JP2010091692A - Image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image forming apparatus capable of performing printing with normal quality, while shortening a time up to a first print by shortening a warm-up time, thereby permitting printing at an early stage. <P>SOLUTION: The image forming apparatus 1 includes: a fixing part 7 for heating and fixing a toner image transferred to a paper; a temperature control part 77 for heat-controlling the fixing part 7, so as to make a temperature detected by a temperature detecting element 73a a target temperature; and a print control part 78 permitting printing after the fixing part 7 is adjusted to the target temperature. The print control part 78 is configured so that after the temperature of the fixing part 7 is adjusted to the target temperature by the temperature control part 77, the temperature distribution in the width direction of a paper of the fixing part 7 is detected and printing is permitted for the paper having a print width determined to be possible to fixing based on the temperature distribution. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention includes a fixing unit that heat-fixes a toner image transferred onto a sheet, a temperature control unit that controls heating of the fixing unit so that a temperature detected by a temperature detection element becomes a target temperature, and the fixing unit that has a target temperature. The present invention relates to an image forming apparatus including a print control unit that allows printing after being adjusted.

  In an image forming apparatus including a fixing unit that heat-fixes a toner image transferred to a sheet to the sheet, there is a possibility that problems such as an increase in internal temperature due to excess heat generated in the fixing unit and a decrease in print quality may occur. Therefore, a louver and a fan for discharging the excess heat to the outside of the machine are provided in the housing.

  Air is taken into the aircraft from the intake louver via the intake fan. The air passes through a flow path provided in the machine, and is discharged from the exhaust louver to the outside through the exhaust fan. Since the air takes away excess heat generated in the fixing unit and exhausts it outside the apparatus, an increase in the temperature inside the apparatus is suppressed. Note that ozone generated in the machine is also exhausted by the air.

  By the way, many of the image forming apparatuses are equipped with a standby mode for cutting off the energization to the fixing unit or reducing the energization amount after a predetermined time has elapsed since printing, in order to save power.

  In the standby mode in which the power is cut off, the temperature of the fixing unit decreases, so if the standby time increases, the warm-up time required to raise the temperature of the fixing unit again to a temperature at which the fixing process can be performed increases. The time to print becomes longer.

  On the other hand, in the standby mode for reducing the energization amount, the temperature of the fixing unit is maintained around a predetermined temperature set lower than the temperature at which the fixing process can be performed, so that the warm-up time can be shortened compared to the former. And the time until the first print can be shortened. During the standby mode, the fan is driven to rotate to discharge excess heat generated in the fixing unit to the outside of the apparatus.

  The temperature in the paper width direction of the fixing unit in the standby mode in which the energization amount is reduced will be described with reference to FIGS. 1 (a) and 1 (b). In the figure, the long chain line indicates the flow of air in the machine.

  As shown in FIG. 1 (a), an intake louver 92 (92a, 92b) is installed on both ends of the fixing unit 91 in the sheet width direction of the housing of the image forming apparatus 9, and the exhaust louver 93 is connected to each intake air. When installed at a substantially equal distance from the louver 92, the temperature at both ends decreases substantially uniformly with respect to the central portion as shown in the lower part of FIG.

  Therefore, if the heating capability of the heater provided in the fixing unit 91 and the heat capacity of the fixing unit 91 are set uniformly along the paper width direction of the fixing unit 91, the warming-up of the both ends of the fixing unit 91 is performed. The temperature rises without substantially increasing or decreasing.

  Here, the mounting positions of the louvers 92 and 93 and the fans 94 (94a, 94b, and 94c) depend on the mounting positions of various components provided in the image forming apparatus 9.

  Therefore, as shown in FIG. 1B, when the exhaust louver 93 is close (or remote) to any one of the intake louvers 92, as shown in the lower part of FIG. High and low temperatures occur at both ends. Further, during warm-up, the temperature at both ends of the fixing unit 91 rises while maintaining a high and low level, and if the fixing process is performed at a fixing unit having a temperature difference between both ends, the print quality deteriorates.

  By rotating a fixing roller (not shown) in which a heater is inserted when the fixing unit 91 is warmed up, the heat of the heater is dispersed and the temperature of the fixing unit 91 is made uniform. However, in the latter case, warm-up must be continued until the temperature becomes substantially uniform, and the time until the first print cannot be shortened.

In Patent Document 1, in a fixing device that grips and conveys a sheet material while heating and fixes the developer attached to the sheet material, a heating roller that has a heater and can be driven in rotation, in parallel with the heating roller And a pressure roller provided rotatably, a pressure device that presses at least the center and both ends of the pressure roller toward the heating roller, and the temperatures of at least the center and both ends of the heating roller. Temperature detecting means for detecting, and when the narrow sheet non-sheet passing portion of the heating roller is hotter than the narrow sheet passing portion by the temperature detecting means, the pressure device is driven to prevent narrow sheet non-passing. There is disclosed a printer provided with a fixing device, which is provided with a control device that weakens the pressure applied to the paper portion.

According to the image forming apparatus disclosed in Patent Document 1, since the narrow sheet having a narrow sheet width is passed, the narrow sheet in a state where the temperature at both ends of the heating roller is higher than that at the center. When passing a wide sheet with a wider paper width, the amount of heat applied to the paper to be passed is reduced by driving the pressure device and weakening the pressure applied to the parts of the pressure roller that are in pressure contact with both ends of the heating roller. The wide sheet can be fixed without reducing the print quality.
JP-A-5-297759

  However, the image forming apparatus disclosed in Patent Document 1 needs to include a pressurizing device, which increases the cost of components and requires an installation space for the pressurizing device. In addition, even if the pressure device is used, the temperature in the low temperature region of the fixing unit cannot be raised to a temperature at which the fixing process can be performed, so the warm-up time can be shortened and the time until the first print can be shortened. I can't.

  In view of the above-described problems, an object of the present invention is to provide an image forming apparatus capable of printing with normal quality while shortening the warm-up time and allowing printing at an early stage and reducing the time to first printing. The point is to provide.

  In order to achieve the above object, a first characteristic configuration of an image forming apparatus according to the present invention is a fixing unit that heat-fixes a toner image transferred to a sheet as described in claim 1 of the document of the claims. And a temperature control unit that controls the heating of the fixing unit so that the temperature detected by the temperature detection element becomes a target temperature, and a print control unit that allows printing after the fixing unit is adjusted to the target temperature. In the forming apparatus, the print control unit detects a temperature distribution along a sheet width direction of the fixing unit after the temperature of the fixing unit is adjusted to a target temperature by the temperature control unit, and the temperature distribution In other words, printing is permitted on a paper having a print width determined to be fixable based on the above.

  In the fixing unit that is heated and controlled by the temperature control unit, the fixing process can be performed in order from a region where the temperature has been increased to a temperature at which the fixing process can be performed (hereinafter referred to as “target temperature”). Fixing processing can be performed in the area. Here, the print control unit detects the temperature distribution along the paper width direction of the fixing unit based on the temperature detected by the temperature detecting element, and based on the temperature distribution, the area that has been heated to a temperature at which the fixing process can be performed. It is configured to recognize and allow printing of paper having a print width within the paper width direction size of the area.

  In other words, the shorter the print width, the shorter the time required for warming up the fixing unit, and the print control unit allows printing faster on paper shorter than paper with a longer print width. The time until the first print can be shortened.

  In the second characteristic configuration, as described in claim 2, in addition to the first characteristic configuration described above, the print control unit fixes the image based on image data in the paper width direction printed on the paper. The point is to determine whether or not the print width is possible.

  The size of the image data printed on the paper is equal to or smaller than the size of the paper, and the portion to be fixed by the fixing unit is a paper portion corresponding to the image data. That is, the actual sheet width of the sheet to be fixed is shorter than the actual sheet width. Since the print control unit determines whether to allow printing based on the actual paper width instead of the actual paper width, the time until the first print can be effectively shortened.

  According to the third characteristic configuration, as described in the third aspect, in addition to the first characteristic configuration described above, the print control unit has a print width that can be fixed based on the selected paper size. The point is to determine whether or not.

  The print control unit determines whether to allow printing based on the paper width of the paper of the selected paper size and allows printing, so that the fixing unit reliably fixes the paper of the selected paper size. can do.

  In the fourth feature configuration, as described in claim 4, in addition to any of the first to third feature configurations described above, the temperature control unit is arranged at the center of the fixing unit along the paper width direction. The fixing unit is heated and controlled so that the temperature detected by the temperature detecting element arranged in the vicinity of the unit becomes the target temperature, and the print control unit is separated from the temperature detecting element along the paper width direction of the fixing unit. The temperature distribution along the paper width direction of the fixing unit is detected on the basis of the temperature detected by the second temperature detecting element arranged in the position.

  The print control unit can easily detect the temperature distribution of the fixing unit based on the detection temperature and the separation distance of the temperature detection element and the second temperature detection element.

  As described above, according to the present invention, it is possible to provide an image forming apparatus capable of printing with normal quality while shortening the warm-up time and allowing printing early and reducing the time to first printing. I was able to do that.

  A printer that is an example of the image forming apparatus of the present invention will be described below.

  As shown in FIG. 2, a printer 1 that employs an electrophotographic system is a man-machine interface, an operation unit 20 that displays an operation state of the printer 1, and a network control unit that is connected to a computer terminal 6 via a network. 3 and a printer engine 40 that forms a toner image based on the image data input from the computer terminal 6, transfers and fixes the toner image onto a sheet, and outputs the sheet.

  The operation unit 20 includes a display unit 20 a configured by a liquid crystal panel that displays a screen indicating the operation state of the printer 1.

  The printer engine 40 includes a photosensitive member, an exposure device that forms an electrostatic latent image on the photosensitive member by exposure scanning, a developing device that visualizes the electrostatic latent image with toner and forms a toner image, and a photosensitive member. A transfer device that transfers the toner image transferred onto the paper and a fixing device that heat-fixes the toner image transferred onto the paper onto the paper. A paper transport mechanism for transporting paper is also provided.

  An operation control unit 2 that controls the operation unit 20, a network control unit 3, an engine control unit 4 that controls the printer engine 40, and a system control unit 5 that performs overall control of the printer 1 include a command bus (a bus indicated by a thin line in the figure). And an image bus (a bus indicated by a thick line in the figure).

  The operation control unit 2, the network control unit 3, the engine control unit 4, and the system control unit 5 are each composed of a CPU, a ROM that stores an operation program of the CPU, a RAM that is a work area of the CPU, and a board that includes peripheral circuits. ing.

  When image data described in a page description language such as PostScript (registered trademark of Adobe Systems Inc.) input from the computer terminal 6 is input, the network control unit 3 inputs the image data to the system control unit 5. input.

  When image data is input from the network control unit 3, the system control unit 5 renders the image data and generates print data including bitmap data (image data for output corresponding to the image data of the present invention). To do.

  In addition, a screen indicating that the printer 1 is performing a printing operation is displayed on the display unit 20 a that is a liquid crystal panel disposed in the operation unit 20 via the operation control unit 2, and the printer engine 40 is displayed on the engine control unit 4. A drive command is output.

  When a drive command is input from the system control unit 5, the engine control unit 4 controls the exposure device based on the print data generated by the system control unit 5 to form an electrostatic latent image on the photoreceptor. The developing device is controlled to develop the electrostatic latent image and form a toner image on the surface of the photoreceptor. The paper conveyance mechanism is controlled to convey the paper.

  The transfer device is controlled to transfer the toner image from the photoreceptor surface to the paper. The fixing device is controlled to raise the temperature of the fixing device to a target temperature, and the toner image is heated and fixed on the paper. The transport mechanism is controlled to discharge the paper.

  Hereinafter, the fixing device provided in the printer engine 40 will be described. The fixing device corresponds to the fixing unit of the present invention.

  FIG. 3A is a diagram illustrating the fixing device 7 viewed from the front side of the printer 1. As shown in FIG. 3A, the fixing device 7 has a nip formed between the fixing roller 71 that heats the sheet by the heat of the heater 70 inserted therein and the fixing roller 71 pressed against the fixing roller 71. A pressure roller 72 for nipping and conveying the paper is provided. The fixing roller 71 is rotated at a predetermined rotation speed by a motor (not shown), and the pressure roller 72 is rotated following the fixing roller 71.

  The thermistor 73 (73a, 73b) is disposed in contact with the fixing roller 71. The thermistor 73a is disposed in the vicinity of the center of the fixing device 7 along the paper width direction, and the thermistor 73b is disposed at a position separated from the thermistor 73a along the paper width direction of the fixing device 7. The thermistor 73a corresponds to the temperature detection element of the present invention, and the thermistor 73b corresponds to the second temperature detection element of the present invention.

  The housing 10 of the printer 1 on both ends of the fixing device 7 in the paper width direction is provided with intake louvers 74a and 74b for taking air into the apparatus and exhaust louvers 74c for discharging the air to the outside of the apparatus. . A fan 75 (75a, 75b, 75c) is attached to each louver 74.

  The fan 75 always rotates at a predetermined speed after turning on the power to the printer 1, and takes in air into the machine or discharges air outside the machine via the louver 74, and the inside of the machine due to excess heat generated in the fixing device 7. Prevent temperature rise. Specifically, the air taken into the machine from the intake louvers 74a and 74b flows through the machine flow path, absorbs excess heat generated in the fixing device 7, and is exhausted from the exhaust louver 74c.

  The engine control unit 4 includes a temperature control unit 77 that controls the heating of the fixing device 7 so that the temperature detected by the thermistor 73a becomes the target temperature, and a print control unit 78 that allows printing after the fixing device 7 is adjusted to the target temperature. It has. The temperature control unit 77 and the print control unit 78 are functional blocks embodied in the engine control unit 4 when a CPU provided in the engine control unit 4 executes an operation program.

  The ROM of the engine control unit 4 stores a target temperature and a second target temperature that is the temperature of the fixing device 7 in a standby mode for reducing the amount of power supplied to the heater 70. An analog signal indicating the temperature detected by the thermistor 73 is input to the A / D conversion port of the engine control unit 4.

  When a drive command for the printer engine 40 is input from the system control unit 5, the print control unit 78 requests the temperature control unit 77 to adjust the temperature detected by the thermistor 73 a to the target temperature. After the temperature of the fixing device 7 is adjusted to the target temperature by the temperature control unit 77, each unit of the printer engine 40 is controlled, and print processing is executed based on the print data generated by the system control unit 5.

  When a predetermined time has elapsed after printing, the system control unit 5 shifts the printer 1 to the standby mode, and the print control unit 78 requests the temperature control unit 77 to adjust the temperature detected by the thermistor 73a to the second target temperature.

  The temperature controller 77 detects the temperature of the fixing device 7 based on the analog signal input from the thermistor 73a. In response to a request from the print controller 78, the target temperature or the second target temperature is read from the ROM, the duty ratio of the current supplied to the heater 70 is adjusted, and the detected temperature is adjusted to the target temperature or the second target temperature. .

  The heat capacity of the fixing roller 71 is designed to be small so that the temperature until the first print can be shortened by increasing the temperature increase rate of the fixing device 7. For example, there is a fixing roller having a heat capacity such that when the heater is energized at a duty ratio of 100%, the temperature of the fixing device is increased by about 50 degrees in about 1 second.

  Since the flow rate of the air that discharges excess heat generated in the fixing device 7 is set based on the temperature of the fixing device 7 being the target temperature, in the standby mode, the cooling capacity by the air is the heating of the heater 70. It exceeds the capacity and heat retention capacity. Further, the exhaust louver 74c has one end side in the sheet width direction of the fixing device 7 due to restrictions on device design (in this embodiment, the end on the right side as viewed from the front side on the back side of the printer 1). It is installed at a position biased to the vicinity.

  Therefore, as shown in FIG. 3B, in the standby mode, the temperature on the thermistor 73 b side of the fixing roller 71 is high, the temperature on the opposite side is low, and a temperature gradient is generated in the fixing device 7. That is, in the standby mode, the temperature distribution of the fixing device 7 is not uniform, and the time required for returning from the standby mode (until the temperature of the fixing device 7 is uniformly equalized to the target temperature) becomes long. When returning from the standby mode, the heater 70 is energized and heated, and the fixing roller 71 is rotationally driven. Due to the warm-up, the temperature of the fixing device 7 becomes uniform over time.

  In order to reduce the time until the first print when returning from the standby mode, the print control unit 78 adjusts the temperature of the fixing device 7 after the temperature control unit 77 has adjusted the temperature of the fixing device 7 to the target temperature. A temperature distribution along the paper width direction is detected, and printing is permitted on a paper having a print width determined to be fixable based on the temperature distribution.

  More specifically, the print controller 78 detects the temperature distribution along the sheet width direction of the fixing device 7 based on the temperature detected by the thermistor 73a and the thermistor 73b. Also, based on the print data in the paper width direction printed on the paper, it is determined whether or not the print width can be fixed.

  Specifically, the print control unit 78 calculates a temperature gradient in the sheet width direction of the fixing device 7 from the detected temperatures by the thermistor 73a and the thermistor 73b and the respective separation distances, and adopts the temperature gradient as the “detected temperature distribution”. To do. With the warm-up during the return from the standby mode, the temperature gradient becomes gentle with the passage of time, and the temperature gradient disappears when sufficient time has passed. At this time, the temperature of the fixing device 7 is uniformly the target temperature.

  Here, among the sheets that are passed through the fixing device 7, the heat treatment is required in the area where the print data printed on the sheet is transferred. In addition, the fixing device 7 is configured to perform fixing processing on a sheet to be passed through a so-called center through which the sheet is passed with respect to a central portion in the sheet width direction.

  Therefore, the print control unit 78 grasps the size in the paper width direction of the print data based on the number of pixels in the paper width direction of the print data generated by the system control unit 5 and the resolution at the time of printing of the printer 1 and fixes the print data. The temperature gradient of the region of the fixing device 7 corresponding to the size in the sheet width direction is confirmed with reference to the central portion of the roller 71 in the sheet width direction, and when the temperature gradient in the region disappears substantially, It is determined that the print data can be heated, and printing is permitted.

  Hereinafter, operations of the temperature control unit 77 and the print control unit 78 when returning from the standby mode will be described with reference to the flowchart shown in FIG.

  When image data is input from the computer terminal 6 via the network (S1) and a drive command for the printer engine 40 is input from the system control unit 5, the print control unit 78 adjusts the temperature detected by the thermistor 73a to the target temperature. The temperature control unit 77 is requested to do so (S2), and the temperature control unit 77 starts the adjustment (S3).

  The print control unit 78 grasps the sheet width direction size of the print data generated by the system control unit 5 (S4), and uses the center of the fixing device 7 in the sheet width direction as a reference sheet of the fixing device 7 corresponding to the size. The temperature gradient in the region in the width direction is detected based on the temperature detected by the thermistor 73a and the thermistor 73b (S5).

  The print control unit 78 continues to detect the temperature gradient until the temperature gradient in the area disappears (S6N), and when the temperature gradient disappears (S6Y), the print is allowed (S7).

  Another embodiment will be described below.

  In the above-described embodiment, the print control unit 78 calculates the temperature distribution along the sheet width direction of the fixing device 7 based on the temperature detected by the thermistor 73a as the temperature detection element and the thermistor 73b as the second temperature detection element. However, the thermistor 73b may not be provided in the printer 1, and the temperature distribution along the sheet width direction of the fixing device 7 may be detected based on the temperature detected by the thermistor 73a.

  In this case, for example, table data indicating the relationship between the elapsed time and the temperature distribution along the paper width direction of the fixing device 7 is obtained through experiments or the like based on the detection of the target temperature by the thermistor 73a. The data is stored in the ROM of the engine control unit 4 or the system control unit 5.

  Then, referring to the ROM, if the print controller 78 is configured to detect the temperature distribution along the paper width direction of the fixing device 7 based on the elapsed time since the target temperature was detected by the thermistor 73a. Good.

  In the above-described embodiment, the image data input from the computer terminal 6 has been described as being described in the page description language. However, the bitmap data constituting the image and the printing conditions (for example, the number of printed sheets and the paper size) The image data may be configured with environmental information or the like.

  In this case, the paper width direction size of the image data is grasped based on the number of pixels in the paper width direction of the bitmap data and the resolution at the time of printing by the printer 1, and the print width that can be fixed based on the paper width direction size. What is necessary is just to comprise the print control part 78 so that it may determine whether it is.

  In the above-described embodiment, the printer 1 employing the present invention has been described. However, the present invention can be applied to all image forming apparatuses including a fixing unit that performs heat fixing. That is, an arbitrary image forming apparatus having a fixing device for performing heat fixing processing, such as a so-called multi-function machine having a plurality of functions such as a printer function, a facsimile function, and a copying function, and a copying machine having a single function In contrast, the present invention can be adopted.

  For example, in a copying machine adopting the present invention, when image data read from a document by a scanner mounted on the copying machine is transferred to a sheet and printed, the image data is printed on the sheet based on the image data in the sheet width direction. The print control unit may be configured to determine whether the print width is fixable.

  In the above-described embodiment, the print control unit 78 has been described as determining whether the print width can be fixed based on the image data in the paper width direction printed on the paper. Based on the size, it may be determined whether the print width is fixable.

  In this case, whether or not the print width can be fixed with the paper size used for printing specified in the image data input from the computer terminal 6 or the paper size set in the operation unit 20 as the “selected paper size”. The print control unit 78 may be configured to determine whether or not.

  In the above-described embodiment, the temperature detection element is described as being constituted by a thermistor. However, the temperature detection element is not limited to the thermistor, and may be constituted by, for example, a thermocouple. .

  In the above-described embodiment, the configuration in which the thermistor 73b is disposed in contact with the fixing roller 71 as the second temperature detection element has been described, but the second temperature element may be two or more. In this case, the print control unit 78 can more accurately detect the temperature distribution along the sheet width direction of the fixing device 7.

  Note that each of the above-described embodiments is merely an example of the present invention, and the scope of the present invention is not limited by the description. The specific configuration of each part is appropriately selected within the scope of the effects of the present invention. It goes without saying that changes can be designed.

(A) And (b) is explanatory drawing of a fixing device and its temperature distribution. Functional block diagram of printer (A) is explanatory drawing of a fixing device, (b) is explanatory drawing of a fixing device and its temperature distribution. Flow chart for explaining operations of the temperature control unit and the print control unit when returning from the standby mode

Explanation of symbols

1: Image forming apparatus (printer)
7: Fixing part (fixing device)
10: Printer casing 71: Fixing roller 72: Pressure roller 73: Temperature detection element (thermistor)
74: Inlet louver 75: Fan 77: Temperature controller 78: Print controller

Claims (4)

A fixing unit that heat-fixes the toner image transferred to the paper, a temperature control unit that controls the heating of the fixing unit so that the temperature detected by the temperature detection element becomes a target temperature, and the fixing unit is adjusted to the target temperature. An image forming apparatus including a print control unit that allows printing later,
The print control unit detects a temperature distribution along the paper width direction of the fixing unit after the temperature control unit adjusts the temperature of the fixing unit to a target temperature, and can fix based on the temperature distribution. An image forming apparatus that allows printing on a paper having a determined print width.   The image forming apparatus according to claim 1, wherein the print control unit determines whether the print width is a fixable print width based on image data in a paper width direction printed on the paper.   The image forming apparatus according to claim 1, wherein the print control unit determines whether the print width is a fixable print width based on a selected paper size. The temperature control unit controls the heating of the fixing unit so that a temperature detected by a temperature detection element disposed near the center of the fixing unit in the paper width direction becomes a target temperature;
The print control unit extends along the paper width direction of the fixing unit based on a temperature detected by a second temperature detection element disposed at a position separated from the temperature detection element along the paper width direction of the fixing unit. The image forming apparatus according to claim 1, wherein a temperature distribution is detected.

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