JPH11277805A - Image writing device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a good image stably by suppressing fluctuation in the quantity of transmitting light due to difference of using frequency of an optical shutter easily at the time of writing. SOLUTION: An optical shutter array 100 arranged with optical shutters 111 comprising an optical modulation member and a polarization means is irradiated with light from a light irradiating means, an electric field is applied to the optical shutters by an optical shutter drive means 40 based on a signal from am image signal generating means 50 and an image carrier is irradiated with light passed through the optical shutter array in an image writing device. The image writing device comprises means 30 for switching the polarization state of the polarization means, means 70 for controlling the polarization state switching means, and an output signal control means 80 for inverting an image signal being outputted from the image signal generating means 50 to the optical shutter drive means depending on the polarization state switched by the polarization state control means.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image writing apparatus used in an image forming apparatus such as a copying machine or a printer, and more particularly, to a light modulation member made of a material having an electro-optic effect and this light modulation member. The present invention relates to an image writing apparatus using an optical shutter array in which optical shutters constituted by polarizing means arranged so as to sandwich them are arranged.

[0002]

2. Description of the Related Art Hitherto, it has been known that when an electric field is applied to a material having an electro-optic effect such as PLZT, a sub-refraction occurs to change the polarization state of light passing through the electro-optic effect. .

Utilizing the above-mentioned characteristics of the material having the electro-optical effect, as shown in FIG. 1, the polarizing member is sandwiched by the light modulating member 1 made of the material having the electro-optical effect. 2a and 2b, and a pair of electrodes 1 provided on the light modulating member 1.
A predetermined voltage Vd is applied to a and 1b to apply an electric field, and in this state, light polarized through one polarizing member 2a is guided to the light modulating member 1 and acts on the light modulating member 1. An optical shutter has been developed in which the polarization state of light guided by an electric field is controlled, thereby controlling light passing through the other polarizing member 2b.

In recent years, in an image forming apparatus such as a copying machine or a printer, a light to be irradiated on an image carrier is controlled by using an optical shutter array in which optical shutters are arranged as described above, and thereby an image is formed. Writing electrostatic latent images on carriers has come to be considered.

However, when an electric field is applied to the light modulating member 1 made of the material having the electro-optical effect many times to polarize the light, the material having the electro-optical effect is Causes a change in the characteristics of the material having the electro-optical effect, whereby the voltage applied to the light modulating member 1 in the optical shutter shown in FIG. 1 and the amount of transmitted light passing through the other polarizing member 2b 2 changes from the initial state shown by the solid line to the state shown by the broken line, and even if the voltage Vd applied to the light modulation member 1 is the same, the initial transmitted light amount Ia and the electric field are reduced. The amount of transmitted light Ib after having acted many times was greatly different.

In an optical shutter array using a light modulating member made of a material having an electro-optical effect, an electrostatic latent image is written on an image carrier by applying an electric field to an appropriate optical shutter. In this case, the amount of light transmitted through each optical shutter varies depending on the frequency of use of the optical shutter in the optical shutter array, and the amount of light applied to the image carrier varies with the optical shutter. When an electrostatic latent image is formed and an image is obtained by developing the electrostatic latent image thus formed, there is a problem that density unevenness occurs in the formed image.

For this reason, in recent years, Japanese Patent Application Laid-Open
As disclosed in Japanese Patent Application Laid-Open No. 3-35214, the optical shutter array is moved with time in the direction in which the optical shutters are arranged to average the driving state of each optical shutter. In such a case, a driving history of the optical shutter is stored, and an opposite electric field is applied to the optical shutter in a state where recording is not performed, thereby eliminating the driving history of the optical shutter. .

However, in the image writing apparatus disclosed in Japanese Patent Application Laid-Open No. 64-64862, the optical shutter array is moved with time in the arrangement direction of the optical shutters.
As the size of the device increases, a mechanical device for moving the optical shutter array is required, which makes it difficult to accurately control the driving of the device.
In the image writing apparatus disclosed in Japanese Patent No. 35214, since an opposite electric field is applied to the optical shutter in a state where recording is not being performed, control cannot be performed in a state where writing is being performed. In such a case, there is a problem that writing must be temporarily stopped in the middle.

[0009]

SUMMARY OF THE INVENTION According to the present invention, there is provided an optical shutter composed of a light modulating member made of a material having an electro-optical effect and polarizing means arranged so as to sandwich the light modulating member. It is an object of the present invention to solve the above-described problem in an image writing apparatus using an optical shutter array, and there is a difference in the frequency of use of the optical shutter in the optical shutter array, and the amount of transmitted light passing through the optical shutter The object of the present invention is to make it possible to easily suppress the occurrence of variations during writing, and to stably obtain a good image with low density unevenness.

[0010]

In the image writing apparatus according to the present invention, in order to solve the above-mentioned problems, a light modulating member made of a material having an electro-optical effect is sandwiched between the light modulating member and the light modulating member. An optical shutter array in which optical shutters composed of arranged polarizing means are arranged, light irradiating means for irradiating the optical shutter array with light, image signal generating means for outputting a signal corresponding to image information, Optical shutter driving means for applying an electric field to an appropriate optical shutter in the optical shutter array based on the image signal output from the image signal generating means, and transmitting light passing through the optical shutter in the optical shutter array to an image. In an image writing device that irradiates the carrier and writes the image on the image carrier in accordance with image information, the polarization state is switched by the above-described polarization unit. Polarization state switching means, polarization state control means for controlling the polarization state switching means, and output from the image signal generating means to the optical shutter driving means in response to the polarization state switching by the polarization state control means. Output signal control means for inverting the image signal.

In the image writing apparatus according to the present invention, the polarization state is switched by the polarization state control means at an appropriate time based on the frequency of use of the optical shutter in the optical shutter array, image mode information of an image to be formed, and the like. By operating the means, the polarization state of the polarizing means is switched, and the output signal control means inverts the image signal output from the image signal generating means to the optical shutter driving means.

Here, when the polarization state switching means is operated to switch the polarization state by the polarization means as described above, for example, the optical shutter which has passed the light by applying the electric field by the optical shutter drive means Does not pass light, and conversely, an optical shutter, which does not pass light without an electric field, passes light, and the image signal output from the image signal generating means is inverted by the output signal control means. The electric field is no longer applied to the optical shutter that has applied the electric field, while the electric field is applied to the optical shutter that does not apply the electric field. In the same manner, light passes through an appropriate optical shutter in the optical shutter array, so that similar image information is written on the image carrier.

Further, in this case, a large number of electric fields do not act only on the optical shutter which frequently transmits light, and the frequency of the electric field acting on each optical shutter is averaged, so that the characteristic of the specific optical shutter can be improved. Is not changed, the variation in the amount of transmitted light passing through each optical shutter is suppressed, stable writing can be performed on the image carrier, and a good image with less density unevenness can be obtained stably. become.

Here, when the polarization state is switched by the polarization means by the polarization state switching means, the first and second polarization means having a polarization angle phase difference of 90 ° on one side of the light modulation member. A polarization member is provided, and a third polarization member having the same polarization angle as one of the first and second polarization members is provided on the opposite side of the light modulation member. The polarization state is switched by switching between the first polarization member and the second polarization member in which the phase of the polarization angle on one side of the light modulation member is different by 90 °, or sandwiches the light modulation member as the polarization means. For one of the polarizing members provided as described above, a polarizing member whose polarization angle phase is changed by the action of an electric field is used, and an electric field is applied to the polarizing member by a polarization state switching unit.
The polarization state can be switched by changing the phase of the polarization angle in the polarization member.

[0015]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An image writing apparatus according to an embodiment of the present invention will be specifically described below with reference to the accompanying drawings.

In the image writing apparatus according to this embodiment, as shown in FIG. 3, light emitted from a halogen lamp
1, the light is guided to the optical shutter array 100 in which the optical shutters are arranged, and an appropriate optical shutter in the optical shutter array 100 is driven.
The light is focused on the image carrier 20 by the converging rod lens array 12, and an electrostatic latent image is written on the image carrier 20.

Here, the above-described optical shutter array 100
Is constituted by a light modulating member 110 made of a material having an electro-optical effect such as PLZT, and a polarizing means 120 arranged so as to sandwich the light modulating member 110. In this embodiment, the light modulating member The first in which the phase of the polarization angle differs by 90 ° on the side of the member 110 to which light is irradiated.
While the polarization member 121 and the second polarization member 122 are provided, on the opposite side of the light modulation member 110, the phase of the polarization angle differs from that of the first polarization member 121 by 90 °.
A third polarizing member 123 having the same polarization angle as that of the second polarizing member 122 is provided.

As the polarization state switching means 30 for switching the polarization state by the polarization means 120, a solenoid 30 is provided, and the first polarization member 121 and the second polarization member 122 are moved by the solenoid 30. Thus, one of the first polarizing member 121 and the second polarizing member 122 is guided to a position facing the light modulation member 110.

Here, in the light modulation member 110 in the above-mentioned light shutter array 100, as shown in FIG. 4, two rows of light shutters 111 are provided at required intervals.
The two rows of optical shutters 111 are arranged in a staggered manner, and a common electrode 112 common to each optical shutter 111 is provided between the two rows of optical shutters 111. On the other side, an individual electrode 113 is provided for each optical shutter 111.

Further, as an optical shutter driving means 40 for applying an electric field to the optical shutter 111 having the common electrode 112 and the individual electrode 113 provided on the optical shutter 111, a driving IC 41 is provided on both sides of the optical modulation member 110. The drive ICs 40 on both sides are connected to the individual electrodes 113 by wire bonding, and the drive ICs 41 are connected to the drive substrate 42 by wire bonding.

In the image writing apparatus according to this embodiment, as shown in FIG. 5, a signal corresponding to the image information is output from the image signal generating means 50 to the driving substrate 42, and this signal is used for driving. The signal is transmitted from the substrate 42 to the drive IC 41, and the drive IC 41 controls the optical shutter 11 at an appropriate position based on the signal.
An electric field is applied to this optical shutter 111 by applying a voltage to one individual electrode 113.

Then, as described above, the halogen lamp 10 is used.
The light emitted from the lens is focused by the cylinder lens 11 and guided to the optical shutter array 100. When the light is guided to the light modulating member 110 through the first polarizing member 121, the light according to the image information as described above. In the portion of the optical shutter 111 to which an electric field is applied based on the signal, the light is polarized and the phase thereof is shifted by 90 °, and the light thus polarized is shifted in phase with the first polarizing member 121 by the phase of the polarization angle. Is 9
This light passes through a third polarizing member 123 different by 0 °, and this light is focused on the image carrier 20 by the converging rod lens array 12 and irradiated, while the light shutter 111 where no electric field is applied is applied. Is the first polarizing member 121
The light guided to the light modulating member 110 passes through without being changed, and is blocked by the third polarizing member 123, thereby forming an electrostatic latent image on the image carrier 20.

In the image writing apparatus of this embodiment, an electrostatic latent image is formed on the image carrier 20 as described above, and an electric field is applied to each optical shutter 111 in the optical shutter array 100. The number of times is stored in the storage means 60, and when the number of times the electric field is applied becomes larger than a predetermined number in the optical shutter 111,
A signal is supplied from the storage unit 60 to the polarization state control unit 70 and the output signal control unit 80, and based on the signal, the solenoid 30 is operated by the polarization state control unit 70 to face the light modulation member 110. The first polarizing member 121 is switched to a second polarizing member 122 having a polarization angle phase difference of 90 °, and the output signal control means 80 is controlled.
To invert the image signal output from the image signal generating means 50.

Here, as described above, the output signal control means 8
When the image signal output from the image signal generating means 50 is inverted by 0, an electric field is not applied to the optical shutter 111 which allows light to pass through and writes an image, while the optical shutter 111 which does not allow light to pass therethrough. Is applied with an electric field.

Then, as described above, the first polarizing member 121 facing the light modulating member 110 has a polarization angle of 9 phase.
When the light is switched to the second polarizing member 122 which is different by 0 °, when the light is guided to the light modulating member 110 through the second polarizing member 122, the light is polarized in the portion of the optical shutter 111 where no electric field is applied. And the polarization angle of the third polarization member 123 is changed to the second polarization member 1.
Since the light has the same polarization angle as that of the light 22, the light passes through the third polarizing member 123, is focused on the image carrier 20 by the converging rod lens array 12, and is irradiated. On the other hand, in the portion of the optical shutter 111 to which the electric field is applied, the light passing through the second polarizing member 122 is polarized and the phase thereof is shifted by 90 °, and the light thus polarized is shifted to the third polarizing member 123. And an electrostatic latent image is formed on the image carrier 20 in the same state as before switching.

When an electrostatic latent image is formed on the image carrier 20 and an electric field is applied so as not to allow light to pass through the optical shutter 111 in a certain number of times in the optical shutter 111, the above-mentioned number is obtained. A signal is supplied from the storage means 60 to the polarization state control means 70 and the output signal control means 80, and based on this signal, switching is performed in the reverse of the above case to return to the original state. The light emitted from the cylinder lens 11 and condensed by the cylinder lens 11 is guided to the light modulation member 110 through the first polarizing member 121, and the light shutter 111 for writing the image by passing the light is provided in accordance with the image information. While the electric field based on the received signal is applied, no electric field is applied to the optical shutter 111 that does not allow light to pass.

In this way, a large number of electric fields do not act only on the optical shutter 111 which frequently transmits light, the frequency of the electric field acting on each optical shutter 111 is averaged, and a specific optical shutter 111 Only the characteristics are not changed, the variation in the amount of transmitted light passing through each optical shutter 111 is suppressed, stable writing can be performed on the image carrier 20, and a good image with less density unevenness can be stably obtained. become.

In the image writing apparatus of this embodiment, the output signal control means 80 inverts the image signal output from the image signal generating means 50 to the optical shutter driving means 40, and
Will be described with reference to the block circuit diagram of FIG.

First, the image data DATA is serially input to the shift register 51 in synchronization with the first clock signal CLOCK1, and the input image data DAT
A is latched by the latch circuit 52 by the latch signal LATCH.

The output terminals of the latch circuit 52 are connected to exclusive OR gates 53 ₁ , 53 ₂ , 53 ₂ , respectively.
, 53 _{n, and} the other input terminal of each exclusive OR gate 53 ₁ , 53 ₂ ,..., 53 _n is connected to a common line 54.
The second clock signal C from the output signal control means 80
LOCK2.

Here, when the second clock signal CLOCK2 is at the low level, the input sides of the exclusive OR gates 53 ₁ , 53 ₂ ,..., 53 _n connected to the common line 54 are at the low level, The image data DATA output from the latch circuit 52 is supplied to each of the exclusive OR gates 53 ₁ ,
53 _2, ..., it will be directly output to the output side of the 53 _n.

On the other hand, if the second clock signal CLOCK2 is high, common to each exclusive OR gates 53 ₁ connected to the line 54, 53 _2, ..., becomes the input side is high level 53 _n, a latch The image data DATA output from the circuit 52 is applied to each of the exclusive OR gates 53 ₁ , 5 3
3 _2, ..., it will be inverted and output from the output side of the 53 _n.

Then, when the drive signal CL is set to a high level, the image data DATA as input as described above is output.
Alternatively, the inverted image data DATA is output from the output side of each of the exclusive OR gates 53 ₁ , 53 ₂ ,..., 53 _n to the optical shutter driving means 40, and this signal is output from the optical shutter driving means 40. The light is output to the optical shutter array 100 through the lead wire 43 and
0, a predetermined voltage Vd is applied to the individual electrode 113 of the appropriate optical shutter 111,
Is applied with an electric field.

The storage means 60 is connected to each lead wire 43 of the optical shutter drive means 40, and the number of times the voltage Vd is applied to each optical shutter 111 through the lead wire 43 as described above is stored in this storage means. When the number of times the voltage Vd is applied and the electric field acts on the optical shutter 111 exceeds a predetermined number of times stored in the means 60, the storage state of the polarization state control means 70
And the output signal control means 80, and the second clock signal CLOCK2 supplied from the output signal control means 80 to the exclusive OR gates 53 ₁ , 53 ₂ ,..., 53 _n through the common line 54 as described above. Switch.

In the image writing apparatus according to this embodiment, as described above, the optical shutter array 100
The solenoid 30 is actuated by the polarization state control means 70 based on the number of times the electric field has acted on each optical shutter 111 in the above, and the first polarization member 121 and the second polarization member 122 facing the light modulation member 110 are switched. At the same time, the output signal control means 80 controls the image signal generation means 50.
Is inverted, but the timing of performing such control is not limited to the case described in the above embodiment.

For example, the above-described control can be performed in accordance with the image mode of an image to be written on the image carrier 20 by the image writing apparatus. Optical shutter 11 at
Since a large number of images are used, the above-described control can be performed by operating the polarization state control unit 70 and the output signal control unit 80 each time a predetermined number of images are formed.

Further, in the image writing apparatus of this embodiment, when the polarization state is switched by the polarization means 120 by the polarization state switching means 30, the phase of the polarization angle of the light modulation member 110 on the side irradiated with light is 90 °. While a different first polarizing member 121 and a different second polarizing member 122 are provided, a third polarized light having a 90 ° different polarization angle from that of the first polarizing member 121 is provided on the opposite side of the light modulating member 110. The member 123 is provided and the solenoid 30
Is operated to switch between the first polarizing member 121 and the second polarizing member 122 which face the light modulation member 110. The method of switching the polarization state by the polarization means 120 by the polarization state switching means 30 is as described above. The third polarization member 123 is not limited to the one having the same polarization angle as that of the first polarization member 121, or the third polarization member 123 may be provided with the third polarization member
It is also possible to provide the first polarizing member 121 and the second polarizing member 122 on the opposite side of the light modulation member 110.

Further, as shown in FIG.
A polarizing member 124 whose phase is changed by the action of an electric field is provided on one side of the optical member 10.
Is changed, and the polarization angle of the polarizing member 124 is changed to the third angle provided on the opposite side of the light modulating member 110.
It is also possible to make the polarization angle of the polarization member 123 the same or to make the phase of the polarization angle differ by 90 °.

[0039]

As described in detail above, in the image writing apparatus according to the present invention, the polarization state controlling means appropriately controls the frequency of use of the optical shutter in the optical shutter array and the image mode information of the image to be formed. At this time, the polarization state switching means is operated to switch the polarization state by the polarization means, and the output signal control means inverts the image signal output from the image signal generation means to the optical shutter driving means, so that light passes through. A large number of electric fields do not act only on the optical shutter that is frequently operated, the frequency of electric fields acting on each optical shutter is averaged, and only the characteristics of a specific optical shutter do not change. Variations in the amount of transmitted light are suppressed, and stable writing on the image carrier can be performed. No good image became stably obtained.

In the image writing apparatus according to the present invention, the polarization state switching means is operated by the polarization state control means as described above to switch the polarization state by the polarization means, and the image signal is generated by the output signal control means. Since only the image signal output from the means to the optical shutter driving means is inverted, as in the case where the optical shutter array is moved with time in the arrangement direction of the optical shutter,
When writing is performed by this image writing device without increasing the size of the device or requiring a mechanical device for moving the optical shutter array, which makes it difficult to accurately control the driving of the device. In this case, the control can be performed, and it is not necessary to temporarily stop the writing during the continuous writing.

[Brief description of the drawings]

FIG. 1 is a schematic explanatory view of an optical shutter.

FIG. 2 is a diagram showing that the relationship between the applied voltage applied to the optical shutter and the amount of transmitted light passing through the optical shutter changes with use of the optical shutter.

FIG. 3 is a schematic explanatory diagram of an image writing device according to the embodiment of the present invention.

FIG. 4 shows an image writing apparatus according to the embodiment.
FIG. 4 is a partial explanatory view showing a state in which an optical shutter driving unit is connected to an optical shutter in the optical shutter array.

FIG. 5 is a schematic explanatory diagram showing a configuration for driving the image writing device according to the embodiment.

FIG. 6 illustrates an image writing apparatus according to the embodiment.
FIG. 4 is a block circuit diagram showing an example of driving an optical shutter array by inverting an image signal output from an image signal generating unit to an optical shutter driving unit.

FIG. 7 shows an image writing apparatus according to the embodiment.
It is the schematic explanatory drawing of the example of change which changed the method of switching the polarization state by the polarization means by the polarization state switching means.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Light irradiation means (halogen lamp) 20 Image carrier 30 Polarization state switching means (solenoid) 40 Optical shutter drive means 50 Image signal generation means 60 Storage means 70 Polarization state control means 80 Output signal control means 100 Optical shutter array 110 Light modulation Member 111 Optical shutter 120 Polarizing means 121 First polarizing member 122 Second polarizing member 123 Third polarizing member 124 Polarizing member whose phase changes by the action of an electric field

Claims (4)

[Claims] 1. An optical shutter array in which an optical shutter composed of a light modulating member made of a material having an electro-optical effect and polarizing means arranged to sandwich the light modulating member is arranged. Light irradiating means for irradiating light to the shutter array, image signal generating means for outputting a signal corresponding to image information, and appropriate light in the optical shutter array based on the image signal output from the image signal generating means. An optical shutter driving unit for applying an electric field to the shutter, and an image writing device that irradiates the image carrier with light that has passed through the optical shutter in the optical shutter array and writes the image carrier according to image information. , A polarization state switching means for switching the polarization state by the polarization means, a polarization state control means for controlling the polarization state switching means, An image writing apparatus, comprising: output signal control means for inverting an image signal output from the image signal generation means to the optical shutter driving means in response to switching of the polarization state by the state control means. . 2. An image writing apparatus according to claim 1, wherein said polarization means includes first and second polarization members having polarization angles different by 90 ° on one side of said light modulation member. A third polarization member having the same polarization angle as one of the first and second polarization members on the opposite side of the light modulation member.
An image writing device, comprising: a polarizing member. 3. The image writing apparatus according to claim 1, further comprising a storage unit for storing a driving history of the optical shutter in the optical shutter array, based on the driving history of the optical shutter stored in the storage unit. An image writing apparatus, wherein the polarization state switching means is controlled by the polarization state control means. 4. An image writing apparatus according to claim 1, wherein said polarization state switching means controls said polarization state switching means based on image mode information of an image to be formed. Image writing device.