JPH02886A - Method for driving image forming device - Google Patents

Abstract

PURPOSE:To easily drive the image forming device under suitable conditions by detecting the potential attenuation of a photosensitive body due to transmitted light from an optical shutter and applying a driving voltage proper for the potential attenuation of the photosensitive body to the optical shutter according to the detected potential attenuation. CONSTITUTION:Light which is transmitted through an analyzer 6 is converged by a converging rod lens array 13 and the photosensitive body 15 which is charged electrostatically by an electrostatic charger 14 is irradiated with the light to attenuate the surface potential of the photosensitive body 15. The sur face potential of the photosensitive body 15 which is attenuated as mentioned above is measured by a surface electrometer 22 and the measured surface poten tial is converted by a transducer 23 into a voltage signal VS. Then the control part of a variable voltage power source 26 adjusts the driving voltage VD applied to the optical shutter 3 properly according to the output of the compara tor 25. Consequently, the image forming device is driven under the optimum conditions.

Description

Detailed Description of the Invention [Industrial Application Field] This invention guides light from a light source to an optical shutter array made of a material having an electro-optic effect such as PLZT, and selects appropriate light based on an image signal. Regarding the driving method of an image forming apparatus, which applies a driving voltage to the shutter to transmit light and form an electrostatic latent image on the photoreceptor, the optical shutter is This is to apply an appropriate driving voltage to the motor.

[Background of the Invention] In principle, an optical shutter made of a material having an electro-optic effect, such as PLZT, uses a light source (
The light emitted from 1) passes through the polarizer (2), which is the first polarizing plate.
), when a driving voltage is applied from the power source (5) to the electrodes (4) provided on both sides of this optical shutter (3), this optical shutter The light incident within (3) is polarized and transmitted through an analyzer (6) which is a second polarizing plate.

Utilizing the characteristics of such optical shutters, it has been considered to use an optical shutter array in an array as a writing device for an image forming apparatus. Usually, light from a light source is polarized. A driving voltage is applied to a suitable shutter based on the image signal, the guided light is polarized and transmitted through an analyzer plate, and this transmitted light forms an electrostatic latent image on the photoreceptor. I was trying to form it.

When forming an electrostatic latent image on the photoreceptor in this manner, it is preferable that the intensity of the transmitted light from the optical shutter is strong and that the transmitted light matches the spectral sensitivity of the photoreceptor.

Here, as a characteristic of the optical shutter, the intensity I of the transmitted light that passes through the optical shutter is expressed by the following formula [I] with respect to the intensity Io of the incident light guided to the optical shutter through the polarizer.

[In the formula, L is the optical path length, n is the refractive index, R is the constant number, E is the electric field strength, and λ is the wavelength of light. ] As shown in this formula [I], in the optical shutter, the transmitted light intensity ■
varies depending on the electric field strength E caused by the drive voltage, the wavelength λ of light, etc.

Therefore, in order to increase the transmitted light intensity I from the optical shutter, it is necessary to change the driving voltage in accordance with the wavelength λ of the light from the light source used.

Here, if a monochromatic light source that emits light of a single wavelength is used as the light source, the optimal driving voltage to be applied to the optical shutter can be uniquely determined. When using a white light source,
Since the wavelength range of the light emitted from the light source is wide, it is necessary to determine the optimal drive voltage in consideration of the amount of light at each wavelength.

Furthermore, even if the driving voltage is determined so that the transmitted light intensity I is maximized in this way, if the transmitted light does not match the spectral sensitivity of the photoreceptor, the photoreceptor may be exposed to light to generate static electricity. This does not mean that the optimal driving voltage has been determined for forming a latent image; in determining the optimal driving voltage, it was necessary to consider the conditions of incident light and transmitted light, the spectral sensitivity of the photoreceptor, etc. .

For this reason, it has been extremely difficult to drive the image forming apparatus by applying the optimum drive voltage to the optical shutter for exposing the photoreceptor to form an electrostatic latent image.

Here, a case will be described in which a halogen lamp and a xenon lamp are used as typical examples of white light sources.

First, we investigated the spectral energy distribution of light emitted from these light sources in a certain wavelength range for halogen lamps and xenon lamps, and the results shown in FIG. 2 were obtained.

In the same figure, ■ indicates a case using a halogen lamp with a distribution temperature of 3400, and ■ indicates a case using a xenon lamp with the maximum peak of spectral energy in the visible light region being 100%. showed that.

On the other hand, Fig. 3 shows three typical types of photoreceptors A, B, and C.
The spectral sensitivity characteristics are shown.

Here, the spectral energy distribution of light emitted from the halogen lamp and xenon lamp shown in Fig. 2 and the spectral sensitivity characteristics of the three typical types of photoreceptors A, B, and C shown in Fig. 3 are explained. When compared, they were not necessarily compatible.

Therefore, even if the driving voltage is set from the above formula [I] based on the wavelength at which the spectral energy distribution is maximum in these light sources, and this is not applied to the optical shutter, it will be difficult to expose these photoreceptors. It could not necessarily be said that it was suitable.

Therefore, for the above halogen lamp and xenon lamp, the wavelength λ of light in the above formula [I] is set to 650 nm,
The driving voltage was set to 550 nm and 450 nm, and a suitable driving voltage was determined for each case, and this was applied to the optical shutter, and the spectral energy distribution in a certain wavelength range of the light transmitted from the optical shutter was investigated for each case.

As a result, in those using halogen lamps, the fourth
The results shown in the figure were obtained using a xenon lamp, and the results shown in FIG. 5 were obtained. In these figures, ■ is 650nm, ■ is 550nm
The case where m and ■ are set to 450 nm is shown.

As an example, if we consider the case where a xenon lamp is used as a light source and the photoreceptor shown in B in Figure 3 is exposed, the spectral energy distribution as shown in The distribution is more suitable for the spectral sensitivity characteristics of the photoreceptor B. For this reason, in the above case, it is preferable to set the wavelength λ of the light to 650 nm and apply the determined driving voltage to the optical shutter. However, when using another photoconductor, the spectral sensitivity characteristics of that photoconductor are different from those of photoconductor B, so applying the drive voltage determined for photoconductor B to the optical shutter is difficult for that photoconductor. It could not be said that this method is necessarily preferable for exposing. Conversely, if the light source changes, even when photoreceptor B is used, it is not necessarily preferable to apply the drive voltage determined as above to the optical shutter in order to expose photoreceptor B. I couldn't say yes.

In this way, in the image forming apparatus as described above, in order to apply the optimum drive voltage to the optical shutter when exposing the photoreceptor to form an electrostatic latent image,
Each time, it is necessary to check the spectral energy distribution of the light source used, the spectral sensitivity characteristics of the photoreceptor, etc., and it is extremely difficult to drive the image forming apparatus under optimal conditions.

The present invention was made in view of the above circumstances, and it measures the state of light emitted from the light source used in the image forming apparatus, the spectral sensitivity of the photoreceptor, etc. each time, and determines an appropriate driving voltage. At the very least, always take these into account and apply a drive voltage suitable for forming an electrostatic latent image on the photoreceptor to the optical shutter, so that the image forming device is driven under optimal conditions. The purpose is to do so.

[Means for solving the problem] In the present invention, light from a light source is guided to an optical shutter array made of a material having an electro-optic effect, and a driving voltage is applied to appropriate optical shutters based on an image signal. When driving an image forming device that transmits light and forms an electrostatic latent image on a photoreceptor, it detects the attenuation of the photoreceptor's potential due to the light transmitted from the optical shutter, and based on this, , a driving voltage suitable for attenuating the potential of the photoreceptor is applied to the optical shutter.

[Function] When the image forming apparatus is driven in this way, the optical shutter always has the Taking these into consideration, a drive voltage suitable for attenuating the potential of the photoreceptor and forming an electrostatic latent image is applied.

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

First, the first embodiment of this invention is shown in FIGS. 6(A) and 6(B).
) to will be specifically explained based on FIG. 11.

The image processing device used in this example is as shown in FIG.
As shown in (B), the light emitted from the light source (1) and the light reflected from the reflecting mirror (1a) provided behind it are passed through the optical fiber (8) through the infrared absorption filter (7).
)", the light from this optical fiber (8) is focused by a rod lens (9), and this focused light is passed through a polarizer (
2) to illuminate the light shutter array (10).

Then, as shown in FIG. 7, an image signal generation circuit (11
), the optical shutter drive circuit (1
2) Apply a driving voltage to a more suitable optical shutter (3),
The light irradiated on this optical shutter (3) is polarized and transmitted through an analyzer (6), this light is focused by a focusing rod lens array (13), and this focused light is transferred to a charger ( 14) to form an electrostatic latent image on the charged photoreceptor (15).

After forming the electrostatic latent image on the photoreceptor (15) in this way, as shown in FIG.
Toner is attached to the electrostatic latent image area, and the photoreceptor (15)
After forming a toner image on the surface, this toner image is transferred to recording paper using a transfer charger (17) and a separation charge remover (18), while the toner remaining on the surface of the photoreceptor (15) is is removed by a cleaning member (19), and then the surface of the photoreceptor (15) is statically removed by a static eliminating lamp (20).

In this embodiment, as shown in FIG. 8, the optical shutter drive circuit (12)
), a monitoring optical shutter (3a) is provided at the end of the optical shutter array (10) outside the printing area, and the above-mentioned The light collected by the rod lens (9) is irradiated through the polarizer (2) as shown in FIG.

Next, an appropriate driving voltage is applied to this monitor light shutter (3a), the irradiated light is polarized in this monitor light shutter (3a), and the light attenuation filter (21) is polarized.
) to the analyzer (6). The light transmitted through the analyzer (6) is focused by a focusing rod lens array (13) and irradiated onto the photoreceptor (15) charged by the charger (14). 1
5) The surface potential was attenuated.

Then, the surface potential of the photoreceptor (15) attenuated in this way is measured with a surface electrometer (22), as shown in FIG.
to convert it into a voltage signal VS.

Next, in the comparator (25), this voltage signal Vs is applied to the photoreceptor (1) determined in the reference voltage generator (24).
7) Reference voltage ■ when sufficiently exposed. ■ When 5≦VO, the high level signal is
When s>Vo, a low level signal is output.

Based on the output from the comparator (25), the control section of the variable voltage power source (26) adjusts the drive voltage Vo applied to the optical shutter (3) to a suitable value.

Here, an example of drive voltage VD control executed in the control section of the variable voltage power supply (26) will be described based on the flowchart shown in FIG.

When the power is turned on, initial setting is performed in step 100 (S100), and in this initial setting, an increase flag is set to 1 in order to perform a process of increasing the drive voltage VD.

Then, in step 101 (SIOI), based on the signal output from the comparator (25),
V. If the output signal from the comparator (25) is low level and Vs>Vo, the process proceeds to step 102 (S102), while the output signal from the comparator (25) is high level. ■ When 5≦VQ, the surface potential of the photoreceptor (15) is sufficiently attenuated by the driving voltage VD, and the driving voltage VD is appropriate.
Returning to step 101 (SIOI), this process is repeated without changing the drive voltage VD.

Next, in step 102 (S102), it is determined whether the increase flag is 1, and the drive voltage is set to ■.

If the increase flag is set to 1 to perform the process of increasing the drive voltage VD, the process proceeds to step 103 (S103).The increase flag is set to 0 to perform the process of decreasing the drive voltage VD. If so, step 106
Proceed to (S106).

Then, in step 103 (S103), the drive voltage VD is increased by 0.1■, and then in step 104 (
In S104), it is determined whether the drive voltage VO has reached a preset upper limit value Vmax. As a result of this judgment, if the drive voltage VD has not reached the upper limit value V max, the process returns to step 101 (SIOI),
Unless it is determined in step 101 (SIOI) that Vs≦Vo and a suitable drive voltage ■o is obtained, the operations in steps 101 to 104 (8101 to 5104) are continued until the drive voltage VD reaches the upper limit value V max. Repeat.

On the other hand, if the drive voltage VO has reached the upper limit value V max, the process proceeds to the next step 105 (S105), the increase flag is set to 0, and the process of decreasing the drive voltage VD is performed.

Then, in step 106 (S106), the driving voltage VO is set to 0. IV is decreased, and in step 107 (S107), it is determined whether the drive voltage VD has reached a preset lower limit value V min. As a result of this judgment, the drive voltage VD reaches the lower limit value V min
If the SL has not been reached, step 101 (SL
OL), and in step 101 (Slot), V
Unless it is determined that s≦VO and a suitable drive voltage VO is obtained, steps 101, 102. 106.
The operation of step 107 (S101, 102, 106, 107) is repeated until the drive voltage VD reaches the lower limit value V min.

On the other hand, if the drive voltage VD has reached the lower limit value V win, the process proceeds to the next step 108 (S10g), sets the increase flag to 1, and performs the process of increasing the drive voltage VD. Step 101 (S101)
Return to

In this way, in the control section of the variable voltage power supply (26), the voltage signal Vs obtained by converting the surface potential measured by the surface electrometer (22) by the transducer (23) and the reference voltage generator (24) Determined appropriate reference voltage Vo
The drive voltage Vo is increased or decreased between the preset upper limit value V max and the lower limit value V min while comparing the values with the comparator (25), and the photoconductor (15 ) is adjusted to a suitable driving voltage Vo that can sufficiently attenuate the surface potential of the electrode.

The drive voltage V applied to the optical shutter (3) in this way
Once o is determined, the type of light source (1) used and the photoreceptor (
The photoconductor (15) can be used without examining the spectral sensitivity characteristics etc.
) to form an electrostatic latent image.
D, that is, a suitable drive voltage VD corresponding to the type of light source (1), the spectral sensitivity characteristics of the photoreceptor (15), etc. can be applied to the optical shutter (3).

In this embodiment, the light polarized by the monitoring optical shutter (3a) as described above is guided to the analyzer (6) through the optical attenuation filter (21). The photoreceptor (15) is exposed to the light transmitted through the photoreceptor (17), thereby reducing the amount of light guided to the photoreceptor (17).

This means that when exposing a photoreceptor, the relationship between the amount of exposure and the potential attenuation on the surface of the photoreceptor is as shown in FIG.
When the photoreceptor is sufficiently exposed, the exposure amount changes ΔE
Since the difference Δ■ in potential attenuation caused by This is to enable setting o.

Further, the relationship between the drive voltage VD applied to the optical shutter and the amount of potential attenuation on the surface of the photoreceptor is generally as shown in FIG. 11, where the drive voltage VD. In determining, it is more preferable to determine the amount of potential attenuation to be the maximum, but it is sufficient as long as it is within a certain range (d) in which potential attenuation is sufficient.

Next, based on FIGS. 12 and 13, the driving voltage VO
Another embodiment that controls the following will be described.

In this embodiment as well, as in the first embodiment, the photoreceptor (15) is
Light is irradiated onto the photoreceptor (15), and the surface potential of the photoreceptor (15) attenuated by this light irradiation is measured with a surface potentiometer <22), and the measured surface potential is converted into a voltage signal Vs by a transducer (23). It is supposed to be converted.

In this embodiment, the voltage signal Vs thus converted by the transducer (23) is input to a comparator (25) and a differentiator (27).

Then, in the comparator (25), as in the case of the first embodiment, this voltage signal (2) is applied to the reference voltage generator (25).
VS
When ≦Vo, a high level signal is sent, and when V s >
When it is Vo, a low level signal is output to the variable voltage power supply unit (26''').

On the other hand, the differentiator (27) differentiates the input voltage signal VS and outputs the result to the second comparator (<28). Then, this second comparator (2
In 8), based on the output from the differentiator (27),
It is determined whether the direction of change in the voltage signal Vs is increasing or decreasing, and the result is output to the variable voltage power supply unit (26').

Here, as shown in FIG. 13, the signal from the comparator (25) described above is input in negative logic to the AND gate (31) in the variable voltage power supply unit (26'), and this signal is If it is a high level signal indicating VO, the photoconductor (15) is driven by the driving voltage VD.
Since the surface potential of is sufficiently attenuated, the pulse signal from the pulse generator (30), which is always input with negative logic to this AND gate (31), is not input to the counter (32), and the drive voltage The VD is maintained in its original state without being changed.

On the other hand, when a low level signal indicating that V s > Vo is input from the comparator (25) in negative logic, the pulse generator (which is always input in negative logic to the AND gate (31)) The pulse signal from 30) is directly input to the counter (32), and the counter (32) starts counting.

The counter (32) also includes the second comparator (2).
8), the result indicating the direction of change in the voltage signal VS is input, and based on this input result, the counter (32) switches whether to count up or count down. As a result, it becomes possible to prevent the drive voltage VD from changing away from the appropriate value.

The count value counted by the counter (32) in this way is converted into an analog signal by the D/A converter (33), and this analog signal and the DC voltage power supply for bias (35) are output. The adder (34) controls the power supply (36) according to the added signal, and the optical shutter drive circuit (12)
) to adjust the input voltage.

[Effects of the Invention] As detailed above, in this invention, when light is transmitted through the optical shutter to form an electrostatic latent image on the photoreceptor, the potential attenuation of the photoreceptor due to the light transmitted through the optical shutter is reduced. Based on this, a drive voltage suitable for attenuating the potential of the photoreceptor is applied to the optical shutter, so the state of the light emitted from the light source used and the spectral sensitivity of the photoreceptor used are adjusted each time. It is now possible to easily apply a driving voltage suitable for forming an electrostatic latent image on a photoreceptor to an optical shutter without measuring it.

As a result, no matter what light source or photoreceptor is used, the image forming device can be easily operated under suitable conditions, and a stable electrostatic latent image can be formed on the photoreceptor. Ta.

[Brief explanation of the drawing]

Figure 1 is a diagram showing the driving state of the optical shutter, Figure 2 is a diagram showing the spectral energy distribution in a certain wavelength range of light emitted from a halogen lamp and a xenon lamp, and Figure 3 is a diagram showing the driving state of the optical shutter.
The figure shows the spectral sensitivity characteristics of three typical types of photoreceptors. Figures 4 and 5 show light from a halogen lamp and a xenon lamp transmitted by changing the driving voltage applied to the optical shutter. Figure 6 (A) is a diagram showing the spectral energy distribution in a certain wavelength range of these transmitted lights in the case of
, (B) is a plan view and a side view of the optical system portion of the image forming apparatus used in the first embodiment of the present invention, and FIG. 7 shows the state in which the driving voltage is controlled in the image forming apparatus of the same embodiment. 8 is a perspective view of the end of the optical shutter array of the same embodiment, and FIG. 9 is a flowchart showing an example of drive voltage control executed in the control section of the variable voltage power supply of the same embodiment. , FIG. 10 is a diagram showing the relationship between the exposure amount and the potential attenuation on the surface of the photoreceptor, FIG. 11 is a diagram showing the relationship between the driving voltage applied to the optical shutter and the amount of potential attenuation on the photoreceptor surface, and FIG. FIG. 12 is a schematic diagram showing a state in which driving voltage is controlled in an image forming apparatus of another embodiment, and FIG. 13 is a diagram showing the structure of a variable voltage power supply unit in the image forming apparatus of FIG. 12. (1)...Light source, (2)...Polarizer, (3)...
Optical shutter, (6)... Analyzer, (10)... Optical shutter array, (11)... Image signal generation circuit, (1
2)... Optical shutter drive circuit, (15)... Photoreceptor, (22)... Surface electrometer, (23)... Transducer, (24)... Reference voltage generator, ( 25)...
- Comparator, (26)...variable voltage power supply. Figure 2 Patent Applicant Minolta Camera Co., Ltd. Agent Patent Attorney Katsuaki Matsukawa Figure 3 Wavelength (nm) (nm) Figure 4 (nm) Wave Figure 5 Length (nm) (B) performance d

Claims (1)

[Claims] 1. Light from a light source is guided to an optical shutter array made of a material that has an electro-optic effect, and a driving voltage is applied to the appropriate optical shutter based on the image signal to transmit the light, creating an electrostatic latent on the photoreceptor. In an image forming apparatus that forms an image, potential attenuation of a photoreceptor due to light transmitted from an optical shutter is detected, and based on this, a drive voltage suitable for the potential attenuation of the photoreceptor is applied to the optical shutter. A method for driving an image forming apparatus, characterized by: