JP3653234B2 - Electrophotographic image printing device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an electrophotographic image printing apparatus such as a facsimile or a printer that prints an image by electrophotography.
[0002]
[Prior art]
Conventionally, this type of image printing apparatus performs image printing by a sequence of charging, exposure, development, transfer, and cleaning. What actually prints an image is a unitized printing mechanism called EP (ELECTRIC PHOTOGRAPHY).
[0003]
The printing mechanism unit is connected to a negative power source and a negative high voltage power source via a contact portion on the apparatus main body side in order to drive and execute the above sequence. In this case, a negative high voltage power source is connected to the charge roller (charging roller) of the printing mechanism unit, and a negative power source is connected to a roller other than the charge roller (mainly the developing roller).
[0004]
Here, the voltage supply from the minus high voltage power source and the minus power source from the contacted part on the apparatus main body side to the contact part on the printing mechanism part side is performed with the following connection structure.
The printing mechanism unit can be mounted on the apparatus main body, and as a voltage supply structure from the apparatus main body side to the printing mechanism unit side, when the mounted printing mechanism unit enters a printing mode, the printing mechanism unit is moved up and down with respect to the apparatus main body. This is performed using a mechanical connection structure that contacts and separates the contact portions.
[0005]
For example, the end surface of each roller shaft (conductive shaft) of the printing mechanism unit or a conductive plate that contacts the end surface is used as the printing mechanism unit side contact unit, and a conductive elastic plate extending from the apparatus main body is used as the device. Used as the body-side contacted part. Then, the printing mechanism section side contact section mechanically contacts the apparatus body side contacted section with the movement of the printing mechanism section relative to the apparatus body, so that a negative high voltage from the apparatus body side to the printing mechanism section side and Negative voltage is being supplied.
[0006]
[Problems to be solved by the invention]
However, the above prior art has the following problems.
In the above mechanical connection structure, when the apparatus is used for a long time and the vertical movement of the printing mechanism section with respect to the apparatus main body is repeated for each printing mode, that is, the contact and separation of the printing mechanism section side contact section with respect to the apparatus main body side contacted section is repeated. Is likely to cause dripping or deformation (turning, warping, bending, etc.) on both contact surfaces (plate shape, key shape, nail shape, etc.), and foreign matter such as toner or paper dust is attached. May cause poor contact.
[0007]
For this reason, even if the mounting position of the printing mechanism unit with respect to the apparatus main body is appropriate, there is a contact abnormality in which the contacted part and the contact part that form a mechanical contact structure for supplying voltage to the apparatus main body do not normally contact. If the above sequence is not executed normally and printing failure occurs, or if this state continues for a long time, the printing mechanism itself may be damaged, especially the electrical and physical properties of the photosensitive drum portion may be deteriorated. There was a problem that there was.
The present invention has been made to solve the above problems of the prior art.
[0008]
[Means for Solving the Problems]
The present invention employs the following configuration in order to solve the above-described problems.
<Configuration 1>
The present invention provides an electrophotographic image printing apparatus for transferring a toner image to a printing part, a charging part for charging the surface of the photoreceptor, and an exposure part for changing the charged surface potential of the photoreceptor based on print data; A printing mechanism having a developing unit that forms a toner image based on a potential on the surface of the photoreceptor, a first contact unit that is electrically connected to the charging unit, and a second contact unit that is electrically connected to the developing unit; An apparatus main body in which the printing mechanism unit is movably disposed; a first contacted part of the apparatus main body that contacts the first contact part in a printing mode and supplies a first voltage; and the second in a printing mode. A second contacted portion of the apparatus body that contacts the contact portion and supplies a second voltage; The toner image was transferred The printed part Of the image forming area A density sensor that detects a density and a density of a non-image area; and when the first contact portion and the first contacted portion are in normal contact, and the second contact portion and the second contacted portion are in normal contact. In the printed part Said Of the image forming area toner Reference concentration and Said Non-painting Image A storage unit for preliminarily storing a reference density of the area; and The image forming area Detected concentration and Said By comparing the detected density of the non-image area and each reference density of the storage unit, it is determined whether or not there is a contact failure between the first contact part, the first contacted part, and the second contact part and the second contacted part. Including a determination unit to perform
[0009]
<Configuration 2>
In another aspect of the present invention, there is provided an electrophotographic image printing apparatus that transfers a toner image to a printing portion, a charging portion that charges the surface of the photosensitive member, and an exposure portion that changes the charged surface potential of the photosensitive member based on print data. A printing mechanism having a developing unit that forms a toner image based on a potential on the surface of the photoreceptor, a first contact unit that is electrically connected to the charging unit, and a second contact unit that is electrically connected to the developing unit. An apparatus main body in which the printing mechanism unit is movably disposed, a first contacted part of the apparatus main body that contacts the first contact unit in a printing mode and supplies a first voltage, and the first unit in a printing mode. A second contacted portion of the apparatus main body that contacts the two contact portions and supplies a second voltage, the first contacted portion and the first contacted portion are in normal contact, and the second contacted portion and the second contacted portion. Print data for testing with the contacted part in normal contact A storage unit for storing a reference density corresponding to the image forming area and the non-image area in the case of forming a toner image on the printing unit by the test pattern based, A density sensor for detecting the density of the image forming area and the density of the non-image area of the printing portion where the toner image is formed by the test pattern; Previous Coat Of the printing department Said Detection density of image forming area and Said The detected density of the non-image area and the storage unit each And a determination unit that determines whether there is a contact failure between the first contact portion, the first contacted portion, the second contact portion, and the second contacted portion by comparison with a reference concentration.
[0010]
<Configuration 3>
According to another aspect of the invention, there is provided an apparatus main body having a contacted part for supplying a voltage, and a printing mechanism having a contact part that is movably attached to the apparatus main body and is brought into contact with the contacted part in a printing mode. An electrophotographic image printing apparatus in which a toner image is transferred from the printing mechanism unit to a printing unit. Darkness of When a printing operation is performed with predetermined print data set to develop and print a predetermined test pattern in the print area of the printing portion and a density sensor for detecting the degree of printing of Each detected density from the density sensor in the print area and the non-print area Compare with the print data The comparison unit and the comparison unit set the print density in the non-printing area. Detection Or in the printing area Non-printing Concentration Detection A moving unit that moves the printing mechanism unit relative to the apparatus main body and re-contacts the contact unit with the contacted unit, and the moving unit moves the contact unit to the contacted unit. The printing mechanism unit is caused to perform a retry operation for performing a printing operation with the predetermined print data after recontacting with the unit, and when the abnormal state is not resolved by the retry operation within a predetermined number of times, a message to that effect is given. It further comprises state detection / notification means for notification.
[0011]
<Configuration 4>
Still another invention includes an apparatus main body having a contacted part for supplying a voltage, and a printing mechanism having a contact part that is movably mounted on the apparatus main body and contacts the contacted part in a printing mode. An electrophotographic image printing apparatus in which a toner image is transferred from the printing mechanism unit to a printing part. Darkness of When a printing operation is performed with predetermined print data set to develop and print a predetermined test pattern in the print area of the printing portion and a density sensor for detecting the degree of printing of Each detected density from the density sensor in the print area and the non-print area Compare with the print data The comparison unit and the comparison unit set the print density in the non-printing area. Detection Or in the printing area Non mark Darkness Degree Detection A moving portion that determines that the printing mechanism portion is moved relative to the apparatus main body and re-contacts the contact portion with the contacted portion, and the moving portion moves the contact portion to the contacted portion. When the abnormal state is resolved by the retry operation within a predetermined number of times, a retry operation for causing the printing mechanism unit to perform a printing operation with the predetermined print data after recontacting with the time is canceled The printer is further provided with a state detection / notification means for notifying that the printer is in a print standby state and not cancelling the state.
[0013]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, specific examples of the present invention will be described with reference to the drawings.
"Concrete example"
<Specific example configuration>
FIG. 1 is a block diagram showing a specific example of an electrophotographic image printing apparatus according to the present invention, FIG. 2 is a schematic diagram of the main part of the apparatus of the present invention shown in FIG. 1 (printing mechanism part ascending state), and FIG. It is a schematic block diagram (printing mechanism part descending state).
[0014]
1 to 3, reference numeral 1 denotes a control unit comprising a CPU, 2 denotes a ROM storing a program for operating the control unit 1, 3 denotes a working RAM for the control unit 1, and 4 denotes an I / O port. .
5 to 8 are motors for the respective colors Y (yellow), M (magenta), C (cyan), and K (black), 9 to 12 are motor drivers for driving the motors 5 to 8, 13 is a density sensor, 14 Is an A / D converter for A / D converting the signal from the density sensor 13, and 15 is a notification device, here a display device, which constitutes a state detection / notification means with the control unit 1 and the ROM 2.
[0015]
Reference numeral 21 denotes a transport belt for running a printing medium (not shown) such as printing paper during a normal printing operation, and Y-EP, M-EP, C-EP, and K-EP are Y for the running printing medium. Y, M, C, K printing mechanism sections (hereinafter simply referred to as Y-EP, M-EP, C-EP, K-EP) that perform overprinting (color printing) in the order of M, C, K .)
[0016]
Here, the I / O port 4 outputs a signal to the motor drivers 9 to 12 for each color in order to control the motors 5 to 8 for each color, or is output from the density sensor 13 to the A / D converter 14. The A / D converted signal is input by the control unit 1 and controlled by the control unit 1.
The density sensor 13 detects the density on the front surface (printed medium placement transport surface) side of the transport belt 21 at a position after the transport belt 21 passes the EP.
[0017]
As described above, the display device 15 is configured by the control unit 1 and the ROM 2 as state detection / notification means.
The state detection / notification means here is a density sensor 13 when a printing operation is performed with print data set so that, for example, a test pattern (local pattern) shown in FIG. The density data from the print data is compared with the print data, and the print data is printed in the non-print area (the area that should not be printed) or not printed in the same print area (the area that should be printed) (contact abnormality) Is detected, a message to that effect is displayed on the display device 15. Note that a region 41 surrounded by an alternate long and short dash line in FIG. 4 indicates a concentration detection region by the concentration sensor 13.
[0018]
Y-EP, M-EP, C-EP, and K-EP are driven by motors 5 to 8 and include a photosensitive drum, a charge roller (charging roller), a developing roller, and the like. A negative high voltage power source is connected to the contact portion), and a negative power source is connected to the other rollers, mainly to the developing roller (non-charge contact portion).
[0019]
2 and 3, the conveyor belt 21 side constitutes a part of the apparatus main body 22, and the EP (Y-EP, M-EP, C-EP, K-EP) is transferred to the apparatus main body 22. It is mounted so as to be movable. Further, the negative high voltage and the negative voltage supply from the apparatus main body 22 side to the EP side are performed by a mechanical connection structure using a charge contact portion and a non-charge contact portion that come in contact with and separate from each other with the movement. .
[0020]
<Operation of specific example>
Next, the operation of the above specific example will be described.
First, the operation in the case where the charge contact portion is in poor contact with the contacted portion of the apparatus main body will be described with reference to the flowchart of FIG.
[0021]
First, when a device power supply (not shown) is turned on, the control unit 1 operates a mechanism unit (not shown), once performs an EP raising operation (see FIGS. 2 and 3), and then lowers the EP. (Step 501). The operation in step 501 is to prevent unnecessary printing from being performed on the printing medium by mounting and lowering the EP during non-printing (only the EP of the color necessary for printing is lowered), and non-printing The purpose is to prevent unexpected high voltage noise from occurring due to the contact between the charge contact portion and the contacted portion between the EP and the apparatus main body 22 sometimes. In the operation of step 501, the EP increases during non-printing, the photosensitive drum is separated from the transport belt 21 through which the printing medium passes, and the charge contact portion is separated.
[0022]
Next, the control unit 1 turns on a negative high voltage power source (not shown) and prints a test pattern (see FIG. 4) based on the print data stored in the RAM 3 (steps 502 to 503).
This test pattern is a repeated pattern of an array in which a belt-like solid print area is developed four times in the order of Y, M, C, and K colors with the belt-like non-printing area in between.
[0023]
If such a test pattern is detected by the density sensor 13 (step 504), normal printing is performed if the charge contact portion and the contacted portion between the EP and the apparatus main body 22 are in normal contact. No printing in the print area (area to be printed) is not detected, and for example, a detection result shown in FIG. 6 is obtained. In FIG. 6, the detected density level is plotted as the reflectance on the vertical axis.
[0024]
However, if the charge contact portion and the contacted portion between the EP and the apparatus main body 22 are in poor contact, the test pattern print result is printed even though it is a non-print region (a region that should not be printed). Therefore, the density (reflectance 71 or 72) different from the density in the area where nothing is printed, that is, the density of only the conveyor belt 21 is detected (see FIG. 7).
[0025]
It is unclear how much the reflectance level will be at this time. This is because the color printed on the conveyor belt 21 differs depending on the type of EP causing the contact failure. In any case, when a contact failure occurs in the charge contact portion, a reflectance (different from the level of the conveyor belt 21 and a constant level) 71 or 72 is obtained, which is different from the reflectance of FIG. The controller 1 determines that a contact failure has occurred in the charge contact portion (step 505).
[0026]
Here, the reason why the non-printing area is printed will be described in detail.
That is, during normal printing operation, a voltage of -1350V is applied to the charging roller, and the surface potential of the photosensitive drum in contact with the charging roller is charged to about -800V. When the photosensitive drum rotates and a portion charged to −800 V reaches the exposure portion, the potential of the portion on the surface of the photosensitive drum becomes about 0 V by the light irradiated from the exposure portion based on the print data. After that, when the developing roller is reached, a voltage of −250 V is applied to the developing roller, so that the negatively charged toner at the contact portion between the developing roller and the photosensitive drum moves from the developing roller to the exposed portion of the photosensitive drum and development is performed. Done. At this time, since the portions other than the exposed portion are charged to −800 V, the toner does not move and normal printing is performed.
[0027]
However, if a contact failure occurs at the contact portion of the charging portion, a voltage of -1350 V is not applied to the charging roller. For this reason, the potential of the photosensitive drum surface is not charged to -800V. For example, if no voltage is applied to the charging roller due to poor contact of the charging unit, the potential on the surface of the photosensitive drum becomes 0V. Accordingly, when the photosensitive drum reaches the developing roller by rotation, the toner adheres to the entire surface of the photosensitive drum. Therefore, when the toner is subsequently transferred by the transfer unit, the toner is transferred over almost the entire region, and the non-printing area is also printed.
[0028]
The slice level when the contact failure of the charging contact portion is determined is set to a range of + X or more and −X or less of the reflectance level of the conveyor belt 21 in consideration of the toner fog on the conveyor belt 21. The reason for the presence of + and − is that, from the experimental results, it is known that Y, M, and C are higher than the reflectance of the conveyor belt 21 alone, and K is lower than the reflectance of the conveyor belt 21 alone. .
[0029]
When the contact failure of the charge contact portion is determined, the control unit 1 causes the display device 15 to display a message indicating that the contact failure between the charge contact portion and the contacted portion between the EP and the device main body 22 has occurred (step 506). When it is determined in step 505 that the charge contact portion does not cause a contact failure (no printing in the non-printing area), the control unit 1 places the apparatus in a print standby state (step 507).
[0030]
Next, the operation when the non-charge contact portion and the contacted portion have poor contact will be described with reference to the flowchart of FIG.
As can be seen by comparing FIG. 8 with FIG. 5, steps 801 to 803 are the same as steps 501 to 503, and therefore step 804 and subsequent steps will be described.
[0031]
In step 804, the density sensor 13 detects the density of the test pattern print area (the area to be printed). At this time, if the charge contact portion and the contacted portion between the EP and the apparatus main body 22 are defective, The print result of the test pattern is not printed even though it is a print area (area to be printed), and the density in an area where nothing is printed, that is, the same density as the density of only the conveyor belt 21 or a light density close thereto. (Reflectivity 91, 92) is detected (see FIG. 9).
[0032]
Here, the reason why printing is not executed for the print area will be described.
That is, when a contact failure occurs at the contact portion of the developing portion, a voltage of −250 V is not applied to the developing roller. For example, when no voltage is applied to the developing roller, the developing roller side becomes approximately 0V. For this reason, the toner does not adhere to the region where the surface potential of the photosensitive drum is charged to −800 V, but the toner does not easily adhere to the exposed portion. In other words, since the developing roller side is 0V and the exposed portion on the surface of the photosensitive drum is also 0V, the toner does not adhere to the exposed portion where the toner should originally adhere. Therefore, since it is not transferred from the exposed portion at the time of transfer, printing is not performed in the area to be printed.
[0033]
The slice level when the contact failure of the non-charge contact portion is determined is in the range of + X to −X centering on the reflectance of only the conveyor belt 21, contrary to the contact failure determination of the charge contact portion.
[0034]
As described above, when a contact failure occurs in the non-charge contact portion, the reflectance 91 or 92 shown in FIG. 9 is obtained, and the control portion 1 determines that a contact failure occurs in the non-charge contact portion. (Step 805).
[0035]
When the contact failure of the non-charge contact portion is determined, the control unit 1 causes the display device 15 to display a message indicating that the contact failure between the EP and the device main body 22 is causing a contact failure (step 806). If it is determined in step 805 that the non-charge contact portion has not caused a contact failure (printing in the print area), the control unit 1 places the apparatus in a print standby state (step 807).
[0036]
<Effects of specific examples>
According to the above-described specific example, when a contact failure with respect to the contacted portion of the apparatus main body 22 occurs in the charge contact portion or the non-charge contact portion of the EP, it is detected and a message is displayed (encourage the operator to pay attention). As a result, it is possible to prevent sag and deformation due to aging deterioration of the above-mentioned charge contact portion, non-charge contact portion and contacted portion of the apparatus main body, printing failure and damage to the printing mechanism portion itself due to this. (In particular, deterioration of the electrical and physical properties of the photosensitive drum portion) can be prevented.
[0037]
In the above-described specific example, the state detection / notification unit performs the printing in the non-printing area (the area that should not be printed) or the printing non-execution in the printing area (the area that should be printed). When a contact abnormality of a part with respect to a contacted part) is detected, a message to that effect is simply displayed on the display device 15, but it may be operated as follows.
[0038]
That is, in the above case, after the EP mounted on the apparatus main body 22 is raised and lowered again, the retry operation for performing the printing operation with the print data again is performed a preset number of times. When the abnormal state is resolved within the predetermined number of times, the print standby state is established when the abnormal state is resolved, and when it is not resolved, a message to that effect is displayed on the display device 15. In addition, a mechanism for moving and returning the EP in the horizontal direction in the apparatus main body may be provided, and the contact portion may be re-contacted with the contacted portion in the same manner, and the contact quality may be determined each time the retry operation is repeated.
[0039]
If this is shown in a flowchart, it is as shown in FIGS. 10 and 11, the same reference numerals as those in FIGS. 5 and 8 denote the same steps.
10 and 11, steps 1001 to 1003 are processing steps for performing the retry operation a preset number of times.
[0040]
According to this, when a contact failure has occurred in the charge contact part and the non-charge contact part between the EP and the apparatus main body 22, it is detected and a message is displayed (to alert the operator). It is possible to prevent aging and deformation due to aging and metal fatigue of the above-mentioned charge contact part and non-charge contact part, and to prevent contact failure due to adhesion of foreign matters such as toner and paper dust. It is possible to prevent defective printing and damage to the printing mechanism itself due to this.
In particular, depending on the retry operation, it is determined that the contact failure is detected at one time as in the case of the above-described specific example, but the contact portion (charge contact portion or non-charge contact) is not performed until the preset number of times. Part)), it is possible to make a normal contact within the number of times.
[0041]
In each of the above-described examples, the contact failure is described as an example of the contact abnormality of the charge contact portion or the non-charge contact portion. However, it goes without saying that the present invention can be applied even when the contact itself is cut off. Further, as a notification method to the outside in the case of a contact abnormality as described above, a message is displayed by the display device 15, but a buzzer may be sounded instead of or together with this message display. Furthermore, although the test pattern shown in FIG. 4 is printed on the conveying belt 21, it may be printed on a printing paper as a printing medium, and further printed on a transfer belt. . And when printing on a printing medium, the reflectance which considered the fog etc. at the time of printing on a printing medium is stored in a memory | storage part beforehand.
[0042]
Incidentally, in the above specific example, the presence / absence of printing in the printing area and the non-printing area is detected, but it may be detected by comparing the image patterns as a whole.
That is, for example, bit map image data for obtaining the test image pattern shown in FIG. 4 by test print data is stored in the storage unit, and density data indicating the density range of each color is used to determine the image portion for each color. Store in the density storage.
Then, under the control of the control unit, the test print data is supplied to the printing mechanism unit for each color, and an image is printed on the printing unit such as the conveyor belt 21.
The printed image is detected as density data by the density sensor 13.
[0043]
The control unit determines the time difference from the image forming to the detection of the density based on the position of each printing mechanism unit and the position of the density sensor 13 and the moving speed of the printing part, and a bitmap stored in advance. The color information of the corresponding area is determined from the image data, and the corresponding density data is read from the density storage unit.
The control unit sequentially compares the read density data with the density data detected by the density sensor, and whether or not the test image pattern indicated by the bitmap image data matches the image pattern printed on the print target part. By detecting this, the quality of the contact between the contact portion and the contacted portion is determined.
[0044]
<Other examples>
FIG. 12 is a block diagram of an electrophotographic image printing apparatus according to another invention, and FIGS. 13 and 14 are configuration diagrams schematically showing main parts of the apparatus.
12 to 14, the control unit 1 </ b> A determines the quality of contact based on the density reference value for each color toner stored in advance in the RAM 3 </ b> A, and displays the determination result on the display device 15. A transfer belt 23 is positioned below the printing mechanism portions Y-EP, M-EP, C-EP, and K-EP for each color, and a transfer roller 24 is disposed downstream of the transfer belt 23.
The other configuration is the same as the configuration shown in FIGS.
[0045]
Here, an image density reference value for each color toner stored in the RAM 3A will be described with reference to FIG. That is, when the Y-EP is attached to the apparatus main body 22 in a state where the Y-EP contact part is normally in contact with the contacted part of the apparatus main body 22, yellow toner is applied to the transfer belt 23 by Y-EP in advance. Images are printed repeatedly, the density level of each image is acquired as a reflectance by the density sensor 13, an upper limit threshold value and a lower limit threshold value are set from the average value of each acquired reflectance, and these threshold values ( The normal range of Y shown in FIG. 15 is stored in the RAM 3A as the density reference value. In addition, the density reference value including the upper threshold value and the lower threshold value is also stored in the RAM 3A for each of the other magenta toner, cyan toner, and black toner images.
[0046]
Next, the operation of this example will be described.
When the apparatus power supply is turned on, the EP is raised (see FIG. 13) and then lowered (see FIG. 14).
Next, the control unit 1A causes the transfer belt 23 to print with each color toner based on a test pattern (see FIG. 4) based on the print data stored in the RAM 3A. Next, the control unit 1A operates the density sensor 13 to detect the density of the image formed on the transfer belt 23.
[0047]
Next, the control unit 1A compares the Y-level reflectance obtained from the Y-EP image (see FIG. 15) with the upper and lower threshold values of Y in the RAM 3A. When the obtained reflectance is within the range of these threshold values, the control unit 1A determines that the contact portion of Y-EP is normally in contact with the contacted portion of the apparatus main body 22.
On the other hand, if the obtained reflectance is larger or smaller than the Y threshold range, the control unit 1A determines that the contact is poor.
Similarly, the control unit 1A compares the M-level reflectivity, the C-level reflectivity, and the K-level reflectivity with respective threshold values to determine whether the contact is good or bad.
[0048]
Next, the control unit 1A causes the display device 15 to display a message indicating whether the contact is good or not for each EP, and puts the device into a print standby state when the contact is good.
The image (toner) printed on the transfer belt 23 is transferred and printed on a printing paper 25 via a transfer roller 24 as shown in FIG.
[0049]
In this specific example, an image may be printed on the printing paper 25 instead of the transfer belt, and the density of the image on the printing paper 25 may be detected by the density sensor 13. In this case, the reflectance of the printing medium considering the fog when printing on the printing paper 25 is stored in the storage unit in advance.
Further, similarly to the specific example of FIG. 1, an image may be printed on the conveyance belt and the density thereof may be detected by the density sensor 13.
In this specific example, the above-described retry operation may be performed to repeat the pass / fail determination several times.
[0050]
【The invention's effect】
As described above, according to the present invention, since it is possible to detect in advance a contact failure between the contact portion of the EP (printing mechanism portion) and the contacted portion of the apparatus main body, it is possible to prevent the printing failure beforehand, and thus This has the effect of preventing damage to the printing mechanism itself (in particular, deterioration of the electrical and physical properties of the photosensitive drum portion).
[Brief description of the drawings]
FIG. 1 is a block diagram showing a specific example of an apparatus of the present invention.
2 is a schematic configuration diagram of a main part of the apparatus of the present invention shown in FIG.
FIG. 3 is a schematic view of the main part (printing mechanism part in a lowered state), similarly;
4 is a diagram showing an example of a test pattern used for contact abnormality detection in the device of the present invention in FIG. 1. FIG.
FIG. 5 is a flowchart for explaining the operation of the apparatus of the present invention.
FIG. 6 is a graph for explaining the operation.
FIG. 7 is a graph for explaining the operation.
FIG. 8 is a flowchart for explaining the operation of the device of the present invention in FIG. 1;
FIG. 9 is a graph for explaining the operation of the device of the present invention.
FIG. 10 is a flowchart for explaining the operation of another inventive apparatus.
FIG. 11 is a flowchart for explaining the operation of another inventive device.
FIG. 12 is a block diagram showing a specific example of still another invention device.
13 is a schematic configuration diagram when the printing mechanism unit of the apparatus of FIG. 12 is raised. FIG.
14 is a schematic configuration diagram when the printing mechanism unit of the apparatus of FIG. 12 is lowered. FIG.
15 is a graph for explaining the operation of the apparatus shown in FIG.
[Explanation of symbols]
1 Control unit
2 ROM
3 RAM
4 I / O ports
5-8 Motor for each color Y, M, C, K
9-12 Motor driver
13 Concentration sensor
14 A / D converter
15 Display device
21 Conveyor belt
22 Main unit
Y-EP, M-EP, C-EP, K-EP Y, M, C, K printing mechanisms

Claims (10)

In an electrophotographic image printing apparatus that transfers a toner image to a printing part,
A charging unit that charges the surface of the photoreceptor, an exposure unit that changes the charged potential of the surface of the photoreceptor based on print data, a developing unit that forms a toner image based on the potential of the surface of the photoreceptor, and the charging unit. A printing mechanism having a first contact part to be electrically connected and a second contact part to which the developing part is electrically connected;
An apparatus main body in which the printing mechanism is movably disposed;
A first contacted portion of the apparatus main body that contacts the first contact portion and supplies a first voltage in a printing mode;
A second contacted part of the apparatus main body for supplying a second voltage in contact with the second contact part in a printing mode;
A density sensor that detects a density of an image forming area and a density of a non-image area of the printing portion to which the toner image is transferred;
The toner reference density of the image forming area in the printing portion when the first contact portion and the first contact portion are in normal contact and the second contact portion and the second contact portion are in normal contact with each other. A storage unit that stores in advance a reference density of the non-image region;
The first contact part, the first contacted part, and the second contact part by comparing the detected density of the image forming area of the printed part and the detected density of the non-image area and the reference density of the storage part. And a determination unit for determining the presence or absence of each contact failure of the second contacted part.   The electrophotographic image printing apparatus according to claim 1, wherein the printing part is any one of a printing medium, a conveying belt for conveying the printing medium, and a transfer belt for directly printing an image. . In an electrophotographic image printing apparatus that transfers a toner image to a printing part,
A charging unit that charges the surface of the photoreceptor, an exposure unit that changes the charged potential of the surface of the photoreceptor based on print data, a developing unit that forms a toner image based on the potential of the surface of the photoreceptor, and the charging unit. A printing mechanism having a first contact part to be electrically connected and a second contact part to which the developing part is electrically connected;
An apparatus main body in which the printing mechanism is movably disposed;
A first contacted portion of the apparatus main body that contacts the first contact portion and supplies a first voltage in a printing mode;
A second contacted part of the apparatus main body for supplying a second voltage in contact with the second contact part in a printing mode;
The first contact portion and the first contacted portion are in normal contact with each other, and the second contact portion and the second contacted portion are in normal contact with each other in accordance with a test pattern based on test print data. A storage unit for storing a reference density corresponding to an image forming region and a non-image region when a toner image is formed;
A density sensor that detects the density of the image forming area and the density of the non-image area of the printing portion on which the toner image is formed by the test pattern;
The first contact portion, the first contact portion, and the second contact portion are compared by comparing the detected density of the image forming region and the detected density of the non-image region of the printed portion with each reference density of the storage portion. An electrophotographic image printing apparatus comprising: a determination unit that determines presence or absence of each contact failure of the second contacted unit.   4. The electrophotographic image printing according to claim 3, wherein the test pattern has an image pattern obtained by printing a plurality of colors of toner, and the density sensor reads each image portion of the plurality of colors of toner. apparatus.   4. The electrophotographic image printing apparatus according to claim 3, wherein the printing part is any one of a printing medium, a conveying belt for conveying the printing medium, and a transfer belt for directly printing an image. .   4. The electrophotographic image printing apparatus according to claim 3, further comprising state detection / notification means for notifying the determined contact failure. An apparatus main body having a contacted part for supplying a voltage; and a printing mechanism having a contact part that is movably attached to the apparatus main body and contacts the contacted part in a printing mode. In an electrophotographic image printing apparatus in which a toner image is transferred from a printing part to a printing part,
A concentration sensor for detecting the concentration of the printing unit,
Said predetermined test pattern in the printing area of the printing unit is deployed, each detected density from the density sensor in the printing area and non-printing area when allowed to printing operation in a predetermined print data that has been set to be printed A comparison unit for comparing with the print data ;
The comparison unit determines that the abnormal state when a non-printing density is detected by the detecting the print density at the non-printing area or the print region, the said contact portion to move the printing mechanism with respect to the apparatus main body A moving part that comes back into contact with the contacted part,
After the contact portion is brought into contact with the contacted portion by the moving portion, the printing mechanism portion is caused to perform a retry operation for performing a printing operation with the predetermined print data, and the retry operation is performed within a predetermined number of times. An electrophotographic image printing apparatus, further comprising state detection / notification means for notifying that an abnormal state has not been resolved.   8. The electrophotographic image printing apparatus according to claim 7, wherein the printing part is any one of a printing medium, a conveying belt for conveying the printing medium, and a transfer belt for directly printing an image. . An apparatus main body having a contacted part for supplying a voltage; and a printing mechanism having a contact part that is movably attached to the apparatus main body and contacts the contacted part in a printing mode. In an electrophotographic image printing apparatus in which a toner image is transferred from a printing part to a printing part,
A concentration sensor for detecting the concentration of the printing unit,
Said predetermined test pattern in the printing area of the printing unit is deployed, each detected density from the density sensor in the printing area and non-printing area when allowed to printing operation in a predetermined print data that has been set to be printed A comparison unit for comparing with the print data ;
The comparison unit determines that the abnormal state when detecting non-printing concentration by detecting the print density at the non-printing area or the print region, the contact portion moving the printing mechanism with respect to the apparatus main body A moving part that re-contacts the contacted part,
After the contact portion is brought into contact with the contacted portion by the moving portion, the printing mechanism portion is caused to perform a retry operation for performing a printing operation with the predetermined print data, and the retry operation is performed within a predetermined number of times. An electrophotographic image printing apparatus, further comprising a state detection / notification means for notifying the printing standby state when the abnormal state is resolved and not canceling the abnormal state. .   The electrophotographic image printing apparatus according to claim 9, wherein the printing part is any one of a printing medium, a conveyance belt for conveying the printing medium, and a transfer belt for directly printing an image. .

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