JPH01188825A - Method for driving optical shutter array - Google Patents

Abstract

PURPOSE:To prevent the increase of a leaking light at the time of turning off when the array is repeatedly used by impressing a voltage to a common electrode and adding the electric field in a periodically different direction to respective optical shutters. CONSTITUTION:The array, in which a common electrode 12 common to respective optical shutters 11 is formed at one side of respective optical shutters 11 is formed and on the other hand, an individual electrode 13 individual for respective optical shutters 11 is formed at other side of respective optical shutters 11, is used. The voltage is impressed to the common electrode 12, and the electric field in the periodically different direction is added to respective optical shutters 11. As the material having an electrical optical effect to constitute respective optical shutters 11 of an optical shutter array 10, PLZT, which is fast in response speed and can be driven at a comparatively low voltage, is used. Thus, the increase of the leaking light at the time of turning off of an optical shutter when the optical shutter array 10 is driven for a long time over and over again repeatedly is prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a method for driving an optical shutter array in which a plurality of optical shutters made of a material having an electro-optic effect such as PLZT are arranged. The present invention relates to a method of driving an optical shutter array that prevents an increase in leakage light during off-time even when used repeatedly.

[Background of the Invention] Conventionally, it has been considered to use an optical shutter array formed by arranging a plurality of optical shutters made of a material having an electro-optic effect such as PLZT as a writing device for an electrophotographic printer. .

Here, the present inventors have discovered that when using an optical shutter array in a writing device of an electrophotographic printer, there are advantages such as no malfunction due to crosstalk, good responsiveness, and the ability to obtain high-quality images. For example, as shown in FIGS. 1(A) and 1(B), as an optical shutter array with
Three-dimensionally formed optical shutters (11) are arranged in a staggered manner on both sides of a common electrode (12) formed to be common to each optical shutter (11), and each optical shutter (
11) The individual electrodes (13) that have become separate for each are the common electrodes mentioned above! Various optical shutter arrays (10) formed on the opposite side of (12) have been disclosed in previous applications.

When using such an optical shutter array as a writing device for an electrophotographic printer, as shown in FIG. 2, a polarizer (14) is placed on the light incident side of the optical shutter array (10). Analyzer (15) on the transmission side of
The light from the lamp (1) and its reflecting mirror (2) is guided to the light shutter array (10) through the polarizer (14), and the light from the light shutter array (10) is guided based on the image/image information. ) was driven to deflect the guided light and transmit it through the analyzer (15).Then, the light that had passed through the analyzer (15) in this way was passed through the focusing rod lens. focused by an array (3);
This focused light was irradiated onto the surface of the photoreceptor (5) charged by the charger (4) to form an electrostatic latent image on the surface of the photoreceptor (5). Thereafter, toner is applied in a developing device (6) to form a toner image corresponding to the electrostatic latent image on the surface of the photoreceptor (5), and then this toner image is transferred to a transfer device (
7) to transfer onto the recording paper, while removing I-ner remaining on the surface of the photoreceptor (5) using a static eliminator (8) and a cleaner (
9).

Here, in order to drive the appropriate optical shutter of the optical shutter array based on the image information as described above,
Usually, as shown in FIG. 3, individual electrodes (13) formed on each optical shutter (11) are connected to individual drivers (
20), while a common electrode (12) common to each optical shutter (11) is grounded. and,
After serially inputting data based on image information to the shift register (21), this data is sent to the latch signal LATC.
It is latched into the latch circuit (22) by H, and the drive signal ■
is set to high level, and this latched data is sent from the driver (20) to the individual type 41 of each optical shutter (11).
ffi (13') in parallel, and drive voltage V only to the individual electrodes (13) of appropriate optical shutters (11).

was applied to allow light to pass through, thereby recording one line of latent image on the surface of the photoreceptor.

After recording on the surface of the photoreceptor in this way, the driving voltage Vh applied to the individual electrodes of the optical shutters is discharged, and as shown in FIG. After waiting for a certain period of time, recording was performed again on the surface of the photoreceptor as described above, and such operations were repeated many times to sequentially form electrostatic latent images on the surface of the photoreceptor.

However, if a voltage is applied only to the individual electrodes of the optical shutter to drive the optical shutter array, an electric field is always applied in the same direction, albeit intermittently, to the optical shutter, and this can be repeated many times. If this is repeated, weak polarization occurs inside each optical shutter, and as shown by the broken line in Figure 5, the amount of transmitted light when no voltage is applied to the optical shutter, that is, the leakage light when it is off, increases. However, a problem arose in that the contrast between on and off was poor, making it impossible to obtain high-quality images.

This invention was made to solve this problem, and it is possible that even when the optical shutter array is repeatedly driven over a long period of time, leakage light increases when the optical shutter is turned off. However, the present invention aims to provide a method for driving an optical shutter array with excellent contrast during on/off.

[Means for Solving the Problems] In the method for driving an optical shutter array according to the present invention, a common electrode common to each optical shutter is formed on one side of each optical shutter made of a material having an electro-optic effect. On the other hand, in an optical shutter array in which an individual electrode is formed for each optical shutter on the other side of each optical shutter, a voltage is applied to the common electrode to periodically cause each optical shutter to move in a different direction. An electric field was applied. Note that as a material having an electro-optic effect constituting each optical shutter of the optical shutter array, it is preferable to use PLZT, which has a fast response speed and can be driven at a relatively low voltage.

[Operation: In this way, by applying a voltage to the common electrode common to each optical shutter in the optical shutter array and applying electric fields in different directions periodically to each optical shutter, the optical shutters are always in the same state. There is no weak polarization inside each optical shutter due to the application of a directional electric field, and even when the optical shutter array is repeatedly driven over a long period of time, there is no leakage of light when the optical shutters are off. There is no increase.

In addition, when applying electric fields in different directions to each optical shutter periodically, if a voltage is applied to a common electrode that is shared by each optical shutter, the electric field in a different direction can be applied to each optical shutter individually. This makes it easier to perform these operations all at once, compared to operations that involve adding.

[Example] Hereinafter, an example of the present invention will be specifically described based on the accompanying drawings.

In each of the embodiments shown below, as the optical shutter array (10), as shown in FIGS.
A common electrode (12) is formed on the other side of each optical shutter (11), and an individual type 8i (13) is formed on the other side of each optical shutter (11). did.

In this embodiment, as shown in FIGS. 6(A) and 6(B), in the optical shutter array (10) as described above, each optical shutter (111), (112), . . .・(11
, ), each individual electrode (131), (13
2), ... (13n), respectively, for each driver (20
+ ), (202>, ... (20,), while each optical shutter (llx), (lh), -(
11o) common type f! (13) is connected to the changeover switch (23), and this changeover switch (23)
This allows the common electrode (12) to be switched between the ground (24) side and the alternating voltage generation circuit (25) side for connection.

Then, by driving this optical shutter array (10),
When recording on the surface of a photoreceptor, etc., please refer to Figure 6 (A
), the changeover switch (23) is set to the ground (24) side, the common type ffi (12) is connected to the ground (24) side, and each Driver (20,).

(20z) ,...(2On> to each optical shutter (
111), (112).

... (11,) individual electrodes (13x), (13z),
- Send data in parallel to (13n), and apply a driving voltage h only to the individual electrode (13) of the appropriate optical shutter (11).
was applied to transmit light and record on the surface of a photoreceptor or the like.

After recording on the surface of the photoreceptor etc. by driving the optical shutter array (10) in this way, each optical shutter (111
>, (112), ... (11,) individual electrodes (131
).

(132), . . . (13n,) at the ground level, as shown in FIG. The common electrode (12) was connected to the alternating voltage generating circuit (25). Then, as shown in FIG. 7, during the standby period, an alternating voltage of ±Vh is applied from the alternating voltage generating circuit (25) to the common electrode (12), and the alternating voltage of ±Vh is applied to each optical shutter (111).

Electric fields in different directions were applied to (112), . . . (11,). After that, select the switch (23)
was again switched from the alternating voltage generation circuit (25) side to the ground (24) side, and the optical shutter array (10) was driven in the same manner as in the previous case to perform recording on the surface of the photoreceptor, etc.

In this way, during the standby period, an alternating voltage of ±7 is applied to the common electrode (12), and each optical shutter (111) is turned on.

When the optical shutter array (10) is driven while applying electric fields in different directions to (112), ... (11,), the amount of leaked light when the optical shutter (11) is turned off is As shown by the solid line in FIG. 5, even when the optical shutter array (10) was used many times, there was almost no change, and the amount of leaked light was maintained at a low level.

Note that in this embodiment, the common electrode (
±V as the alternating voltage applied to 12).

In this example, the waveform of the applied voltage is not limited to this, and may be, for example, a sine wave. As shown in the block circuit diagram of FIG. 8, an exclusive OR gate (26) is provided to input data to the shift register (21), and the negative input of the exclusive OR gate (26) is provided. The first data DATAI is inputted to the terminal, and the output Q of the first flip-flops F and Fl is inputted to the other input terminal, and the second data DAT outputted from this exclusive OR gate (26).
A2 is serially input to the shift register (21) in synchronization with the first clock signal CLOCKI.

Here, a second clock signal CLOCK2 is applied to the first flip-flops F and Fl connected to the input terminal of the exclusive OR gate (26), and this second clock signal C
The outputs Q of the first flip-flops 1F and Fl are switched between high and low in synchronization with LOCK2. and,
When the outputs Q of the first flip-flops F and Fl are at low level, the exclusive OR gate (26) outputs second data DATA2 having the same phase as the first data DATAI; When the output Q is at a high level, the first data DA is output from the exclusive OR gate (26).
Second data DATA2 having an opposite phase to TAI is now output.

After inputting the second data DATA2, which has the same phase or the opposite phase to the first data DATAI outputted from the exclusive OR gate (26), to the shift register (21) as described above, 2 clock signal CLOC
The latch circuit (22) receives second data DATA2. is latched, the drive signal CL is set to high level, and the second data DATA2 latched in the latch circuit (22) is sent from the driver (20) to each optical shutter (111), (11□), ... (11,
) for each individual electrode (13!>, <132>, ... (1
3o) in parallel, and a suitable light shutter (11)
The voltage Vh was applied only to the individual electrodes (13).

On the other hand, each optical shutter (11□), (112), ... (
A high voltage driver (27) that outputs a voltage h is connected to the common electrode (12) of the high voltage driver (27).
) is given by the output Q of the second flip-flop F, F2. Further, a third clock signal CLOCK3 is applied to the second flip-flops F and F2, and the output Q of the second flip-flops F and F2 is connected to the third clock signal CL.
Changed to switch between high and low in synchronization with OCK3.

When the second data DATA2 sent from the driver (20) is in the same phase as the first data DATAI, the outputs Q of the second flip-flops F and F2 are set to low level, and the high voltage driver (27) The common electrode (12) is connected to the ground (24) without outputting the voltage Vh from the terminal. On the other hand, the second data DATA2 sent from the driver (20) is the first data DATAI.
If the phase is opposite to that of the second flip-flop F, F
Set the output Q of 2 to high level and connect the high voltage driver (27).
output voltage ■ゎ from , and apply voltage V to the common electrode (12).
was applied.

As mentioned above, the second data DATA2 sent from the driver (20) is in the same phase as the first data DATA1,
When the common electrode (12) is connected to the ground (24), that is, during the period T shown in the timing chart of FIG. 9, the phase is the same as that of the first data DATAI, as shown in FIG. Based on the second data DATA2, only the optical shutter (11) to which the voltage V is applied to the individual electrode (13) is driven to transmit light.

On the other hand, the second data DA sent from the driver (20)
TA2 is in opposite phase to the first data DATAI, and the common type [!
(12), when voltage ■ is applied to
As shown in FIG. 0 (B), the individual electrodes (13)
The optical shutter (11) to which the voltage v is applied is
The optical shutter (11) is not driven at the same voltage as the common electrode (12) to which h is applied, and conversely, the optical shutter (11) to which the voltage Vh is not applied to the individual electrode (13) is applied to the common electrode (12). voltage V.

It is driven by the light to transmit light.

As a result, even during the period T2, recording based on the first data DATAI is eventually performed.

When the optical shutter array (10) is driven in this way, electric fields in different directions act on the driven optical shutter (11) during the periods T1 and T2, and if this is repeated, , the electric fields of the four different directions of the optical shutters (11) are now averaged and act on each of the optical shutters (11).

As a result, as in the case of Example 1 above, even though the optical shutter array (10) was used many times, the amount of leaked light when each optical shutter (11) was turned off hardly changed. Light leakage is now maintained at a low level.

and 111 In this embodiment, as shown in the block circuit diagram of FIG.
1 in synchronization with the shift register (21), and the latch circuit (22) by the latch signal LATCH.
The process up to the point of latching is similar to the conventional case shown in FIG.

In this embodiment, the latch circuit ('22>
each output terminal of each exclusive OR gate (26
1), (262), ... (26n), while each exclusive OR gate (26,).

The other input terminals of (262), . . . (26,) are connected to the common line (28), and the second clock signal CLOCK2 is applied to this common line (28).

Here, when the second clock signal CLOCK2 is at low level, each exclusive OR gate (26□), (26□), ... (26,) connected to the common line (28)
The input side of becomes low level, and the data DATA output from the latch circuit (22) is sent to each exclusive OR gate (
261), (262), . . . (26,,) are output as they are. On the other hand, the second clock signal CL
When OCK2 is high level, the common line (28)
Each exclusive OR gate (261) connected to (2
62), ... (26n) becomes high level, and the data DATA output from the latch circuit (22) is transmitted to each exclusive OR gate (26+), (262), ...
・The signal will be inverted and output from the output side of (26,).

Then, when the drive signal d is set to high level, each exclusive OR gate (261), (262), ... (26,
) is output in the same or opposite phase as the data DATA from the output side of the driver (20). 13), the voltage V,
is now applied. Note that when the drive signal CL is at a low level, each output terminal HVO of the driver (20)
□ to HVO are all turned off.

On the other hand, each optical shutter (111), (112), ... (
11, ) is connected to a high voltage driver (27) that outputs a voltage h, and this high voltage driver (27
) is provided with the second clock signal CLOCK2.

Then, when this second tarlock signal CLOCK2 is at a low level and the data DATA output from the latch circuit (22) as described above is output from each output terminal HVO1 to HVO8 of the i-ma driver (20), , the voltage Vh is not output from the high voltage driver (27), the common electrode (12) is connected to the ground (24), and the optical shutter (11) has the voltage Vh applied to the individual electrodes (13). Only the light will be driven and the light will be transmitted through it.

On the other hand, when the second clock signal CLOCK 2 is at a high level, the data DATA output from the latch circuit (22) is inverted as described above, and each output terminal H of the driver (20) is
When outputting from VO□ to HVO, a voltage Vh is applied from the high voltage driver (27) to the common electrode (12), and a voltage ■ゎ is applied to the individual electrodes (13) of the optical shutter (11). is the common electrode 12 to which voltage ■1 is applied.
) and is not driven at the same voltage as the individual electrode (13).
The optical shutter (11) to which the voltage Vh is not applied is
It is driven by the voltage Vh applied to the common type & (12) and becomes transparent to light. As a result, even in this case, recording is performed based on the data DATA output from the latch circuit (22).

Here, to explain the output terminal HVO of the driver (20) as an example, as shown in the timing chart of FIG. 14, during the period T1, the voltage vh is applied from the output terminal HVO1 to the individual electrode (13). The timing coincides with the timing of applying voltage (1) to the common electrode (12). Therefore, during the period Tl, the voltages at the picture electrodes (12) and (13) of the optical shutter (11) are the same, and the optical shutter (11) is not driven. On the other hand, during the period T2, the output terminal HVO
The timing of applying the voltage ■h from s to the individual electrode (13) and the common type! (12) is in reverse phase with the timing of applying the voltage Vh to the optical shutter (11), the voltage Vh is applied to the optical shutter (11) while reversing the electric field in synchronization with the second tarlock signal CLOCK2. Shutter (1
1) comes to be driven.

When the optical shutter array (10) is driven in this way, when the drive signal CL is at a high level as described above, the optical shutter (11) to be driven is different in synchronization with the second clock signal CLOCK2. When this process is repeated based on the data DATA, the electric fields in different directions act on each optical shutter (11) in a manner that is averaged to some extent.

As a result, even in the case of this example, even though the optical shutter array (10) was used many times,
The amount of leakage light when each optical shutter (11) is off hardly changes, and the amount of leakage light is maintained at a low level.

[Effects of the Invention] As detailed above, in the present invention, a voltage is applied to a common electrode common to each optical shutter of an optical shutter array, and an electric field is periodically applied to each optical shutter in a different direction. As a result, even if the optical shutter array is repeatedly driven over a long period of time, weak polarization will occur inside each optical shutter, resulting in light leakage when the optical shutter is off. There was no increase in light leakage and light leakage was maintained at a low level.

As a result, by driving the optical shutter array in this way,
When used as a writing device in an electrophotographic device,
It is now possible to obtain high-quality images with high contrast between on and off states.

In addition, when applying electric fields in different directions to each optical shutter periodically, voltage is applied to a common electrode that is shared by each optical shutter, so the electric field in a different direction is applied to each optical shutter individually. This makes it easier to perform these operations all at once compared to adding .

[Brief explanation of the drawing]

Figures 1 (A) and (B) are a plan view and a sectional view of the optical shutter array, Figure 2 is a schematic diagram of the optical shutter array used as a writing device for an electrophotographic printer, and Figure 3 is the optical shutter array. 4 is a timing diagram showing the state of the driving voltage pulse applied to the optical shutter during the recording period and standby period by the circuit of FIG. 3, and FIG. 5 is a conventional block circuit diagram when driving the optical shutter. Figures 6 (A), (B), and 7 show the relationship between the number of drive voltage pulses applied to the individual electrodes and the amount of light leakage in the off state, and show the first embodiment of the present invention. , No. 67 (A), (
B) is a circuit diagram showing the switching state of the circuit during the recording period and the standby period of the optical shutter array; FIG. 7 is a timing diagram showing the state of the driving voltage pulse applied to the optical shutter during the recording period and the standby period; Figures 8 to 10 (A). (B) shows a second embodiment of the present invention, FIG. 8 is a block circuit diagram for driving the optical shutter array, FIG. 9 is a timing chart for driving the optical shutter array, and FIG. 10 (A ), (B) are diagrams showing the driving states of the optical shutter array in the T1 period and T2 period shown in the timing chart diagram of FIG. 9, and FIGS. 11 to 14 show a third embodiment of the present invention. , FIG. 11 and FIG. 12 are block circuit diagrams for driving the optical shutter array, FIG. 13 is a timing chart diagram for driving the optical shutter array, and FIG. 14 is an example of the output terminal HVO of the driver. FIG. 3 is a timing chart showing the driving state of the shutter. (10)... Optical shutter array, <11)... Optical shutter, (12)... Common electrode, (13)... Individual electrode, Vh... Voltage. Fig. 2 12 Fig. 3/) 1 Fig. 4 1 ! Figure 5 Number of applied pulses (X 10' times) Figure 7 Figure 6 (A) (B) Figure 11 Figure 14

Claims (1)

[Claims] 1. A common electrode common to each optical shutter is formed on one side of each optical shutter made of a material having an electro-optic effect, while an individual electrode is formed for each optical shutter on the other side of each optical shutter. 1. A method of driving an optical shutter array, characterized in that in the optical shutter array, a voltage is applied to the common electrode so that electric fields in different directions are periodically applied to each optical shutter.