JP2005148333A - Image forming apparatus, resistance value measuring method for intermediate transfer belt and image forming method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image forming apparatus capable of shortening the warm-up time or the like by decreasing the rotational amount of an intermediate transfer belt at resistance measuring time for controlling transfer voltage, and a resistance value measuring method for the intermediate transfer belt and an image forming method. <P>SOLUTION: The image forming apparatus 1 has respective color image forming units 20 along the intermediate transfer belt 10. In measuring the resistance value of the belt 10 in order to control the transfer voltage at image forming time, sampling is started simultaneously at the position of a primary transfer device 26K and the position of a primary transfer device 26Y. Then, the part of the belt 10 where a spot existing at the position of the device 26Y at the starting time of the sampling reaches the position of the device 26K is sampled at the position of the device 26K. The other part is sampled at the position of the device 26Y. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to an image forming apparatus such as a copying machine or a printer, a method for measuring a resistance value of an intermediate transfer belt performed for controlling the image formation, and an image forming method using the image forming apparatus. More specifically, the present invention relates to a tandem color image forming apparatus, an intermediate transfer belt resistance value measuring method, and an image forming method.

  Conventionally, a tandem type color image forming apparatus in which image forming units of respective colors are arranged along an intermediate transfer belt is known. In such an image forming apparatus, in order to keep the transfer performance of a plurality of primary transfer units and secondary transfer units constant regardless of environmental changes, the electrical characteristics of the transfer site such as an intermediate transfer belt are detected at appropriate times. doing. This is because the electrical characteristics of the intermediate transfer belt and the like change due to environmental changes and durability variations. Then, using the result, control is performed to determine a transfer voltage to be applied to each transfer portion during image formation. For this purpose, the resistance value of the intermediate transfer belt is obtained by supplying a predetermined current value to each transfer portion during warm-up and detecting the voltage value applied at that time (for example, patent Reference 1, Reference 2).

In general, the detection of the voltage value is performed for the entire circumference of the intermediate transfer belt, and the average value is used. This is because the belt thickness and composition are somewhat uneven, and appropriate control may not be possible with partial detection. However, it takes a very long time if the intermediate transfer belt is rotated once for each detection at each primary transfer portion. Therefore, for example, in the image forming apparatus described in Patent Document 1, the voltage value is simultaneously detected at the primary transfer portion of each image forming unit. Alternatively, in the image forming apparatus described in Patent Document 2, control for determining transfer voltages applied to transfer members that are not adjacent to each other is simultaneously performed.
JP 2001-125338 A (page 5-6) JP 2001-356541 A (Page 5)

  However, in any of the above-described conventional image forming apparatuses, the intermediate transfer belt is rotated at least one turn in order to obtain the resistance value of the entire intermediate transfer belt during warm-up. The intermediate transfer belt has a useful life determined by the cumulative number of rotations, and repeating the rotation for purposes other than image formation causes a shortened life. Furthermore, the time required for this rotation operation accounts for a large part of the warm-up time. For these reasons, there has been a demand to reduce the amount of rotation of the intermediate transfer belt during warm-up as much as possible.

  The present invention has been made to solve the problems of the conventional image forming apparatus described above. That is, the problem is that an image forming apparatus capable of reducing the rotation amount of the intermediate transfer belt at the time of resistance measurement for transfer voltage control and shortening the warm-up time and the resistance value measuring method of the intermediate transfer belt. An image forming method is provided.

  An image forming apparatus of the present invention, which has been made for the purpose of solving this problem, corresponds to each of a rotating intermediate transfer belt, a plurality of image forming units arranged along the intermediate transfer belt, and a plurality of image forming units. An image forming apparatus for transferring the images respectively formed by the plurality of image forming units onto the intermediate transfer belt by using the transfer members, Among them, a first resistance measuring unit that measures the resistance value of the intermediate transfer belt using the upstream one in the running direction of the intermediate transfer belt, and a downstream side in the running direction of the intermediate transfer belt among the plurality of image forming units and transfer members A second resistance measuring means for measuring the resistance value of the intermediate transfer belt using the above-mentioned belt, and a sampling means for sampling the resistance value by the first resistance measuring means and the second resistance measuring means. The sampling means performs sampling by the first resistance measuring means until the portion of the intermediate transfer belt that was at the measurement position by the second resistance measurement means at the start of sampling reaches the measurement position by the first resistance measurement means. Sampling by the second resistance measuring means is performed until the portion of the intermediate transfer belt that was at the measurement position by the first resistance measuring means at the start of sampling reaches the measurement position by the second resistance measuring means.

  According to the image forming apparatus of the present invention, since there are a plurality of image forming portions and transfer members along the intermediate transfer belt, different ones (first resistance measuring means and second resistance measuring means) are used. Thus, the resistance values at different positions of the intermediate transfer belt are simultaneously measured. Here, according to the sampling means, the sampling until the position at the measurement position by the second resistance measurement means at the start of sampling in the intermediate transfer belt reaches the measurement position by the first resistance measurement means is the first resistance measurement means. Sampling is performed by the second resistance measuring means until the portion of the intermediate transfer belt that was at the measurement position by the first resistance measuring means at the start of sampling reaches the measurement position by the second resistance measuring means. That is, if the sampling intervals performed by the first resistance measuring means and the second resistance measuring means are summed, the entire sampling of the intermediate transfer belt is sampled. Accordingly, if the sampling of the longer one of the sections is performed while the other sampling is finished, it is not necessary to make the intermediate transfer belt make one round. As a result, the amount of rotation of the intermediate transfer belt during resistance measurement for transfer voltage control can be reduced, and the warm-up time and the like can be shortened.

The present invention further includes representative resistance value calculation means for calculating a representative resistance value for the entire intermediate transfer belt based on the resistance value sampled by the sampling means, and the representative resistance value calculated by the representative resistance value calculation means. It is desirable to use the value for transfer voltage control during image formation.
In this way, the representative resistance value for the entire intermediate transfer belt is used in the transfer voltage control during image formation.

  The present invention further includes a rotating intermediate transfer belt, a plurality of image forming units disposed along the intermediate transfer belt, and a transfer member provided corresponding to each of the plurality of image forming units. A method for measuring a resistance value of an intermediate transfer belt in an image forming apparatus that superimposes and transfers an image formed by each of the image forming units onto the intermediate transfer belt by each transfer member. A first resistance measuring unit that measures the resistance value of the intermediate transfer belt using an upstream one in the belt running direction, and a plurality of image forming units and transfer members that are downstream in the running direction of the intermediate transfer belt. Second resistance measuring means for measuring the resistance value of the intermediate transfer belt, and sampling by the first resistance measuring means for measuring the second resistance at the start of sampling of the intermediate transfer belt. Until the position at the measurement position by the means reaches the measurement position by the first resistance measurement means, and sampling by the second resistance measurement means is performed at the measurement position by the first resistance measurement means at the start of sampling of the intermediate transfer belt. This also extends to the method of measuring the resistance value of the intermediate transfer belt, which is performed until the spot reaches the measurement position by the second resistance measuring means.

  The present invention further includes a rotating intermediate transfer belt, a plurality of image forming units disposed along the intermediate transfer belt, and a transfer member provided corresponding to each of the plurality of image forming units. An image forming method in an image forming apparatus for transferring an image formed by each of the image forming portions on an intermediate transfer belt by each transfer member, wherein the image forming portion and the transfer member are arranged in a running direction of the intermediate transfer belt. A first resistance measuring means for measuring the resistance value of the intermediate transfer belt using the upstream one, and an intermediate transfer belt using a plurality of image forming units and transfer members downstream in the running direction of the intermediate transfer belt The second resistance measuring means for measuring the resistance value of the intermediate transfer belt, and the sampling position by the second resistance measuring means at the start of sampling of the intermediate transfer belt. Until the position reached by the first resistance measuring means reaches the position measured by the first resistance measuring means, and sampling by the second resistance measuring means is performed. The measurement is performed until the measurement position is reached by the second resistance measuring means, and the representative resistance value for the entire intermediate transfer belt is calculated based on the sampled resistance value, and the transfer voltage control is performed based on the calculated representative resistance value. It extends to image forming methods.

  According to the image forming apparatus, the intermediate transfer belt resistance measurement method, and the image formation method of the present invention, the rotation amount of the intermediate transfer belt during resistance measurement for transfer voltage control is reduced, and the warm-up time and the like are shortened. be able to.

  DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the best mode for embodying the present invention will be described in detail with reference to the accompanying drawings. In this embodiment, the present invention is applied to a tandem color image forming apparatus.

  The image forming apparatus 1 according to the present embodiment is a tandem color printer as shown in FIG. The intermediate transfer belt 10 is wound around three rollers 11, 12, and 13 and rotated in the direction of the arrow in the figure. In addition, image forming units 20Y, 20M, 20C, and 20K for each color of YMCK are arranged along the intermediate transfer belt 10. The image forming units 20Y, 20M, 20C, and 20K for the respective colors have the same configuration, and a charging device 22, an exposure device 23, a developing device 24, and a cleaner device 25 are disposed around each photosensitive drum 21. It is a thing. Here, the subscript YMCK of each color is omitted.

  Further, primary transfer devices 26Y, 26M, 26C, and 26K for the respective colors are arranged to face the image forming units 20Y, 20M, 20C, and 20K for the respective colors with the intermediate transfer belt 10 interposed therebetween. Further, a secondary transfer device 27 is provided on the right side of the drawing, and a belt cleaner device 28 is provided on the left side of the drawing. Since all the above configurations are general, the details are omitted.

  Next, FIG. 2 shows an outline of the electrical configuration of the primary transfer devices 26Y, 26M, 26C, 26K, and the secondary transfer device 27. In the image forming apparatus 1 of the present embodiment, as shown in FIG. 2, one common high voltage power supply (HV) 31 is connected to the three primary transfer devices 26Y, 26M, and 26C. A high voltage power source 32 is connected to the primary transfer device 26K, and a high voltage power source 33 is connected to the secondary transfer device 27. Further, the high voltage power supply 31 and the high voltage power supply 32 are connected to and controlled by the CPU 34. Further, a switch 35 is connected between the high-voltage power supply 31 and the primary transfer device 26M.

  The high-voltage power supplies 31 and 32 supply predetermined transfer voltages to the primary transfer devices 26Y, 26M, 26C, and 26K under the control of the CPU 34. The high voltage power supply 33 supplies a transfer voltage to the secondary transfer device 27. These high-voltage power supplies 31, 32, and 33 can perform voltage control such that a specified current value flows or voltage control that applies a predetermined voltage. Here, the reason why only black (K) is a separate power source among the four colors is that the black toner has slightly different electrical properties from the other three colors of toner.

  The CPU 34 controls the entire image forming apparatus 1. The switch 35 can apply the voltage of the high-voltage power supply 31 only to the primary transfer device 26Y by switching. Alternatively, it can be applied to all of the primary transfer devices 26Y, 26M, and 26C. Although only the switch 35 is shown in FIG. 2, a configuration in which the voltage generated by the high-voltage power supply 31 can be selectively applied to any of the primary transfer devices 26Y, 26M, and 26C is also possible. .

  Next, a color image forming operation by the image forming apparatus 1 will be described briefly. First, the respective color toner images are formed on the respective photosensitive drums 21Y, 21M, 21C, and 21K by the respective color image forming units 20Y, 20M, 20C, and 20K. The toner images on the photosensitive drums 21Y, 21M, 21C, and 21K are sequentially transferred to the same position on the intermediate transfer belt 10 by the primary transfer devices 26Y, 26M, 26C, and 26K, and are superimposed. Thereafter, a sheet is supplied between the roller 12 and the secondary transfer device 27, and the superimposed toner image is transferred to the sheet by the secondary transfer device 27.

  Here, in order to improve the transfer performance of the primary transfer devices 26Y, 26M, 26C, and 26K, transfer voltage control processing is performed. That is, the transfer current flowing between the primary transfer devices 26Y, 26M, 26C, and 26K and the photosensitive drums 21Y, 21M, 21C, and 21K is the optimum transfer current regardless of environmental changes, durability variations, and the like. Thus, the high voltage power supplies 31 and 32 are controlled. This corresponds to the fact that the electrical properties of the members related to the transfer such as the intermediate transfer belt 10 fluctuate due to environmental changes or the like.

  For this purpose, the state detection process is performed at the time of warm-up or after a predetermined number of images are formed, and the applied transfer voltage determination process at the time of image formation is performed based on the result. In general, the detection process is performed by controlling the high-voltage power supply (constant current control) so that a specified current value flows through the transfer device, and detecting the voltage value applied at that time. Alternatively, on the contrary, a specified voltage value may be applied and a current value passed may be measured. Thus, the electric resistance value in the transfer section is calculated, and the applied voltage for supplying an appropriate transfer current is determined by the determination process based on the resistance value.

  Since the image forming apparatus 1 includes both the high-voltage power supplies 31 and 32, the high-voltage power supply 31 and the high-voltage power supply 32 are connected to the primary transfer device 26Y and the primary transfer device 26K so that the specified current values flow respectively. Can be controlled simultaneously. At the same time, each voltage value can be detected. Here, the primary transfer devices 26Y, 26M, 26C, and 26K for the respective colors are all formed of the same material and the same size, and their electrical properties are substantially the same. That is, the electrical unevenness of each primary transfer device 26Y, 26M, 26C, 26K is much smaller than the change in the resistance value of the intermediate transfer belt 10. Therefore, the detection result under substantially the same condition can be obtained by the combination of the high voltage power supply 31 and the primary transfer device 26Y and the combination of the high voltage power supply 32 and the primary transfer device 26K.

  Therefore, different portions of the intermediate transfer belt 10 are measured simultaneously at these two locations. That is, since the intermediate transfer belt 10 is rotated as indicated by an arrow in FIG. 2, the primary transfer device 26 </ b> Y includes the portions initially spanned on the rollers 11, 13, and 12 at the position of the primary transfer device 26 </ b> Y. The intermediate transfer belt 10 up to the portion at the position of 26K is detected by the high voltage power supply 31. At the same time, at the position of the primary transfer device 26K, the intermediate transfer belt 10 from the portion initially located at the primary transfer device 26K to the portion located at the primary transfer device 26Y is detected by the high voltage power source 32. . That is, by detecting at these two locations simultaneously, the detection process for one round can be performed without making the intermediate transfer belt 10 make one round.

  Next, the contents of this detection process will be described with reference to the flowchart of FIG. When this process is started, first, the rotation of the intermediate transfer belt 10 is started by the rollers 11, 12, and 13 (S101). Next, the CPU 34 controls the high-voltage power supplies 31 and 32 at a constant current so that a specified current value flows through the primary transfer devices 26Y and 26K (S102). Then, sampling of both voltage values applied to the high voltage power supplies 31 and 32 is started (S103). The state at this time is shown in FIG. In this figure, a position Y indicates a contact position between the primary transfer device 26Y and the photosensitive drum 21Y, and a position K indicates a contact position between the primary transfer device 26K and the photosensitive drum 21K. A section A indicates a portion of the intermediate transfer belt 10 between the position Y and the position K.

  Next, it is determined whether or not the intermediate transfer belt 10 at the contact point between the primary transfer device 26Y and the photosensitive drum 21Y at the start of sampling has been rotated to the contact point between the primary transfer device 26K and the photosensitive drum 21K ( S104). When it is determined that the rotation has been performed (S104: Yes), the constant current control of the primary transfer device 26K by the high voltage power source 32 and the sampling of the high voltage power source 32 are stopped (S105). At this time, the intermediate transfer belt 10 has reached the position shown in FIG. In the section A in FIG. 5, sampling is completed by the measurement at the position K. Alternatively, if it is determined in S104 that the rotation has not been made (S104: No), sampling is further continued.

  Next, it is determined whether or not the intermediate transfer belt 10 at the contact point between the primary transfer device 26K and the photosensitive drum 21K at the start of sampling has been rotated to the contact point between the primary transfer device 26Y and the photosensitive drum 21Y ( S106). If it is determined that it has not been rotated so far (S106: No), the process returns to S103 to continue sampling. Alternatively, if it is determined that the rotation has been completed (S106: Yes), the constant current control of the primary transfer device 26Y by the high voltage power source 31 and the sampling of the high voltage power source 31 are stopped (S107). At this time, the intermediate transfer belt 10 has reached the position shown in FIG. Then, the sampling of the portion other than the section A is completed by the measurement at the position Y.

  As a result, the sampling of the entire intermediate transfer belt 10 for one round is completed, and the driving of the intermediate transfer belt 10 is stopped (S108). Then, all the data sampled in S103 are averaged (S109). The average value obtained in S109 is the representative resistance value, and is stored in the RAM of the CPU 34 (S110). This completes the detection process. At the time of image formation, an appropriate transfer voltage is determined using the data stored in S110.

  As described above in detail, according to the image forming apparatus 1 of the present embodiment, the high-voltage power supply 31 can control the primary transfer device 26Y, and the high-voltage power supply 32 can control the primary transfer device 26K simultaneously. Therefore, by performing the detection process for one rotation of the intermediate transfer belt 10 at these two locations and performing them simultaneously, the intermediate transfer belt 10 has the portion that was at the position of the image forming unit 20K positioned at the position of the image forming unit 20Y. Rotate until it reaches. Accordingly, the rotation amount of the intermediate transfer belt at the time of resistance measurement for transfer voltage control can be reduced, and the warm-up time can be shortened.

Note that this embodiment is merely an example, and does not limit the present invention. Therefore, the present invention can naturally be improved and modified in various ways without departing from the gist thereof.
For example, each configuration other than the transfer device shown in FIG. 1 is an example, and the present invention can be applied to any tandem image forming apparatus having an intermediate transfer belt.
Further, for example, the order of each color is not limited to this.

1 is a block diagram illustrating a schematic configuration of an image forming apparatus according to an embodiment. It is a block diagram which shows the electrical structure of a transfer apparatus. It is a flowchart figure which shows a detection process. It is explanatory drawing which shows the state in measurement. It is explanatory drawing which shows the state in measurement. It is explanatory drawing which shows the state in measurement.

Explanation of symbols

1 Image forming apparatus 10 Intermediate transfer belt 20Y, 20M, 20C, 20K Image forming unit (image forming unit)
26Y, 26M, 26C, 26K Primary transfer device (transfer member)
31 High-voltage power supply (second resistance measurement means)
32 High-voltage power supply (first resistance measurement means)
34 CPU (sampling means, representative resistance value calculating means)

Claims (4)

A rotating intermediate transfer belt; a plurality of image forming portions arranged along the intermediate transfer belt; and a transfer member provided corresponding to each of the plurality of image forming portions. In the image forming apparatus for superimposing and transferring the images respectively formed in the forming unit on the intermediate transfer belt by each transfer member,
First resistance measuring means for measuring a resistance value of the intermediate transfer belt using an upstream one of the plurality of image forming units and the transfer member in the traveling direction of the intermediate transfer belt;
Second resistance measuring means for measuring a resistance value of the intermediate transfer belt using a downstream one of the plurality of image forming units and the transfer member in the traveling direction of the intermediate transfer belt;
Sampling means for sampling the resistance value by the first resistance measuring means and the second resistance measuring means;
The sampling means includes
Sampling by the first resistance measuring unit is performed until a portion of the intermediate transfer belt that is at the measurement position by the second resistance measuring unit at the start of sampling reaches the measurement position by the first resistance measuring unit;
Sampling by the second resistance measuring means is performed until a portion of the intermediate transfer belt that was at the measurement position by the first resistance measuring means at the start of sampling reaches the measurement position by the second resistance measuring means. An image forming apparatus. The image forming apparatus according to claim 1,
Representative resistance value calculating means for calculating a representative resistance value for the entire intermediate transfer belt based on the resistance value sampled by the sampling means;
An image forming apparatus, wherein the representative resistance value calculated by the representative resistance value calculating means is used for transfer voltage control during image formation. A rotating intermediate transfer belt; a plurality of image forming portions arranged along the intermediate transfer belt; and a transfer member provided corresponding to each of the plurality of image forming portions. A method of measuring a resistance value of an intermediate transfer belt in an image forming apparatus that superimposes and transfers an image formed by a forming unit onto the intermediate transfer belt by each transfer member,
First resistance measuring means for measuring a resistance value of the intermediate transfer belt using an upstream one of the plurality of image forming units and the transfer member in the traveling direction of the intermediate transfer belt;
A second resistance measuring unit that measures a resistance value of the intermediate transfer belt using a downstream one of the plurality of image forming units and the transfer member in the traveling direction of the intermediate transfer belt;
Sampling by the first resistance measuring unit is performed until a portion of the intermediate transfer belt that is at the measurement position by the second resistance measuring unit at the start of sampling reaches the measurement position by the first resistance measuring unit;
Sampling by the second resistance measuring unit is performed until a portion of the intermediate transfer belt that is at the measurement position by the first resistance measuring unit at the start of sampling reaches the measurement position by the second resistance measuring unit. A method for measuring the resistance value of the intermediate transfer belt. A rotating intermediate transfer belt; a plurality of image forming portions arranged along the intermediate transfer belt; and a transfer member provided corresponding to each of the plurality of image forming portions. An image forming method in an image forming apparatus for superimposing and transferring an image formed by a forming unit on each intermediate transfer belt by each transfer member,
First resistance measuring means for measuring a resistance value of the intermediate transfer belt using an upstream one of the plurality of image forming units and the transfer member in the traveling direction of the intermediate transfer belt;
A second resistance measuring unit that measures a resistance value of the intermediate transfer belt using a downstream one of the plurality of image forming units and the transfer member in the traveling direction of the intermediate transfer belt;
Sampling by the first resistance measuring unit is performed until a portion of the intermediate transfer belt that is at the measurement position by the second resistance measuring unit at the start of sampling reaches the measurement position by the first resistance measuring unit;
Sampling by the second resistance measuring means is performed until a portion of the intermediate transfer belt that was at the measurement position by the first resistance measuring means at the start of sampling reaches the measurement position by the second resistance measuring means,
Based on the sampled resistance value, a representative resistance value for the entire intermediate transfer belt is calculated,
An image forming method, wherein transfer voltage control is performed based on a calculated representative resistance value.

Images