JP2008152174A - Image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To suppress decrease in productivity of image formation and reduce the consumption of toner in detecting by reducing the time required for detecting image flow. <P>SOLUTION: An image forming apparatus having: an image carrier; a charging means; a writing means; a developing means; a transfer means; a cleaning means; a discharging means; a pattern storage means; and a pattern detection means has a humidity detection means and a control means controlling the operation of each section. In the image forming apparatus, only in exceeding a predetermined humidity based on a detection value by the humidity detection means, the control means calls out a pattern for determining image quality, forms it on the image carrier, and allows the pattern detection means to detect the pattern for determining image quality. In addition, the control means determines whether or not the detection value by the pattern detection means is within a predetermined range and performs control so as to execute an image quality adjustment operation, when the detection value by the pattern detection means is out of the predetermined range. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an image forming apparatus such as a copying machine, a printer, and a facsimile using an electrophotographic system.

  2. Description of the Related Art Conventionally, image forming apparatuses such as copying machines, printers, and facsimiles using an electrophotographic system have been used under various conditions such as environments with different temperatures and humidity, and different properties of paper used. Under such conditions, for example, when the image forming apparatus is used in a high temperature and high humidity environment, an image abnormality called “image flow” occurs in which a part of the copy image flows with water. There are things to do.

  In the image stream, additives and paper dust contained in the paper adhere to the surface of the photosensitive drum, and they react with ozone generated in the charging device and moisture in the surrounding air over a certain period of time. This is because the resistance of the surface of the photosensitive drum is lowered. In particular, immediately after the end of continuous copying (also called printing) that forms images on multiple sheets of paper, the power is turned off and left for several hours or more, and copying is resumed, or during high humidity It is easy to generate.

  The reason why image flow is likely to occur when copying resumes is that ozone generated around the charging device is exhausted by the exhaust fan while the image forming apparatus is performing a copying operation, but immediately after the continuous copying is finished. This is probably because when the power is turned off, the exhaust fan stops and ozone is not exhausted, and the remaining ozone adheres to the photosensitive drum.

  Further, the reason why the image flow is likely to occur when the humidity is high is thought to be because the additive or paper powder adhering to the surface of the photosensitive drum absorbs moisture and lowers the resistance of the photosensitive drum.

In order to solve this problem, a technique is disclosed in which a test pattern is formed on the surface of a photosensitive drum, and an image flow is detected and adjusted using a potential difference at a boundary portion of the test pattern (patent) Reference 1).
Japanese Patent Laid-Open No. 11-265097

  However, the technique described in Patent Document 1 has a problem in that since a test pattern is formed every time warm-up is performed, the time for detecting an image stream increases, and the productivity of image formation decreases. Further, when the frequency of forming the test pattern is lowered, there is a problem that the detection power is reduced.

  SUMMARY OF THE INVENTION An object of the present invention is to solve the above-described problems, to reduce the time required for detecting an image flow, to suppress a decrease in image formation productivity, and to reduce the amount of toner consumed at the time of detection.

  The present inventors paid attention to the humidity in the image forming apparatus as a condition for determining whether or not to perform image quality determination on the image flow.

  The object of the present invention can be achieved by the following constitution.

1. An image bearing member; a charging unit that applies a charge to the surface of the image bearing member; a writing unit that irradiates a light beam for forming an electrostatic latent image on the surface of the image bearing member; Developing means for supplying a developer to the image to form a toner image; transfer means for transferring the toner image formed on the image carrier to paper; and cleaning for removing residual toner remaining on the image carrier. Means for neutralizing the surface of the image carrier, pattern forming means for forming an image quality judgment pattern for judging image quality on the image carrier, and pattern detection for detecting the image quality judgment pattern And an image forming apparatus comprising:
While having humidity detection means for detecting humidity,
Control means for controlling to perform an image quality adjustment operation based on the detection result of the pattern detection means,
The control means causes the pattern forming means to form the image quality determination pattern on the image carrier only when a predetermined humidity is exceeded based on a detection value by the humidity detection means, and causes the pattern detection means to The image quality of the image quality determination pattern is detected, it is determined whether or not the detection value by the pattern detection means is within a predetermined range, and when the detection value by the pattern detection means is outside the predetermined range, the image quality adjustment An image forming apparatus controlled to execute an operation.

  2. 2. The image forming apparatus according to 1, wherein the image quality determination pattern is for determining image flow.

  3. 3. The image forming apparatus according to claim 1, wherein the image quality adjustment operation is an operation of executing operations of the image carrier, the charging unit, and the charge eliminating unit during non-image formation.

  4). In the image quality adjustment operation, the control means controls to change at least one operation time of the charging means and the charge eliminating means in accordance with a detection value by the pattern detecting means. The image forming apparatus described in 1.

  5. 4. The image forming apparatus according to 3, wherein the image quality adjustment operation further includes execution of operations of the writing unit, the developing unit, and the cleaning unit.

  6). In the image quality adjustment operation, the control means sets at least one operation time of the charging means, the charge eliminating means, the writing means, the developing means, and the cleaning means to a detection value by the pattern detecting means. 6. The image forming apparatus according to 5, wherein the image forming apparatus is configured to be controlled to change in response.

7). The control means includes elapsed time storage means for counting elapsed time thereafter and storing elapsed time data when the image forming apparatus maintains a state where image formation is not started while the power is on or when the power is turned off. Built-in,
When image formation is started, the control unit calls the elapsed time data from the elapsed time storage unit and compares the called elapsed time data with a preset reference value to determine whether or not to perform an image quality adjustment operation. The image forming apparatus according to any one of claims 1 to 6, wherein when the elapsed time data exceeds a reference value, control is performed so as to perform an image quality adjustment operation.

  8). The image forming apparatus according to claim 1, wherein the pattern detection unit is an image density sensor that detects an image density of the image quality determination pattern.

  9. The image according to any one of claims 1 to 8, wherein a length of the image quality determination pattern in the rotation direction of the image carrier has a length corresponding to one circumference of the outer periphery of the image carrier. Forming equipment.

  According to the present invention, by detecting the image flow only when the humidity is high, the time required for detection is reduced to suppress a decrease in image formation productivity, and the consumption of toner during detection is reduced. It is possible to provide an image forming apparatus that prevents image flow.

  The present invention will be described based on the illustrated embodiment, but the present invention is not limited to the embodiment.

  FIG. 1 is a schematic diagram showing the overall configuration of an image forming apparatus according to an embodiment of the present invention.

  In FIG. 1, the image forming apparatus includes a double-sided document automatic feeder RADF and an image forming apparatus main body A.

  The double-sided document automatic feeder RADF is located at the upper part of the image forming apparatus main body A and can be opened and closed. The document on the document feed tray a is transported to a paper feed roller b, a separation roller c, a registration roller d, and a transport drum e, and the document is transported.

  Next, the image forming apparatus main body A includes an image reading apparatus 1, an image processing apparatus (including pattern storage means 20) 2, an image writing apparatus 3, an image forming means 4, a paper feeding means 5, a conveying means 6, and a fixing device 7. , Paper discharge means 8, re-conveyance means 9, and control means 10 and the like.

  The optical system of the image reading apparatus 1 includes an exposure unit 14 including a light source and a first mirror, a V mirror unit 15 including a second mirror and a third mirror, a lens 16, and a CCD image sensor 17.

  The image forming unit 4 includes a photosensitive drum 21 as an image carrier, a charger 22 as a charging unit, an image writing unit 3 as a writing unit, a developing unit 23 as a developing unit, a transfer unit 29A as a transfer unit, It consists of a separator 29B as a separation means, a cleaning device 26 as a cleaning means, a static elimination lamp 30 as a static elimination means, and the like.

  Document reading by the double-sided document automatic feeder RADF is performed at a position where the exposure unit 14 is stopped at the initial position below the slit exposure glass 13. Reading a document on the platen glass 11 is performed while moving the exposure unit 14 and the V mirror unit 15.

  Image information of the original image read by the image reading device 1 is subjected to image processing by the image processing device 2, converted into a signal as image data, and temporarily stored in a memory. Output light from a semiconductor laser (not shown) included in the image writing device 3 is applied to the photosensitive drum 21 to form an electrostatic latent image.

  In the image forming unit 4, a charge (negative polarity having the same polarity as that of toner in the present embodiment) is added to the surface of the photosensitive drum 21 by the charger 22, and electrostatic is generated by laser light irradiation from the image writing device 3. A latent image is formed, and the electrostatic latent image is visualized by the developing device 23 to become a toner image. The toner image is transferred by the transfer device 29A onto the paper P that is a transfer material conveyed from the paper supply means 5, the paper P is peeled off by the separator 29B, and the residual toner after transfer is removed by the cleaning device 26. . The charge remaining on the surface of the photosensitive drum 21 after cleaning is removed by the charge eliminating lamp 30.

  In addition, a control unit 10 that is a control unit that controls the operation of each unit of the image forming apparatus and a humidity sensor HS that is a humidity detection unit that detects humidity in the image forming apparatus are also housed in the image forming apparatus main body A. ing.

  The sheet P on which the toner image has been transferred is conveyed by a conveying means 6 composed of a belt, fixed by a fixing means 7, and discharged by a paper discharging means 8 to a paper discharge tray 81 outside the apparatus.

  In the case of double-sided copying, the paper P on which the image is formed on the first side is sent to the re-transport unit 9 by the transport path switching plate 82, is reversed, and the image forming unit 4 forms an image on the second side again. Thereafter, the paper is discharged by a paper discharge means 8 to a paper discharge tray 81 outside the apparatus. In the case of reverse paper discharge, the paper P branched from the normal paper discharge path by the transport path switching plate 82 is switched back and upside down in the reverse paper discharge unit 83 and then discharged from the apparatus by the paper discharge means 8. The paper is discharged to the paper tray 81.

  FIG. 2 is a block diagram showing the configuration of an embodiment of a control system related to image flow detection and image quality adjustment operations in the image forming apparatus of the present invention.

  In FIG. 2, the control unit 10 includes a memory 10 </ b> A having a pattern storage unit 10 </ b> B for storing an image quality determination pattern, a command for switching from the normal image formation mode to the image quality adjustment mode, for example, when an image flow occurs. The image quality adjusting unit 10C for causing the image forming apparatus to perform the image quality adjusting operation by issuing the above and the elapsed time storage unit 10D for measuring and storing the elapsed time when the image formation is not performed are incorporated.

  Based on information from a power button PS (not shown), a humidity sensor HS, or an image density sensor DS which is a pattern detection means, the control unit 10 performs image processing device 2, image writing device 3, charger 22, developing device 23, The operations of the transfer device 29A, the cleaning device 26, and the charge removal lamp 30 are controlled.

  The pattern forming unit according to the present invention includes a control unit 10, a pattern storage unit 10B, an image processing device 2, and an image writing device 3.

  First, a description will be given of operation control from humidity detection to image quality adjustment performed by the image forming apparatus according to the embodiment of the present invention at high humidity.

  In the first embodiment of the image quality adjustment operation according to the present invention, the photosensitive drum 21 is rotated at the time of non-image formation such as when the apparatus is activated or during preliminary rotation, and at the same time, the operation of the charger 22 and the charge removal lamp 30 is executed. Is.

  In the first embodiment, the control unit 10 uses the image quality adjustment unit 10C to perform an image quality adjustment operation when the predetermined humidity based on the detection value by the humidity sensor HS is exceeded, that is, when the humidity exceeds the predetermined humidity. Issue a command to Next, the control unit 10 causes the pattern forming unit to form an image quality determination pattern on the photosensitive drum 21 and cause the image density sensor DS to detect the formed image quality determination pattern. When the detected value is outside the predetermined range, as the image quality adjustment operation, the photosensitive drum 21 is rotated at the time of non-image formation such as when the apparatus is activated or during preliminary rotation, and at the same time, the operation of the charger 22 and the charge removal lamp 30 is performed. Is executed.

  The photoconductive performance of the photoconductive drum 21 can be recovered by rotating the photoconductive drum 21 and repeating the formation and removal of the charge layer on the surface of the photoconductive drum 21.

  In the second embodiment of the image quality adjustment operation according to the present invention, the photosensitive drum 21 is rotated at the time of non-image formation such as when the apparatus is activated or during preliminary rotation, and at the same time, the charger 22, the charge eliminating lamp 30, and the image writing apparatus 3. The operations of the developing device 23 and the cleaning device 26 are executed.

  In the configuration in which only the charger 22 and the charge removal lamp 30 according to the first embodiment are operated, the load on the photosensitive drum 21 is reduced because the image writing device 3, the developing device 23, and the cleaning device 26 are not operated. However, it is desirable that the developing device 23 and the cleaning device 26 be separated from the photosensitive drum 21 from the viewpoint of preventing the scattering of the developer.

  On the other hand, the configuration in which the image writing device 3, the developing device 23, and the cleaning device 26 according to the second embodiment are also operated is compared with the configuration in which only the charger 22 and the charge removal lamp 30 according to the first embodiment are operated. Thus, there is a negative aspect of increasing the load on the surface of the photosensitive drum 21.

Further, the determination of high humidity is measured by a saturated water vapor amount E (T) (E (T) = 5.03 × exp (0.061T)) when the environmental temperature is T ° C. and the humidity sensor HS. The absolute humidity was calculated from the value of the relative humidity, and when the absolute humidity was 20 g / m ³ or more, it was determined that the humidity was high. When the absolute humidity is 20 g / m ³ or more, an image quality determination pattern is created, its density is detected, and the image quality adjustment operation is controlled as necessary. With this configuration, even in an image forming apparatus using an organic semiconductor (OPC) that may generate an image flow under high humidity as a photosensitive drum, the image flow can be effectively prevented. Note that a CPU (not shown) provided in the control unit 10 has a temperature value in the apparatus detected by a temperature sensor (not shown) provided in the image forming apparatus and a relative humidity detected by the humidity sensor HS. It has a function that can calculate the absolute humidity from the value.

  The control unit 10 includes an elapsed time storage unit 10D. The elapsed time storage unit 10D counts the elapsed time and stores the elapsed time data when the image is not formed for a long time. have. The state where image formation is not performed herein refers to a state where the next image formation is not started regardless of whether the image forming apparatus is turned on or off.

  The elapsed time storage unit 10D includes a known time measuring device such as a mechanical device or an electric device with a built-in battery that operates even when the power of the image forming apparatus is turned off, and a nonvolatile memory.

  In addition to the humidity detection, when image formation is started again after a long time has elapsed, the control means 10 calls the elapsed time data from the elapsed time storage means 10D, and the called elapsed time data is a preset reference time. It is determined whether or not the image quality adjustment operation is performed. If the called elapsed time exceeds the reference time, the image quality adjustment operation is performed.

  The reference value of the elapsed time for determining whether or not to create the image quality determination pattern is an elapsed time during which image flow is likely to occur in advance by experiment (in the embodiment, when the time during which image formation is not performed has passed for 6 hours or more) The image quality determination pattern is created when a time longer than this has elapsed, and the image quality adjustment operation is controlled as necessary. As a result, the image quality can be adjusted with higher accuracy without waste.

  FIG. 3 is a diagram showing an image density determination pattern of one dot line pair formed on the photosensitive drum and an image density sensor (reflection type optical sensor) for measuring the density thereof.

  In the present embodiment, as shown in FIG. 3, the image quality determination pattern is a one-dot line pair pattern formed with a width W of 10 mm and a length L of 250 mm, which is substantially the circumferential length of the photosensitive drum 21. This pattern is formed on the surface of the photosensitive drum 21.

  Even if there is a variation in the ozone generation state of the charger 22 due to the difference in the position on the photosensitive drum 21, even if there is a difference in the degree of image flow, the length of the pattern for image quality determination is approximately the circumference of the photosensitive drum 21. By setting to, it is possible to detect the image flow without omission.

  In this embodiment, a pattern based on one dot line pair is used as the image quality determination pattern, but a pattern based on an error diffusion image may be used.

  FIG. 4 is a graph for explaining the result of measurement using the image quality determination pattern and the image density sensor shown in FIG. 3 and the image flow detection method.

  In FIG. 4, the horizontal axis represents the position in the length direction of the image quality determination pattern, and the vertical axis represents the output voltage of the image density sensor DS. The measurement locations on the image quality determination pattern are plotted at locations where the pattern length L is equally divided into 512, and the positions of 5 points are measured while shifting the position in the axial direction of the photosensitive drum 21 for each location. The value of the moving average was obtained.

  The standard for determining image flow is that the difference between the reference value of the image density sensor DS obtained in advance by experiment and the measured output voltage of the image density sensor DS is converted into a color difference ΔE * ab, and the converted value into the color difference ΔE * ab. It was determined that the image flow occurred when the value was 10 or more.

  FIG. 5 is a flowchart for explaining the procedure from image flow detection to image quality adjustment according to the embodiment of the present invention. FIG. 6 is a flowchart for explaining the procedure for the first embodiment of the image quality adjustment operation according to the present invention, and FIG. 7 explains the procedure for the second embodiment of the image quality adjustment operation according to the present invention. It is a flowchart for. FIG. 8 is a flowchart for explaining the procedure when the operation time of the image quality adjustment operation is changed with respect to the first or second embodiment of the image quality adjustment operation.

  In FIG. 5, the control unit 10 receives an ON signal of the power button PS, issues a command to each unit of the image forming apparatus, and starts a preparation operation for image formation (step S11).

  Next, the control unit 10 receives information on the humidity detected by the humidity sensor HS (step S12), calculates the absolute humidity, and determines whether or not the calculated absolute humidity exceeds a preset predetermined humidity ( Step S13). When the predetermined humidity is exceeded (Yes at Step S13), the process proceeds to Step S14, and when the predetermined humidity is not exceeded (No at Step S13), the process proceeds to Step S18.

  In step S <b> 14, the control unit 10 calls the elapsed time storage unit 10 </ b> D for a time during which image formation has not been performed since the previous image formation, and determines whether the called elapsed time exceeds a preset reference value. Judgment is made (step S14). When the reference value is exceeded (Yes at Step S14), the process proceeds to Step S15. When the reference value is not exceeded (No at Step S14), the process proceeds to Step S18.

  In step S15, the control unit 10 calls the image quality determination pattern from the pattern storage unit 10B in the memory 10A, causes the image processing device 2 to perform image processing, and causes the electrostatic latent image on the photosensitive drum 21 via the image writing device 3. And a toner image is formed by the developing device 23 (step S15).

  In step S16, the control unit 10 causes the image density sensor DS to read the image density of the image quality determination pattern formed on the photosensitive drum 21 (step S16).

  In step S17, the control unit 10 converts the difference between the output voltage value, which is the detected value of the pattern read by the image density sensor DS, and the reference value into the color difference ΔE * ab, and the converted value into the color difference ΔE * ab (hereinafter referred to as “color difference ΔE * ab”) It is determined whether the detected value of the pattern is within a predetermined range, that is, within a predetermined value (here, ΔE * ab = 10 is a predetermined value) (step S17). When the detected value of the pattern is within the predetermined value (Yes at Step S17), the process proceeds to Step S18, and when it exceeds the predetermined value (No at Step S17), the process proceeds to Step S19.

  When the detected value of the pattern is within the predetermined value, the process proceeds to step S18, and the control unit 10 causes the image quality adjusting unit 10C to cancel the image quality adjustment operation and switch to the mode for forming an image, and issues a command to each unit of the image forming apparatus. Then, image formation is performed (step S18).

  If the detected value of the pattern exceeds the predetermined value, the process proceeds to step S19, and the control unit 10 causes each unit of the image forming apparatus to perform an image quality adjustment operation via the built-in image quality adjustment unit 10C (step S19). Details of the image quality adjustment operation will be described later (see FIGS. 6 and 7).

  After the image quality adjustment operation in step S19 is completed, the process returns to step S15, and the control unit 10 instructs each unit of the image forming apparatus to repeat the operations in and after step 15.

  Next, a specific operation of the image quality adjustment operation will be described with reference to FIGS.

  FIG. 6 is a flowchart showing a specific procedure for the first embodiment of the image quality adjustment operation in step 19 of FIG. 5. Here, the image quality adjustment operation from step S17 to step S15 in FIG. A procedure for shifting from the step S17 to the image formation in the step 18 after the completion of the image quality adjustment operation or the image quality adjustment operation will be described.

  If the detected value of the pattern exceeds the predetermined value in step S17 in FIG. 5 (No in step S17), the process proceeds to step S19. Here, step 19 is divided into four steps from step 21 to step 24.

  If the detected value of the pattern exceeds the predetermined value in step S17, the control unit 10 issues an image quality adjustment command via the built-in image quality adjusting means 10C (step S21), and the photosensitive drum 21 is used as the image quality adjusting operation. (Step S22), the charger 22 is operated (Step S23), and the static elimination lamp 30 is further operated (Step S24). In the first embodiment, this image quality adjustment operation is performed for 3 minutes.

  Thereafter, the process proceeds to step S15 described with reference to FIG. 5, and the control unit 10 forms an image quality determination pattern on the photosensitive drum 21 as a toner image (step S15), and determines the image quality determination formed on the photosensitive drum 21. The image density sensor DS reads the image density of the pattern (step S16), and the process proceeds to step 17.

  The image quality adjustment operation from step S21 to step S16 is repeated until the pattern detection value falls within the predetermined value in step S17. When the pattern detection value falls within the predetermined value, the image quality adjustment ends, and the process proceeds to step S18. After proceeding to step S18, the control unit 10 causes the image quality adjusting unit 10C to cancel the image quality adjustment operation and switch to a mode for forming an image, and causes the image forming apparatus to perform image formation (step S18).

  According to an experiment conducted by the present inventor, the amount of toner consumed in one month for confirming the occurrence of image flow is determined by the conventional method of creating an image quality determination pattern at every warm-up. This amount corresponds to 440 copies in terms of the number of copies with an image occupation ratio of 6%. On the other hand, in the image forming apparatus that performs the image quality adjustment operation according to the first embodiment of the present invention, the amount of toner consumed in the method of creating the image quality determination pattern at high humidity is an amount corresponding to 120 copies under the same conditions. (However, the days when the humidity is high were calculated assuming that there are 6 days in 22 working days of a month). That is, it is possible to reduce the amount of toner used for creating image quality determination patterns for the number of days other than the day when the humidity is high.

  Further, a special configuration such as incorporating a heater in the photosensitive drum 21 is not required, and the manufacturing cost of the image forming apparatus can be kept low.

  FIG. 7 is a flowchart showing the procedure for the second embodiment of the image quality adjustment operation in step 19 of FIG. 5. Here, the procedure of the image quality adjustment operation from step S17 to step S15 in FIG. Alternatively, a procedure for shifting from step S17 to image formation in step S18 after the image quality adjustment operation is completed will be described.

  If the detected value of the pattern exceeds the predetermined value in step S17 in FIG. 5 (No in step S17), the process proceeds to step S19. Here, step 19 is divided into four steps from step 31 to step 34.

  If the detected value of the pattern exceeds the predetermined value in step S17, the control unit 10 issues an image quality adjustment command via the built-in image quality adjusting means 10C (step S31), and the image forming means 4 is used as the image quality adjusting operation. Is operated (step S32). The operation of the image forming unit 4 is performed in the order of the photosensitive drum 21, the charger 22, the image writing device 3, the developing device 23, the transfer unit 29 </ b> A, the cleaning device 26 that is a cleaning unit, and the charge eliminating lamp 30.

  Next, the control unit 10 operates the paper feeding means 5 to send out the paper P (step S33), and an image for visually confirming the image flow formed on the photosensitive drum 21 is transferred to the paper P by the transfer device 29A. The copy is output (step S34). However, copy output is performed intermittently to save paper P and copy materials. In the present embodiment, one copy is made every 30 seconds.

  Thereafter, the process proceeds to step S15 described with reference to FIG. 5, and the control unit 10 forms an image quality determination pattern on the photosensitive drum 21 as a toner image (step S15), and determines the image quality determination formed on the photosensitive drum 21. The image density sensor DS reads the image density of the pattern (step S16), and the process proceeds to step 17.

  The image quality adjustment operation from step S21 to step S16 is repeated until the detected value of the pattern falls within the predetermined value in step S17. When the detected value of the pattern falls within the predetermined value, the image quality adjustment operation ends, and the process proceeds to step S18. The unit 10 causes the image quality adjustment unit 10C to cancel the image quality adjustment operation and switch to a mode for forming an image, and causes the image forming apparatus to perform image formation (step S18).

  By performing the image quality adjustment operation of the second embodiment, it is possible to visually confirm the occurrence state of the image flow.

  In the image quality adjustment operation in step S19, the image quality adjustment operation time may be changed according to the detection value of the image quality determination pattern read by the image density sensor DS in step S16. In other words, when the difference between the detected value of the pattern in step S17 and the predetermined reference value is large, the image quality adjustment operation time is lengthened, and when the difference is small, the image quality adjustment operation time is shortened.

  FIG. 8 is a flowchart for explaining the procedure of the configuration of the image forming apparatus that changes the image quality adjustment operation time according to the degree of the generated image flow in the first or second embodiment of the image quality adjustment operation. It is. Here, the procedure from step S17 in FIG. 5 until returning to step S15, or the procedure for shifting from step S17 to image formation in step 18 will be described.

  In the present embodiment, when the detected value of the pattern exceeds the predetermined value in Step S17 in FIG. 5 (No in Step S17), the process proceeds to Step S41, and the control unit 10 detects the detected value of the pattern, that is, the color difference ΔE * ab. It is determined whether or not the difference between the converted value and the predetermined value is large (step S41). In the present embodiment, when the detected value of the pattern, that is, the converted value to the color difference ΔE * ab is 12, the determination reference value is used, and when it exceeds 12, the difference from the predetermined value is large. It was determined that the difference from the predetermined value was small.

  When the difference between the detected value of the pattern and the predetermined value is large (Yes at Step S41), the process proceeds to Step S42, and the control unit 10 lengthens the execution time of the image quality adjustment operation (see Step S19 in FIG. 5, 6 or 7) ( The specific operation of step S42 and step S42 will be described later).

  When the difference between the detected value of the pattern and the predetermined value is small (No at Step S41), the process proceeds to Step S43, and the control unit 10 shortens the execution time of the image quality adjustment operation (Step S43).

  Next, the process proceeds to step S15, where an image quality determination pattern is formed (step S15), the image density sensor DS detects the image density of the image quality determination pattern in step S16 (step S16), and the process returns to step S17 again.

  If the detected value of the pattern exceeds the predetermined value in Step S17 (No in Step S17), the process proceeds to Step S41, and the operations from Step S41 to Step S17 are repeated. If the detected value is within the predetermined value (Yes in Step S17). Proceed to step S18. When the process proceeds to step S18, the control unit 10 causes the image quality adjustment unit 10C to cancel the image quality adjustment operation and switch to a mode for forming an image, and causes the image forming apparatus to perform image formation (step S18).

  The operation for extending the execution time of the image quality adjustment operation in step S42 will be described below.

  The execution time in the first embodiment of the image quality adjustment operation according to the present invention is the operation time for executing the operations of the photosensitive drum 21, the charger 22, and the charge removal lamp 30 described in step S19 of FIG. With respect to this operation time, in step S42, the operation of one or a plurality of members among the three members of the photosensitive drum 21, the charger 22, or the charge removal lamp 30 according to the detected value of the pattern detected in step S17. Change the time selectively. That is, the detected value of the pattern detected in step S17 is compared with a predetermined value, and when the difference is large, the operation time for executing the operation of the photosensitive drum 21, the charger 22, or the charge removal lamp 30 is lengthened, and the difference When is small, the operation time is shortened.

  In the second embodiment of the image quality adjustment operation described in step S19 in FIG. 7, the photosensitive drum 21, the charger 22, the image writing device 3, the developing device 23, the transfer device 29A, the cleaning device 26 as a cleaning unit, and Seven devices or members of the static elimination lamp 30 are operated. For the operation times of these devices or members, as in the first embodiment, in step S42, the operation times of one or more devices or members are selectively selected according to the detected value of the pattern detected in step S17. To change.

  By changing the execution time of the image quality adjustment operation according to the degree of the generated image flow, the occurrence of the image flow can be suppressed more efficiently.

  In the embodiment of the present invention, the image quality determination pattern formed on the photosensitive drum is a visible image, and the pattern detection means is an image density sensor. However, the image quality determination pattern is a latent image, and the pattern detection means is A sensor capable of measuring potential may be used. Detection of image flow in this configuration is performed by operating at least the charger 22 and the charge removal lamp 30 in the image forming unit 4 and measuring the potential formed on the photosensitive drum 21 with an electrometer.

1 is a schematic diagram illustrating an overall configuration of an image forming apparatus according to an embodiment of the present invention. FIG. 3 is a block diagram illustrating a configuration of an embodiment of a control system related to image flow detection and image quality adjustment operations in the image forming apparatus of the present invention. It is a figure which shows the image density sensor which measures the pattern for image quality determination of 1 dot line pair formed on the photoconductive drum, and its density | concentration. FIG. 4 is a graph for explaining a result of measurement using an image quality determination pattern and an image density sensor shown in FIG. 3 and an image flow detection method. FIG. It is a flowchart for demonstrating the procedure from the detection of the image flow to image quality adjustment which concerns on embodiment of this invention. 5 is a flowchart for explaining a procedure for a first embodiment of an image quality adjustment operation in the image forming apparatus according to the present invention. 6 is a flowchart for explaining a procedure for a second embodiment of an image quality adjustment operation in the image forming apparatus according to the present invention. 5 is a flowchart for explaining a procedure for the configuration of an image forming apparatus that changes an image quality adjustment operation time with respect to the first or second embodiment of the image quality adjustment operation.

Explanation of symbols

2 Image processing device 3 Image writing device (writing means)
4 Image forming means 10 Control unit (control means)
10A Memory 10B Pattern storage means 10C Image quality adjustment means 10D Elapsed time storage means 21 Photosensitive drum (image carrier)
22 Charger (charging means)
23 Developing device (developing means)
26 Cleaning device (cleaning means)
29A Transfer device (transfer means)
30 Static elimination lamp (static elimination means)
DS Image density sensor (pattern detection means)
HS Humidity sensor (humidity detection means)
PS Power button

Claims (9)

An image bearing member; a charging unit that applies a charge to the surface of the image bearing member; a writing unit that irradiates a light beam for forming an electrostatic latent image on the surface of the image bearing member; Developing means for supplying a developer to the image to form a toner image; transfer means for transferring the toner image formed on the image carrier to paper; and cleaning for removing residual toner remaining on the image carrier. Means for neutralizing the surface of the image carrier, pattern forming means for forming an image quality judgment pattern for judging image quality on the image carrier, and pattern detection for detecting the image quality judgment pattern And an image forming apparatus comprising:
While having humidity detection means for detecting humidity,
Control means for controlling to perform an image quality adjustment operation based on the detection result of the pattern detection means,
The control means causes the pattern forming means to form the image quality determination pattern on the image carrier only when a predetermined humidity is exceeded based on a detection value by the humidity detection means, and causes the pattern detection means to The image quality of the image quality determination pattern is detected, it is determined whether or not the detection value by the pattern detection means is within a predetermined range, and when the detection value by the pattern detection means is outside the predetermined range, the image quality adjustment An image forming apparatus controlled to execute an operation. The image forming apparatus according to claim 1, wherein the image quality determination pattern is for determining image flow. 3. The image forming apparatus according to claim 1, wherein the image quality adjustment operation is an operation of executing operations of the image carrier, the charging unit, and the charge eliminating unit during non-image formation. The control means controls the image quality adjustment operation to change at least one operation time of the charging means and the charge removal means in accordance with a detection value by the pattern detection means. Item 4. The image forming apparatus according to Item 3. The image forming apparatus according to claim 3, wherein the image quality adjustment operation further includes execution of operations of the writing unit, the developing unit, and the cleaning unit. In the image quality adjustment operation, the control means sets at least one operation time of the charging means, the charge eliminating means, the writing means, the developing means, and the cleaning means to a detection value by the pattern detecting means. The image forming apparatus according to claim 5, wherein the image forming apparatus is configured to be controlled to change in response. The control means includes elapsed time storage means for counting elapsed time thereafter and storing elapsed time data when the image forming apparatus maintains a state where image formation is not started while the power is on or when the power is turned off. Built-in,
When image formation is started, the control unit calls the elapsed time data from the elapsed time storage unit and compares the called elapsed time data with a preset reference value to determine whether or not to perform an image quality adjustment operation. The image forming apparatus according to claim 1, wherein when the elapsed time data exceeds a reference value, control is performed so as to perform an image quality adjustment operation. The image forming apparatus according to claim 1, wherein the pattern detection unit is an image density sensor that detects an image density of the image quality determination pattern. 9. The length of the image quality determination pattern in the image carrier rotation direction has a length corresponding to one circumference of the outer periphery of the image carrier. Image forming apparatus.

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