etc., or stored on magnetic tape, microfilm, etc. is often output as an electrostatic latent image, and it is difficult to visualize such an electrostatic latent image. Needless to say, there is a great need to do so.

Traditionally, electrophotographic recording or electrostatic recording is a method in which an electrostatic latent image is formed on an electrophotographic photoreceptor or electrostatic recording medium, and this is developed with toner to obtain a visualized image. Are known.

The image recording method according to the above method provides the highest resolution and best image quality among existing recording methods, and is used in copying machines, LBPs (laser beam printers), electrostatic printers, and the like.

However, the visualization method described above involves adhering a powder developer or a liquid developer to an electrostatic latent image recording medium, and when the electrostatic latent image recording medium is repeatedly used, the adhesion of the developer or This method has the disadvantage that the medium is worn out, deteriorated, etc. during the cleaning process of the developer, and its lifespan is shortened.

In addition, when recording an electrostatic latent image directly on a disposable visible image carrier such as electrostatic recording paper, even if a hard copy is not required and only a soft copy is required, as a result, it is only for visualization. This results in wasted recording paper.

The present invention has been researched in order to provide an electrostatic latent image visualization device that takes advantage of the high image quality achieved by the above-mentioned electrophotographic recording or electrostatic recording, and further reduces wear and deterioration of the electrostatic latent image forming medium. As a result, they focused on the fact that many of the problems in electrophotographic recording and the like described above are caused by powder development being performed on an electrostatic latent image forming medium for visualization. Moreover,
A hard copy may not always be necessary to visualize an electrostatic latent image, and the potential of the electrostatic latent image formed by the above method reaches around 500V, and if this can be used as the driving voltage for a liquid crystal display, it would be We found that it is possible to reduce the burden of copying and obtain both hard copies and soft copies.

However, there is one problem in driving a liquid crystal element using an electrostatic latent image as described above.
In other words, in order for such a liquid crystal element to operate, it is basically sufficient to stack the electrostatic latent image bearing surface and the liquid crystal element in close proximity. Between the liquid crystal layer of the device, there is always a support such as a glass plate to support the liquid crystal, and in order to maintain appropriate strength, this support must be at least 0.1 mm thick.
It requires a certain thickness or more. Therefore, even if the latent image potential is around 500 V, the voltage actually applied to the liquid crystal element is insufficient to drive the liquid crystal due to the voltage drop caused by this support.

In view of the above-mentioned circumstances, the main object of the present invention is to provide an electrostatic latent image visualization device that can effectively apply the latent image potential of an electrostatic latent image to a liquid crystal layer and has a wide range of applicability.

The electrostatic latent image visualization device of the present invention was developed to achieve such an objective, and more specifically, it includes a first substrate provided with an electrode, a predetermined distance from the first substrate, and a first substrate provided with an electrode. A second substrate is disposed facing each other with a fine conductor placed thereon so that electrical continuity occurs only in the thickness direction, and a second substrate is disposed between the first and second substrates and is arranged to face each other with a polarity of the applied voltage. a liquid crystal cell including a ferroelectric liquid crystal that produces a first orientation state and a second orientation state that are different from each other depending on the orientation; an electrostatic latent image carrier disposed close to and facing the second substrate; a first means for applying to the ferroelectric liquid crystal a one-polar voltage sufficient to uniformly bring the orientation state of the ferroelectric liquid crystal into a first orientation state; forming a latent image on the electrostatic latent image carrier such that a voltage of the other polarity sufficient to reverse the orientation to a second orientation state is applied to the ferroelectric liquid crystal; A second means for applying a voltage between the electrode and the fine conductor by being electrically connected to a conductor, and a third means for applying a bias voltage to the ferroelectric liquid crystal. That is.

Hereinafter, the present invention will be explained in more detail with reference to the drawings.

Figure 1 shows that a liquid crystal element is driven by an electrostatic latent image.
FIG. 2 is a schematic side view showing a basic stacked state of an electrostatic latent image carrier and a liquid crystal element in an apparatus for visualizing an electrostatic latent image.

In FIG. 1, a liquid crystal element (cell) 1 is constructed by fixing a pair of supports 2 and 3 (at least two of which are transparent) made of glass plates or the like via a spacer 4 made of Mylar or the like. , a liquid crystal 5 is sealed between both. Further, on the inner surface of the support 2, there is a transparent electrode 6 made of In ₂ O ₃ , SnO ₂ , ITO (indium-tin composite oxide), etc., and the support 3 can be made of a transparent or non-transparent material. A dielectric mirror 7 is provided on the inner surface of the liquid crystal cell, if necessary, in case the liquid crystal cell is used in a reflection mode. This dielectric mirror 7 is obtained, for example, by forming a dielectric multilayer film with absorption close to zero by vacuum deposition.

Furthermore, a polarizing plate 8 is disposed on the outer surface (front surface) of the support 2 as required depending on the display mode of the liquid crystal cell. In addition, the transparent electrode 6, dielectric mirror 7, etc. located on the innermost surfaces of the supports 2 and 3 in contact with the liquid crystal layer 42 may be coated with SiO vapor deposition, rubbing with cloth, etc., coating with an alignment agent, etc. as necessary. Orientation control processing may also be performed.

On the other hand, on the back surface of the liquid crystal cell 1, a latent image carrier 11 is formed by forming a charge retention carrier 10 on a conductive substrate 9.
are brought into close contact with each other on the charge retention carrier side. Further, a power source E is connected to the transparent electrode 6 between the transparent electrode 6 and the conductive substrate 9 for applying a voltage for erasing an image or a bias voltage during writing.

When visualizing an electrostatic latent image using such a device, for example, when there is a positive electrostatic latent image 12 on the latent image carrier 11, the liquid crystal cell has a structure as shown by the arrow in the figure. Directional voltage is applied. For convenience,
At this time, it is assumed that both the transparent electrode 6 and the conductive substrate 9 are in a grounded state. As mentioned earlier, the support 2 needs to have a thickness of at least 100 μm, whereas the liquid crystal layer 5 usually has a thickness of 0.5 μm to 100 μm.
The voltage is approximately 10 μm, and the divided voltage distributed from the latent image potential to the liquid crystal layer 5 is extremely small and tends to be insufficient to operate the liquid crystal.

The electrostatic latent image visualization device of the present invention solves this problem. Corresponding to FIG. 1, FIG. 2 shows a schematic side view of essential parts of an embodiment of the electrostatic latent image visualization device of the present invention. In this example, the support 13 is a plate 13a made of an insulating material such as acrylic resin, with both ends exposed on both sides thereof.
A device in which a plurality of fine conductive wires 13b are spaced apart from each other and uniformly embedded is used. By using such a support 13, the voltage necessary for changing the alignment can be more easily applied to the liquid crystal layer 5. That is, according to this support, conduction is established between the front and back sides of the support, that is, the liquid crystal layer side and the latent image carrier side, in a one-to-one point-to-point relationship by the fine conductive wires 13b, and each Since the pairs are insulated from each other, the front and back sides of the support can be made to have approximately the same potential, and substantially most of the voltage given by the electrostatic latent image can be applied to the liquid crystal layer 5.
Further, the fine conductor 13b is 1 m above the support 13.
It is possible to embed at a density of about 100 to 250 lines per ^m2 , and high-definition image quality can be maintained sufficiently.

FIG. 3 is a schematic side view showing an example of the overall arrangement of the visualization device whose main parts are shown in FIG. 2. That is, a belt-shaped latent image carrier 11 is placed in an outer box 31 with an open front surface, and is placed around a pair of driving rollers 32a and 32b, and is located at a hidden position (as shown by the dotted line in FIG. 3). ) A liquid crystal cell (element) 1a is arranged on the front surface at a slight distance from the display section A. Further, on the back side of the latent image carrier 11 which is stretched around in a belt shape, a static eliminating section 33 and a latent image forming section 34 are arranged along the extension thereof.
Further, a pair of pressing rollers 35a and 35b are disposed near the upper and lower ends of the latent image carrier 11 facing the liquid crystal cell 1a, on the opposite side of the liquid crystal cell.

Latent image carrier 11, especially its charge retention carrier 10
The material shown in FIG. 2 is selected depending on the method of latent image formation. Various methods can be used to form a latent image; for example, a conventional electrophotographic latent image formation method using a photoreceptor having a photoconductive layer as the charge-retaining carrier 10, or a charge-retaining sheet such as electrostatic recording paper. A conventional latent image forming method in electrostatic recording can be applied using the medium. The latent image carrier 11 on which the latent image has been formed in the latent image forming section 34 is moved to the drive roller 32
By rotating a and 32b in the direction of the arrow, they are guided to a position facing the display section A or the liquid crystal element 1a. At this position, the latent image bearing surface of the latent image bearing member 11 stops, and the liquid crystal cell 1a is moved by pressing rollers 35a and 35b.
closely followed.

Next, the process of visualizing an electrostatic latent image using the above device will be explained with reference to FIG. 2 and FIG. 4 and subsequent drawings.

First, as shown in FIG. 2, for example, when a positive electrostatic latent image is formed on the charge carrier 10,
An electric field 15a in the direction indicated by the arrow in the figure acts on the liquid crystal layer 5. In the device of the present invention, the electric field produced by such an electrostatic latent image is effectively utilized to bring about a change in the orientation of the liquid crystal in the liquid crystal layer 5, thereby visualizing the electrostatic latent image. As the liquid crystal, a ferroelectric liquid crystal such as a chiral smectic liquid crystal is suitably used. Such ferroelectric liquid crystals not only have a much faster response speed than other field-effect liquid crystals, such as TN (twisted nematic) liquid crystals, but also have a memory property and are driven by a direct current electric field, so they can be used as soft materials. It is possible to obtain a hard copy of an electrophotographic record while displaying a copy, that is, a liquid crystal display image.

For detailed operation of ferroelectric liquid crystal, please refer to Ap−
plied Physics Lettrs 36(11)1, June, 1980
“Submicrosecond Bistable Electrooptic
There are many reports such as "Switching in Liquid Crystals", and the operation will be briefly described here.

In FIG. 4a, 16 is a ferroelectric liquid crystal molecule (for example, chiral smectic liquid crystal),
It is an elongated molecule as shown in the figure, and exhibits refractive index anisotropy in its long and short axis directions. A characteristic feature of this liquid crystal is that when an electric field is applied in directions forming an angle of 2θ to each other, as shown by arrows 17 or 18 in the figure, if the electric field is above a certain threshold,
The orientation direction of the molecules changes in each case. That is, as an example, as shown in Fig. 4b, the above-mentioned
The orientation direction 16a of the molecules relative to the electric field in the direction 17, represented by , and the orientation direction 16b of the molecules relative to the electric field in the direction 18, represented by , form an angle 2θ. Another feature of this liquid crystal is that it responds quickly to changes in the orientation of molecules when this electric field is applied, and the response speed can be as fast as several microseconds. When the polarizer 19 and the analyzer 20 are set on both sides of a liquid crystal cell sandwiching this liquid crystal in a crossed Nicol arrangement, for example, the polarizer 19 has a polarization direction parallel to the orientation direction of molecules due to a directional electric field. When the molecular orientation direction is the orientation direction due to the electric field in the direction, birefringence does not occur for the incident light, so the light is cut off by the analyzer and does not pass through.
On the other hand, in the case of alignment direction due to an electric field in the 〓 direction, a state in which light is transmitted is obtained due to the action of birefringence.

Another advantage of using such a ferroelectric liquid crystal is that the alignment of liquid crystal molecules has bistability. To further explain this point with reference to FIG. 4b, when an electric field 17 is applied, the liquid crystal molecules
It is oriented as shown in a, but this state is stable even when the electric field is turned off. Furthermore, when an electric field 18 in the opposite direction is applied, the liquid crystal molecules change direction as shown in 16b.
It remains in this state even if the electric field is turned off. In order to effectively realize such bistability, it is preferable that the cell be as thin as possible.

Next, an example of visualizing a latent image using the apparatus shown in FIGS. 2 and 3 when using a ferroelectric liquid crystal as described above will be described. First, as shown in Figure 5 a1,
The latent image carrier 11 on which no latent image is formed is brought into close contact with the liquid crystal cell, and a voltage in the direction 15b is uniformly applied between the transparent electrode 6 and the conductive substrate 9 by the power source E. Due to the electric field in such a direction, the liquid crystal molecules are uniformly aligned as shown by 16b, for example. However, in this case, the magnitude of the electric field applied to the liquid crystal molecules by the power source E is set to be equal to or higher than the threshold value at which the liquid crystal molecules change their alignment.

Thereafter, the latent image carrier 11 is separated from the liquid crystal cell 1a by releasing the pressing rollers 35a and 35b shown in FIG. 16
Maintain the state shown in b.

Next, for example, the latent image bearing surface on which the positive electrostatic latent image is formed is sent to the display section A and the pressing roller 35
By bringing the liquid crystal layer 5 into close contact with the liquid crystal cell 1a through the layers a and 35b, an electric field in the direction of the arrow 15a acts on the liquid crystal layer 5 due to the latent image in the latent image bearing portion, as shown in FIG. 5b1.

At this time, the voltage applied to the liquid crystal layer 5 is above or below the threshold voltage at which orientation change occurs, and its magnitude is determined by the potential of the electrostatic latent image to be formed.

When the voltage applied to the liquid crystal layer 5 is set to be higher than the threshold value, the liquid crystal molecules corresponding to the latent image portion are as shown in Fig. 5b2.
The orientation changes in the direction 16a shown in FIG. On the other hand, in a portion where the threshold value has not been reached, the liquid crystal molecules remain in the 16b orientation.

Further, as shown in FIG. 5c1, a bias voltage can be applied to the liquid crystal layer by a power source E. In other words, the bias voltage is set to 15a so that the liquid crystal molecules become slightly smaller than the threshold value at which the alignment changes in the direction of 16a.
By applying the electric field in the direction 16a, the electric field acting on the liquid crystal layer corresponding to the latent image portion exceeds the threshold value, and the orientation changes in the direction 16a.

Applying a bias voltage to the liquid crystal layer in this manner is actually very effective. This is because by applying the bias voltage, it becomes easy to apply a voltage equal to or higher than the threshold value to the liquid crystal layer 5 by adding up the contribution of the voltage given by the electrostatic latent image.

In this case, it is even more effective to apply the bias voltage after the latent image bearing surface is brought into close contact with the liquid crystal cell, since it is possible to eliminate all harmful effects such as image blurring that may occur during the contact operation. .

In order to write an image on the liquid crystal cell using a positive electrostatic latent image, the method shown in FIGS. 6a and 6b may also be used.

That is, as shown in FIG. 6a1, the latent image carrier 11 on which no latent image is formed is brought into close contact with the liquid crystal cell, and a power source E is applied to uniformly apply a voltage equal to or higher than the threshold in the direction 15a between the transparent electrode 6 and the conductive substrate 9. Apply a voltage of Due to the voltage in this direction, the liquid crystal molecules
Uniformly oriented in the a direction.

Next, the pressing roller 35a shown in FIG.
35b is released, the latent image bearing surface on which the positive electrostatic latent image is formed is sent to the display section A, and the pressing roller 3 is pressed again.
5a and 35b, it is brought into close contact with the liquid crystal cell 1a.
Thereafter, a bias voltage equal to or higher than the threshold value is applied by the power source E in the direction 15b as shown in FIG. 6b1. At this time, by carefully selecting the bias voltage, the bias voltage can be reduced in the area where the electrostatic latent image is formed, and the voltage applied to the liquid crystal molecules can be kept below the threshold value. The molecule remains 16a, and outside this part it becomes 16b due to the bias voltage 15b.
The molecules are arranged in the direction shown by .

Above, we have described the case in which a positive electrostatic latent image causes a change in the orientation of liquid crystal molecules, but a negative latent image can also be produced in almost the same way by reversing the direction of the voltage applied by the power source E. It is clear that it can be done.

As described above, using a ferroelectric liquid crystal as the liquid crystal layer 5, it is possible to obtain a change in the orientation of the liquid crystal using an electrostatic latent image, but in order to make this visible, the polarization direction of the polarizer 8 must be adjusted appropriately. It is sufficient to set the 1
For example, by arranging the polarization direction parallel or perpendicular to the orientation direction 16b in FIG. 5 or 6, a state in which the liquid crystal looks bright when the orientation direction is 16b and dark when it is 16a. It can be done.

In order to obtain the best image contrast in such a cell configuration, a liquid crystal whose 2θ angle in FIG. 4b is approximately 45° is used, and the thickness of the liquid crystal layer is appropriately selected.

Next, FIG. 7 shows a specific example of another application of the electrostatic latent image visualization device incorporating the liquid crystal element of the present invention. The apparatus shown in FIG. 7 has a latent image transfer drum 21, and transfers an electrostatic latent image on a latent image carrier 11.
It has the function of once transferring to this drum. A toner developing device 22, a transfer charger 23 for transferring the toner image on the transfer drum onto plain paper 26, a cleaner 24, and a charge eliminating means 25 are arranged in this order around the latent image transfer drum.

First, the latent image carrier 11 on which no electrostatic latent image is formed is pressed against the liquid crystal cell 1a by the pressing rollers 35a and 35b, and the image is uniformly erased by the method described above. Next, the pressing roller 35a,
35b and drive the rollers 2a and 2b in the direction of the arrow to rotate the latent image carrier 11 and form an electrostatic latent image by the latent image forming means 34, so that the latent image forming surface is on the display section A. When the latent image carrier 11 reaches the position, rotation of the latent image carrier 11 is stopped, and the latent image is pressed against the liquid crystal cell by pressing rollers 35a and 35b. At this time, as described above, a latent image is visualized on the liquid crystal cell surface. Here, if a hard copy of the image is required, after releasing the pressing rollers 35a and 35b, the latent image forming surface is sent to the latent image transfer drum 21, and the latent image is transferred to the drum. The image is developed with toner, further transferred to plain paper 26, fixed by a fixing device 27, and discharged to a paper discharge tray 28. During this time, if the liquid crystal element itself has a memory property, as in the case of using the above-mentioned ferroelectric liquid crystal, it is possible to keep the image being displayed while the hard copy is being created.

As explained above, according to the present invention, when the latent image potential on the electrostatic latent image carrier from which a hard copy can be obtained is used for driving the liquid crystal cell, the voltage of the latent image potential is selectively applied to the liquid crystal cell. By acting on the layer, the liquid crystal element can be effectively driven. In this way, a rational electrostatic latent image visualization device can be obtained that can simultaneously obtain a hard copy and a soft copy, and that reduces as much as possible the deterioration of the electrostatic latent image that accompanies the production of the hard copy.

[Brief explanation of the drawing]

FIG. 1 is a schematic side view of a laminated state of an electrostatic latent image carrier and a liquid crystal element, showing the principle of driving a liquid crystal element by an electrostatic latent image; FIGS. A schematic side view of the main part and the whole of an embodiment of the electro-latent image visualization device; FIGS. 4a and 4b are schematic explanatory diagrams of the change in orientation direction and bistability of ferroelectric liquid crystal due to the application of an electric field; FIG. a1, Figure 5b
1, FIG. 5 c1, FIG. 6 a1, and FIG. 6 b1 are schematic cross-sectional views showing the state of applying an electric field to the liquid crystal layer due to the interaction between the electrostatic latent image potential and the external power source in the present invention, and FIG. Figure a2, Figure 5 b2, Figure 5 c
2. FIG. 6 a2 and FIG. 6 b2 are schematic explanatory diagrams showing the alignment directions of liquid crystal molecules corresponding to the above electric field, respectively; FIG. 7 is an overall diagram of another example of the electrostatic latent image visualization device of the present invention FIG. DESCRIPTION OF SYMBOLS 1...Liquid crystal element, 1a...Liquid crystal element used in the present invention, 2...Transparent support, 3...Support, 5...
Liquid crystal layer, 6...Transparent electrode, 7...Dielectric mirror, 8
... Polarizing plate, 9 ... Conductive substrate, 10 ... Charge carrier layer, 11 ... Latent image carrier, 13 ... Conductive support, 13a ... Insulator plate, 13b ... Fine conducting wire, 33 ...Charge eliminating means, 34...Latent image forming section, 3
5a, 35b...pressing roller, 15a, 15
b, 17, 18...Direction of electric field application to liquid crystal, 16
a, 16b...Alignment direction of liquid crystal molecules, A...Display section, E...External power source.

Claims (1)

[Scope of Claims] 1. A first substrate provided with an electrode, which is arranged to face the first substrate at a predetermined distance, and a fine conductor is arranged so as to create electrical continuity only in the thickness direction. a second substrate, and a first substrate disposed between the first and second substrates, which differ from each other depending on the polarity of the applied voltage.
a liquid crystal cell comprising a ferroelectric liquid crystal that produces an orientation state of a first means for applying a one-polar voltage sufficient to uniformly produce a first alignment state to the ferroelectric liquid crystal; forming a latent image on the electrostatic latent image carrier and conducting the latent image to the fine conductor such that a voltage of the other polarity sufficient to reverse the state is applied to the ferroelectric liquid crystal; an electrostatic latent image, characterized in that it has a second means for applying a voltage between the electrode and the fine conductor, and a third means for applying a bias voltage to the ferroelectric liquid crystal. Visualization device.