JPH03291619A - Optical printer - Google Patents

Abstract

PURPOSE:To exactly recover the optical fatigue irrespective of the applied frequency of a driving voltage by applying a voltage for generating an electric field in the direction reverse to the time of recording operation to plural electro- optical materials, respectively at the time when the recording operation is finished, based on recording information at the time of recording operation. CONSTITUTION:When a recording operation of a prescribed period is finished, it becomes a holding period, a clock signal CLK2 is inputted to a first and a second flip-flops 17, 18 and the respective outputs are switched, a signal whose phase is opposite to that of a recording signal DATA2 from a recording memory is inputted to a shift register 15, and also, a driving voltage Vh from a driving power source is supplied to a common electrode Ec. Accordingly, the internal polarization of electro-optical materials 91 - 9n generated by applying an electric field in one direction by a prescribed number of times in order to execute recording is obviated by applying an electric field in the reverse direction by the same number of times. In such a way, accumulation of optical fatigue is prevented, and recording which is uniform and has a good quality can always be executed.

Description

Detailed Description of the Invention [Field of Industrial Application] The present invention relates to an optical printer using an electro-optic material such as PLZT for light modulation. A light modulation section is provided in which a plurality of electro-optic materials are arranged in a row, and a recording control means is provided for applying a driving voltage for modulation according to recording information to each of the plurality of electro-optic materials. Regarding a certain optical printer.

[Conventional technology]

In an optical printer equipped with electro-optic materials such as PLZT, the amount of transmitted light changes depending on the drive voltage applied to each electro-optic material, which results in the density of recording.

However, the plurality of electro-optic materials are always irradiated with light from a light source, and by applying a driving voltage to the electro-optic materials at the required locations, the light modulation section at that location transmits the recording light. However, during long-term use, internal polarization of the electro-optic material due to repeated application of driving voltage for recording under light irradiation, that is, optical fatigue, occurs, resulting in a decrease in transmittance. It has been found that the driving voltage at which the wavelength is the maximum, the so-called half-wave voltage, changes.

Therefore, in order to prevent the change in the half-wave voltage by eliminating the internal polarization described above and recovering optical fatigue, the applicant first proposed that each electric current be We have proposed a system in which an optical fatigue recovery voltage is applied to an optical material to generate an electric field in the opposite direction to the electric field generated by the drive voltage applied during the recording period (for example, Japanese Patent Application No. 1-170965 (see issue).

[Problem to be solved by the invention]

However, in the optical printer of the prior application mentioned above, there is a possibility that the following problems may occur, and there is still room for improvement.

In other words, when recording, a plurality of electro-optical materials for light modulation are used, based on the recorded information, for example, in an optical printer that develops using a negative-positive method, toner is required to be applied to the locations where toner needs to be attached. A driving voltage is applied to the electro-optic material corresponding to the electro-optic material, but the frequency of application of the driving voltage differs depending on the electro-optic material. Therefore, the degree of optical fatigue naturally differs depending on the electro-optic material. On the other hand, in the optical printer of the earlier application mentioned above, the optical fatigue recovery voltage is uniformly applied to all the electro-optic materials during the standby period, so the drive voltage is applied frequently. If an optical fatigue recovery voltage sufficient to recover optical fatigue is applied to the electro-optic material, the electro-optical material to which the drive voltage is applied less frequently will be optically fatigued.

On the other hand, a voltage for recovering from optical fatigue that is enough to prevent optical fatigue in an electro-optic material to which a driving voltage is applied infrequently cannot sufficiently recover optical fatigue in an electro-optic material to which a driving voltage is applied frequently.

In view of the above circumstances, an object of the present invention is to provide an optical printer that can accurately recover from optical fatigue regardless of the frequency of application of drive voltages to each of a plurality of electro-optical materials.

[Means to solve the problem]

The characteristic configuration of the optical printer of the present invention is that a driving voltage for light modulation according to recorded information is applied to each of a plurality of electro-optic materials arranged in a row in a light modulation section provided between a light source and a photoreceptor. At the end of the recording operation by the recording control means for recording, light is applied to each of the plurality of electro-optic materials, based on the recorded information at the time of the recording operation, to generate a voltage that generates an electric field in a direction opposite to that during the recording operation. This is because a fatigue compensation means is provided.

[For production]

In other words, optical fatigue due to internal polarization of the electro-optic material that occurs due to the application of a driving voltage that generates an electric field in one direction for recording can be recovered by applying a voltage that generates an electric field in the opposite direction to that during recording. , since the voltage for recovering from optical fatigue is applied at the end of the recording operation based on the recorded information during the recording operation, electro-optic materials that perform many recordings during the recording operation and have a high frequency of application of the driving voltage. For electro-optic materials, a voltage for recovery from optical fatigue is applied over a long period of time or at a large voltage value, whereas for electro-optic materials, where a lot of recording is not performed during the recording operation and the frequency of application of driving voltage is low. The application of voltage for recovery from photofatigue can be varied depending on the frequency of application of the driving voltage for recording, such as applying voltage for recovery from photofatigue in a short period of time or with a small voltage value. It is possible to make a recovery commensurate with the degree.

〔Example〕

Hereinafter, the present invention will be described in detail based on the drawings.

As shown in FIG. 2, a charging device (2) for uniformly charging the surface of the photoreceptor (1) is provided around a drum-shaped photoreceptor (1) that is driven and rotated in a fixed direction; An optical print head (PH) as a light modulation unit for forming an electrostatic latent image corresponding to recorded information on the photoreceptor (1), and a toner for attaching toner to the electrostatic latent image to make it visible. developing device (
3), the toner image formed on the photoconductor (1) is transferred onto a recording paper (not shown) by the operation of the developing device (3), and then the recording paper is separated from the photoconductor (1). a main eraser (5) for erasing residual charge on the photoconductor (1), and a cleaning device (6) for scraping off residual toner on the photoconductor (1).
and an optical printer that records recorded information on recording paper using an electrophotographic method.

The optical print head (PH) includes a light source (7), a reflecting mirror (8), a PLZT array (9) which is a plurality of electro-optic materials arranged in parallel along the longitudinal direction of the photoreceptor (1), and , a pair of polarizers (
10) Optical shutter (S) composed of (11)
The light passing through the optical shutter (S) is directed to the photoreceptor (S).
1) It is equipped with a gradient index lens array (12) for irradiating and imaging the surface.

The PLZT array (9) has a plurality of transparent sintered PLZT chips arranged in a row, and as shown in FIG. A plurality of PLZT microsections (indicated by capacitors in FIG. 1) (9,) to (9,l) are formed along the alignment direction of
Each micro-section (9,)-(
Individual electrodes (El) to (E, l) for each PLZT microsection (9I) to (9,) and a common electrode (EC) shared by all PLZT microsections (9I) to (9,) are formed.

Drive pulses from the driver (13) are selectively applied to the plurality of PLZT microsections (9I) to (9,l) through separate individual electrodes (El) to (Efi). It's so organized. This driver (13) is supplied with a drive voltage [v1] from a drive power source, and also
E from the recording memory (M) under the operation control of P U (C)
Recorded information transferred via the X-OR circuit (14), accumulated in the shift register (15), and collectively held in the latch circuit (16) is input. The driver (1
3) is configured to apply the driving voltage to the necessary minute sections of PLZT at a predetermined pulse rate based on the recording information described above.

An optical print head (
PH), as shown in Figure 2, the light from the light source (7) passes through the polarizer (10) on the light source (7) side of the optical shutter (S).
). This polarizer (1o) transmits only polarized light components in a certain direction.

The PLZT that makes up the PLZT array (9) has birefringence, and when a predetermined voltage is applied, the polarization plane of the incident light is rotated by an angle corresponding to the applied voltage and transmitted. . The polarizer (11) on the photoreceptor (1) side of the optical shutter (S) is arranged in a crossed Nicol configuration in which the plane of polarization that transmits light is different by 90° from the polarizer (10) on the light source (7) side. Therefore, the PLZT micro sections (91) to () where no voltage was applied to the individual electrodes (g+) to (E, ,)
The light transmitted through the polarizer (1) on the photoreceptor (1) side
1), while a predetermined voltage was applied to the individual electrodes (El) to (E7).
9,) is transmitted through the polarizer (11) on the photoconductor (1) side at a rate that corresponds to the magnitude of the applied voltage, and then passes through the polarizer (11) on the photoconductor (1) side by the gradient index lens array (12). An electrostatic latent image is formed by irradiating and forming an image on the surface of the object, thereby erasing the charge in that area. Thereafter, in the above-mentioned developing device (3), toner is applied to the charge disappearing portion to visualize the electrostatic latent image and obtain a toner image. Thereafter, the toner image is transferred onto recording paper and fixed, thereby obtaining a recording.

The output of the first flip-flop circuit (17) is input to one input terminal of the EX-OR circuit (14), and when this output is at "H" level, the EX-OR circuit (14) ) output (DATA2) is stored in the recording memory (M
), and when the output of the first flip-flop circuit (17) is at "L" level, the output of the EX OR circuit (14) (DATA
2) is the recording signal (DATA) from the recording memory (M).
2) and is inputted to the shift register (15) as a signal with the opposite phase. The clock signal (CLK2) from the CPU (C) for switching the output of the first flip-flop circuit (17) is input to the second flip-flop circuit (18). , this second flip-flop circuit (18
) according to the output from the switch (1
9) is provided.

The operation of the optical printer configured as described above will be explained with reference to the time chart shown in FIG.

During the recording period [PR'J, the output of the first flip-flop (17) is at "H" level, and a signal having the same phase as the recording signal (DATAI) from the recording memory (M) is sent to the shift register (15). is input to the latch pulse (LATCH
) is latched by the latch circuit (16), and then the necessary electro-optic material (9□) is latched according to the gate signal (CL).
The driving voltage [
Vh] is applied. At this time, the common electrode (EC) is grounded, and the electro-optic materials (9,) to (91,)
A unidirectional electric field will be applied to the selected one. As a result, as described above, the recording light is selectively transmitted through the optical shutter (S), and recording for one line is performed.

When the recording for one page is completed by repeating the above operation, that is, when the recording operation for a predetermined period is completed, the waiting period [p
w], the clock signal (CLK2) is input to the first and second flip-flops (17) and (18) and their respective outputs are switched, and the phase is opposite to that of the recording signal (DATA2) from the recording memory. The signal comes to be input to the shift register (15), and at the same time, the drive voltage [V,] from the drive power supply comes to be supplied to the common electrode (EC). During this waiting period [ptn], a signal having an opposite phase to the recording signal (DATAI) from the recording memory input to the shift register (15) responds to the latch pulse (LATCll) as in the recording operation. and is latched by the latch circuit (16). Then, necessary electro-optic materials (9I) to (
A driving voltage [v
1] is applied.

The recording signal (DATAI) mentioned above is a binary signal, and for example, one page is divided into five dots in the width direction and seven dots in the longitudinal direction.
If it is simplified and represented as consisting of two dots, the contents of the data are as shown in FIG. During the recording period [PH1, these 1 2 recording signals (DATAI) are in the same phase, that is, they have the same value, and the shift register (1 2
5). Then, this recording signal (DATAI
) is “1”, the driving voltage [vh] is applied to the corresponding one of the individual electrodes (El) to (E, , ) via the driver (13), and the common electrode (II !c
), an electric field of magnitude [v6] is generated and recorded as described above.

On the other hand, during the standby period [PW], the recording signal (DATA
I) are in opposite phase, ie "1" and "0°".

The contents are input to the shift register (15) line by line, as shown in FIG. 5, in which the lines are reversed.

When this signal is "1", the drive voltage [Vh] is applied to the corresponding one of the individual electrodes (El) to (E, ) via the driver (13), but during this waiting period [
P%1], the common electrode (E!c) has a driving voltage [Vh]
is supplied, the electric field becomes [0]. On the other hand, when the signal input to the shift register (15) is "0", the corresponding one of the individual electrodes (El) to (E, l) is grounded, so that the common electrode (EC) Between [-v
h] is generated.

The magnitude of the electric field during the recording period [Pa] and the standby period [Pw] is summarized in Table 1 below.

3 4 Therefore, those who were involved in the recording during the recording period [p, t]
In other words, an electro-optic material to which an electric field with a magnitude of [V,] is applied with a timing according to recorded information has a waiting period [V,].
Pl, l] and E-V, ], that is, an electric field in the opposite direction to that during the recording operation is applied at the same timing, while the electro-optic material that was not involved in recording is , no electric field is applied during the standby period [P, 1]. This situation is shown in FIG.

In the embodiment shown in FIG. 6, the length of the recording period [CPR] and the length of the standby period [P- are the same, and in any period, the duty ratio, which is the ratio of the voltage application period to the pulse width, is [
50%]. The configuration is such that during the standby period [p, l, recorded recording paper is ejected and new unrecorded recording paper is introduced.

In other words, each electro-optic material has [
The electric field r−v,3 is applied to the waiting period [p, ] the same number of times as the electric field of V, ] is applied. Therefore,
The internal polarization of the electro-optic material that occurs when an electric field is applied in one direction a predetermined number of times for recording is canceled by applying an electric field in the opposite direction the same number of times, and this internal polarization, so-called optical fatigue, accumulates. This makes it possible to eliminate changes in half-wavelength voltage in electro-optic materials caused by optical fatigue, and to always obtain uniform, high-quality recording.

i.e. CP TJ (C) and two flips 7
The tff tubes (17), (18) and the Ex-OR circuit (14) constitute optical fatigue compensating means.

Note that the operation for recovering from optical fatigue may be performed after the recording operation for a plurality of pages is completed, and the period and frequency are not critical as long as the recording operation is completed.

[Another example]

Next, another example of the present invention will be listed.

1> In the embodiment shown in FIG. 8, the length of the standby period [pw] is shorter than the length of the recording period [PH1]. The premise is that optical fatigue may reach saturation at a certain level, and in such cases, applying an electric field in the opposite direction to recover from optical fatigue may not necessarily require the same length as during recording. Because there is.

In this embodiment, the standby period [P1] need not be made excessively long to recover from optical fatigue, and the entire recording time can be shortened when recording is performed continuously. In this embodiment as well, the duty ratio during the rainy period is set to [50%].

<2> The embodiment shown in FIG. 9 is an improvement of the embodiment shown in FIG. In order to cope with this, the duty ratio during the recording period [CPR] is set to [50%].
], and on the other hand, the duty ratio in the waiting period CP, 1] is set to [100χ]. In this example,
The overall recording time can be shortened without causing insufficient recovery from optical fatigue. Note that the duty ratio in the waiting period [P8] can be set to any value other than [100χ].

<3> In the previous embodiment, the driving voltage [v1] is applied to the individual electrode (E3) using a signal obtained by inverting the recording signal (DATAl).
The configuration was such that the same driving voltage [vh] was applied to the common electrode (EC) at the same time, but instead of that, although not shown, another driving power source was applied using the same recording signal (DATAI). An electric field may be applied to the electro-optic material in a direction opposite to that during recording by applying a voltage supplied from the source.

〔Effect of the invention〕

As described above, in the optical printer according to the present invention, in order to recover from optical fatigue that occurs in a plurality of electro-optic materials due to long-term use, the optical printer according to the information recorded on each electro-optic material is used. Recovery can be made commensurate with the frequency of voltage application, that is, the degree of photofatigue.
It is possible to prevent insufficient recovery from optical fatigue or adverse effects, and it is possible to always accurately recover from optical fatigue and reliably prevent uneven recording even after long-term use. Optical printers are now available.

[Brief explanation of the drawing]

1 to 6 show an embodiment of the optical printer according to the present invention, in which FIG. 1 is a schematic diagram, FIG. 2 is a schematic diagram of the surroundings of the photoreceptor, and FIG. 3 is a time chart of recording operation. 4 and 5 are explanatory diagrams of data, and FIG. 6 is a time chart of driving voltage application. 7 and 8 are time charts corresponding to FIG. 6 showing different embodiments, respectively. (1)...Photoreceptor, (7)...Light source,
(91) to (9n)... Electro-optic material.

Claims (1)

[Claims] A light modulation section in which a plurality of electro-optic materials for light modulation are arranged in a row is provided between the light source and the photoreceptor, and each of the plurality of electro-optic materials is provided with a drive for light modulation according to recorded information. In an optical printer provided with a recording control means for applying a voltage, after the recording operation by the recording control means is completed, a voltage is generated in each of the plurality of electro-optic materials in the opposite direction to that during the recording operation. The optical printer is provided with optical fatigue compensating means for applying the following information based on recorded information during the recording operation.