JPH07311532A - Recorder - Google Patents

Abstract

PURPOSE:To control the density of image and the resist position based on the result of the detection from one sensor. CONSTITUTION:This recorder is provided with a detection pattern generating means controlling processors 2-5 prior to the start of the transfer of the image onto a paper sheet and transferring a prescribed detection pattern onto the surface of a carrying belt 8, a pattern detecting sensor 14 arranged to face the carrying belt 8 on the most downstream side along the carrying direction of the paper sheet by the carrying belt 8 and simultaneously, detecting the density of the detection pattern and the resist position on the carrying belt 8 and further, a control means controlling the processors 2-5 based on the result of the detection from the pattern detecting sensor 14, to control the density of the image transferred to the paper and the resist position to a proper state.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a recording apparatus capable of effectively performing image density control and resist position control.

[0002]

2. Description of the Related Art In a recording apparatus utilizing electrophotographic printing technology, image density control and resist position control are one of important controls. Particularly, in a recording apparatus that performs color printing, color misregistration occurs unless the resist position control for each color is performed accurately.

Conventionally, regarding the density control of an image, a density detection sensor for optically detecting a toner image formed on a photoconductor is arranged so as to face the surface of the photoconductor, and based on the detection result from the density detection sensor. By controlling each process device (charger, optical writing device, developing device, transfer device, etc.).

Further, regarding the registration position control of an image, a detection pattern is transferred onto a conveyance belt for conveying a sheet, and a registration position detection sensor for detecting the detection pattern is arranged so as to face the conveyance belt, and the registration position is adjusted. This is performed by controlling an optical writing device, which is one of the process devices, based on the detection result from the detection sensor.

[0005]

Therefore, two types of sensors, a density detecting sensor and a resist position detecting sensor, are required, and the manufacturing cost increases due to an increase in the number of parts. Furthermore, when a plurality of photoconductors are provided for performing color printing, a density detection sensor and a control circuit to which the density detection sensors are connected are required for each photoconductor, resulting in a large number of parts. The production cost will increase significantly.

Further, in the conventional example in which the density of the image is controlled by detecting the density of the toner image formed on the photosensitive member by the density detection sensor, the effect of the transfer device is not taken into consideration, but the transfer is performed. The influence of the transfer device on the image density is large, and the density control without considering the effect of the transfer device cannot be said to have sufficient accuracy.

[0007]

The invention according to claim 1 is
Various process devices for forming an image on the surface of the photoconductor and transferring the image to a sheet, and a sheet for moving the image in contact with the surface of the photoconductor and transferring the image formed on the surface of the photoconductor In a recording device having a transport belt for transporting an image, and a detection pattern generating means for controlling the process device to transfer a predetermined detection pattern to the surface of the transport belt before starting the transfer of an image onto a sheet. A pattern detection sensor which is arranged on the most downstream side of the conveyance belt along the conveyance direction of the paper so as to face the conveyance belt and detects the density of the detection pattern transferred onto the surface of the conveyance belt and the registration position. Based on the detection result from the pattern detection sensor, the process device is controlled to control the density and registration of the image transferred on the paper. It provided control means for controlling the preparative located in a proper state.

According to a second aspect of the invention, in the first aspect of the invention, a plurality of photoconductors for color printing are provided.

According to a third aspect of the present invention, in the first or second aspect of the present invention, the detection pattern has a plurality of lines formed in a direction parallel to the main scanning direction at least over the entire circumference of the photosensitive member. These lines were made to have a width capable of detecting the concentration.

According to a fourth aspect of the present invention, in the first aspect of the present invention, the density control of the image by the control means is performed by the charging device, which is one of the process devices, based on the detection result from the pattern detection sensor. Change of electric potential, change of output of optical writing device which is one of process devices, change of developing bias of developing device which is one of process devices, replenishment of toner, transfer of one of process devices The change of the transfer potential of the device is selectively combined.

[0011]

According to the first aspect of the present invention, the detection pattern generating means controls the process device prior to starting the transfer of the image onto the sheet, and the predetermined detection pattern is transferred onto the surface of the conveyor belt. Then, the density of the detection pattern and the resist position are detected by the pattern detection sensor, and the process means is controlled by the control means based on the detection result, so that the density of the image transferred onto the sheet and the resist position are in proper states. Controlled. Therefore, the image density control and the registration position control can be performed based on the detection result from the pattern detection sensor, and it is not necessary to provide two types of sensors, the image density detection sensor and the registration position detection sensor.
Furthermore, since the effect of the transfer device, which is one of the process devices, is taken into consideration for the image density control, the accuracy of the density control becomes high.

According to the second aspect of the invention, even when a plurality of photoconductors are provided to perform color printing, the density control and the resist position control for each color can be performed by providing only one pattern detection sensor, and the color misregistration can be performed. Is prevented from occurring.

According to the third aspect of the invention, the detection pattern has a plurality of lines in a direction parallel to the main scanning direction over the entire circumference of the photoconductor, so that not only the registration position adjustment of the leading edge of the image but also the entire image is performed. The registration position can be adjusted, and when the rotation irregularity of the photoconductor or the speed irregularity of the conveyor belt occurs, the image can be written at the timing to cancel the rotation irregularity. Further, since the plurality of lines have a width capable of detecting the image density, the image density control can be performed based on the detection result of the lines.

According to the fourth aspect of the present invention, the density control of the image by the control means includes changing the charging potential by the charger and changing the output of the optical writing device based on the detection result from the pattern detection sensor. This is performed by selectively combining the change of the developing bias of the developing device and the replenishment of toner with the change of the transfer potential of the transfer device.

[0015]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described with reference to the drawings. FIG. 2 shows different colors (cyan,
The schematic structure of a color copying machine, which is a recording apparatus having four photoconductor drums 1a to 1d for forming images of magenta, yellow, and black, is shown. Are the photosensitive drums 1a, respectively.
A charger 2, an optical writing device 3, a developing device 4, a transfer device 5 and the like, which are various process devices for forming an image on the surface of 1d to 1d and transferring the image to a sheet, are arranged. Further, a transfer belt 8 that moves while being in contact with the surfaces of the photoconductor drums 1a to 1d and transfers the paper fed from the paper feed tray 6 or the manual feed tray 7, and is transferred to the paper conveyed by the transfer belt 8. A fixing device 9 for fixing the formed image, a paper discharge tray 10 for discharging the paper that has passed through the fixing device 9, and the like are provided.

Next, in the color copying machine, rotation of the photosensitive drums 1a to 1d, movement of the conveyor belt 8,
A control board 11 having a large number of circuits for controlling the operations of the various process devices 2 to 5, the paper feeding operation of a paper feeding device (not shown), the display of a display unit (not shown), and the like. ,
A power supply device 12 that supplies electric power to each operating unit is provided. Further, in this color copying machine, detection pattern generating means for controlling the process devices 2 to 5 so as to transfer a predetermined detection pattern onto the surface of the conveyor belt 8 before starting the transfer of the image onto the paper. Is provided for driving the detection pattern generating circuit section 13 and the detection pattern generating circuit section 13 provided in the control board 11 and connected to the process devices 2 to 5. It is formed by the program of. The detection pattern is composed of a plurality of lines formed in the direction parallel to the main scanning direction over the entire circumference of the photosensitive drums 1a to 1d, and each line has a width capable of detecting density.

Further, in the color copying machine, it is arranged facing the conveyor belt 8 at the most downstream side in the sheet conveying direction by the conveyor belt 8 and formed on the surface of the conveyor belt 8. A pattern detection sensor 14 for detecting the density of the detection pattern and the resist position, and a detection sensor control means for controlling the pattern detection sensor 14 are provided. The detection sensor control means is formed by the detection sensor control circuit section 15 provided in the control board 11 and connected to the pattern detection sensor 14, a program for driving the detection sensor control circuit section 15, and the like. Has been done. A pair of the pattern detection sensors 14 are provided on both end sides of the conveyor belt 8 in the width direction.

Next, in the color copying machine, by controlling the process devices 2 to 5 on the basis of the detection result from the pattern detection sensor 14, the density of the image transferred onto the paper and the registration position are properly adjusted. Control means for controlling the state is provided. This control means is provided in the control board 11 and is connected to the optical writing device 2, and a control circuit part 16 is also provided in the control board 11 and is connected to the process devices 2 to 5. The circuit section 17 and a program for driving the control circuit sections 16 and 17 are formed. The control unit including the control circuit unit 16 controls the registration position of the image, and the registration position control is performed by changing the timing of starting writing by the optical writing device 3. Further, the control means including the control circuit section 17 controls the density of the image, and this density control is performed by the charger 2.
By changing the charging potential, changing the output of the optical writing device 3, changing the developing bias of the developing device 4, replenishing toner, and changing the transfer potential of the transfer device 5.

In such a structure, the detection pattern generating circuit section 13 is driven prior to starting the transfer of the image onto the sheet, the photosensitive drums 1a to 1d are rotationally driven, and the conveyor belt 8 is moved. Driven. And
By driving the detection pattern generation circuit unit 13, the detection pattern is written on the surface of each of the photoconductor drums 1a to 1d by the optical writing device 3, the written detection pattern is developed by the developing device 4, and the developed detection pattern. Is transferred onto the surface of the conveyor belt 8 by the transfer device 5.

The density and the resist position of the detection pattern transferred to the surface of the conveyor belt 8 are detected by the pattern detection sensor 14, and based on the detection result from the pattern detection sensor 14, the density of the image and the resist position are detected. The control circuit units 16 and 17 are driven to control the proper state.

First, the control circuit section 16 is driven to control the image registration position, and the image writing timing by the optical writing device 3 is adjusted as necessary. The detection pattern written on the surfaces of the photoconductor drums 1a to 1d is formed by a plurality of lines formed in the direction parallel to the main scanning direction over the entire circumference of the photoconductor drums 1a to 1d. By detecting the detection pattern transferred to the belt 8, not only the registration position adjustment of the leading edge of the image but also the registration position adjustment of the entire image can be performed. Therefore, when the rotation unevenness of the photosensitive drums 1a to 1d and the speed unevenness of the conveyor belt 8 occur, the image can be written at the timing to cancel the rotation unevenness and the speed unevenness, and the color misregistration does not occur over the entire image. A beautiful color image can be obtained.

Next, the density of the image is controlled by driving the control circuit section 17. The density control is performed by changing the charging potential by the charger 2, changing the output of the optical writing device 3, and the developing device 4. This is performed by selectively combining the change of the developing bias and the replenishment of the toner with the change of the transfer potential of the transfer device 5. Here, since the density control can be performed for all colors by the pair of pattern detection sensors 14, it is not necessary to separately provide the density detection sensor for each color as in the conventional example, and the manufacturing cost can be reduced by reducing the number of parts. . Further, this density control is performed by the transfer device 5.
Since the quality of transfer due to can be taken into consideration, extremely accurate density control can be performed.

The image density control and the resist position control described above can be performed based on the detection results of the pair of pattern detection sensors 14, and it is not necessary to separately provide the density detection sensor and the resist position detection sensor. Also,
It is possible to reduce the manufacturing cost by reducing the number of parts.

In this embodiment, the conveyor belt 8
The pair of pattern detection sensors 14 provided on both end sides in the width direction of the conveyor belt 8 has been described as an example. However, with respect to the pattern detection sensor 14, one pattern detection sensor is provided at a substantially central portion of the conveyor belt 8 in the width direction. The sensor 14 may be provided.

In this embodiment, a color copying machine provided with four photoconductor drums 1a to 1d has been described as an example, but the present invention is applied to a recording apparatus having only one photoconductor. It is also effective when you do.

[0026]

As described above, according to the present invention, various process devices for forming an image on the surface of a photoconductor and transferring the image onto a sheet of paper, and moving in a state of being in contact with the surface of the photoconductor. In addition, in a recording apparatus having a conveyance belt that conveys a sheet on which an image formed on the surface of the photoconductor is transferred, the process apparatus is controlled by a predetermined amount before starting the transfer of the image onto the sheet. Detection pattern generating means for transferring the detection pattern of the above to the surface of the conveyor belt, and on the surface of the conveyor belt, which is arranged facing the conveyor belt at the most downstream side along the conveying direction of the paper by the conveyor belt. A pattern detection sensor for detecting the density and resist position of the transferred detection pattern, and the process based on the detection result from the pattern detection sensor. Since the control means for controlling the apparatus to control the density of the image transferred to the paper and the resist position to an appropriate state is provided, the image density control and the resist position control are detected by one pattern detection sensor. Therefore, since it is not necessary to separately provide the density detection sensor and the resist position detection sensor, it is possible to reduce the manufacturing cost by reducing the number of parts. Can be performed in consideration of the influence of the transfer device, which is one of the process devices, and therefore has the effect of enabling extremely accurate density control.

According to the second aspect of the invention, as described above, in the first aspect of the invention, since a plurality of photoconductors for color printing are provided, images of different colors are formed on the plurality of photoconductors. Even when color printing is performed by forming, it is not necessary to provide a density detection sensor for each photoconductor, and only one pattern detection sensor can detect density for all colors. The number of points can be significantly reduced, and the manufacturing cost can be significantly reduced.

As described above, the invention according to claim 3 is the same as the invention according to claim 1 or 2, wherein the detection patterns are formed in a direction parallel to the main scanning direction over at least the entire circumference of the photosensitive member. Since the lines are provided and the lines have a width capable of detecting the density, not only the registration position adjustment of the leading edge of the image but also the registration position adjustment of the entire image can be performed. If there is unevenness in the speed of the conveyor belt or the conveyor belt, the image can be written at the timing to cancel the unevenness in rotation, so that even if unevenness in the rotation of the photoconductor occurs, a partially expanded or contracted image It is possible to prevent the occurrence of color misregistration over the entire image especially when performing color printing. In addition, since a plurality of lines with possible image density detection width, an effect such as can be performed density control of an image on the basis of the detection result of the line.

As described above, in the invention according to claim 4, in the invention according to claim 1, the image density control by the control means is performed based on the detection result from the pattern detection sensor.
Changing the charging potential by the charger, which is one of the process devices, changing the output of the optical writing device, which is one of the process devices, changing the developing bias of the developing device, which is one of the process devices, and changing the toner. Since the replenishment and the change of the transfer potential of the transfer device, which is one of the process devices, are selectively combined, there is an effect that the density control in the most effective state can be performed.

[Brief description of drawings]

FIG. 1 is a block diagram showing a control system for image density control and resist position control according to an embodiment of the present invention.

FIG. 2 is a front view showing a schematic structure of a color copying machine.

[Explanation of symbols]

 1a to 1d Photoconductor 2 process device, charger 3 process device, optical writing device 4 process device, developing device 5 process device, transfer device 8 conveyor belt 14 pattern detection sensor

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Internal reference number FI Technical display location G03G 15/01 113 A 114 Z 15/02 102 15/16 103

Claims (4)

[Claims] 1. A process apparatus for forming an image on a surface of a photoconductor and transferring the image onto a sheet, and an image formed on the surface of the photoconductor while moving while being in contact with the surface of the photoconductor. In a recording device having a conveyance belt that conveys a sheet on which the image is transferred, the process device is controlled to transfer a predetermined detection pattern onto the surface of the conveyance belt before starting the transfer of the image onto the sheet. The detection pattern generating means and the density of the detection pattern transferred to the surface of the conveyor belt and the registration position are arranged so as to face the conveyor belt at the most downstream side in the conveying direction of the paper by the conveyor belt. An image to be transferred onto a sheet by controlling the process device based on the pattern detection sensor for detecting and the detection result from the pattern detection sensor. And a control means for controlling the density and the resist position of the toner to an appropriate state. 2. A recording apparatus according to claim 1, further comprising a plurality of photoconductors for color printing. 3. The detection pattern has a plurality of lines formed in a direction parallel to the main scanning direction over at least the entire circumference of the photoconductor, and these lines have a width capable of density detection. The recording device according to claim 1 or 2. 4. The density control of the image by the control means is based on the detection result from the pattern detection sensor, the charging potential is changed by the charger which is one of the process devices, and the optical writing which is one of the process devices. The output of the charging device is changed, the developing bias of the developing device, which is one of the process devices, the supply of toner, and the transfer potential of the transfer device, which is one of the process devices, are selectively combined. The recording apparatus according to claim 1, wherein the recording apparatus is configured as described above.