JP2000275872A - Characteristic evaluation apparatus for photoreceptor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To execute evaluation with high reliability by evaluating the sensitivity characteristic of a photoreceptor in the time of the same scale as the scale of a digital machine having a laser scan optical system. SOLUTION: An electrostatic charger 2, destaticizer 4, first surface electrometer 5 and second surface electrometer 6 arranged around the photoreceptor 1 are arbitrarily moved with respect to the electrophotoreceptor 1, by which the characteristics of the photoreceptor 1 are evaluated from the outside diameter of the electrophotoreceptor 1, the line speed of the photoreceptor, the resolution of a laser scan sub-scanning direction, electrostatic charge time, exposure time, the arrangement position information in the peripheral direction of the electrostatic charger 2 and the surface potentials of the photoreceptor 1 before and after exposure measured by the first surface electrometer 5 and the second surface electrometer 6.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus for evaluating the characteristics of a photosensitive member used in an electrophotographic copying machine or printer.

[0002]

2. Description of the Related Art Various methods have been adopted for evaluating the characteristics of a photoreceptor used in an electrophotographic system, especially for measuring the sensitivity characteristics, in a copying process. The first measurement method uses a photoconductor of 1000
r. p. m, the surface of the photoreceptor is charged for a predetermined time or until a predetermined surface potential is reached, and then the surface of the photoreceptor is irradiated with light for a predetermined time or a predetermined surface potential. Exposure to This is a dynamic measurement method in which the product of the time required for the photoconductor to attenuate a predetermined surface potential by this exposure and the illuminance, that is, the amount of exposure, is calculated, and the required amount of exposure is used as the sensitivity of the photoconductor.

[0003] The second measuring method is based on the Electrographic Society of Japan, 199
As shown in the electrophotographic society standard established on March 31, 2000, the dynamic measurement method standardized by the white light sensitivity measurement method, the photoreceptor was set to 100 r. p. m, the surface of the photoreceptor is charged under charging conditions adjusted to a predetermined surface potential in advance, and when the charged portion of the surface of the photoreceptor passes through the exposure section, it is determined in advance. After irradiating the slit light with the illuminance and passing through the exposure part, the surface potential of the photoreceptor is measured at a predetermined position or time, and a constant light intensity is set so that the measured surface potential value is the sensitivity of the photoreceptor. This is a method for measuring a change in surface potential when continuous exposure is performed with white light.

[0004] A third measuring method is as follows:
As shown in the electrophotographic society standard established on March 31, 2000, the static measurement method standardized by the white light sensitivity measurement method, the photoconductor was charged at 100 r. p. m, the surface of the photoreceptor is charged under charging conditions adjusted to a predetermined surface potential in advance, and the photoreceptor rotates when the charged portion of the photoreceptor surface comes to the exposure section. Stop, irradiate the light of the predetermined illuminance for the predetermined time,
The change in surface potential is measured by a light transmission surface potential meter, and the exposure amount required for a predetermined surface potential attenuation is defined as the sensitivity of the photoconductor.

[0005]

The above sensitivity evaluation methods are based on the fact that a tungsten lamp or a halogen lamp is used as a light source for light irradiation, and a mechanical shutter or an electromagnetic shutter is used for controlling irradiation time. Exposure time is generally 0.1 second or more in the first measurement method, 0.01 second or more in the second measurement method, and 0.
001 seconds or more, and there is a common problem that the time for exposing one point of the photoconductor cannot be shortened. Further, the intensity of light becomes 10 .mu.W / cm ² from 0.1μW / cm ^2. However, recently, digital copiers and printers using an electrophotographic process are mainly digital machines using laser scanning. In this digital machine, the exposure time of one point on the photoreceptor is usually several tens ns to about 100 ns, and the light intensity is often several tens W / cm ^2. This is a measurement condition of a possible area.

Further, in order to predict and evaluate the characteristics of the photoconductor in an actual copying machine or the like, it is necessary to evaluate the photoconductor on the same scale as the condition applied to the photoconductor in the actual copying machine or the like. The sensitivity of the photoconductor may be measured by a copying machine or the like that actually uses the photoconductor, but usually, the development of the photoconductor and the development of a copying machine in which the photoconductor is mounted are performed in parallel, and the development of the photoconductor is performed. In some cases, a copying machine or the like that can be used stably as a measuring device cannot be prepared, and it is often difficult to evaluate a photoconductor using a copying machine or the like actually mounted.

Further, even if it is attempted to evaluate the sensitivity of the photoreceptor using a copying machine or the like that actually uses the photoreceptor, the operating conditions such as the size of the photoreceptor, the arrangement of the processing apparatus, the linear velocity, and the process timing are not sufficient. Since it is uniquely determined and cannot be changed, there is a problem that every time the drum diameter or drum length of the photoconductor changes, it is necessary to prepare a copying machine or the like in accordance with the change.

The present invention solves such a problem, and can evaluate the sensitivity characteristics of a photosensitive member in the same scale of time as a digital machine having a laser scanning optical system, and has a high degree of freedom without relying on a specific digital machine and has high reliability. It is an object of the present invention to provide a digital photoreceptor characteristic evaluation apparatus capable of performing high-quality evaluation.

[0009]

An apparatus for evaluating characteristics of a photoreceptor according to the present invention includes a charging device, an exposure device, and a static eliminator which are sequentially arranged around a photoreceptor to be inspected. A first surface voltmeter is disposed between the exposure device, a second surface voltmeter is disposed between the exposure device and the static eliminator, the photoconductor is rotatably held, and the charging device, the static eliminator and the first The surface voltmeter and the second surface voltmeter are mounted on a common frame so that they can move in the circumferential direction, the radial direction, and the longitudinal direction of the photoreceptor, and the exposure device comprises a laser writing device. The second surface voltmeter is provided with a maximum degree of freedom in the circumferential movable range, and is provided so as to be movable in the direction and the longitudinal direction, continuously illuminating the laser light emitting device and continuously exposing the photosensitive member. Devices placed around the body give maximum freedom The on / off control is performed based on the outer diameter of the photoconductor, the linear velocity of the photoconductor, the resolution in the laser scanning sub-scanning direction, the charging time, the exposure time, and the arrangement position information of the device arranged around the photoconductor. Surface electrometer and the second
The characteristics of the photoconductor are evaluated and analyzed based on the surface potential of the photoconductor before and after exposure measured by the surface voltmeter and information on the arrangement position of each device.

A light attenuating filter is provided between the laser light emitting device of the exposure apparatus and the polygon mirror, and the transmittance T (%) of the light attenuating filter with respect to the wavelength of the laser beam is determined by the drive current of the exposure power of the laser light emitting device. The maximum exposure power in the adjustment range is Pmax, and the minimum exposure power is P
When n is a positive integer, T ≧ ｛(Pm
(in / Pmax) × n (100) (%). The light attenuating filter is preferably made of colored glass as a substrate. Further, it is preferable to provide a plurality of optical attenuation filters having the transmittance T of n = 1.

It is preferable that the surface potential before and after the exposure is repeatedly measured while changing the exposure power of the exposure apparatus, and then the same measurement is repeated by changing the light attenuating filter.

Further, the surface potential of the photosensitive member may be measured a plurality of times by changing the number of light attenuating filters according to the exposure power while varying the exposure power of the exposure apparatus.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An apparatus for evaluating characteristics of a photoreceptor according to the present invention has a charging device, an exposing device, and a static eliminator disposed around a photoreceptor to be inspected. , A first surface voltmeter is disposed between the exposure device and the static eliminator. The photoreceptor is held rotatably. The charging device and the static eliminator, and the first surface voltmeter and the second surface voltmeter are mounted on a common base so as to be movable in the circumferential direction, the radial direction and the longitudinal direction of the photoconductor. The exposure device comprises a laser writing device,
It is movable in the radial direction and the longitudinal direction of the photoconductor, and is positioned in the radial direction of the photoconductor so as to be spaced by the focal length of the surface of the photoconductor and the fθ lens of the laser writing system.

When the evaluation of the photoreceptor is started, the surface of the photoreceptor is neutralized by the static eliminator while the polygon mirror of the exposure device is rotated and the photoreceptor is rotated at a constant rotation speed, and the surface of the photoreceptor is charged by the charging device. Is charged so as to have a predetermined surface potential, and the charged photoconductor is irradiated with laser light by an exposure device. The surface potential of the photoconductor when charged is measured with a first surface voltmeter, and the surface potential of the photoconductor after exposure is measured with a second surface electrometer.
Potential decay from the outer diameter and linear velocity of the photoconductor, resolution in the laser scanning sub-scanning direction, charging time, exposure time, the arrangement position of the charging device in the circumferential direction, and the measured surface potential of the photoconductor. Is calculated, and the relationship between the calculated exposure amount and the measured potential after exposure or the amount of change in potential before and after exposure is defined as the sensitivity of the photoreceptor. This process is repeated a predetermined number of times by changing the exposure power applied to the photoconductor.

[0015]

FIG. 1 is a block diagram of one embodiment of the present invention.
As shown in the figure, the device for evaluating the characteristics of a photoreceptor includes a charging device 2, an exposing device 3, and a static eliminator 4 around a photoreceptor 1, and a first surface potential between the charging device 2 and the exposing device 3. 5 in total
Are arranged, and a second surface voltmeter 6 is arranged between the exposure device 3 and the static elimination device 4. The photoconductor 1 is rotatably held by a drive mechanism. The charging device 2, the static eliminator 4, and the first surface voltmeter 5 and the second surface voltmeter 6
Are mounted on a common gantry so as to be movable in a circumferential direction, a radial direction, and a longitudinal direction. The exposure device 3 is composed of a laser writing device, and can be moved in the radial direction and the longitudinal direction of the photoreceptor 1. In the radial direction of the photoreceptor 1, an interval is set between the surface of the photoreceptor 1 and the focal length of the fθ lens of the laser writing system. It is decided to be taken.

The focal length f1 of the fθ lens of the laser writing system of the exposure device 3 is close to the focal length f2 of the fθ lens of the laser scan writing system of an actual copying machine or the like (hereinafter referred to as an actual machine). For example, the ratio f2 / f to the focal length f2 of the fθ lens of the laser scan writing system of the actual machine
1 is "1", preferably in the range of 0.75 to 1.33. This is for minimizing the difference between the exposure time of one rotation on the photoconductor 1 and the actual machine.

As shown in the block diagram of FIG. 2, the control unit of the characteristic evaluation device includes an input unit 8, a controller 9, an evaluation unit 10, and an output unit 11. The input unit 8 includes an outer diameter of the photoconductor 1, a linear velocity of the photoconductor 1, a resolution of the exposure device 3 in a laser scanning sub-scanning direction, a charging time by the charging device 2, a laser exposure time of the exposure device 3, Charging device 2 and static eliminator 4
And photoreceptor 1 of first surface voltmeter 5 and second surface voltmeter 6
Is input in the circumferential direction. The controller 9 controls the photosensitive member 1 based on various information input from the input unit 8.
, And controls the operations of the charging device 2, the exposure device 3, and the static elimination device 4, and various information input from the input unit 8 and the photosensitive information input from the first surface voltmeter 5 and the second surface voltmeter 6. The surface potential of the body 1 is sent to the evaluation unit 10. Evaluation unit 1
0 evaluates the transmitted various information, the surface potential of the photoconductor 1 and the exposure amount as the sensitivity of the photoconductor 1, and outputs the evaluation information to a display device or a printer via the output unit 11.

When measuring the sensitivity of the photoreceptor 1 in the characteristic evaluation apparatus constructed as described above, as shown in the time chart of FIG. 3, the polygon mirror of the exposure apparatus 3 is rotated and the photoreceptor 1 is kept constant. The surface of the photoconductor 1 is neutralized by the static eliminator 4 while being rotated at the rotation speed, and the surface of the photoconductor 1 is charged by the charging device 2 so as to have a predetermined surface potential. In step 3, laser light is applied. The surface potential of the photoconductor 1 when charged is measured by a first surface voltmeter 5, the surface potential of the photoconductor 1 after exposure is measured by a second surface voltmeter 6, and the outer diameter of the photoconductor 1 is measured. And photoconductor 1
From the linear velocity of the laser, the resolution in the laser scanning sub-scanning direction, the charging time, the exposure time, the arrangement position of the charging device in the circumferential direction, and the measured surface potential of the photoreceptor 1, the amount of exposure (energy reached) required for the potential attenuation is calculated. The relationship between the calculated exposure amount and the measured potential after exposure or the amount of change in potential before and after exposure is defined as the sensitivity of the photoconductor. This process is repeated a predetermined number of times by changing the exposure power applied to the photoconductor.

The focal length f1 of the fθ lens of the laser writing system of the exposing device 3 for exposing the photosensitive member 1 is determined by the fθ lens of the laser scan writing system of a copying machine or the like actually used (hereinafter referred to as an actual machine). One close to the focal length f2, for example,
The ratio f2 / f1 to the focal length f2 of the fθ lens of the laser scan writing system of the actual machine is “1”, preferably 0.7
It is in the range of 5 to 1.33. By setting the range of the focal length f1 of the fθ lens of the laser writing system of the exposure device 3 in this manner, exposure can be performed in the same manner as in a real machine without using a real machine. That is, the exposure apparatus 3
When trying to reproduce the conditions of a specific real machine with
The linear velocity (mm / s) of the photoconductor 1 and the sub-scanning direction resolution (DP)
Even if I) is the same, fθ of the laser writing system of the exposure apparatus 3
If the focal length of the lens is different, the scanning speed of the photoconductor 1 in the main scanning direction is different, and even if the number of laser writing system polygon mirrors and the laser beam diameter are the same, one point on the surface of the photoconductor 1 The time during which the camera is exposed changes by the ratio of the difference in focal length. The time during which one point on the surface of the photoreceptor 1 is exposed is obtained by (laser beam diameter in main scanning direction / laser scanning speed). If the time during which one point on the photoconductor 1 is exposed is t1 and the time during which one point on the photoconductor is exposed in the actual machine is t2, the following relationship exists between the two. t1 = (φ1 / φ2) · (f2 / f1) · (N1 / N
2) · t2 Here, the suffix 1 is the exposure device 3 of the characteristic evaluation device,
Suffix 2 represents the actual machine, φ represents the laser beam diameter (main scanning direction), f represents the focal length of the fθ lens, and N represents the number of surfaces of the polygon mirror.

Since almost the same laser beam diameter is often used in many real machines, many actual machines can be simulated by using a general laser beam diameter in the exposure apparatus 3. become. To match an actual machine with a small laser beam diameter, an aperture can be attached to the laser device to make the laser beam diameter of the same size.
And the above equation is t1 ≒ (f2 / f1) ·
(N1 / N2) · t2. In many cases, six or eight polygon mirrors are used. Therefore, when six surfaces are used in the exposure apparatus 3, the exposure time when the actual machine has six surfaces is different from the focal length of the fθ lens. Determined by the ratio. When eight surfaces are used in the actual machine, the exposure time t1 of the exposure device 3 is t1 = (6/8) · (f2 / f1) · t2. At this time, the ratio f2 / f1 of the focal length f2 of the real machine to the focal length f1 of the fθ lens of the exposure device 3 is represented by f2
F of the exposure apparatus 3 so that /f1=(1-1.33)
If the focal length f1 of the θ lens is small, the exposure device 3
Can be set to t1 = (0.75 to 1) t2. Similarly, when the exposure apparatus 3 employs an eight-sided polygon mirror and the actual machine has six sides, the exposure time t1 of the exposure apparatus 3 is t1 = (8/6). (F2 / f).
1) t2. Therefore, the ratio f2 / of the focal length f2 of the real machine to the focal length f1 of the fθ lens of the exposure device 3
If the focal length f1 of the fθ lens of the exposure apparatus 3 is set to be large so that f1 is f2 / f1 = (0.75 to 1), the exposure time t1 of the exposure apparatus 3 can be reduced by the actual machine. For the exposure time t2, t1 = (1-1.33) t2
When the actual machine has eight surfaces, the exposure device 3
And the difference in the exposure time of the actual machine can be made the difference (0.75 to 1) of only the focal length, so that the sensitivity of the photoconductor 1 can be increased without using the actual machine, as in the case of using the actual machine. Can be measured.

In order to evaluate the sensitivity characteristics of the photoreceptor 1,
It is necessary to accurately evaluate the exposure energy that has reached the photoconductor 1. For this reason, it is preferable that the laser beam irradiation of the exposure apparatus 3 is performed in a laser device continuous lighting state. This means that the laser light is turned on / off at a high speed in the order of MHz like a real machine.
When the switch is turned off, the exposure output which is originally rectangular becomes larger than the actual light output as shown in the waveform diagram of FIG. 4, so that the exposure energy which has reached the photoconductor 1 can be accurately grasped. It is because it disappears. Here, the exposure energy E arriving at the photoreceptor 1 is P _{0 for} laser stationary power, ER for the effective scanning period ratio, L for the effective scanning image width, V for the linear velocity of the photoreceptor 1, and f for the focal length of the fθ lens. If the number of surfaces of the polygon mirror is N, then E = P ₀ ER / (LV) = P ₀ (4fπ / N).

A charging device 2 provided around the photosensitive member 1
When the surface potential with respect to the exposure energy E is measured, the surface potential data obtained differs depending on the position where the second surface voltmeter 6 is installed when the exposure device 3 and the static eliminator 4 are fixedly arranged at one place. In general, the position where the second surface electrometer 6 is installed is incomplete at one location as measured data. For this reason, the range in which the position of the second surface voltmeter 6 corresponding to the developing unit is variable in the circumferential direction of the drum is set sufficiently large.

[Specific Example] The results of measuring the sensitivity of the photoconductor 1 by changing the rotation speed of the photoconductor 1 having different drum diameters and drum lengths are shown. The charging device 2 uses a scorotron method, can apply a grid voltage up to ± 1500 V, and uses a main high-voltage power supply having a maximum voltage of ± 10 KV. The exposure apparatus 3 and the static eliminator 4 used were those under the following conditions (1) and (2). (1) Exposure device 3 LD scanning method Light source wavelength 780 nm fθ lens Focal length: 251 mm Main scanning beam diameter 68.5 μm Sub scanning beam diameter 81.5 Light intensity (image surface static power) 0.833 to 3.3 mW (no filter) Writing width 60mm Lighting frequency Continuous lighting only Polygon mirror surface number 6 Polygon rotation speed 6,000-40,000r. p. m. Rotation variable Polygon rotation stabilization time 5 s (2) Static eliminator 4 LED light source around 660 nm Light amount Max1060 μW / cm2 (light amount variable) Exposure width Width of about 2 mm above the photoconductor (distance from the photoconductor surface 2 mm)

The variable range of the position of the second surface voltmeter 6 is as follows: when the drum diameter of the photoconductor 1 is 24 mm, the angle is 20 to 130 degrees from the exposure position of the exposure device 3; When the distance is 60 mm, the angle is 20 to 145 degrees from the exposure position of the exposure device 3, and the drum diameter of the photoconductor 1 is 120 mm.
In this case, the angle is 20 to 150 degrees from the exposure position of the exposure apparatus 3.
Degree.

[Specific Example 1] The positions of the charging device 2, the exposing device 3, the discharging device 4, the first surface voltmeter 5 and the second surface voltmeter 6 were set under the following condition 1, and the drum diameter was 24 mm.
While rotating the photoconductor 1 at a linear speed of 38 mm / s, the surface potential of the photoconductor 1 was measured. Here, the positions of the charging device 2, the exposure device 3, the static eliminator 4, the first surface voltmeter 5 and the second surface voltmeter 6 are such that the clockwise direction is “+” with respect to the exposure position of the exposure device 3, The counterclockwise direction was expressed as an angle with "-". [Condition 1] Resolution in the sub-scanning direction (DPI) 600 Image plane stationary power (mW) 0.266 Paper feed size (mm) 210 Repetition interval (ms) 500 Static eliminator -180 degrees Charger -90 degrees First surface potential Total -20 degrees Exposure device 0 degrees Second surface voltmeter +55 Charging grid bias (V) -750

As a result, the surface potential of the photosensitive member 1 measured by the first surface voltmeter 5 was -750 V, the surface potential of the photosensitive member 1 measured by the second surface voltmeter 6 was -81 V, Exposure energy E is 21.05 (erg / cm ² )
Met.

[Specific Example 2] Next, the drum diameter is 60 mm.
The position of the second surface voltmeter 6 was changed using the photoreceptor 1 described above, and after the laser exposure by the exposure device 3, the measurement position dependency of the surface potential, that is, the time dependency from exposure to potential measurement was examined.

[Specific Example 2-1] Linear velocity (mm / s) 180 Sub-scanning direction resolution (DPI) 400 Image plane stationary power (mW) 0.36 Paper feed size (mm) 210 Repetition interval (ms) 500 Static electricity removal Device -160 degrees Charging device -80 degrees First electrometer -40 degrees Exposure device 0 degree Second surface electrometer +20 degrees Charging grid bias (V) -950

In this case, the surface potential of the photosensitive member 1 measured by the first surface voltmeter 5 is -950 V, the surface potential of the photosensitive member 1 measured by the second surface voltmeter 6 is -150 V, The exposure energy E was 3.8 (erg / cm ² ).

[Specific Example 2-2] Linear velocity (mm / s) 180 Sub-scanning direction resolution (DPI) 400 Image plane stationary power (mW) 0.36 Paper feed size (mm) 210 Repetition interval (ms) 500 Static electricity removal Device -160 degrees Charging device -80 degrees First surface voltmeter -40 degrees Exposure device 0 degree Second surface voltmeter +40 degrees Charging grid bias (V) -950

In this case, the surface potential of the photosensitive member 1 measured by the first surface voltmeter 5 is -950 V, the surface potential of the photosensitive member 1 measured by the second surface voltmeter 6 is -125 V, The exposure energy E was 3.8 (erg / cm ² ).

[Specific Example 2-3] Linear speed (mm / s) 180 Sub-scanning direction resolution (DPI) 400 Image plane stationary power (mW) 0.36 Paper feed size (mm) 210 Repetition interval (ms) 500 Static electricity removal Device -160 degrees Charging device -80 degrees First surface voltmeter -40 degrees Exposure device 0 degree Second surface voltmeter +120 degrees Charging grid bias (V) -950

In this case, the surface potential of the photosensitive member 1 measured by the first surface voltmeter 5 is -950 V, the surface potential of the photosensitive member 1 measured by the second surface voltmeter 6 is -121 V, The exposure energy E was 3.8 (erg / cm ² ).

As a result of the measurement in the specific examples 2-1 to 2-3, the surface potential VL (V) of the photosensitive member 1 with respect to the elapsed time (s) after exposure (surface potential measurement position after exposure) is shown in FIG. As shown in FIG. 7, it is apparent that the time depends on the time until the potential measurement after the exposure.

[Specific Example 3] Next, the drum diameter is 80 m.
Using the photosensitive member 1 of m, the surface potential after laser exposure was examined by the exposure device 3 under the following conditions. [Conditions] Linear velocity (mm / s) 105 Sub-scanning direction resolution (DPI) 400 Image plane stationary power (mW) 0.687 Paper feed size (mm) 210 Repetition interval (ms) 500 Static eliminator-160 degree charging device- 80 degrees First surface voltmeter -40 degrees Exposure device 0 degree Second surface voltmeter +55 degrees Charging grid bias (V) -670

In this case, the surface potential of the photosensitive member 1 measured by the first surface voltmeter 5 is -670 V, the surface potential of the photosensitive member 1 measured by the second surface voltmeter 6 is -108 V, Exposure energy E is 12.43 (erg / cm ² )
Met.

As shown in the specific examples 1 to 3, it is possible to easily measure the change in the surface potential when various types of photosensitive members 1 having different sizes are exposed to laser light. As shown, different surface potentials can be measured according to the potential measurement position after exposure, and the surface potential is measured in the same arrangement as various actual machines by changing the measurement range of the second surface voltmeter 6. And a measurement result equivalent to that obtained by using an actual machine can be obtained with high accuracy.

As described above, in order for one characteristic evaluation device to correspond to the exposure power of various actual machines, the exposure device 3
It is necessary to adjust the drive current of the laser diode (LD). In a laser writing device, in order to stably operate the light emission of the LD, the adjustment range of the drive current is often optimized and the adjustment range is narrow. In order to evaluate the sensitivity of the photoreceptor 1, it is necessary to obtain surface potential data for various exposure energies E. Since the potential range is from 1500 V to 50 V, an adjustment range corresponding to the exposure power can be obtained. You need to do that. Therefore, in order to increase the adjustment range of the exposure device 3, a filter having a spectral transmittance corresponding to the wavelength of the laser is combined. In order to increase the exposure power adjustment range, it is only necessary to prepare a filter with a further reduced spectral transmittance or to combine a plurality of filters with one type of spectral transmittance. The transmittance T (%) with respect to the wavelength of this filter is as follows: When the maximum exposure power in the drive current adjustment range of a normal LD device is Pmax, and the minimum exposure power is Pmin, n is a positive integer. {(Pmin / Pmax) nth power} × 100
By setting (%), a continuous exposure adjustment range can be obtained, and data of the surface potential with respect to the exposure power can be measured for the various photoconductors 1 without fail. Here, when combining a plurality of filters having the same spectral transmittance, it is preferable that n = 1 in the above equation.

For example, the maximum value Pmax of the image-surface exposure power without the filter of the exposure device 3 is 3.32 mW, the minimum value Pmin is 0.833 mW, and (Pmin / Pma
x) × 100 (%) = 25.1 (%), L
Three filters having a spectral transmittance of 27% for the wavelength 780 nm of D were prepared, and one to three filters were installed between the LD device and the polygon mirror, and the result of measuring the exposure power (mW) on the image plane was obtained. It is shown in the table below.

[0040]

[Table 1]

As shown in the above table, the range of the exposure power that can be set by the exposure apparatus 3 could be widened without any break. This means that the spectral transmittance is 27%, 7.3.
The same is true even when the measurement is performed while changing the% and 2% filters.

As a filter for reducing transmitted light, an absorption type ND filter in which a light absorbing material is thin-film deposited on a white glass substrate or quartz glass as a substrate or a reflection type in which a light reflecting material is thin-film deposited is used as a substrate. There is an ND filter. In addition to these, there is an ND filter using colored glass containing a substance that absorbs light in its components. Exposure device 3
It is preferable to use an ND filter made of colored glass as the fill used for the above. That is, a filter in which a thin film is deposited on a glass surface is an absorption type or a reflection type,
Reflected light that cannot be ignored on the surface of the thin film returns to the LD, causing light interference and a stable amount of light cannot be obtained.
The ND filter using the color glass can obtain a stable light amount without this phenomenon.

For example, using a thin film absorption type ND filter having a transmittance of 25% using a white glass substrate and an ND filter using color glass, the maximum value P of the image plane exposure power is used.
The drive current is set so that max becomes 3.32 mW, and L
Place a filter between the D device and the polygon mirror, LD
After turning on, the change of the image surface exposure power for 3 minutes was examined with a light meter. Here, the monitor current of the LD device was measured at the same time, but there was no fluctuation and there was no problem on the LD device side. The change in the measured image plane exposure power decreased linearly with a change of -8.7% when the ND filter of the thin film absorption type was used, but when the ND filter using the colored glass was used, The change was + 0.1%, and a stable light amount could be obtained.

As shown in the time chart of FIG. 3, the charging, exposure, and potential measurement of the photosensitive member 1 are repeated a plurality of times as one step. Is controlled within the adjustment range (exposing power is changed), and the next step is executed. This is repeatedly performed while changing the LD drive current at a predetermined level. When this processing is completed, the filter is mounted between the LD device and the polygon mirror, and the above processing is repeated. By repeating this process, the data of the surface potential with respect to the exposure energy can be automatically collected, and the sensitivity characteristics of the photoconductor 1 can be measured efficiently. FIG. 6 shows the change in the surface potential of the photoconductor 1 measured using one to three filters while changing the exposure power. In FIG. 6, rhombic marks indicate the case where the measurement was performed in this example, and square marks indicate the case where the measurement was performed by the conventional static measurement method for comparison. The photoconductor 1 used for the evaluation had an exposure power of 4.5 (erg / cm) in a real machine.
² ), the surface potential of the photosensitive member 1 after the exposure is -120 V
From -140 V, it is clear that the sensitivity of the photoconductor in the actual machine is well predicted in the case of this embodiment.

[0045]

As described above, according to the present invention, an exposing device and a static eliminator including a charging device and a laser writing device are arranged around a photoreceptor to be inspected, and a charging device and an exposing device are disposed between the charging device and the exposing device. A first surface voltmeter is disposed, a second surface voltmeter is disposed between the exposure device and the static eliminator, and the charging device and the static eliminator, and the first surface voltmeter and the second surface voltmeter are a photoconductor. The exposure device can be moved in the radial and longitudinal directions of the photoreceptor so that each device disposed around the photoreceptor can be moved arbitrarily with respect to the photoreceptor. It can be moved, and the characteristics of photoreceptors of various sizes can be measured.

The outer diameter of the photosensitive member and the linear velocity of the photosensitive member, the resolution in the laser scanning sub-scanning direction, the charging time, the exposure time, the positional information of the charging device in the circumferential direction, the first surface voltmeter and the second The characteristics of the photoreceptor are evaluated based on the surface potential of the photoreceptor before and after the exposure measured by the surface voltmeter, so that the evaluation according to various actual machines can be performed with high accuracy.

Further, since the laser light emitting device is continuously turned on by the exposure apparatus, the evaluation of the exposure energy can be accurately performed.
Evaluation accuracy can be improved.

Further, a light attenuating filter is provided between the laser light emitting device of the exposure apparatus and the polygon mirror, and the transmittance T (%) of the light attenuating filter with respect to the wavelength of the laser light is set to the maximum value and the minimum value of the laser light emitting device. By determining the exposure power according to the exposure power, it is possible to broaden the applicable range of applicable real machines and photoconductors.

Further, since the light attenuating filter is made of colored glass as a substrate, the image surface exposure power during measurement can be secured stably, and the evaluation accuracy can be secured stably.

Further, by sequentially switching the light attenuating filters having different transmittances or by providing a plurality of light attenuating filters, the image surface exposure power during the measurement can be adjusted over a wide range without any interruption.

Further, the surface potential of the photosensitive member is changed while changing the LD drive current of the exposure apparatus by changing the number of light attenuating filters or the type of the light attenuating filter in accordance with the required exposure power. By measuring, all necessary data of exposure energy and surface potential can be obtained,
Stable evaluation can be performed.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of an embodiment of the present invention.

FIG. 2 is a block diagram showing a configuration of a control unit of the embodiment.

FIG. 3 is a time chart showing a measurement operation of the embodiment.

FIG. 4 is a waveform diagram showing a laser waveform of an actual machine.

FIG. 5 is a graph showing a change characteristic of a surface potential of a photoconductor after exposure.

FIG. 6 is a graph showing a change characteristic of a surface potential of a photoconductor with respect to exposure energy.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 photoconductor 2 charging device 3 exposure device 4 static elimination device 5 first surface voltmeter 6 second surface voltmeter 7 control unit 8 input unit 9 controller 10 evaluation unit 11 output unit

Claims (6)

[Claims] A first surface voltmeter disposed between the charging device and the exposure device, wherein the first surface voltmeter is disposed between the charging device and the exposure device; A second surface voltmeter is disposed between the device and the static eliminator, the photoconductor is rotatably held, and the charging device and the static eliminator and the first surface voltmeter and the second surface voltmeter are arranged around the photoconductor. It is mounted on a common frame so that it can move in the direction, the radial direction, and the longitudinal direction, and the exposure device is composed of a laser writing device, is provided movably in the radial direction and the longitudinal direction of the photoconductor, and continuously connects the laser emitting device. Lights to scan and expose the photoreceptor. The second surface voltmeter has the maximum degree of freedom in the circumferential movable range, and the devices arranged around the photoreceptor have the maximum degree of freedom. The outer diameter of the photoconductor, the linear velocity of the photoconductor, and laser scanning Scanning direction resolution, charging time,
On / off control based on the exposure time and the arrangement position information of the devices arranged around the photoconductor, the surface potential of the photoconductor before and after exposure measured by the first surface voltmeter and the second surface voltmeter, and each device A characteristic evaluation apparatus for a photoreceptor, wherein the characteristic of the photoreceptor is evaluated and analyzed from the arrangement position information of the photoreceptor. 2. A light attenuating filter is provided between a laser light emitting device of the exposure apparatus and a polygon mirror, and a transmittance T (%) of the light attenuating filter with respect to a wavelength of laser light.
Is defined as T ≧ T, where Pmax is the maximum exposure power and Pmin is the minimum exposure power in the drive current adjustment range of the exposure power of the laser light emitting device, where n is a positive integer.
The photoconductor characteristic evaluation apparatus according to claim 1, wherein {(Pmin / Pmax) nth power} x 100 (%). 3. An apparatus according to claim 2, wherein said light attenuating filter is made of a colored glass substrate. 4. An apparatus according to claim 3, wherein a plurality of filters for light attenuation having a transmittance T of n = 1 are provided. 5. The characteristic evaluation of the photoreceptor according to claim 2, wherein the surface potential before and after the exposure is repeatedly measured while changing the exposure power of the exposure apparatus, and then the same measurement is repeated by changing a light attenuation filter. apparatus. 6. The characteristic evaluation of a photoconductor according to claim 4, wherein the surface potential of the photoconductor is measured a plurality of times by changing the number of light attenuating filters according to the exposure power while varying the exposure power of the exposure apparatus. apparatus.