JP5487706B2 - Photoreceptor characteristic evaluation device - Google Patents

Description

  The present invention relates to an apparatus for evaluating characteristics of an electrophotographic photoreceptor.

  As the electrostatic characteristics of the photoconductor, there are charging characteristics (charge retention performance in the dark) and sensitivity characteristics (performance of quickly releasing charged charges by light irradiation), which need to be evaluated. The evaluation may be performed after repeating the initial state, charging and exposure, and giving fatigue. In either case, the charging starts with charging first. The charging means is usually applied by corona discharge by applying a high voltage to a thin tungsten wire. At this time, ozone, NOx, etc. generated by the corona discharge may contaminate the surface of the photoreceptor and affect the characteristic evaluation. is there.

  In particular, when fatigue is given by the same evaluation apparatus, ozone and NOx stay around the charger and gradually contaminate the photoreceptor. This is already known, and as a countermeasure, it has been devised to put contaminants around the photoconductor on the flow of the air current and discharge it out of the apparatus, and many ideas have been proposed and implemented. In many cases, an air current is caused to flow when the photosensitive drum rotates or stops. The use of a fan to create this airflow is the exclusive method, but conversely, there is also a proposal of a device characterized by not using a fan to create an airflow. Furthermore, there is also a proposal for preventing the contamination of the photoreceptor by ozone and NOx by blocking the opening of the charger without generating an air flow. However, this causes contamination products of ozone and NOx to adhere to the inside of the charger itself, and the contamination products fall on the photosensitive member over a long period of time, resulting in irreparable deterioration. It is effective to quickly remove ozone and NOx generated by the charger.

  In order to efficiently discharge ozone and NOx using a fan, a strong air current is made to flow through the gap portion between the charger and the photosensitive member. At this time, if the photoconductor is stopped, the surface temperature of the portion of the photoconductor on which the airflow is applied is lower than the portion of the photoconductor that is not exposed.

  That is, temperature unevenness occurs around the photosensitive drum. In this state, when the photosensitive drum is rotated and immediately charged and the evaluation of the characteristics of the photosensitive member is started, if the temperature dependence of the characteristics is strong, the characteristics are uneven within one round. Further, when the evaluation is repeated continuously, the uneven temperature is uniformly applied to the air flow within one circle, so that the temperature gradually becomes equal, and this also has different characteristics after being repeated a plurality of times. In addition, whether or not the unevenness of the characteristics within one round is due to a difference in temperature cannot be determined only from the evaluation results of the characteristics. Needless to say, this is not true even in an image forming apparatus, because the image quality is different after the first time and after a plurality of times.

  Prior art documents were investigated, but no electrophotographic photosensitive member that addressed this problem was found. If it dares to pick up, there existed the thing of Unexamined-Japanese-Patent No. 4-324143 of patent document 1. FIG. However, this is because the upper and lower temperatures of the magneto-optical recording medium are controlled by the heating means, and the means is different from the present invention.

  In the present invention, even when airflow hits only a specific part of the photosensitive drum and temperature unevenness occurs within the circumference of the photosensitive drum, evaluation or image formation is started after the temperature within the circumference becomes uniform. An object of the present invention is to provide an evaluation apparatus or an image forming apparatus configured to do so.

The present invention is solved by the following (1) to (7).
(1) Around the cylindrical photosensitive drum, charging means for charging at least the photosensitive member, exposure means for forming an electrostatic latent image on the photosensitive member, and surface electrometer measuring means for measuring the electrostatic latent image potential And a neutralizing unit that exposes the surface of the photosensitive member to remove residual charges, an ozone exhaust fan that exhausts ozone generated by the charging unit, and a non-contact radiation thermometer that measures the photosensitive member temperature on the same circumference. It is a device in which a heater for drum heating is installed inside the photosensitive drum, and the measurement is started after the temperature indicated by the non-contact radiation thermometer becomes constant within the circumference of the drum after the drum rotates. An apparatus for evaluating a photoreceptor, which is characterized by the above.
(2) Around the cylindrical photosensitive drum, charging means for charging at least the photosensitive member, exposure means for forming an electrostatic latent image on the photosensitive member, and surface electrometer measuring means for measuring the electrostatic latent image potential And a neutralizing unit that exposes the surface of the photosensitive member to remove residual charges, an ozone exhaust fan that exhausts ozone generated by the charging unit, and a non-contact radiation thermometer that measures the photosensitive member temperature on the same circumference. It is a device in which a heater for drum heating is installed inside the photosensitive drum, and the ozone exhaust fan rotates at the same time as the drum rotation or immediately after the drum rotation, and the temperature indicated by the non-contact radiation thermometer is A photoconductor evaluation apparatus configured to start measurement after being constant within one round of a drum.
(3) A charging unit that charges at least the photosensitive member around the cylindrical photosensitive drum, an exposure unit that forms an electrostatic latent image on the photosensitive member, and a surface potential meter measuring unit that measures the electrostatic latent image potential And a neutralizing unit that exposes the surface of the photosensitive member to remove residual charges, an ozone exhaust fan that exhausts ozone generated by the charging unit, and a non-contact radiation thermometer that measures the photosensitive member temperature on the same circumference. This is a device with a drum heater installed inside the photosensitive drum. The ozone exhaust fan is rotated at the same time as the drum rotation or immediately after the drum rotation, and measurement is started after a predetermined time has elapsed. A photoreceptor evaluation apparatus configured to perform the above-described process.
(4) Around the cylindrical photosensitive drum, charging means for charging at least the photosensitive member, exposure means for forming an electrostatic latent image on the photosensitive member, and surface electrometer measuring means for measuring the electrostatic latent image potential And a neutralizing unit that exposes the surface of the photosensitive member to remove residual charges, an ozone exhaust fan that exhausts ozone generated by the charging unit, and a non-contact radiation thermometer that measures the photosensitive member temperature on the same circumference. Is a device in which a drum heating heater is installed inside the photosensitive drum, and is configured such that when the ozone exhaust fan is in operation and the heater enters a heating operation, the drum rotates in conjunction with it. A photoreceptor evaluation apparatus characterized by the above.
(5) A charging unit that charges at least the photosensitive member around the cylindrical photosensitive drum, an exposure unit that forms an electrostatic latent image on the photosensitive member, a developing unit that uses the electrostatic latent image as a toner image, Generated by transfer means for transferring the toner image onto a transfer medium, fixing means for heat-fixing the toner image on a recording medium, charge eliminating means for exposing the surface of the photoreceptor to remove residual charges, and charging means An ozone exhaust fan that exhausts ozone and a non-contact radiation thermometer that measures the temperature of the photoconductor are arranged on the same circumference, and a drum heating heater is installed inside the photoconductor drum, An image forming apparatus configured to start image formation after the temperature indicated by the non-contact radiation thermometer becomes constant within the circumference of the drum after the drum rotates.
(6) A charging unit that charges at least the photosensitive member around the cylindrical photosensitive drum, an exposure unit that forms an electrostatic latent image on the photosensitive member, a developing unit that uses the electrostatic latent image as a toner image, Generated by transfer means for transferring the toner image onto a transfer medium, fixing means for heat-fixing the toner image on a recording medium, charge eliminating means for exposing the surface of the photoreceptor to remove residual charges, and charging means An ozone exhaust fan that exhausts ozone and a non-contact radiation thermometer that measures the temperature of the photoconductor are arranged on the same circumference, and a drum heating heater is installed inside the photoconductor drum, The ozone exhaust fan is configured to rotate at the same time as the drum rotation or after the drum rotation, and to start image formation after the temperature indicated by the non-contact radiation thermometer becomes constant within the circumference of the drum. Images Forming equipment.
(7) A charging unit that charges at least the photosensitive member around the cylindrical photosensitive drum, an exposure unit that forms an electrostatic latent image on the photosensitive member, a developing unit that uses the electrostatic latent image as a toner image, Generated by transfer means for transferring the toner image onto a transfer medium, fixing means for heat-fixing the toner image on a recording medium, charge eliminating means for exposing the surface of the photoreceptor to remove residual charges, and charging means An ozone exhaust fan that exhausts ozone and a non-contact radiation thermometer that measures the temperature of the photoconductor are arranged on the same circumference, and a drum heating heater is installed inside the photoconductor drum, An image forming apparatus, wherein an ozone exhaust fan is rotated at the same time as drum rotation or after drum rotation, and image formation is started after elapse of a predetermined time.

According to the photosensitive member evaluation apparatus described in (1) above, at least a charging unit for charging the photosensitive member around the cylindrical photosensitive drum, an exposure unit for forming an electrostatic latent image on the photosensitive member, and the static A surface potential meter measuring means for measuring the electrostatic latent image potential, a charge removing means for exposing the surface of the photoreceptor to remove residual charges, an ozone exhaust fan for exhausting ozone generated from the charging means, and a photoreceptor temperature. A non-contact radiation thermometer is arranged on the same circumference, and a drum heating heater is installed inside the photosensitive drum, and the temperature indicated by the non-contact radiation thermometer is within the circumference of the drum after the drum rotates. By being configured to start the measurement after it becomes constant, it is possible to reliably perform measurement without the influence of the drum temperature being uneven in the circumferential direction on the measurement data.
According to the photosensitive member evaluation apparatus described in the item (2), a charging unit that charges at least the photosensitive member around the cylindrical photosensitive drum, and an exposing unit that forms an electrostatic latent image on the photosensitive member, A surface potential meter measuring means for measuring the electrostatic latent image potential; a charge removing means for exposing the photoreceptor surface to remove residual charges; an ozone exhaust fan for exhausting ozone generated by the charging means; and a photoreceptor temperature. A non-contact radiation thermometer to be measured is arranged on the same circumference, and a drum heating heater is installed inside the photosensitive drum, and the ozone exhaust fan rotates at the same time as the drum rotation or after the drum rotation. In this way, the measurement is started after the temperature indicated by the non-contact radiation thermometer becomes constant within the circumference of the drum. Uniform It is possible to measure that excludes the impact of.
According to the photosensitive member evaluation apparatus described in the item (3), a charging unit that charges at least the photosensitive member around the cylindrical photosensitive drum, and an exposing unit that forms an electrostatic latent image on the photosensitive member, A surface potential meter measuring means for measuring the electrostatic latent image potential; a charge removing means for exposing the photoreceptor surface to remove residual charges; an ozone exhaust fan for exhausting ozone generated by the charging means; and a photoreceptor temperature. A non-contact radiation thermometer to be measured is arranged on the same circumference, and a drum heating heater is installed inside the photosensitive drum, and the ozone exhaust fan rotates at the same time as the drum rotation or after the drum rotation. In this way, measurement is started after a predetermined time has elapsed, so that measurement that eliminates the effects of uneven drum temperature in the circumferential direction on measurement data can be performed more quickly and reliably. When That.
According to the photosensitive member evaluation apparatus described in the item (4), a charging unit that charges at least the photosensitive member around the cylindrical photosensitive drum, and an exposing unit that forms an electrostatic latent image on the photosensitive member, A surface potential meter measuring means for measuring the electrostatic latent image potential; a charge removing means for exposing the photoreceptor surface to remove residual charges; an ozone exhaust fan for exhausting ozone generated by the charging means; and a photoreceptor temperature. A non-contact radiation thermometer to be measured is arranged on the same circumference, and a drum heating heater is installed inside the photosensitive drum, and the ozone exhaust fan is in operation and the heater enters the heating operation. In this case, since the drum is configured to rotate in conjunction with the drum temperature, it is possible to prevent the temperature from becoming uneven in the circumferential direction during the drum temperature setting, and the measurement can be started immediately after the target temperature is set.
According to the image forming apparatus described in (5), the charging unit that charges at least the photoconductor around the cylindrical photoconductor drum, the exposure unit that forms an electrostatic latent image on the photoconductor, A developing unit that uses an electrostatic latent image as a toner image, a transfer unit that transfers the toner image onto a transfer target, a fixing unit that thermally fixes the toner image on a recording medium, and a photosensitive member surface that is exposed to light. A static elimination unit that removes residual charges, an ozone exhaust fan that exhausts ozone generated by the charging unit, and a non-contact radiation thermometer that measures the temperature of the photosensitive member are arranged on the same circumference. The apparatus is provided with a drum heating heater, and is configured to start image formation after the temperature indicated by the non-contact radiation thermometer becomes constant within the circumference of the drum after the drum rotates. Non-uniform in the circumferential direction Effect becomes possible image formation eliminates by.
According to the image forming apparatus described in item (6), the charging unit that charges at least the photoconductor around the cylindrical photoconductor drum, the exposure unit that forms an electrostatic latent image on the photoconductor, A developing unit that uses an electrostatic latent image as a toner image, a transfer unit that transfers the toner image onto a transfer target, a fixing unit that thermally fixes the toner image on a recording medium, and a photosensitive member surface that is exposed to light. A static elimination unit that removes residual charges, an ozone exhaust fan that exhausts ozone generated by the charging unit, and a non-contact radiation thermometer that measures the temperature of the photosensitive member are arranged on the same circumference. This is a device equipped with a drum heating heater. The ozone exhaust fan rotates at the same time as the drum rotation or after the drum rotation, and the temperature indicated by the non-contact radiation thermometer becomes constant within the circumference of the drum. Start forming By configured so that, the impact of drum temperature is not uniform in the circumferential direction, speed, it is possible to reliably eliminate image formation.
According to the image forming apparatus described in the item (7), the charging means for charging at least the photoconductor around the cylindrical photoconductor drum, the exposure means for forming an electrostatic latent image on the photoconductor, A developing unit that uses an electrostatic latent image as a toner image, a transfer unit that transfers the toner image onto a transfer target, a fixing unit that thermally fixes the toner image on a recording medium, and a photosensitive member surface that is exposed to light. A static elimination unit that removes residual charges, an ozone exhaust fan that exhausts ozone generated by the charging unit, and a non-contact radiation thermometer that measures the temperature of the photosensitive member are arranged on the same circumference. A device in which a heater for drum heating is installed, and the ozone exhaust fan is rotated at the same time as the drum rotation or after the drum rotation, and is configured to start image formation after elapse of a predetermined time. Drum temperature The impact of the circumferential direction is nonuniform, rapidly, it is possible to reliably eliminate image formation.

It is an outline of the device composition of the present invention, and explanation of measurement data (surface potential data). It is an example of the timing chart in the measuring apparatus of this invention. It is an example of data on the surface temperature and surface potential of the photosensitive drum.

  Around the cylindrical photosensitive drum, charging means for charging at least the photosensitive member, exposure means for forming an electrostatic latent image on the photosensitive member, surface electrometer measuring means for measuring the electrostatic latent image potential, and photosensitive A neutralization unit that exposes the body surface to remove residual charges, an ozone exhaust fan that exhausts ozone generated by the charging unit, and a non-contact radiation thermometer that measures the temperature of the photoconductor are arranged on the same circumference, An apparatus in which a drum heating heater is installed inside the photosensitive drum will be described.

  In the present invention, the charging means may be either a corotron type or scorotron type charger, or a charging roller (non-contact type or contact type). In the embodiment, a scorotron type charger is used.

  The exposure means may be any of a laser scanning method, an LED method, and the like. In the embodiment, a laser scanning method is used. The wavelength of the laser device may be selected according to the photoconductor.

  A commercially available surface potential meter is used as the surface potential measuring means. In the embodiment, a surface potential meter Model 344 + probe Model 555P-4 manufactured by Trek Japan Co., Ltd. is used. However, it is not limited to this. The gap between the probe tip and the photoreceptor surface was approximately 2 mm. When the gap is increased, the potential detection range (size) on the surface of the photosensitive member is increased, so that it cannot be separated unnecessarily. On the other hand, if it is too close, the detection range is narrowed, but the risk of contact when the photoconductor is taken in and out increases, so the appropriate range is 1 mm to 3 mm. This distance is within a range in which the electrometer assures measurement accuracy as a self-calibrating type. Although it is the circumferential position of the probe, it is placed at the position where the developing means is placed in the image forming apparatus, and in the measuring device, it is the same position as the position of the developing means. A device that can move as much as possible in the circumferential direction and can determine the position is preferable. This is because a single measuring apparatus is required to be able to cope with various conditions. In the embodiment, such a measuring apparatus is used.

  The surface potential meter measures the latent image potential after exposure, but a surface potential meter probe is installed between the charging means and the exposure means so that the potential after charging and before exposure can be measured. It may be. In the measuring apparatus of the embodiment, a measurement electrometer before exposure is installed, and this electrometer also measures the influence on the potential due to the uneven temperature in the circumferential direction.

  The charge eliminating means removes the charge remaining on the photosensitive member, and when repeating measurement repeatedly, it is essential to prevent the influence of the previous cycle from affecting the next cycle as much as possible. Some image forming apparatuses are not mounted due to layout restrictions due to demands for downsizing the apparatus, but mounting is preferable for measurement apparatuses. By mounting, it is possible to easily confirm the influence on the photosensitive member due to the presence or absence of the charge eliminating means. An LED light source that is often used in image forming apparatuses may be used. The wavelength is 660 nm, and LED elements arranged in the axial direction are used, and the light intensity is set to a light intensity in the range of 2 to 5 times the amount of light required to attenuate the photoreceptor from a predetermined potential to 100 V. Used.

  From the charging means, there are products such as ozone and NOx, and pollutants generated when they act on atmospheric components (including moisture), and it is already known that these affect the characteristics of the photoreceptor. That is. In particular, when a corotron charger, a scorotron charger, a charging roller, or the like is used with a negative polarity, it is said that the ozone concentration around the charger is about 10 times that of a positive polarity. Photoconductors, especially OPCs, are often used with a negative polarity, and are easily affected by contamination products generated in the charger and staying around the OPC. For this reason, in order to remove the contamination products, it is common to install an exhaust fan and remove it from the periphery of the photoreceptor by placing it on an air stream. A large amount of the contaminated product stays in the gap (gap) between the charger and the surface of the photosensitive member, so a fan is installed so that an airflow flows in the gap. Since the purpose is to remove the accumulated contamination products, the image forming apparatus rotates the fan while the photosensitive member is rotating (during the operation of the charger). The fan is rotated even when the body is stopped. It is preferable that the measuring device also conforms to this rotational operation timing.

  However, if this is done, if an air current is applied while the photoconductor is stopped rotating, only that portion is deprived of heat, and the photoconductor has uneven temperature in the circumferential direction. In this state, when image formation or measurement of photoreceptor characteristics with a measuring apparatus is performed, a result reflecting the influence due to temperature unevenness is obtained. This effect becomes more prominent when the photosensitive member temperature is increased. In order to prevent this, it is necessary to adjust the timing of fan rotation, photoconductor rotation, and measurement start (or image formation start). An example of such a case is shown in FIG. When temperature unevenness exists, the temperature adjustment control functions so as to make it constant, and it can be seen that “unevenness” and “variation” due to the control temporarily continue.

  The reason why the measuring device is provided with a heater for raising the temperature of the photoreceptor is to evaluate the temperature dependence of the photoreceptor characteristics. In the image forming apparatus, the function of double-sided printing due to the demand for speeding up printing and resource saving (environmental problem) is used. When the latent image formed on the photoreceptor is developed, the developed toner image is transferred to paper, and then the toner image is fixed, the paper is heated immediately after fixing. When this goes to the immediate backside printing process, the heated paper comes into contact with the photoconductor at the time of transfer, and heat is transferred to the photoconductor to raise the temperature of the photoconductor. When this process is repeated in a large amount in a short time, the photoconductor can be combined with the heat from the fixing device (by the air current) and the temperature can be raised in a short time. It may exceed 50 ° C in a short time. Therefore, it is necessary to grasp the temperature dependence of the photoreceptor characteristics. As a method for raising the temperature of the photoconductor in the measuring apparatus, 1. 1. Apply hot air from the outside of the photoreceptor with a dryer. 2. Increase the temperature with a tape heater from the inside of the photoreceptor. For example, air adjusted in temperature and humidity is introduced into the measuring device through a duct. 1. Is easy, but the hot air from the dryer increases the temperature of the charger, the exposure device, the surface potential meter, etc. around the photoreceptor, and the measurement conditions are likely to fluctuate. 2. If the number and interval of tape heaters are properly designed and manufactured, the temperature will rise in a short time, and the conditions will be reproduced even if the heater device is removed and mounted and measured. Is suitable. However, it is necessary to prepare a built-in heater device for each photosensitive drum diameter. 3. Can be controlled up to humidity and is convenient as a measuring device, but the entire device is heated and conditioned, and it takes several hours to prepare for measurement under one temperature condition. Further, it is necessary to seal the apparatus, and ozone, NOx, etc. generated in the apparatus are trapped inside the apparatus, which is not preferable. For this reason, it is necessary to increase the temperature of the photosensitive member in the measuring apparatus by 2. This method is appropriate.

A non-contact radiation thermometer measures the temperature of the photosensitive drum. This is not particularly specified, but it is preferable to select a small one in consideration of incorporation into the apparatus. In the example, the radiation temperature sensor head FT-H20 + manufactured by Keyence Corporation + the sensor amplifier FT-55A + temperature controller E5EN manufactured by OMRON Corporation was used.
More specific description will be given below.

<< Equipment common to each embodiment >>
Measuring device: Drum type photoconductor characteristic measuring device manufactured in-house An outline of the device (including explanatory diagrams of the data obtained) is shown in FIG.
FIG. 2 shows a timing chart for characteristic evaluation (an example).
In the default operation, when the measurement start button is clicked on the PC screen, the drum mirror and the polygon mirror of the exposure unit start to rotate, and the time for the polygon mirror to reach the target number of revolutions (set to 5 s in this device) has elapsed. The static eliminator is turned on, and the measurement starts from the timing shown in FIG.

  There are several parameters in the conditions for operating this measurement system. Here, the parameters “linear velocity” and “paper length” that define the charging time will be described.

  “Linear speed” is the linear speed of the photosensitive member, and its unit is specified in mm / s. “Paper length” relates to the paper size used in the image forming apparatus, and the paper has vertical feed and horizontal feed, and the size (mm) in the paper feed direction is designated as “paper length”. The system divides this value by the linear speed at which the photoconductor rotates, calculates the charging time, and charges and exposes only during this time.

  In this embodiment, unless otherwise noted, the linear velocity is specified to be 200 mm / s, the “paper length” is specified to be a drum circumference (188 mm) or larger, and the potential fluctuation in the circumference of the photosensitive drum is observed. did.

Photoconductor: OPC (manufactured by Ricoh), φ60, CGM are phthalocyanine pigments.
・ Charger: Scorotron charger (manufactured in-house), high voltage -5.5kV, grid -800V
Exposure unit: LSU (laser scan unit) manufactured by Ricoh Optical Co., Ltd., LD wavelengths 780 nm, 655 nm (selection designation).
When measuring characteristics, use the LD with continuous lighting (that is, not pulse lighting).
Surface potential meter: Model 344 + Model 555P-4 Trek Japan Co., Ltd. electrometer probe is placed between the charger and the exposure device, and one between the exposure device and the static eliminator.
-Static eliminator: In-house manufactured, 660 nm LED is used.
Non-contact radiation thermometer: Radiation temperature sensor head FT-H20 made by Keyence Co., Ltd. OFF control).
Installed on a pedestal on which an electrometer probe is placed between the charger and the exposure unit, and fixed so that the optimum temperature detection distance is achieved for a drum diameter of 60 mm.

Tape heater: Crabon tape heater F-16 Sakaguchi Electric Heat Co., Ltd. Max150W photoreceptor is heated from the inside.
A tape heater is wound around a cylinder having a diameter smaller than the inner diameter of the target photoreceptor.
Exhaust fan: The exhaust fan is located between the charger and the surface electrometer probe, and is designed to rotate with the main power supply ON of the measurement system and to stop rotating when OFF (default operation). Fan rotation start and stop timings related to the present invention can be handled by changing the system (sequencer) program that controls the system.

  Next, the present invention will be described in more detail with reference to examples. However, the present invention is not limited to the following examples. In each of the following embodiments, a charging means for charging at least the photoconductor around the cylindrical photoconductor drum, an exposure means for forming an electrostatic latent image on the photoconductor, and the electrostatic latent image potential are set. Surface electrometer measuring means for measuring, charge eliminating means for exposing the surface of the photoreceptor to remove residual charges, an ozone exhaust fan for exhausting ozone generated from the charging means, and a non-contact radiation thermometer for measuring the temperature of the photoreceptor Are arranged on the same circumference, and a device in which a drum heating heater is installed inside the photosensitive drum is used.

[Example of measurement start after the temperature indicated by the non-contact thermometer becomes constant after rotation of the photosensitive drum]
A φ60 mm photosensitive drum was set in the measuring apparatus shown in FIG. The exhaust fan is rotating. The drum temperature was set in two ways: (1) when the heater was turned off and the room temperature was reached, and (2) at 40 ° C. In the case of 40 ° C., the temperature was raised with a heater from room temperature and reached 40 ° C. in 5 minutes. After confirming that the temperature was stable, the measurement start button was clicked. When the rotation of the photosensitive drum starts, the temperature of the drum is measured with a non-contact radiation thermometer, and the temperature unevenness ΔT is 1 ° C. or more within one revolution even after a period of time during which the rotation of the polygon mirror is stabilized. Is programmed so that the measurement does not start.

(result)
It took 15 to 20 s for the temperature irregularity ΔT within one revolution after the rotation of the drum to be 1 ° C. or less. In both cases (1) and (2), the temperature measurement data did not have a portion that decreased within one rotation of the drum, and the potential data did not have a portion that decreased within one rotation.
In this configuration, the polygon rotation stabilization time + waiting time is generated before the data is output, but it can be seen that the data in which the potential unevenness in one round due to the temperature is eliminated can be surely obtained.

[Example of starting the measurement after the exhaust fan rotates at the same time as the drum rotation or immediately after the drum rotation and the temperature becomes constant within the circumference of the drum]
A φ60 mm photosensitive drum was set in the measuring apparatus shown in FIG. The exhaust fan is stopped. The drum temperature was (1) one at 40 ° C. The temperature was raised from room temperature with a heater, and the temperature reached 40 ° C in 5 minutes. After confirming that the temperature was stable, the measurement start button was clicked. At the same time as the rotation of the photosensitive drum starts, the exhaust fan also rotates, and the temperature of the drum is measured with a non-contact radiation thermometer. It is programmed so that the measurement does not start while the temperature is above 1 ° C.

(result)
It took about 10 seconds for the temperature irregularity ΔT within one revolution after the rotation of the drum to be 1 ° C. or less. While the potential data was being output, there was no portion of the temperature measurement data that decreased within one revolution of the drum, and there was no portion of the potential data that decreased within one rotation.
With this configuration, since the exhaust fan rotates simultaneously with the start of drum rotation, it is not preferable for ozone removal, but it can be seen that there is a merit that measurement can be performed with a waiting time of polygon mirror rotation stabilization time +5 s.

[Exhaust fan rotates at the same time as drum rotation or immediately after drum rotation, and measurement starts after a predetermined period of time]
A φ60 mm photosensitive drum was set in the measuring apparatus shown in FIG. The exhaust fan is stopped. The drum temperature was set in two ways: (1) room temperature and (2) 40 ° C. In the case of 40 ° C., the temperature was raised with a heater from room temperature and reached 40 ° C. in 5 minutes. After confirming that the temperature was stable, the measurement start button was clicked.
At the same time as the rotation of the photosensitive drum starts, the exhaust fan also rotates, and after the start of rotation, the program is programmed so that the measurement starts after 15 seconds, including the time during which the rotation of the polygon mirror is stabilized.

(result)
While the measurement starts 15 seconds after the drum rotates and the potential data is output, in (1), there is no portion in the temperature measurement data that falls within the drum circumference, and the potential data also falls in the circle. There was no. In (2), the temperature measurement data had a portion that slightly decreased within the circumference of the drum. However, there was no portion in the potential data that decreased within one round.
With this configuration, the time until the start of measurement is uniform, but it can be seen that measurement can be performed without any problem.

[Example of a configuration in which the drum rotates in conjunction with the exhaust fan operating and when the heater starts heating]
A φ60 mm photosensitive drum was set in the measuring apparatus shown in FIG. The exhaust fan is rotating. The drum temperature was one way at 40 ° C. During the temperature increase, (1) the drum did not rotate and (2) the drum rotated at the same time as the heater was turned on. In either case, the temperature reached 40 ° C. in about 5 minutes. After confirming that the temperature was stable, the measurement start button was clicked. In both the former case where the rotation of the photosensitive drum starts after the click and the latter in which the photosensitive drum is already rotating with the heater ON (the present invention described in the above (4)), the polygon mirror is rotated. It is programmed so that the measurement starts after waiting for 5 s to be stable (same as the conventional start timing condition).

(result)
In the case of (1), while the potential data was output, the temperature measurement data had a portion that decreased within one revolution of the drum, and the potential data also had a portion that decreased within one revolution.
In the case of (2), the temperature measurement data did not have a portion that decreased within one rotation of the drum, and the potential data did not have a portion that decreased within one rotation. With the configuration (2), it can be seen that the measurement can be started immediately after the rotation of the polygon mirror is stabilized after the drum rotation starts.

(Comparative Example 1)
[Example of measurement start after a short time (5 sec) after heater ON]
Even when the heater is ON, it is programmed so that data is output almost immediately after the measurement start button is clicked (after 5 seconds have elapsed) without monitoring that the temperature indicated by the non-contact thermometer has become constant. The measurement was performed under the same conditions as in Example 1.
Table 1 is a list of Comparative Example 1 and Examples 1 to 4.

[Configuration example of rotating the exhaust fan at the same time as the drum rotation or after the drum rotation, and starting image formation after a predetermined time]
As the image forming apparatus, the RICOH Image Neo 425 and the drum chuck mechanism were remodeled, and the same heater as that used in the measuring apparatus was used inside the photosensitive drum. Also, the exhaust fan was modified to be placed near the charging roller. The exhaust fan now works when the print button is turned on. The drum temperature was 40 ° C. The temperature was raised with a heater from room temperature, and the temperature was confirmed with a contact thermometer (thermocouple) (the side cover of the device was removed). After confirming that the temperature was stable, the print button was turned on. At the same time as the rotation of the photosensitive drum started, the exhaust fan was also rotated, and after the rotation started, images were output in two ways, 3 seconds and 15 seconds later. The polygon mirror is forcibly rotated and modified so that an image can be output at any time.

(result)
In the image output 3 seconds after the drum was rotated, density unevenness was slightly observed in the circumferential direction. No uneven density in the circumferential direction was observed in the image after 15 seconds.

(Figure 2)
1 Time between the static eliminator and the charger 2 Time to the static eliminator and the exposure device (laser irradiation position) 3 Determined by the time for charging and exposure (“paper length” / linear velocity) 4 Repeat time 5 One rotation of the photoconductor Time to do

JP-A-4-324143

Claims (2)

Around the cylindrical photosensitive drum, charging means for charging at least the photosensitive member, exposure means for forming an electrostatic latent image on the photosensitive member, surface electrometer measuring means for measuring the electrostatic latent image potential, and photosensitive A neutralization unit that exposes the body surface to remove residual charges, an ozone exhaust fan that exhausts ozone generated by the charging unit, and a non-contact radiation thermometer that measures the temperature of the photoconductor are arranged on the same circumference, A drum heating heater is installed inside the photosensitive drum , and the ozone exhaust fan is arranged so that the air flow of the exhaust fan is blown directly onto the photosensitive drum, and the ozone exhaust fan is installed in the drum. so as to rotate immediately after rotation and simultaneously or drum rotation, and the measurement of the electrostatic latent image potential by the surface electrometer measuring means after the temperature indicated by the noncontact radiation thermometer becomes constant within the drum circumference Photoreceptor evaluation apparatus characterized by being configured to start. Around the cylindrical photosensitive drum, at least a charging unit that charges the photosensitive member, an exposure unit that forms an electrostatic latent image on the photosensitive member, a developing unit that uses the electrostatic latent image as a toner image, and the toner image Transfer means for transferring the toner image onto the transfer medium, fixing means for heat-fixing the toner image on the recording medium, charge eliminating means for exposing the surface of the photoreceptor to remove residual charges, and ozone generated by the charging means. an ozone exhaust fan for exhausting, a non-contact radiation thermometer for measuring the photoconductor temperature is arranged on the same circumference, inside the photosensitive drum a device drum heater is installed, the ozone exhaust fan is arranged as a stream of the exhaust fan is blown directly photosensitive drum, so as to rotate the ozone exhaust fan to the drum rotation and simultaneously or after the drum rotation, and a non-contact radiation thermometer shown Temperature image forming apparatus characterized by being configured to start image formation after reaching constant within the drum circumference.

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