JPS63131075A - Reading of electrostatic image - Google Patents

Abstract

PURPOSE:To enable the reading of an electrostatic image with high resolutions, by arranging a light modulation cell adapted to vary in the intensity or phase in accordance with an electric field between an electrostatic image to be measured and an opposed electrode to admit light into or emit it from the cell through an optical fiber. CONSTITUTION:An opposed electrode 5 being grounded is provided above an object 1 to be measured and a light modulation cell 6 is arranged therebetween. Light from a light source 7 passes through an optical fiber 8a for incidence, a cell 6 and an optical fiber 8b for emission and enters a photo detector 9. The cell 6 modulates the intensity or phase of the light passing through the cell 6 depending on an electric field formed by the eletrostatic image 4 and the electrode 5. Thus, the electrostatic image can be read out with high resolutions.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method for reading out an electrostatic image, and more specifically to a method for reading out an electrostatic image as a light signal.

[Prior art] When developing equipment that uses electrophotographic technology, such as electrophotographic copying machines, it is necessary to accurately understand the state of electrostatic latent images formed on photoreceptors or electrostatic recording paper. .

The following methods are available for reading an electrostatic latent image on an electrophotographic photosensitive member or an electrostatic latent image on an electrostatic recording paper, or for observing an electrostatic latent image.

Namely, the first method is to electrically read out the surface potential of the electrostatic latent image using a surface electrometer, the second is to confirm the existence of the electrostatic latent image by visualizing the electrostatic latent image using a so-called developer, and 3. A method in which a liquid crystal layer is provided on an electrophotographic photoreceptor, and an image is formed by charging and exposing the layer to light. 4. A method in which an electrostatic latent image and a liquid crystal layer are brought into contact with each other to form a visible image using liquid crystal. etc.

[Problem that the invention seeks to solve]

However, all of these methods have drawbacks as described below.

First, in a surface electrometer that electrically reads out the first electrostatic latent image, reading is performed based on the charge induced by the electrostatic latent image, so in normal devices, the size of the electrode for reading is extremely large. The resolution is low because it cannot be made smaller. Further, a method of developing the second electrostatic image with a developer, and a third method. Fourth
Although the presence of an electrostatic image can be confirmed using the liquid crystal visualization method, it is difficult to quantitatively measure the potential level, shape, etc.

An object of the present invention is to provide an electrostatic image readout method that can quantitatively read out an electrostatic image with high resolution.

[Means and effects for solving the problem] In order to achieve the above-mentioned object, the electrostatic image readout method of the present invention uses an electric field to increase the intensity or phase of light between the electrostatic image to be measured and the counter electrode. The present invention is characterized in that a light modulation cell in which the light modulation value changes is arranged, light is incident on the light modulation cell through an input optical fiber, and light emitted from the light modulation cell is extracted through the output optical fiber.

According to the invention, an electric field based on the charge of the electrostatic image is applied to the light modulation cell. In a light modulation cell, the intensity or phase of light passing through it is changed by an electric field. That is,
The amount of charge is converted into an optical signal.

Since this amount of change has a correspondence with the amount of charge, the charge of the electrostatic image can be quantitatively measured by detecting the light from the light modulation cell.

(Examples) Hereinafter, the features of the present invention will be specifically explained based on examples with reference to the drawings.

FIG. 1 is a schematic diagram showing the basic configuration for implementing the reading method according to the present invention.

In the figure, 1 is the object for measuring the electric field 0
For example, in the case of an electrophotographic photoreceptor, an electrostatic image 4 is formed on a photoconductive layer N3 provided on a conductive substrate 2.

A grounded counter electrode 5 is provided above the object to be measured 1, and a light modulation cell 6 is arranged between them.

Reference numeral 7 indicates a light source that illuminates the light modulation cell 6. Light emitted from the light source 7 passes through an input optical fiber 8a, the light modulation cell 6, and an output optical fiber 8b, and enters the photodetector 9.

Note that the counter electrode 5 may be integrated with the light modulation cell 6, and lenses may be provided at the tips of the optical fibers 8a and 8b to prevent light entering the light modulation cell 6 and light exiting from the light modulation cell 6. may be appropriately focused.

The light modulation cell 6 modulates the intensity or phase of light passing through the light modulation cell 6 by an electric field formed by the electrostatic image 4 and the counter electrode 5.

FIG. 2 shows the basic configuration of a light modulation cell when liquid crystal is used as the light modulation material.

Alignment films 11a and 11 are formed on the glass substrate 10a and IQb.
spacer 12 between orientation 1111a and llb
The space formed by a and 12b is filled with liquid crystal 13. These glass substrates 10a, 10b + orientation tllll
The cell main body 6a is composed of the spacers 12m and 12b, and the liquid crystal 13. alignment film 11a,
llb is provided to orient the liquid crystal molecules in a certain direction. The materials for the orientation filla and 11b are as follows:
:fi of resins such as polyimide and polyvinyl alcohol
Apply liquid I onto the glass substrates 10a and 10b and dry it,
A film is used.

Orientation treatment is performed by rubbing this layer in a certain direction with a cloth or the like.

The liquid crystal 13 is aligned by placing the liquid crystal 13 in a cell provided with such alignment films 11a and llb. LCD 13
There are other methods for orienting, and it goes without saying that this method is not the only method that is effective.Also, when making cells, it is also possible to arrange the rubbing directions of the alignment films parallel to each other. The liquid crystal material may be arranged orthogonally to each other, as long as the direction of its molecules changes depending on the electric field, but nematic liquid crystal is particularly suitable.

Furthermore, polarized light Fi 14a, 14b is provided on both sides of the cell body 6a.
are attached to form a liquid crystal cell 6b as a whole. This liquid crystal cell 6b corresponds to the light modulation cell 6 in FIG.

The polarizing plates 14a and 14b are provided to extract changes in the alignment state of liquid crystal molecules caused by an electric field as changes in light intensity. That is, since the cell main body 6a only changes the polarization direction of the light, this and the polarizing plate 14a,
14b, a change in the polarization direction caused by an electric field is converted into a change in the intensity of light. Polarizing plate 14
By appropriately combining the directions of a and 14b and the 13 alignment direction of the liquid crystal, it is possible to increase or decrease the amount of light that passes through the light modulation cell 6 when an electric field is applied.

For example, in the case of a so-called twisted nematic cell in which the rubbing directions of the alignment films 11a and 11b are perpendicular to each other and a P-type nematic is used as the liquid crystal material, two polarizing plates 1
By arranging 4a and 14b so that their polarization directions match the direction of the electric field, the amount of transmitted light increases when the electric field is applied.

In the liquid crystal cell 6b having the above configuration, as shown in FIG. 1, an optical fiber 8 for inputting light into one polarizing plate 14a and an optical fiber 8b for extracting light from the other polarizing plate 14b are provided. Further, a counter electrode 5 is provided on one end surface of the alignment film 11a of the liquid crystal 13 of the liquid crystal cell 6b, which is perpendicular to the llb surface (see FIG. 2) to constitute a sensor. If this sensor is placed on the electrostatic image 4 as shown in FIG. 1, the amount of light measured by the photodetector 9 will change depending on the amount of charge.

In the photodetector 9, a change in the amount of light can be converted into a voltage, for example, and used as a charge detection signal.

Furthermore, it is also possible to control, for example, the charging conditions and development conditions of the electrophotographic photoreceptor using this detection signal.

By moving the light modulation cell 6 composed of the liquid crystal cell 6b on the electrostatic image 4, for example, in the direction of the arrow,
Electrostatic images can be quantitatively read out in real time as optical signals corresponding to the amount of electricity at each location.

In Fig. 1, an electrostatic image on an electrophotographic photoreceptor is shown as a measurement target, but there are other electrostatic images that occur when a voltage is applied to a patterned electrode as shown in Fig. 4, which will be described later. Of course, electrostatic images can also be measured.

Next, a specific example for implementing the reading method according to the present invention will be described.

(Example 1) An embodiment of the liquid crystal cell 6b will be described based on FIG.

Approximately 5% polyimide resin solution dissolved in N-methylpyrrolidone is applied onto the transparent glass substrates 10a and 10b using a spinner, and after drying and heat treatment is performed to form a thin film, this film is spread evenly with a dry cloth. The alignment film 11 is rubbed in the direction of
a, llb was formed. Such a glass substrate 10a
, 10b are arranged so that the alignment films 11a and llb face each other with their rubbing directions perpendicular to each other, and a spacer 12a made of a polyimide film of several microns to several tens of microns in size is provided between them.

A cell was created by sandwiching 12b and fixing the circumference with epoxy resin. Needless to say, when fixing, it is necessary to leave a portion open in order to seal in the liquid crystal 13. A commercially available nematic liquid crystal (4-cyano-4'-alkylbiphenyl) was added to the empty cell thus prepared in a nitrogen atmosphere.
and the injection port was sealed with epoxy resin.

Polarizing plates 14a and 14b were provided on the outer surfaces of glass substrates 10a and 10b on both sides of the so-called twisted nematic cell main body 6a produced in this way to form a liquid crystal cell 6b. The direction of polarization of the polarizing plates 14a and 14b is such that one direction is the direction of polarization of the polarized light of the polarizing plates 14a and 14b.
1a.

11b, and the other direction was perpendicular to this. Taking FIG. 2 as an example, the polarization direction of the polarizing plate 14a and the alignment direction of the alignment film 11a are parallel, and the polarization direction of the polarization plate 14b and the alignment direction of the alignment film 11b are orthogonal. Therefore, the polarization directions of the two polarizing plates 14a and 14b are parallel to each other.

Furthermore, as shown in FIG. 3, the optical fiber 88 for incident light and the optical fiber 8b for output light are fixed to the fixing member 15 with their optical axes aligned with the light modulation cell 6 composed of the liquid crystal cell 6b, and then An electrode 5 was provided to serve as a sensor. The electrode surface of the counter electrode 5 is a polarizing plate 14a.

14b (see FIG. 2) so as to be perpendicular to the polarization direction.

The sensor made as described above is placed on the insulator which is the object 1 on which the electrostatic image 4 has been formed as shown in FIG. The output light amount was measured at the other end of the optical fiber 8b. When the light modulation cell 6 was moved over the surface of the insulator (object 1), the amount of light emitted from the optical fiber 8b changed depending on the presence or absence of an electrostatic image. In other words, the amount of charge on the electrostatic image 4 changed. When the electric field formed in the measuring section is large, the amount of emitted light is large, and in the opposite case, the amount of emitted light is small, and the electrostatic image 4 could be read out as an optical signal.

(Example 2) FIG. 4 shows another specific example of the sensor.

In this example, a light modulation cell 6 composed of a liquid crystal cell 6b having the same structure and material as in Example 1 is used, but furthermore, between the counter electrode 5 and the light modulation cell 6, and the light modulation cell Insulating layers 16a and 16b of polyimide film are provided between the charge carrier 6 and the charge carrier 17 to form a sensor.

In the example shown in FIG. 4, the optical readout output can be further increased by providing insulating layers 16a and 16b. This seems to be because the provision of the insulating layers 16a and 16b alleviates the leakage of charges into the cell. Further, the insulating layer 16b on the lower surface also functions as a protective layer.

In the example shown in FIG. 4, an electrostatic image formed by patterned electrodes to which a voltage is applied is read out. In this case, if this sensor is placed on an object to be measured that has a conductive pattern 18 formed on a charge carrier 17 such as an insulator, and the sensor is moved while a voltage is applied to the conductive pattern 18 from a power source 19, , a light output was obtained depending on the arrangement of the conductive pattern 18 and the applied voltage.

In the example, a case was shown in which the intensity of light was changed by a light modulation cell. When the phase is changed by a light modulation cell, the light emitted from the light source is divided into two parts, one passes through the light modulation cell,
The other light does not pass through the light modulation cell, and the phase difference between these lights is detected.

In addition to liquid crystal, piezoelectric materials such as polyvinylidene fluoride can also be used as materials for the light modulation cell.

Furthermore, in the example, the input optical fiber and the output optical fiber were separate, but it is also possible to provide a reflective member on one side of the light modulation cell so that part of the input optical fiber and the output optical fiber can also be used. .

〔Effect of the invention〕

As described above, according to the readout method of the present invention, an electrostatic image is converted into light intensity or phase by a light modulation cell and detected. Therefore, the electrostatic image can be read out quantitatively and in real time as an optical signal. Furthermore, the thickness of a light modulation cell such as a liquid crystal cell can be made several microns, and the diameter of an optical fiber can also be made 10 microns or less, so it is possible to read out an electrostatic image with high resolution.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing the basic configuration for carrying out the electrostatic image reading method according to the present invention, FIG. 2 is a basic configuration diagram showing an example of a liquid crystal cell used in the present invention, and FIG. FIG. 4 is a schematic diagram showing an embodiment of the electrostatic image reading method according to the invention. FIG. 4 is a schematic diagram showing another embodiment of the electrostatic image reading method according to the invention. Object 2: Conductive substrate 3: Photoconductive layer 4: Electrostatic image 5: Counter electrode 6: Light modulation cell 6a: Cell body 6b: Liquid crystal cell 7: Light source
8a, 8b: Optical fiber 9: Photodetector
10a, 10b Niglass substrate 11a, llb:
Orientation film' 12a, 12b Varnish spacer-13
: i crystal 14a, 14b : polarizing plate 1
5: Fixing member 16a, 16b: Insulating layer 1
7: Charge carrier 18: Conductive pattern patent applicant Fuji Xerox Co., Ltd. Agent Masu Kodo (and 2 others) Figure 1 Figure 2 a + 2b Figure 3 An Figure 4

Claims (1)

[Claims] 1. A light modulation cell in which the intensity or phase of light changes due to an electric field is arranged between the electrostatic image to be measured and a counter electrode, and light is passed through an input optical fiber to the light modulation cell. A method for reading out an electrostatic image, comprising the step of extracting the incident light and the light emitted from the light modulation cell through an output optical fiber. 2. The electrostatic image reading method according to claim 1, wherein the light modulation cell is composed of a nematic liquid crystal cell. 3. The electrostatic image readout method according to claim 2, wherein the counter electrode is provided on an end face of the nematic liquid crystal cell so as to be orthogonal to the alignment film surface of the nematic liquid crystal cell.