JP5333994B2 - Device for evaluating characteristics of electrophotographic photosensitive member - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a characteristic evaluation device for evaluating the temperature characteristics of a photoreceptor at low cost with high accuracy, while keeping versatility, concerning a photoreceptor characteristic evaluation device. <P>SOLUTION: In the photoreceptor characteristic evaluation device, a charging device, an exposure device, a surface potential detecting device and a destaticizer are arranged around the photoreceptor. The photoreceptor characteristic evaluation device includes a heating device heating the photoreceptor, a controller controlling the output of the heating device, and a temperature sensor measuring the surface temperature of the photoreceptor and is configured so that the heating device and the temperature sensor can be moved in the axial direction of the photoreceptor and the centers in the axial direction of the photoreceptor of the charging device, the exposure device, the surface potential detecting device and the destaticizer coincide with each other. An area occupied by each of the charging device, the exposure device, the surface potential detecting device and the destaticizer in the axial direction of the photoreceptor is within an area occupied by the heating device in the axial direction of the photoreceptor. The relation of the length L1 in the axial direction of the heating area of the heating device, the total length L of the photoreceptor, and the length L2 in the axial direction of the charging area of the charging device is L2&le;L1&lt;L. <P>COPYRIGHT: (C)2011,JPO&amp;INPIT

Description

  The present invention relates to an apparatus for evaluating characteristics of an electrophotographic photosensitive member used in an image forming apparatus such as a laser printer or a copying machine.

  An electrophotographic photosensitive member (hereinafter, also referred to as “photosensitive member” or “electrostatic latent image carrier”) is the most important component in an image forming apparatus using an electrophotographic process such as a copying machine or a laser printer. One of the elements, it is necessary to satisfy various characteristics in order to bring out the performance of the image forming apparatus main body. Therefore, the photoreceptor is inspected for various characteristics relating to electrophotography before shipment. In addition, when developing a new photoreceptor for use in a new electrophotographic apparatus, various characteristics relating to electrophotography of the prototyped photoreceptor have been evaluated in the development process. Various body characteristic evaluation apparatuses have been proposed.

  An electrophotographic photoreceptor characteristic evaluation apparatus has charging characteristics (charge retention performance in the dark) and light attenuation characteristics (performance of quickly releasing charged charges by light irradiation), and it is necessary to evaluate them. . In particular, since the temperature of the photoreceptor rises in the image forming apparatus, it is necessary to measure the dependence of these characteristics on the temperature by measuring various characteristics when the surface temperature of the photoreceptor is changed. I know that.

  For example, in Patent Document 1, a heating unit that heats the surface of the photoconductor and a temperature detection unit that detects the temperature of the surface of the photoconductor are provided, and the surface temperature of the photoconductor is controlled by controlling the heating unit based on the result of the temperature detection unit. An image forming apparatus for controlling the image is described. In Patent Document 1, it is described that a heater is used as the heating means to be used, but no further description is seen. Furthermore, since it is used in the image forming apparatus, the length of the heater is predicted to be a heater length that covers the entire length of the photoconductor, but the heater used in the electrophotographic photoconductor characteristic evaluation apparatus is Since the method and shape of each device used is different, it is difficult to use it as it is.

  Patent Document 2 describes a photoconductor evaluation apparatus that measures various characteristics of a photoconductor while changing the surface temperature of the photoconductor using a heating / cooling device that heats or cools the photoconductor. Yes. In Patent Document 2, the photoconductor evaluation device is provided with a means / device for heating the photoconductor, but only describes that the heating means is a heater, and details of the heater are not described at all. Not.

  In the characteristic evaluation apparatus, in order to deal with a wide variety of photoconductors, the holding member for holding the photoconductor can correspond to a photoconductor of the same shape with a single holding member, so that cost reduction and versatility can be improved. It is often a device that takes into account. Further, in the case of photoconductors having the same drum inner diameter, consideration is given to making the device further cost-saving, such as a device that can be handled by the same holding member. As described above, there is also a demand for a heating device that has reduced cost and improved versatility.

  Since the evaluation apparatus sometimes measures and evaluates a plurality of points, it is necessary to prevent photoconductor deterioration caused by repeated charging and exposure. For this reason, the unit length in consideration of the unit length is set so that the unit around the photosensitive member is charged and exposed only in a necessary area. On the other hand, the heating device may be a heating device that covers the entire area of the photoconductor, but if it is made longer, it will be necessary to manufacture a new short heating device in order to measure a short photoconductor, thus reducing costs. For this purpose, a heating device having a general purpose length is necessary. However, because the temperature at both ends of the heating device is lower than the center temperature due to the influence of radiant heat, making the heating device too short will cause temperature unevenness in the axial direction and circumferential direction.

  Further, in order to prevent the discharge device such as ozone and NOx discharged from the charging device from being filled inside the evaluation device, an air flow for exhausting out of the device is created. However, the air flow causes a difference in surface temperature within the circumference of the photoreceptor. When the photosensitive drum is rotated in the state where the temperature unevenness is generated and immediately charged and the various characteristics of the photosensitive member are evaluated, if the temperature dependence of the characteristic is strong, the characteristic is uneven within one round. become. Therefore, there has been a demand for a characteristic evaluation apparatus that can solve the above problems.

  An object of the present invention is to solve various problems in the prior art and achieve the following objects. That is, an object of the present invention is to provide a characteristic evaluation apparatus for accurately evaluating the temperature characteristic of a photosensitive member at low cost while maintaining versatility in the photosensitive member characteristic evaluation apparatus.

In order to solve the above problems, a characteristic evaluation apparatus according to the present invention has technical features described in the following (1) to (7).
(1) Around a photosensitive member provided with a photosensitive layer on a drum-shaped support,
A photoconductor characteristic evaluation device in which a charging device, an exposure device, a surface potential detection device, and a charge removal device are arranged,
A heating device that heats the photosensitive member from the inside of the drum, a control device that controls the output of the heating device, and a temperature sensor that measures the surface temperature of the photosensitive member on the photosensitive layer side;
The heating device and the temperature sensor are movable in the axial direction of the photoreceptor,
Each of the charging device, the exposure device, the surface potential detection device, and the static elimination device is configured so that the respective centers of the photosensitive member axial direction and the parallel direction coincide with each other.
In addition, the region that each of the charging device, the exposure device, the surface potential detection device, and the slow current device occupies in the direction parallel to the photosensitive member axial direction is within the region that the heating device occupies in the direction parallel to the photosensitive member axial direction.
The relationship between the axial length L1 of the heating region of the heating device, the overall length L of the photosensitive member, and the axial length L2 of the charging region of the charging device is L2 ≦ L1 <L
Is a photoreceptor characteristic evaluation apparatus.
The charging area of the charging device means the opening area of the corotron charger, the grid opening area of the scorotron charger, and the roller width in the case of the charging roller.
(2) The photoconductor characteristic evaluation apparatus according to (1), wherein the temperature sensor for measuring the surface temperature of the photoconductor is a non-contact type radiation thermometer.
(3) The photoconductor is heated in a stopped state, measured by a temperature sensor that a predetermined temperature has been reached, and then rotated for a predetermined time before measuring the surface potential. The photoconductor characteristic evaluation apparatus according to (1) or (2), wherein the photoconductor characteristic evaluation apparatus is characterized.
(4) The photoconductor is heated in a stopped state, measured by a temperature sensor to reach a predetermined temperature, the photoconductor is rotated, and the temperature width within the circumference of the photoconductor reaches a predetermined range. The photoconductor characteristic evaluation apparatus according to (1) or (2) above, wherein measurement of the surface potential is started from the above.
Note that the temperature width within the circumference of the photoreceptor is a temperature width for one circumference measured by the temperature sensor when the photoreceptor is rotated once.
(5) The above-described (1), wherein the photoconductor is heated in a rotated state, and after measuring by a temperature sensor that a predetermined temperature has been reached, measurement of the surface potential is started. ) Or (2).
(6) The photoconductor characteristic evaluation apparatus according to any one of (1) to (5), wherein the temperature characteristic of the photoconductor is evaluated by measuring a post-exposure potential.
(7) The photoconductor characteristic evaluation apparatus according to any one of (1) to (5), wherein the temperature characteristic of the photoconductor is evaluated by measuring a charged potential.

  According to the present invention, various problems in the prior art can be solved, and it is possible to perform evaluation at a low cost while maintaining versatility in the photoreceptor characteristic evaluation apparatus. Furthermore, it is possible to measure temperature characteristics with high accuracy in a state in which the temperature irregularity within the circumference of the photoconductor caused by the airflow in the evaluation apparatus is also improved.

Specifically, according to the present invention, firstly, a photosensitive member characteristic evaluation apparatus in which a charging device, an exposure device, a surface potential detection device, and a static elimination device are arranged around a photosensitive member provided with a photosensitive layer on a drum-like support. A heating device for heating the photosensitive member from the inside of the drum, a control device for controlling the output of the heating device, and a temperature sensor for measuring the surface temperature of the photosensitive member on the photosensitive layer side. The temperature sensor is movable in the photosensitive member axial direction, and is configured such that the center of the charging device, the exposure device, the surface potential detection device, and the neutralization device is aligned with the center of the photosensitive member axial direction. The region that each of the apparatus, the exposure device, the surface potential detection device, and the grading device occupies in the direction parallel to the photosensitive member axial direction is within the region that the heating device occupies in the direction parallel to the photosensitive member axial direction. Axial length of heating zone 1. By defining the relationship between the overall length L of the photoconductor and the axial length L2 of the charging area of the charging device, it is possible to accurately evaluate the temperature characteristics of the photoconductor at low cost while maintaining versatility. .
Second, the temperature sensor for measuring the surface temperature of the photoconductor is a non-contact type radiation thermometer, so that the temperature characteristics of the photoconductor can be evaluated without damaging the photoconductor due to scratches or deterioration. I can do it.
Thirdly, in the photoconductor characteristic evaluation apparatus described in (1) or (2) above, the photoconductor is heated in a stopped state, and a temperature sensor is used to measure that the photoconductor has reached a predetermined temperature. By being configured to start the measurement after rotating the time, it is possible to evaluate the temperature characteristics of the photoconductor in a state where the temperature unevenness in the circumferential direction of the photoconductor is reduced.
Fourth, in the photoconductor characteristic evaluation apparatus described in (1) or (2) above, the photoconductor is heated in a stopped state, and after having reached a predetermined temperature, the photoconductor is rotated. The temperature of the photoconductor is reduced in a state in which the temperature unevenness in the circumferential direction of the photoconductor is reduced by being configured to start the measurement after the temperature width in the circumference of the photoconductor reaches a predetermined range. The characteristics can be evaluated.
Fifth, in the photoconductor characteristic evaluation apparatus described in (1) or (2) above, the photoconductor is heated in a rotated state, and after reaching a predetermined temperature with a temperature sensor, measurement is performed. Thus, the temperature characteristics of the photoconductor can be evaluated by reducing the temperature unevenness in the circumferential direction of the photoconductor and shortening the time until measurement.
Sixth, in the photoconductor evaluation apparatus according to any one of (1) to (5) above, the post-exposure potential of the photoconductor is evaluated by evaluating the temperature characteristics of the photoconductor by measuring the post-exposure potential. Temperature characteristics can be evaluated.
Seventh, in the photosensitive member evaluation apparatus according to any one of (1) to (5), the temperature characteristic of the charging potential of the photosensitive member is evaluated by measuring the temperature characteristic of the photosensitive member by measuring the charging potential. Can be evaluated.

It is an example (front view) of the schematic of the characteristic evaluation apparatus which concerns on this invention. It is an example (side view) of the schematic of the characteristic evaluation apparatus which concerns on this invention. It is a temperature transition graph when it switches from the photoconductor stop state in Example 2a to a rotation state.

  Embodiments of an electrophotographic photosensitive member property evaluation apparatus according to the present invention will be described below with reference to the drawings. FIG. 1 is a schematic view (front view) of a photoconductor characteristic evaluation apparatus according to the present invention, and FIG. 2 is a schematic view (side view) of the photoconductor characteristic evaluation apparatus according to the present invention. The characteristic evaluation apparatus will be described with reference to FIGS.

  As shown in FIG. 1, in the photoconductor evaluation apparatus of this embodiment, a charger 6 for charging the photoconductor 1, an exposure device 3 for forming a latent image, and a static eliminator 5 are arranged around the drum photoconductor, and Between the charger 6 and the exposure device 3 and between the exposure device 3 and the charge eliminator 5, electrometer probes 2 and 4 for measuring the surface potential on the photosensitive member are respectively arranged for supplying a voltage to the charger. It is a device comprising a power source 12 and a power source 13 for supplying a voltage to the grid of the charger. As shown in FIG. 2, the photosensitive drum is held at both ends by drum chuck jigs 18 and is rotated in the direction of the arrow in FIG. The motor driver in the motor can control the number of rotations and can be rotated at an arbitrary linear speed. Further, a heating device (heater) 17 for heating the drum and a temperature sensor 24 for measuring the surface temperature of the photoconductor are arranged inside the photoconductor. The temperature sensor 24 is connected to the controller 25 shown in FIG. 2, and the controller 25 controls the ON / OFF of the heater based on the result of the temperature sensor 24, and the output is controlled to the set temperature. The controller control method here is set to a predetermined set temperature by a known control method such as feedback control or PID control.

A plurality of electrometer probes 2 and 4 may be installed in the axial direction position. By installing a plurality of electrometer probes 2 and 4 in the charging region, it is possible to obtain a charge distribution in the region in a short time.
The electrometer probes 2 and 4, the charger 6, the static eliminator 5, and the exposure device 3 have a structure that can advance and retreat in the normal direction of the surface of the photoconductor 1 so that the electrometer probes 2 and 4, the static eliminator 5, and the exposure device 3 can be arranged at a certain distance from the surface of the photoconductor 1. Therefore, it can cope with various outer diameters of the photoreceptor 1. Further, the electrometer probe 4 can be moved in the circumferential direction while keeping the distance from the photoconductor constant, and the potential can be measured by changing the time from exposure. Further, the structure is movable not only in the normal direction and the circumferential direction, but also in the axial direction of the photosensitive member, and measurement at an arbitrary position in the photosensitive member axial direction is possible. Further, the heating device 17 and the temperature sensor 24 are also structured to be movable with respect to the axial direction of the photosensitive member, and can be measured at arbitrary positions in the photosensitive member axial direction. And the center of the heating device 17 can be measured, and the temperature sensor 24 can measure the temperature at an arbitrary measurement position.

For this reason, the photoreceptor evaluation apparatus according to the present embodiment can align the centers of the charger 6, exposure apparatus 3, electrometer probes 2, 4, and static eliminator 5 in the direction parallel to the photoreceptor axis direction. By making these centers coincide with each other, specifically, by making each center position shift less than 2 mm, more preferably less than 1 mm, stable and highly accurate characteristic evaluation becomes possible.
Further, by making the heating device 17 movable with respect to the axial direction of the photoreceptor, each of the charger 6, the exposure device 3, the electrometer probes 2, 4 and the slow charger 5 is parallel to the axial direction of the photoreceptor. The potential can be measured in such a way that the area occupied is within the area occupied by the heating device 17 in the direction parallel to the axial direction of the photoreceptor. Thereby, the charged region of the photoconductor can be heated without unevenness, and temperature characteristics can be evaluated with high accuracy. Therefore, the length of the heating device 17 in the photosensitive member axial direction needs to be equal to or longer than the length of the charger 6.

It is more preferable that the charger 6, the exposure device 3, the electrometer probes 2, 4 and the grading device 5 are configured such that the center position of the heating device 17 in the direction parallel to the photosensitive member axial direction coincides. In this case, it is configured that the center of the charger 6 and the exposure device 3 and the like in the direction parallel to the photosensitive member axial direction and the center of the heating device in the direction parallel to the photosensitive member axial direction coincide with each other. It means that the respective center positions are aligned with respect to the axial direction of the photoreceptor, and the shift of the center position is preferably less than 2 mm, more preferably less than 1 mm. In particular, when the lengths of the charger 6 and the heating device 17 in the photosensitive member axial direction are the same, it is preferable that the deviation width of the center position is as small as possible.
The relationship between the axial length L1 of the heating region of the heating device 17, the total length L of the photosensitive member 1, and the axial length L2 of the charging region of the charger 6 is L2 ≦ L1 <L. .

  In this characteristic evaluation apparatus, the photosensitive drum 1 is held at both ends by the drum chuck jig 18 and the main shaft 21 passes through the center of the chuck jig 18 (FIG. 2). In the main shaft 21, the front face plate 19 and the rear face plate 20 serve as a bearing function of the main shaft 21, and the main shaft 21 is a mechanism that is rotated by a belt 22 connected to a motor 23. Rotate in the direction.

  A high voltage is output from the power supplies 12 and 13, and the photosensitive drum 1 is charged by the charger 6. Thereafter, the passing current in the photosensitive drum 1 is sent to the signal processing circuit 10. Thereafter, it is converted into a digital signal by the A / D converter 15 and sent to the controller 16 where the digital signal is processed.

  Further, the surface potential after charging of the photosensitive drum 1 is sent from the surface potential meter probe 2 to the surface potential meter 8 which is a monitor unit, monitored, and sent to the signal processing circuit 9. Thereafter, the data is converted by the A / D converter 15 and then sent to the controller 16 for arithmetic processing. Similarly, the surface potential after exposure of the photosensitive drum 1 is sent from the surface potential meter probe 4 to the surface potential meter 7 as a monitor unit, monitored, and sent to the signal processing circuit 9. Thereafter, the data is converted by the A / D converter 15 and then sent to the controller 16 for arithmetic processing. The controller 16 is connected to a motor driver in the motor 23 that rotates the photosensitive drum 1. The motor driver is also equipped with functions to output the rotation speed, position detection function, and remote control of the rotation speed. It is also possible to control the rotation speed, recognize the rotation speed, and stop the drum at the set angle. It is.

  The units around the photosensitive drum 1 are ON / OFF controlled by digital relay output, and the power supplies 12 and 13 of the charger are ON / OFF controlled by the relay output of the switch 14. Further, the post-exposure potential of the photosensitive member can be measured by using the exposure device 3, and when removing the surface potential of the photosensitive member, it can be removed by using the static eliminator 5. It is possible to evaluate characteristics such as charging characteristics and light attenuation characteristics.

  For the exposure apparatus 3, general light emitting materials such as a fluorescent lamp, a tungsten lamp, a halogen lamp, a mercury lamp, a sodium lamp, a light emitting diode (LED), a semiconductor laser (LD), and electroluminescence (EL) can be used. In order to irradiate only light in a desired wavelength range, various filters such as a sharp cut filter, a band pass filter, a near infrared cut filter, a dichroic filter, an interference filter, and a color temperature conversion filter can be used. A neutral density filter can also be used to lower the value.

  Further, in this evaluation apparatus, after charging the photosensitive member, an electrostatic latent image is formed at the timing of charging and exposure ON / OFF so that exposure is performed when the charging start position comes to the exposure position. I can do it.

  In this evaluation apparatus, the charging process by the charger 6 and the exposure process by the exposure apparatus 3 can be repeated a predetermined number of times to degrade the photoconductor, and the post-exposure potential V1 before degradation and the post-exposure potential V2 after degradation are obtained. You can also compare and evaluate.

  As the charger 6 used in the present invention, a corotron charger or a scorotron charger which is a corona charger can be used, but a scorotron charger which is uniform and can easily reach a predetermined potential is preferable. The photoconductor used in the practice of the present invention may be one in which a charge generation layer and a charge transport layer are formed on a conductive support, and further in which a protective layer is formed on the charge transport layer. The As the conductive support, the charge generation layer, and the charge transport layer, known ones can be used.

  The control means of the power supply circuit for the charging device for charging the surface of the sample to be tested and the control means of the power supply circuit for the light source for irradiating the test sample with light are not shown in the figure. A well-known thing can be used as it is.

  As the temperature sensor 24, a contact-type thermometer or a non-contact-type thermometer can be used. However, since the temperature measurement during rotation is easy and there is no risk of scratching the photoconductor, the temperature sensor 24 is not used. A contact type thermometer (non-contact type infrared radiation thermometer) is preferable.

The characteristic evaluation apparatus of the present invention heats the photosensitive member in a stopped state, measures the arrival at a predetermined temperature with a temperature sensor, and then starts measuring the potential after rotating a predetermined time. It is preferable to configure. As a result, it is possible to evaluate the temperature characteristics of the photoconductor in a state where the temperature unevenness in the circumferential direction of the photoconductor is reduced.
In addition, the photoconductor is heated in a stopped state, and the photoconductor is rotated after measuring a predetermined temperature, and the temperature width within one circumference of the photoconductor reaches a predetermined range. By starting the measurement of the potential from the above, it is possible to evaluate the temperature characteristics of the photoconductor in a state where the temperature unevenness in the circumferential direction of the photoconductor is reduced.
Further, after heating the photoconductor in a rotating state, measuring the potential at a predetermined temperature with a temperature sensor, and measuring the potential, the temperature unevenness in the circumferential direction of the photoconductor is reduced, and It is possible to evaluate the temperature characteristics of the photoreceptor by shortening the time until measurement.

  The characteristic evaluation apparatus is covered with a dark box that does not transmit light, or a black curtain. If it is not covered with a dark box or a black curtain, it will be affected by the external environment (wind, light, temperature) during testing, making accurate characterization difficult. However, a controller, a signal processing circuit, or the like that does not affect the evaluation of the photosensitive drum does not need to be covered with a dark box or a black curtain.

EXAMPLES Hereinafter, although an Example demonstrates this invention concretely, this invention is not limited at all by these Examples.
<Devices and configurations common to each example and comparative example>
The characteristic evaluation was performed using the photosensitive drum (drum diameter 100 mm, drum total length 360 mm) mounted on the Ricoh imagio MF7070 with the characteristic evaluation apparatus as shown in FIGS.
As a characteristic evaluation device, the exposure device is an LD (laser diode) with a wavelength of 655 nm, and the light of the LD is exposed to the axial direction side of the photosensitive member with a polygon mirror, and the beam diameter is the image plane. 70 × 85 μm, writing resolution (sub-scanning direction) 400 dpi, LD writing is continuously lit. High voltage power supply, surface potential meter, surface potential meter probe is made by TREK, charger is in-house manufactured scorotron charger (grid opening size: 60mm x 15mm), custom line LED (wavelength 660nm), motor for static elimination Is manufactured by Oriental, controller is a PC manufactured by Dell, A / D converter and digital output are manufactured by National Instruments, and a non-contact type radiation thermometer is a radiation temperature sensor head manufactured by Keyence Corporation + sensor amplifier manufactured by the company + Omron's temperature controller (ON / OFF control of the power supply to the heater), the heater uses an in-house heating device made by Crabon Tape Heater Sakaguchi Electric Heat Co., Ltd. A tape heater is wound around a cylinder with a diameter smaller than the inner diameter, and the outer diameter of the heating device is 93 mm. All other signal processing circuits are manufactured in-house. Using the work was characteristic evaluation apparatus.

  Incidentally, the axial center position of each unit around the photosensitive member was aligned with the axial center position of the photosensitive member, and the axial center position of the heating device (heater) was also aligned with the axial center position of the photosensitive member. The thermometer was configured to measure the measurement position. Moreover, the heating apparatus produced internally was used so that the temperature difference in a heating area | region (area | region where the heater of the heating apparatus was wound) was set within 2 degreeC. Moreover, the area | region where the heater of the heating apparatus was wound was made the same with the heating apparatus full length.

[Example 1a] to [Example 1d]
Four heating devices with different axial lengths (length: 60 mm, 100 mm, 200 mm, 300 mm) were manufactured, and three axial positions in the grid opening area of the charger (30 mm before the opening center position, Table 1 shows the results of the temperature difference (maximum value−minimum value) when the temperature at the opening center position and the temperature at the 30 mm depth side from the opening center position was measured. The set temperature was set so that the center position in the photoconductor axis direction was 40 ° C. Regarding the temperature measurement, the thermometer used in the device only at the center position was used, and the temperature measurement at a position shifted by 30 mm from the center was performed by separately attaching two thermometers of the same type.

[Comparative Example 1a]
A heating device with an axial length of 30 mm was manufactured, and three axial positions within the grid opening area of the charger (30 mm before the opening center position, the opening center position, and 30 mm from the opening center position) Table 1 shows the results of the temperature difference (maximum value-minimum value) when the temperature of each was measured. The set temperature is set so that the center position in the photoconductor axis direction is 40 ° C. For temperature measurement, a thermometer used in the apparatus is used only at the center position, and the temperature measurement at a position shifted by 30 mm from the center is performed. In addition, two thermometers of the same type were attached and measured.

[Comparative Example 1b]
Using the same heating device having an axial length of 60 mm as in Example 1, three axial positions in the grid opening area of the charger (30 mm before the opening center position, the opening center position, and the opening center position) Table 1 shows the result of the temperature difference (maximum value−minimum value) when the temperature of 30 mm from the back is measured. However, the measurement was performed by setting the axial center position of the heating device to a position shifted by 10 mm from the axial center position of the charging unit (shifted by 10 [mm] toward the back of the apparatus). The set temperature is set so that the center position in the photoconductor axis direction is 40 ° C. For temperature measurement, a thermometer used in the apparatus only at the center position is used, and the temperature at a position shifted by 30 mm from the center is used. The measurement was performed by separately attaching two thermometers of the same type.

As a necessary condition for accurately measuring the temperature characteristics of the photoconductor in the charging area, a temperature difference of 2 ° C. or less is necessary. However, the length of the heating device is the axial length of the charging area of the charger (Scorotron). If it is smaller than the grid opening width of the charger, the temperature width exceeds 2 ° C., and it can be seen from the results in Table 1 that the temperature characteristics cannot be measured with high accuracy (Comparative Example 1a). Moreover, although the length of the heating device of this time could only be manufactured up to 300 mm, the length of the drum holding jig was 30 mm each, and the total value was 60 mm at both ends, so 300 mm was the maximum value. Therefore, when the length of the drum holding jig is ignored, the relationship between the axial length L1 of the heating area of the heating device, the overall length L of the photosensitive member L, and the axial length L2 of the charging area of the charging device is L2 ≦ L1. <It can be seen that L is the optimum condition. That is, if the heating device becomes longer than the entire length, it becomes difficult to hold the photosensitive member with the chuck jig. L1 <L
Is the optimal condition.

Next, the relationship between the axial length L2 of the charging area of the charging device and the axial length L1 of the heating area of the heating device is such that L1 is shorter than L2 (L1 <L2).
As shown in Table 1, since the temperature difference is large, it is necessary that L2 <L1.
Also, when L2 = L1, there is no problem because the temperature difference is small.
L2 ≦ L1
Is the optimal condition. From the above, the optimum condition is L2 ≦ L1 <L
It becomes.

  In addition, the thermometer used this time was a non-contact infrared radiation thermometer, but because it was non-contact, it was possible to measure without damaging the photoreceptor, so a non-contact infrared radiation thermometer It is understood that is preferable. Furthermore, although the drum length which can be measured on each condition is described in Table 1, it can be understood that the shorter the length of the heating device, the shorter the drum length can be measured. From this fact, it can be seen that shortening the length of the heating device increases versatility and reduces the cost (the number of heating devices to be manufactured can be reduced).

  That is, when the heating device is short, the degree of freedom with respect to the length of the photosensitive drum is high, and a single heating device can cope with a short full length drum to a long full length drum. On the other hand, when the heating device is long, the degree of freedom with respect to the length of the photosensitive drum is low, and it is impossible to cope with a short full-length drum. Therefore, it is necessary to prepare a plurality of heating devices having different lengths.

However, when shortening the length of the heating device, if the region occupied in the axial direction of the charging device is not within the region occupied in the axial direction of the heating device, the temperature range exceeds 2 ° C., and the temperature characteristics are accurate. It can also be seen from the results in Table 1 (Comparative Example 1b) that measurement cannot be performed.
From the above, the axial length of the charging unit is preferably the same as or shorter than the axial length of the heating device, and the area occupied by the charging unit in the axial direction is in the axial direction of the heating device. It can be seen that it is preferably within the occupied area.

[Example 2a]
Measurement was performed with the above-described characteristic evaluation apparatus. The axial length of the heating device was 60 mm. The photoconductor was heated in a stopped state, and after the thermometer display reached 40 ° C., the photoconductor was rotated for 30 seconds and then measurement of the post-exposure potential and the charged potential was started.
[Example 2b]
Measurement was performed with the above-described characteristic evaluation apparatus. The axial length of the heating device was 60 mm. The photoconductor is heated in a stopped state, and after the thermometer display reaches 40 ° C., the photoconductor is rotated, and the temperature range within the circumference of the photoconductor reaches within 1 ° C. After the exposure and the charging potential Measurement was started.
[Example 2c]
Measurement was performed with the above-described characteristic evaluation apparatus. The axial length of the heating device was 60 mm. The photoconductor was heated while being rotated, and after the thermometer display reached 40 ° C., measurement of the post-exposure potential and the charged potential was started.

Table 2 shows the results of the temperature range within the circumference of the photoreceptor confirmed before the measurement and the results of the time elapsed from the start of heating to the start of measurement. Table 2 shows the width of the post-exposure potential and the charging potential at that time. (Charging conditions: conditions in which the high voltage output voltage and grid voltage are adjusted so that the charging potential is in the vicinity of −800 V, exposure conditions: 0.2 [μJ / cm ² ], linear velocity: 200 [mm / s], paper length : 314 [mm], exposure development time 100 [ms]). Furthermore, FIG. 3 shows a temperature transition graph when switching from the stopped state of Example 2a to the rotating state.

※測定前の１周内温度幅の判断基準は、○は温度幅が１［℃］以内であり、×は温度幅が１［℃］を超えるものである。また露光後電位幅、帯電電位幅とは、感光体１周内の露光後電位幅、帯電電位幅である。

* Judgment criteria for the temperature range in one circle before measurement are: ○ is a temperature range within 1 [° C], and x is a temperature range exceeding 1 [° C]. Further, the post-exposure potential width and the charge potential width are the post-exposure potential width and the charge potential width within the circumference of the photoreceptor.

  From the results shown in FIG. 3, the temperature unevenness is confirmed by rotating the photoconductor immediately after being heated in the stopped state. Due to the flow of the air current in the apparatus, the temperature unevenness in the circumference of the photoconductor is generated in the stopped state. I understand that. Therefore, when measured immediately after heating in the stopped state as shown in Table 2, the temperature width in one circumference before the measurement exceeds 1 ° C.

  However, when heating is performed in a stopped state, the temperature within the circumference of the photoconductor is measured before the measurement by rotating the temperature for a predetermined time after reaching the temperature or rotating the temperature until the temperature width within the circumference of the photoconductor is within the range. Unevenness can be suppressed. In addition, it is possible to suppress uneven temperature within the circumference of the photoreceptor by rotating from the time of heating. It can also be seen that by rotating from the time of heating, it is possible to shorten the time until measurement starts.

  When the post-exposure potential and the charged potential were measured immediately after the photoconductor stopped and heated with the thermometer display reaching 40 ° C. using the same characteristic evaluation apparatus as in Examples 2a to 2c. Both the potential width after exposure and the potential width after charging were larger than those in Examples 2a to 2c. This is because when the post-exposure potential or charging potential is measured under conditions where temperature non-uniformity exceeds 1 ° C., the temperature non-uniformity affects the charge potential and post-exposure potential. Both show that it will grow.

DESCRIPTION OF SYMBOLS 1 Photosensitive drum 2 Surface potential meter probe 3 Exposure apparatus 4 Surface potential meter probe 5 Charger 6 Charger 7 Surface potential meter 8 Surface potential meter 9 Signal processing circuit 10 Signal processing circuit 12 Power supply 13 Power supply 14 Power switch 15 A / D Converter 16 Controller 17 Heating device 18 Drum chuck jig 19 Face plate (front side)
20 face plate (back side)
21 Spindle 22 Belt 23 Motor 24 Temperature sensor 25 Controller

JP 2006-119308 A JP 2003-029572 A

Claims (7)

Around the photosensitive member provided with a photosensitive layer on a drum-shaped support,
A photoconductor characteristic evaluation device in which a charging device, an exposure device, a surface potential detection device, and a charge removal device are arranged,
A heating device that heats the photosensitive member from the inside of the drum, a control device that controls the output of the heating device, and a temperature sensor that measures the surface temperature of the photosensitive member on the photosensitive layer side;
The heating device and the temperature sensor are movable in the axial direction of the photoreceptor,
Each of the charging device, the exposure device, the surface potential detection device, and the static elimination device is configured so that the respective centers of the photosensitive member axial direction and the parallel direction coincide with each other.
In addition, the region that each of the charging device, the exposure device, the surface potential detection device, and the slow current device occupies in the direction parallel to the photosensitive member axial direction is within the region that the heating device occupies in the direction parallel to the photosensitive member axial direction.
The relationship between the axial length L1 of the heating region of the heating device, the overall length L of the photosensitive member, and the axial length L2 of the charging region of the charging device is L2 ≦ L1 <L
Is a photoreceptor characteristic evaluation apparatus.   The photoconductor characteristic evaluation apparatus according to claim 1, wherein the temperature sensor for measuring the surface temperature of the photoconductor is a non-contact infrared radiation thermometer.   The photoconductor is heated in a stopped state, measured by a temperature sensor that it has reached a predetermined temperature, and then measured for a surface potential after rotating a predetermined time. The photoreceptor characteristic evaluation apparatus according to claim 1 or 2.   The photoconductor is heated in a stopped state, measured by a temperature sensor to reach a predetermined temperature, the photoconductor is rotated, and the surface potential is reached after the temperature width within the circumference of the photoconductor reaches a predetermined range. The photoconductor characteristic evaluation apparatus according to claim 1, wherein the measurement of the photoconductor is started.   3. The structure according to claim 1, wherein the photoconductor is heated in a rotating state, and the measurement of the surface potential is started after the temperature sensor has measured that a predetermined temperature has been reached. The photoreceptor characteristic evaluation apparatus described.   6. The photoconductor characteristic evaluation apparatus according to claim 1, wherein the temperature characteristic of the photoconductor is evaluated by measuring a post-exposure potential.   6. The photoconductor characteristic evaluation apparatus according to claim 1, wherein the temperature characteristic of the photoconductor is evaluated by measuring a charging potential.

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