JPH0449065A - Optical modulator - Google Patents

Abstract

PURPOSE:To shorten a warming-up time of a device with a simple structure by directly adding heating means for heating an electro-optical material to a securing part of an optical shutter chip. CONSTITUTION:An optical shutter is heated by a heat generating member 15 of a heating means added directly to a base plate 13 of a securing part of an optical shutter chip 9a. In addition, the plate 13 is formed of a glass plate with low thermal conductivity so that little heat is transferred through the plate 13. As a result, the chip 9a is efficiently and quickly heated. Since the member 15 is also used as a member for positioning the chip 9a at a predetermined interval from the plate 13, the structure of the optical shutter is simple and compact even if the heating means is added.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention mainly relates to a PL that performs recording using an electrophotographic method.
The present invention relates to a light modulation device using an electro-optic material such as PLZT, which is used to form an electrostatic latent image on a photoreceptor in a ZT printer or the like. More specifically, the light modulation includes an optical shutter chip in which a plurality of microscopic sections of an electro-optic material are formed in pixel units, and a driving means for applying a driving voltage for light modulation to each of the plurality of microscopic sections. Regarding equipment.

[Conventional technology]

In a light modulation device including an electro-optic material such as PLZT described above, the amount of transmitted light changes depending on the driving voltage applied to each of a plurality of microscopic sections. For example, when this light modulation device is applied to an electrophotographic optical printer, the amount of transmitted light in the light modulation device is changed to vary the degree of charge disappearance on the photoconductive photoreceptor, thereby recording. It is configured so that it can realize the recording itself in gradation or binary recording.

[Invention or problem to be solved]

However, the conventional optical modulation device described above has the following problems.

In other words, it is known that electro-optic materials such as PLZT used in this type of optical modulation device have different operating characteristics depending on the environmental temperature. Specifically, the relationship between the driving voltage and the amount of transmitted light changes depending on the temperature, so even if the same driving voltage is applied, the amount of transmitted light in each microsection in the electro-optic material will differ depending on the temperature. . When the device is operating in a steady state, the environmental temperature of the light modulator stays within a nearly constant range, and there is not much difference in the amount of transmitted light when the same driving voltage is applied. On cold winter mornings, the equipment is completely cold, and there is a significant difference from the steady state described above.

Therefore, in order to obtain high-quality recording, it is essential to warm up the optical modulation device to bring the ambient temperature to a steady state, and for this reason, the user has to wait a long time before the device can actually be used. be forced to.

By the way, in order to compensate for the temperature characteristics of the electro-optic material mentioned above, it may have a purpose different from solving such problems, or it may be necessary to adjust the drive voltage based on the temperature detection means and the detection result thereof. It has been proposed that a device is provided with a means for controlling. Is it possible to use this configuration to shorten the warm-up mentioned above by changing the driving voltage until the temperature reaches a steady state? In this case, the following It's inconvenient. That is, by taking advantage of the fact that this type of electro-optic material has the characteristic that the amount of transmitted light changes depending on the applied driving voltage,
A printer or the like that reproduces gradation by changing the driving voltage may be constructed. In that case, the drive voltage must be controlled based on two parameters: the gradation level to be reproduced and the changing temperature, resulting in the problem that the control configuration becomes complicated. .

SUMMARY OF THE INVENTION In view of the above circumstances, an object of the present invention is to provide an optical modulation device that has a simple configuration and can shorten the warming-up time of the device.

[Means to solve the problem]

The characteristic configuration of the light modulation device according to the present invention is that a heating means for heating an electro-optic material is provided, and the heating means is connected to a fixed part of an optical shutter chip in which a plurality of micro sections of the electro-optic material are formed in units of pixels. This is because it was attached directly to the .

[For production]

In other words, by activating the heating means to heat the electro-optic material at the beginning of the device's operation, the electro-optic material can be quickly brought into a steady state and the device can be used even if the ambient temperature of the device is low. I'm coming. Furthermore, the configuration for this purpose is not complicated, such as controlling the drive voltage based on temperature detection, but may be as simple as simply heating.

〔Example〕

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

As shown in FIG. 3, 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) for forming an electrostatic latent image corresponding to recorded information on a photoreceptor (1), and a developing device (3) for attaching toner to the electrostatic latent image and making it visible. ), and to transfer the toner image formed on the photoconductor (1) onto a recording paper (not shown) by the operation of this developing device (3) and then detach the recording paper from the photoconductor (1). a transfer separation device (4), a main eraser (5) for erasing residual charges on the photoconductor (1), and a cleaning device (6) for scraping off residual toner on the photoconductor (1). are arranged to constitute 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), and a plurality of PLZT arrays (9) as recording electro-optic materials arranged in parallel along the flow direction of the photoreceptor (1). ), a pair of polarizers (IQ) and (II) arranged in crossed nicols before and after the polarizers, and a pair of polarizers that distributes light from the light source (7) to each part of the PLZT array (9). (10), (11) and a PLZT array (9), and an optical fiber bundle (not shown) for entering the optical shutter (S), which is a light modulation device, and a PLZT array (9). and a gradient index lens array (14) for irradiating and imaging the light onto the surface of the photoreceptor (1).

The PLZT array (9) has a plurality of PLZT chips made of a transparent sintered body arranged in a row, and each PLZT chip has a plurality of PLZT chips arranged in a dot unit, which is a unit of image formation, along the direction in which the PLZT chips are arranged. an individual electrode for each micro-section for forming micro-sections of PLZT and applying a driving voltage for modulation to the plurality of micro-sections;
A common electrode is formed which is shared by the micro sections of all the PLZT chips.

An optical print head (
At PH), light from a light source (7) is distributed and guided by an optical fiber bundle and passes through a polarizer (10) on the light source (7) side of an optical shutter (S). This polarizer (10) transmits only polarized light components in one direction. Said PLZ
PLZT constituting the T array (9) has birefringence, and when a predetermined voltage is applied, the plane of polarization of incident light is rotated by an angle corresponding to the applied voltage and transmitted.

A polarizer (1) on the photoreceptor (1) side of the optical shutter (S')
1) The plane of polarization that transmits light is the polarizer (
Since the orthogonal Nicol arrangement differs by 90° from 10), no voltage was applied to the individual electrodes of the PLZT.
The light that has passed through the micro-divisions of the polarizer (
11), and on the other hand, the light that has passed through the PLZT microdivisions with a predetermined voltage applied to the individual electrodes is transmitted through the polarizer (11) on the photoreceptor (1) side at a rate corresponding to the applied voltage. The photoreceptor (
1) An electrostatic latent image is formed by irradiating and forming an image on the surface and eliminating 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.

The configuration is configured such that drive pulses corresponding to recording information are selectively applied to the plurality of PLZT micro sections from a drive IC (not shown in FIG. 3) via separate individual electrodes. It has been done. As a result, the aforementioned optical shutter (S) is activated to form an electrostatic latent image on the photoreceptor (1) according to the recorded information, and then a toner image that visualizes it is transferred onto the recording. It can be fixed and recorded.

In the optical shutter (S), as shown in FIGS. 1 and 2, the PLZT chips (9a), which are a plurality of optical shutter chips, are an example of driving means corresponding to each of the plurality of PLZT microsections described above. The drive IC (
12) and is mounted on a plywood board (13) made of transparent glass.

The PLZT chip (9a) is mounted on a pair of heat generating members (15) on which tantalum nitride, chromium silicide, etc., which are thin film plate resistors, are deposited in rows.

Here, the function of the heat generating member (15) described above will be explained. As described above, PLZT, which is an electro-optic material having an electro-optic effect, has a different amount of phase change of a polarized light component depending on an applied voltage, and as a result, the amount of transmitted light varies.

The applied driving voltage [VD] and the amount of transmitted light [when the application time expressed by the pulse rate in the case of pulse driving is kept constant]
AL] has the relationship shown in FIG. Transmitted light amount [AL
] or the maximum drive voltage [V, ] is generally expressed as the half-wave voltage [V,]
PLZT has temperature dependence, so the relationship between the applied driving voltage [V, ] and the amount of transmitted light [AL] changes depending on the temperature, and the half wavelength that becomes the optimum driving voltage changes accordingly. The voltage [1'Dhw] also changes as shown in FIG.

When recording, the amount of charge dissipated on the photoreceptor (1) varies depending on the amount of transmitted light from the optical shutter (S), and the amount of charge dissipated on the photoreceptor (1) also varies depending on the amount of toner attached or the recording density. manifested as a difference. That is, if the same driving voltage is applied even when the half-wave voltage or the temperature is different as described above, the density of the recording will change.

By the way, the environmental temperature of the optical shutter (S) [±5°C]
In a steady state in which the temperature is within a certain range, the change in the amount of transmitted light is not so large when the same driving voltage is applied [only about ±5%], especially when starting at a low temperature in winter, There is a large temperature difference between the two states, and this causes a significant difference in the amount of transmitted light for the same driving voltage. In addition, at low temperatures, as shown in Figs. 6 and 7, the falling characteristic of the amount of transmitted light in the case of pulse driving with no driving voltage applied becomes different from that when the optical shutter (S) is turned on. There will be a change in the light amount ratio compared to when it is off. Therefore, in order to obtain good quality records, warm-up is essential. Therefore, by directly heating the optical shutter (S), it is possible to quickly bring it into a steady state and reduce the waiting time.

Moreover, the heating of the optical shutter (S) is performed by the heating member (15), which is the heating means (W) mentioned above, which is directly attached to the plywood (13), which is the fixed part of the optical shutter chip (9a). The base plate (13) is made of a glass plate, which has poor thermal conductivity, and combined with the fact that less heat escapes through the plywood (13), the optical shutter chip (9a)
) can be heated efficiently and its temperature can be raised quickly. Moreover, since it will also be used as a member for positioning the heat generating member (15) or the optical shutter chip (9a) from the plywood (13) at a predetermined interval,
The structure of the optical shutter (S) is simple and compact despite the addition of a heating means (W).

As shown in FIG. 2, the pair of heat generating members (15) are configured to be applied with a driving voltage from a heater power source (17) whose operation is controlled by a temperature control circuit (16). The temperature control circuit (16)
For this purpose, the plywood (I
The output from the temperature detection circuit (19) that detects the temperature of step 3) is input, and this temperature control circuit (16)
The heater power source (I7) is operated to heat the optical shutter chip (9a) until the temperature of the plywood (13) reaches a predetermined temperature range (c±2°C relative to the target temperature) in which the temperature of the plywood (13) is in a steady state. It is designed to stay within that range.

[Another example]

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

<1> In the embodiment shown in FIGS. 8 and 9, the heat generating member (I5) having the same structure as in the previous embodiment is
3) is attached to the surface opposite to the surface on which the optical shutter chip (9a) is mounted. In this configuration, the heat generating member (15
) and the light shutter chip (9a), there is a plywood (13) made of a glass plate, so the time required for the temperature of the light shutter chip (9a) to rise is slightly longer than in the previous example. However, this is not a problem in actual use.

Further, since no sudden temperature change occurs when the heat generating member (15) is turned on or off, this embodiment is more preferable than the previous embodiment in terms of stability.

<2> In the embodiment shown in FIGS. 10 and 11, the optical shutter chip (9a) is attached to a pair of adhesive layers (20).
The optical shutter chip (9a) is positioned at a predetermined distance from the plywood (13), and the adhesive layer (20) is attached on both sides of the pair of adhesive layers (20). Adhesive light shutter chip (9a) constituting the
A glass rail (21) is attached to prevent light from flowing into the portion corresponding to the light transmitting portion of the glass, and a base plate (21) is installed between the glass rail (21) and the plywood (13).
13) A heater (22) as a heating means (W) is formed of, for example, gold used in the above wiring pattern. In this embodiment, the heating means (W) can be formed at the same time as the wiring pattern is formed on the plywood (13). According to the device:
It is possible to quickly bring the electro-optic material into a steady state by simply heating the electro-optic material by operating a heating means with a simple configuration, and even when a constant voltage is used as the driving voltage, it can be used without the risk of shading in the image. The condition that will occur will appear quickly. In particular, when creating a configuration that reproduces gradation by controlling the drive voltage, there is no need to take the temperature factor into consideration because there is a heating means, so whether it is a parameter for controlling the drive voltage or
Only the gradation to be reproduced is required, and the configuration can be simplified.

[Brief explanation of the drawing]

1 to 7 show an embodiment of the optical modulation device according to the present invention, FIG. 1 is a sectional view, FIG. 2 is a schematic configuration diagram, FIG. 3 is a schematic configuration diagram of an optical printer, and FIG. 4 is a schematic diagram of an optical printer. is a graph of the relationship between drive voltage and amount of transmitted light, Figure 5 is a graph of the relationship between temperature and optimal drive voltage, Figure 6 is a timing chart for driving the optical shutter, and Figure 7 is a graph of the relationship between temperature and amount of transmitted light. It is a graph. 8 to 11 show another embodiment, FIG. 8 is a sectional view corresponding to FIG. 1 showing another embodiment, FIG. 9 is a bottom view of the embodiment of FIG. 8, and FIG. The figure is a sectional view corresponding to FIG. 1 showing yet another embodiment, and FIG. 11 is a plan view of the embodiment of FIG. 10. (9a)... Optical shutter chip, (12)...
... Drive means, (13) ... Fixed part, (W
)... Heating means.

Claims (1)

[Claims] In the light modulation device, the light modulation device includes an optical shutter chip in which a plurality of microscopic sections of an electro-optic material are formed in pixel units, and a driving means for applying a driving voltage for light modulation to each of the plurality of microscopic sections. A light modulation device comprising a heating means for heating an electro-optic material, and the heating means is directly attached to a fixing part of the optical shutter chip.