JP2004054016A - Color image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a color image forming apparatus capable of controlling density or color, and also, capable of detecting transfer-jamming and a residual paper, even though the apparatus has a small-sized and inexpensive constitution wherein the number of the whole sensors is reduced. <P>SOLUTION: A color sensor 29 for reading a patch pattern formed on a transfer material 2 in order to control the density or the color is used also as a sensor for detecting the presence or absence of the transfer material 2, and transfer-jamming is detected based on whether or not the transfer material is detected by this sensor at a prescribed timing. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a color image forming apparatus such as a color printer and a color copying machine, and more particularly to a color image forming apparatus having a sensor (hereinafter, referred to as a color sensor) for detecting a color of a patch on a transfer material.
[0002]
[Prior art]
2. Description of the Related Art In recent years, a color image forming apparatus employing an electrophotographic method, an ink jet method, or the like, such as a color printer or a color copying machine, has been required to have high quality output images. In particular, the gradation of the density and its stability greatly affect the judgment of the quality of an image made by a human.
[0003]
However, in a color image forming apparatus, if there is a change in each part of the apparatus due to a change in environment or long-term use, the density of an obtained image fluctuates. In particular, in the case of an electrophotographic color image forming apparatus, it is necessary to have a means for always maintaining a constant density-gradation characteristic, since even a slight environmental change may cause a change in density and a color balance may be lost. .
[0004]
Therefore, for each color toner, there are several kinds of process conditions such as exposure amount and developing bias according to the absolute humidity, and gradation correction means such as a look-up table (LUT). , The process condition at that time and the optimum value of the gradation correction are selected. In addition, a toner patch for density detection is formed on an intermediate transfer member or a drum with toner of each color so that a constant density-gradation characteristic can be obtained even if a change in each unit of the apparatus occurs. The density of the unfixed toner is detected by a density detection sensor for unfixed toner (hereinafter referred to as density sensor), and based on the detection result, feedback is given to the process conditions such as the exposure amount and the developing bias, and the density is controlled, thereby providing a stable image It is configured to obtain.
[0005]
However, in the density control using the density sensor, a patch is formed and detected on an intermediate transfer body or a drum, and a change in the color balance of an image due to transfer and fixing to a transfer material performed thereafter is controlled. I haven't. The color balance also changes depending on the transfer efficiency of the transfer of the toner image to the transfer material and the heating and pressurization due to fixing. This change cannot be handled by the density control using the density sensor.
[0006]
Therefore, a gray patch of black (K) and a process gray patch of a mixture of cyan (C), magenta (M), and yellow (Y) are formed on the transfer material, and the colors of both patches are relatively compared after fixing. A color image forming apparatus provided with a sensor (color sensor) for detecting a color of a patch on a transfer material, which can output a mixture ratio of CMY in which a process gray patch becomes achromatic has been considered.
[0007]
In this color image forming apparatus, a detected result is converted into a color matching table for converting an RGB signal of an image processing unit into a color reproduction range of the color image forming apparatus, and an RGB signal to a CMYK signal. The density or chromaticity of the final output image formed on the transfer material can be controlled by feeding back to a color separation table, a calibration table for correcting density-gradation characteristics, and the like.
[0008]
The same control can be performed by detecting the output image of the color image forming apparatus with an external image reading device or a chromaticity meter or a densitometer, and this method is excellent in that the control is completed in the printer. . This color sensor uses, for example, three or more light sources having different emission spectra such as red (R), green (G), and blue (B) as light emitting elements, or a light source that emits white (W) light. , And three or more filters having different spectral transmittances such as red (R), green (G), and blue (B) are formed on the light receiving element. As a result, three or more different outputs such as RGB outputs can be obtained.
[0009]
Even in the ink jet type printer, the color balance changes due to the temporal change of the ink discharge amount, environmental difference, and individual difference of the ink cartridge, and the density-gradation characteristic cannot be kept constant. Therefore, it has been considered to install a color sensor near the output unit of the printer, detect the density or chromaticity of the patch on the transfer material, and control the density or chromaticity.
[0010]
[Problems to be solved by the invention]
However, in the conventional color image forming apparatus, in addition to the color sensor, a jam detection sensor for detecting a transfer material conveyance jam or a residual transfer material in the machine is required. This leads to an increase in the size and cost of the image forming apparatus, resulting in a problem of lowering the commercial value of the color image forming apparatus.
[0011]
SUMMARY OF THE INVENTION The present invention has been made under such a situation, and performs density or chromaticity control while detecting a conveyance jam and a residual paper detection while having a small and inexpensive configuration in which the number of sensors of the entire apparatus is reduced. It is an object of the present invention to provide a color image forming apparatus capable of performing the following.
[0012]
Means and action for solving the problem
To achieve the above object, the color image forming apparatus of the present invention is configured as in the following (1) to (9).
[0013]
(1) a color sensor that reads a patch pattern formed on a transfer material;
Detecting means for detecting the presence or absence of a transfer material at the mounting position of the color sensor using the color sensor,
A color image forming apparatus comprising:
[0014]
(2) In the color image forming apparatus according to (1),
The color image forming apparatus, wherein the detecting unit detects the presence or absence of the transfer material based on whether or not the reflected light of the transfer material is detected by the color sensor.
[0015]
(3) an image forming unit;
Conveying means for conveying the transfer material,
A color sensor that reads a patch pattern formed on the transfer material,
Detecting means for detecting the presence or absence of a transfer material at the mounting position of the color sensor using the color sensor,
At the time of transfer material transfer by the transfer unit, a transfer jam determination unit that determines that a transfer jam has occurred based on the result of the presence or absence detection of the transfer material by the detection unit at a predetermined timing,
Notifying means for notifying the user of the occurrence of a transport jam;
Control means for stopping the operations of the image forming means and the transport means when the transport jam determination means determines that a transport jam has occurred, and controlling the notification means to notify the user of the occurrence of the transport jam; and ,
A color image forming apparatus comprising:
[0016]
(4) In the color image forming apparatus according to (3),
Media determination means for determining whether the transfer material is an OHT sheet,
The transport jam determining unit determines, when the media determining unit determines that the transfer material is an OHT sheet, that a transport jam has not occurred regardless of the result of the presence / absence detection of the transfer material at a predetermined timing. Image forming device.
[0017]
(5) In the color image forming apparatus according to (3),
Media determination means for determining whether the transfer material is an OHT sheet,
The control means controls the image forming means to forcibly form a mark image on the transfer material when the medium determining means determines that the transfer material is an OHT sheet;
The detecting means detects the presence or absence of the transfer material based on whether the mark image formed on the transfer material is read by the color sensor when the medium determining means determines that the transfer material is an OHT sheet. Color image forming device.
[0018]
(6) In the color image forming apparatus according to (4) or (5),
The color image forming apparatus, wherein the media determination unit determines whether the sheet is an OHT sheet based on a setting by a user.
[0019]
(7) In the color image forming apparatus according to (4) or (5),
The color image forming apparatus according to claim 1, wherein the medium determination unit determines whether the transfer material is an OHT sheet based on a detection result of an OHT sensor that detects whether the transfer material is an OHT sheet.
[0020]
(8) a color sensor for reading a patch pattern formed on the transfer material;
Detecting means for detecting the presence or absence of a transfer material at the mounting position of the color sensor using the color sensor,
When power is turned on, or when the door is closed, the presence / absence of a transfer material is detected by the detection unit, and a remaining paper presence / absence determination unit that determines whether there is any remaining paper based on the detection result,
Notification means for notifying the user that there is residual paper;
Control means for controlling the notifying means to notify the user of the presence of the residual paper when the residual paper presence / absence determining means determines that there is residual paper;
A color image forming apparatus comprising:
[0021]
(9) In the color image forming apparatus according to any one of (1) to (8),
A color image forming apparatus in which the color sensor is disposed between a fixing device and a paper discharge port.
[0022]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described in detail with reference to examples of a color image forming apparatus.
[0023]
【Example】
(Example 1)
First Embodiment A “color image forming apparatus” according to a first embodiment will be described. This embodiment is an example in which a color sensor is used to determine the presence or absence of a transfer material at a location where the color sensor is disposed on the transfer material transport path, and the presence or absence of the transfer material is determined at a predetermined timing to detect a jam. It is.
[0024]
FIG. 1 is a sectional view showing the configuration of the “color image forming apparatus” of the present embodiment. In FIG. 1, 1 is a paper feed cassette, 2 is a transfer material, 3 is an MP tray, 4 is a density detection sensor, 5Y, 5M, 5C, and 5K are photosensitive drums, 6 is a registration detection sensor, 7Y, 7M, 7C, 7K is a charger, 7YS, 7MS, 7CS and 7KS are charging sleeves, 8Y, 8M, 8C and 8K are developing devices, 8YS, 8MS, 8CS and 8KS are developing sleeves, 9a and 9b are secondary transfer rollers, 10Y and 10M. , 10C and 10K are scanner units, 11Y, 11M, 11C and 11K are toner cartridges, 12 is an intermediate transfer member, 13 is a fixing unit, 14 is a fixing roller, 15 is a pressing roller, 16 and 17 are heaters, and 18 is an intermediate unit. Transfer member driving roller, 19 is a pre-registration sensor, 20 is a fixing unit discharge sensor, 21 is a cleaner unit, 22Y, 22M, 22C, and 22K are developing cartridges, 23, 24, 25, and 26. Feeding sensor, the sensor front fixing portion 27, the sheet discharge sensor 28, the color sensor 29, 30 OHT sensor, 31 is a pre-registration roller.
[0025]
The photoconductor drums (photoconductors) 5Y, 5M, 5C, and 5K are formed by applying an organic photoconductive layer to an outer periphery of an aluminum cylinder, and are rotated by transmitting a driving force of a driving motor (not shown). The motor rotates the photosensitive drums 5Y, 5M, 5C, 5K in a counterclockwise direction according to the image forming operation. Exposure light to the photoconductor drums 5Y, 5M, 5C, and 5K is sent from the scanner units 10Y, 10M, 10C, and 10K, and selectively exposes the surfaces of the photoconductor drums 5Y, 5M, 5C, and 5K, thereby providing static exposure. It is configured so that an electrostatic latent image is formed.
[0026]
As primary charging means, four injection chargers 7Y, 7M, 7C, 7K for charging the yellow (Y), magenta (M), cyan (C), and black (K) photoconductors are provided for each station. In the configuration, each injection charger is provided with a sleeve 7YS, 7MS, 7CS, 7KS.
[0027]
As developing means, four developing units 8Y and 8M for developing yellow (Y), magenta (M), cyan (C) and black (K) for each station in order to visualize the electrostatic latent image. , 8C, and 8K, and each developing unit is provided with a sleeve 8YS, 8MS, 8CS, and 8KS. Each developing unit is detachably attached.
[0028]
The intermediate transfer body 12 is in contact with the photosensitive drums 5Y, 5M, 5C, and 5K, rotates clockwise during color image formation, and rotates with the rotation of the photosensitive drums 5Y, 5M, 5C, and 5K. , Receive a visible image transfer. Further, the intermediate transfer body 12 simultaneously superimposes and transfers the color visible image on the intermediate transfer body 12 to the transfer material 2 by the transfer roller 9a, which will be described later, contacting and conveying the transfer material 2 during image formation.
[0029]
The transfer roller 9a is in contact with the intermediate transfer body 12 while the color visible image is being superimposedly transferred onto the intermediate transfer body 12, but is separated to the position 9b at the end of the printing process.
[0030]
The fixing unit 13 fixes the transferred color visible image while transporting the transfer material 2. As shown in FIG. 1, the fixing unit 14 heats the transfer material 2 and the transfer material 2 is fixed to the fixing roller 14. And a pressure roller 15 for pressure contact. The fixing roller 14 and the pressure roller 15 are formed in a hollow shape, and have heaters 16 and 17 therein, respectively. That is, the transfer material 2 holding the color visible image is transported by the fixing roller 14 and the pressure roller 15, and the toner is fixed on the surface by applying heat and pressure.
[0031]
The transfer material 2 after the fixing of the visible image is thereafter discharged to a paper discharge section by a discharge roller, and the image forming operation is completed.
[0032]
The cleaning unit 21 is for cleaning the toner remaining on the photosensitive drums 5Y, 5M, 5C, and 5K and the intermediate transfer body 12, and is visible by the toner formed on the photosensitive drums 5Y, 5M, 5C, and 5K. The waste toner after transferring the image to the intermediate transfer body 12 or the waste toner after transferring the four color visible images formed on the intermediate transfer body 12 to the transfer material 2 is stored in a cleaner container.
[0033]
The color sensor 29 is disposed downstream of the fixing unit 13 of the transfer material transport path toward the image forming surface of the transfer material 2 in the color image forming apparatus of FIG. An RGB output value of the color of the mixed color patch is detected. By arranging the fixed image inside the color image forming apparatus, it is possible to automatically detect the image after fixing before discharging the image to the paper discharge unit.
[0034]
FIG. 2 shows an example of the configuration of the color sensor 29. The color sensor 29 includes a white LED 203 and a charge storage sensor 204a with an RGB on-chip filter. The white LED 203 is made obliquely incident on the transfer material 2 on which the patch after fixing is formed at an angle of 45 degrees, and the intensity of the irregularly reflected light in the 0 degree direction is detected by the charge storage type sensor with RGB on-chip filter 204a. The light receiving section of the charge storage type sensor with RGB on-chip filter 204a is a pixel in which RGB is independent like 204b. The chromaticity of the patch can be detected from the intensity of the irregularly reflected light when the patch pattern 205 is at the position of the color sensor 29.
[0035]
The charge storage sensor of the charge storage sensor 204 with the RGB on-chip filter may be a photodiode. A set of several sets of three RGB pixels may be arranged. Further, the configuration may be such that the incident angle is 0 degree and the reflection angle is 45 degrees. Further, it may be constituted by an LED emitting three colors of RGB and a sensor without a filter.
[0036]
FIG. 3 shows an example of a density-gradation characteristic control patch pattern formed on the transfer material 2 after fixing. The density-gradation characteristic control patch pattern 2 is a gray gradation patch pattern which is the center of the color reproduction range and is a very important color for achieving color balance. It is composed of a gray tone patch 301 of black (K), and a process gray tone patch 302 of a mixture of cyan (C), magenta (M), and yellow (Y), 301a and 302a, 301b and 302b, and 301c. In the standard color image forming apparatus, a gray tone patch 301 of K having similar chromaticity and a CMY process gray tone patch 302 are arranged in pairs as shown in FIGS.
[0037]
At the time of executing the density-gradation characteristic control, the RGB output value of this patch is detected by the color sensor 29. Then, by comparing the RGB output values of the gray gradation patch by K and the CMY process gray gradation patch, three colors of CMY, which have almost the same chromaticity as the gray patch by K of a certain gradation, are mixed. By calculating the mixture ratio of the three CMY colors of the process gray patch and feeding it back to a calibration table for correcting the density-gradation characteristics of the image processing unit (not shown), the density or the density of the final output image formed on the transfer material is calculated. Chromaticity control can be performed.
[0038]
FIG. 4 shows a flowchart of a jam detection process using the color sensor 29 during printing of the color image forming apparatus of the present embodiment.
[0039]
First, when the printing operation is started, paper feeding is started as shown in step 401 (indicated as S401 in the figure, the same applies hereinafter), and the transfer material 2 is fed from the paper feeding cassette 1 or the MP tray 3. Next, in step 402, the process waits until the time for the fed transfer material 2 to reach the color sensor 29 elapses. By this time, a laser beam is emitted in the scanner unit 10 of each color in response to an image signal input from an image processing unit (not shown), and the latent image is formed on the photosensitive drum 5 by the laser emission of the scanner unit 10. Is formed, the formed latent image is visualized as a toner image in the developing device 8, the toner image formed on the photosensitive drum 5 is transferred onto the intermediate transfer body 12, and is transferred onto the intermediate transfer body 12. The transferred toner image is further transferred to the transfer material 2 by the transfer roller 9a, and the transfer material 2 to which the toner image has been transferred is fixed by the fixing unit 13 with the toner image.
[0040]
Next, at a timing when the fed transfer material 2 reaches the color sensor 29, it is detected whether or not the transfer material 2 exists at the position of the color sensor 29 based on the output value of the color sensor 29 in step 403. If the transfer material 2 is present at the position of the color sensor 29 in step 404, the process proceeds to step 407. If the transfer material 2 is not present at the position of the color sensor 29, it is determined that a conveyance jam has occurred, and the process proceeds to step 405. If it is determined in step 404 that a conveyance jam has occurred, the printing operation is interrupted in step 405, and the occurrence of the conveyance jam is displayed on a panel (not shown) to notify the user in step 406, and the printing operation ends. .
[0041]
If it is determined in step 404 that the conveyance jam has not occurred, the process waits in step 407 for the time that the rear end of the transfer material 2 passes the position of the color sensor 29 to elapse. Next, at the timing when the rear end of the transfer material 2 reaches the downstream side from the position of the color sensor 29, in step 408, the output value of the color sensor 29 determines whether the transfer material 2 exists at the position of the color sensor 29. Detect whether. Then, if the transfer material 2 is not present at the position of the color sensor 29 in step 409, it is determined that a conveyance jam has not occurred, and the jam detection processing at the color sensor position is terminated. If the transfer material 2 is present at the position of the color sensor 29 in step 409, it is determined that a conveyance jam has occurred, and the process proceeds to step 410. If it is determined in step 409 that a conveyance jam has occurred, the printing operation is interrupted in step 410, and the occurrence of the conveyance jam is displayed on a panel (not shown) to notify the user in step 411, and the printing operation ends. .
[0042]
As described above, according to the present embodiment, the color sensor has a configuration in which a dedicated transfer material presence / absence detection sensor for judging a conveyance jam is not provided and the size and cost can be reduced. By detecting at a predetermined timing whether or not the transfer material 2 exists at the position of the color sensor 29 based on the output value of 29, it is determined whether or not a transport jam has occurred. A color image forming apparatus capable of performing various processes.
[0043]
(Example 2)
Second Embodiment A “color image forming apparatus” according to a second embodiment will be described. In the first embodiment, a color image forming apparatus that determines whether a conveyance jam has occurred by detecting at a predetermined timing whether or not the transfer material 2 exists at the position of the color sensor 29 based on the output value of the color sensor 29 is described. explained. In the second embodiment, an image forming apparatus that does not erroneously detect a conveyance jam even when a medium such as an OHT sheet in which the presence of the transfer material 2 cannot be confirmed only by an output value of a color sensor is fed.
[0044]
The overall configuration and the image forming operation of the “color image forming apparatus” of the present embodiment are the same as those of the first embodiment, and the description thereof will be referred to, and the same description will be omitted.
[0045]
In FIG. 1, an OHT sensor 30 is a sensor for detecting whether the medium of the transfer material 2 fed from the paper feed cassette 1 or the MP tray 3 is a plain paper or an OHT sheet. The operation of the OHT sensor 30 will be described with reference to FIG. The OHT sensor 30 includes a light emitting unit 601 and a light receiving unit 602. For example, when the pre-registration sensor 19 can confirm that the transfer material 2 exists at the position of the pre-registration roller 31, the light-emitting unit 601 is turned on. Whether or not the transfer material 2 has the property of transmitting light is detected based on whether or not the light emitted from the light emitting unit 601 can be received by the light receiving unit 602. When the transfer material 2 transmits light, OHT is used. This sensor detects that the sheet is a sheet, and detects that the transfer material 2 is plain paper when the transfer material 2 does not transmit light.
[0046]
FIG. 5 is a flowchart illustrating a jam detection process using the color sensor 29 during printing of the color image forming apparatus according to the present exemplary embodiment.
[0047]
First, when the printing operation is started, sheet feeding is started as shown in step 501, and the transfer material 2 is fed from the sheet feeding cassette 1 or the MP tray 3. Next, in step 502, the process waits until the fed transfer material 2 reaches the OHT sensor 30. In step 503, the OHT sensor 30 determines whether the transfer material 2 is an OHT sheet or a plain sheet. Next, in step 504, if the transfer material 2 is an OHT sheet, the printing operation is performed without detecting the conveyance jam by the color sensor 29. If it is determined in step 504 that the transfer material 2 is plain paper, the process proceeds to step 505. In step 505, the process waits until the time for the transfer material 2 to reach the color sensor 29 elapses. By this time, the transfer material 2 to which the toner image has been transferred has the toner image fixed in the fixing unit 13.
[0048]
Next, at the timing when the fed transfer material 2 reaches the color sensor 29, it is detected in step 506 whether or not the transfer material 2 exists at the position of the color sensor 29 based on the output value of the color sensor 29. If the transfer material 2 is present at the position of the color sensor 29 in step 507, the process proceeds to step 510. If the transfer material 2 does not exist at the position of the color sensor 29, it is determined that a conveyance jam has occurred, and the process proceeds to step 508. If it is determined in step 507 that a conveyance jam has occurred, the printing operation is interrupted in step 508, and in step 509, the occurrence of the conveyance jam is displayed on a panel (not shown) to notify the user and end the printing operation. .
[0049]
If it is determined in step 507 that a conveyance jam has not occurred, the process waits in step 510 for a time period in which the rear end of the transfer material 2 passes the position of the color sensor 29. Next, at the timing when the rear end of the transfer material 2 reaches the downstream side from the position of the color sensor 29, the output value of the color sensor 29 determines whether the transfer material 2 exists at the position of the color sensor 29 in step 511. Detect whether. Then, if the transfer material 2 is not present at the position of the color sensor 29 in step 512, it is determined that no conveyance jam has occurred, and the jam detection processing at the color sensor position is terminated. If the transfer material 2 is present at the position of the color sensor 29 in step 512, it is determined that a conveyance jam has occurred, and the process proceeds to step 513. If it is determined in step 512 that a conveyance jam has occurred, the printing operation is interrupted in step 513, and the occurrence of the conveyance jam is displayed on a panel (not shown) to notify the user in step 514, and the printing operation ends. .
[0050]
As described above, according to the color image forming apparatus of the present embodiment, a dedicated transfer material presence / absence detection sensor for judging a conveyance jam is not provided, and the size and cost can be reduced. However, by detecting at a predetermined timing whether or not the transfer material 2 is present at the position of the color sensor 29 based on the output value of the color sensor 29, it is determined whether or not a transport jam has occurred. If so, appropriate processing can be performed. Further, according to the present embodiment, it is possible to provide a color image forming apparatus which does not erroneously detect a conveyance jam even during an OHT sheet printing operation.
[0051]
(Example 3)
Third Embodiment A “color image forming apparatus” according to a third embodiment will be described. In the second embodiment, when a medium, such as an OHT sheet, which cannot confirm the presence of the transfer material only by the output value of the color sensor is fed, the detection of the conveyance jam is not performed, and the presence of the transfer material is determined by the output value of the color sensor. The color image forming apparatus that determines whether a conveyance jam has occurred when a confirmable medium is fed has been described. In a third embodiment, a description will be given of a color image forming apparatus capable of detecting a conveyance jam even when a medium, such as an OHT sheet, in which the presence of the transfer material 2 cannot be confirmed only by an output value of a color sensor is fed. Note that the overall configuration and the image forming operation of the “color image forming apparatus” of the present embodiment are the same as those of the first embodiment, and the description thereof will be referred to, and the same description will be omitted.
[0052]
FIG. 7 shows a flowchart of a jam detection process using the color sensor 29 during printing of the color image forming apparatus of the present embodiment.
[0053]
First, when the printing operation is started, paper feeding is started as shown in step 701, and the transfer material 2 is fed from the paper feeding cassette 1 or the MP tray 3. Next, in step 702, the process waits for the time until the fed transfer material 2 reaches the OHT sensor 30. In step 703, the OHT sensor 30 determines whether the transfer material 2 is an OHT sheet or a plain sheet. Next, in step 704, if the transfer material 2 is an OHT sheet, the process proceeds to step 715. In step 715, an OHT sheet detection mark 801 as shown in FIG. 8 is formed as an image. The OHT sheet detection mark 801 forms a toner image at the end of the OHT sheet so that the color sensor 29 can determine whether or not the OHT sheet has arrived. If it is determined in step 704 that the transfer material 2 is plain paper, the process proceeds to step 705.
[0054]
Next, in step 705, the process waits until the time required for the transfer material 2 to reach the color sensor 29 elapses. By this time, the transfer material 2 to which the toner image has been transferred has the toner image fixed in the fixing unit 13. If the transfer material is an OHT sheet, the OHT sheet detection mark 801 is image-formed and fixed, and is conveyed to the color sensor 29.
[0055]
Next, at the timing when the fed transfer material 2 reaches the color sensor 29, it is detected in step 706 whether or not the transfer material 2 is present at the position of the color sensor 29 based on the output value of the color sensor 29. Here, even if the transfer material is an OHT sheet, whether or not the transfer material exists can be detected by the OHT sheet detection mark 801. If the transfer material 2 is present at the position of the color sensor 29 in step 707, the process proceeds to step 710. If the transfer material 2 does not exist at the position of the color sensor 29, it is determined that a conveyance jam has occurred, and the process proceeds to step 708. If it is determined in step 707 that a conveyance jam has occurred, the printing operation is interrupted in step 708, and in step 709, the occurrence of the conveyance jam is displayed on a panel (not shown) to notify the user and end the printing operation. .
[0056]
If it is determined in step 707 that a conveyance jam has not occurred, the process waits in step 710 for the time that the rear end of the transfer material 2 passes the position of the color sensor 29 to elapse. Next, at the timing when the rear end of the transfer material 2 reaches the downstream side of the position of the color sensor 29, in step 711, the output value of the color sensor 29 determines whether the transfer material 2 exists at the position of the color sensor 29. Detect whether. Here, even if the transfer material is an OHT sheet, whether or not the transfer material exists can be detected by the OHT sheet detection mark 801. Then, if the transfer material 2 is not present at the position of the color sensor 29 in step 712, it is determined that a conveyance jam has not occurred, and the jam detection processing at the color sensor position is terminated. If the transfer material 2 is present at the position of the color sensor 29 in step 712, it is determined that a conveyance jam has occurred, and the process proceeds to step 713. If it is determined in step 712 that a conveyance jam has occurred, the printing operation is interrupted in step 713, and the occurrence of the conveyance jam is displayed on a panel (not shown) to notify the user in step 714, and the printing operation ends. .
[0057]
As described above, according to the color image forming apparatus of the present embodiment, a dedicated transfer material presence / absence detection sensor for judging a conveyance jam is not provided, and the size and cost can be reduced. Meanwhile, it is determined at a predetermined timing whether or not the transfer material 2 exists at the position of the color sensor 29 based on the output value of the color sensor 29, so that it is determined whether or not a transport jam has occurred. If so, appropriate processing can be performed. Further, it is possible to provide a color image forming apparatus capable of detecting a conveyance jam even during an OHT sheet printing operation.
[0058]
In the description of the present embodiment, for example, the OHT sensor 30 detects and determines that the OHT sheet is being fed and conveyed. However, it is determined whether or not the OHT sheet is fed according to a user setting. You may.
[0059]
(Example 4)
Fourth Embodiment A “color image forming apparatus” according to a fourth embodiment will be described. In this embodiment, the presence or absence of the transfer material at the place where the color sensor is disposed on the transfer material transport path is determined using the color sensor, and the presence or absence of the transfer material is determined when the power is turned on and when the door is closed. A color image forming apparatus that detects a residual sheet will be described. Note that the overall configuration and the image forming operation of the “color image forming apparatus” of the present embodiment are the same as those of the first embodiment, and the description thereof will be referred to, and the same description will be omitted.
[0060]
FIG. 9 shows a flowchart of the remaining paper detection process using the color sensor 29 when the power of the color image forming apparatus of this embodiment is turned on and when the door is closed.
[0061]
9, when the power of the present color image forming apparatus is first turned on, in step 901 the self-diagnosis of the color image forming apparatus and the cleaning of the unnecessary toner remaining on the photosensitive drum 5 and the intermediate transfer body 12 are performed. An initial rotation operation for rotating the photosensitive drum 5 and the intermediate transfer body 12 for a predetermined time is started. Next, in step 902, it is detected whether or not the transfer material 2 exists at the position of the color sensor 29 based on the output value of the color sensor 29.
[0062]
If the transfer material 2 is not present at the position of the color sensor 29 in step 903, the residual paper detection processing is terminated in step 906 after the end of the initial rotation. If the transfer material 2 exists at the position of the color sensor 29, it is determined that there is a sheet remaining in the apparatus, and the process proceeds to step 904.
[0063]
If it is determined in step 903 that the paper remains in the apparatus, the initial rotation operation is interrupted in step 904, and in step 905, the presence of the paper in the apparatus is displayed on a panel (not shown) to notify the user, The paper detection processing ends.
[0064]
As described above, according to the present embodiment, it is possible to reduce the size and cost by not providing a dedicated transfer material presence / absence detection sensor for determining whether or not there is a residual sheet when the power is turned on. In spite of the configuration, by detecting whether or not the transfer material 2 is present at the position of the color sensor 29 based on the output value of the color sensor 29, it is determined whether or not the paper remains in the apparatus, and it is determined whether or not the paper remains in the apparatus. If there is a paper sheet, appropriate processing can be performed.
[0065]
【The invention's effect】
As described above, according to the present invention, density or chromaticity control can be performed, and conveyance jam detection and residual paper detection can be performed with a small and inexpensive configuration in which the number of sensors in the entire apparatus is reduced. A color image forming apparatus can be provided.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view illustrating a configuration of a first embodiment.
FIG. 2 illustrates a configuration of a color sensor.
FIG. 3 is a diagram showing a density-gradation characteristic control patch pattern;
FIG. 4 is a flowchart illustrating a jam detection process according to the first embodiment.
FIG. 5 is a flowchart illustrating a jam detection process according to the second embodiment.
FIG. 6 is a diagram showing a configuration of an OHT sensor.
FIG. 7 is a flowchart illustrating a jam detection process according to the third embodiment.
FIG. 8 is a diagram showing marks formed on an OHT sheet.
FIG. 9 is a flowchart illustrating a residual paper detection process according to the fourth embodiment.
[Explanation of symbols]
2 Transfer material
29 color sensor

Claims (9)

A color sensor that reads a patch pattern formed on the transfer material,
Detecting means for detecting the presence or absence of a transfer material at the mounting position of the color sensor using the color sensor,
A color image forming apparatus comprising: The color image forming apparatus according to claim 1,
The color image forming apparatus according to claim 1, wherein the detecting unit detects the presence or absence of the transfer material based on whether or not the reflected light of the transfer material is detected by the color sensor. Image forming means;
Conveying means for conveying the transfer material,
A color sensor that reads a patch pattern formed on the transfer material,
Detecting means for detecting the presence or absence of a transfer material at the mounting position of the color sensor using the color sensor,
At the time of transfer material transfer by the transfer unit, a transfer jam determination unit that determines that a transfer jam has occurred based on the result of the presence or absence detection of the transfer material by the detection unit at a predetermined timing,
Notifying means for notifying the user of the occurrence of a transport jam;
Control means for stopping the operations of the image forming means and the transport means when the transport jam determination means determines that a transport jam has occurred, and controlling the notification means to notify the user of the occurrence of the transport jam; and ,
A color image forming apparatus comprising: The color image forming apparatus according to claim 3,
Media determination means for determining whether the transfer material is an OHT sheet,
The transport jam determining means, when the media determining means determines that the transfer material is an OHT sheet, determines that no transport jam has occurred regardless of the result of the detection of the presence or absence of the transfer material at a predetermined timing. A color image forming apparatus. The color image forming apparatus according to claim 3,
Media determination means for determining whether the transfer material is an OHT sheet,
The control means controls the image forming means to forcibly form a mark image on the transfer material when the medium determining means determines that the transfer material is an OHT sheet;
The detecting means detects the presence or absence of the transfer material based on whether the mark image formed on the transfer material is read by the color sensor when the medium determining means determines that the transfer material is an OHT sheet. A color image forming apparatus, comprising: The color image forming apparatus according to claim 4, wherein
The color image forming apparatus according to claim 1, wherein the media determination unit determines whether the sheet is an OHT sheet based on a setting by a user. The color image forming apparatus according to claim 4, wherein
The color image forming apparatus according to claim 1, wherein the medium determination unit determines whether the transfer material is an OHT sheet based on a detection result of an OHT sensor that detects whether the transfer material is an OHT sheet. A color sensor that reads a patch pattern formed on the transfer material,
Detecting means for detecting the presence or absence of a transfer material at the mounting position of the color sensor using the color sensor,
When power is turned on, or when the door is closed, the presence / absence of a transfer material is detected by the detection unit, and a remaining paper presence / absence determination unit that determines whether there is any remaining paper based on the detection result,
Notification means for notifying the user that there is residual paper;
Control means for controlling the notifying means to notify the user of the presence of the residual paper when the residual paper presence / absence determining means determines that there is residual paper;
A color image forming apparatus comprising: The color image forming apparatus according to any one of claims 1 to 8,
A color image forming apparatus, wherein the color sensor is disposed between a fixing device and a paper discharge port.

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