JP2006017764A - Image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To realize reliable paper conveyance by controlling conveying speed after paper reaches a feed-out sensor according to the time taken until the paper reaches the feed-out sensor from a paper supply tray and the set time for judging paper jamming. <P>SOLUTION: The image forming apparatus 1 comprises the feed-out sensor S1 arranged just behind the paper supply tray 10, a registration sensor S2 provided on a more downstream side in a paper conveying direction than the feed-out sensor S1 and adjusting timing in which an image is formed, a paper jamming judging means for judging the jamming of the paper according to the time taken until the paper gets to the registration sensor S2, and a conveyance control means for controlling the speed for conveying the paper. In the apparatus 1, the conveyance control means controls the speed for conveying the paper from the feed-out sensor S1 to the registration sensor S2 according to the time taken until the paper gets to the feed-out sensor S1 after designating starting to convey the paper, and also adjusts the time for judging the paper jamming by the paper jamming judging means according to the speed for conveying the paper. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an image forming apparatus having a function of controlling conveyance of a sheet conveyed from a sheet feed tray and determining a paper jam on a conveyance path.

  Conventionally, the paper transport control in an image forming apparatus has a JAM (paper jam) timer arbitrarily set for each section, and the leading or trailing edge of the paper reaches or passes a specified sensor within that section. If not, it will be stopped as JAM.

  At present, a method of narrowing a gap between sheets in order to improve productivity and reduce noise and power consumption is becoming common. In order to achieve this, the paper tip position varies, and the paper transport system has a separation function to prevent paper double run due to slip, and the arrival time to the sensor provided after the paper separation mechanism. Then, there is a paper transport system that controls by changing the transport speed to the image transfer mechanism set thereafter. Further, as disclosed in Patent Document 1, a method for setting a JAM timer according to a sheet attribute has been proposed.

JP 2000-118790 A

  However, in the technique described in Patent Document 1, only one type of JAM timer is provided for a delay in arrival time due to variations in paper between the same paper types. This decreases the degree and causes a decrease in the reliability of paper conveyance. In other words, the possibility of exceeding the allowable range for the reference JAM timer increases due to the change in the sheet conveyance speed, and even if the JAM is not actually set, it is erroneously determined as JAM.

  The present invention has been made to solve such problems. That is, the present invention is an image forming apparatus having a function of controlling the conveyance speed of a sheet on a conveyance path of a sheet fed from a sheet feed tray, and includes a feedout sensor disposed immediately after the sheet feed tray, and a feed Provided on the lower side of the paper conveyance direction from the out sensor, a registration sensor for adjusting the timing of image formation, a paper jam judgment means for judging the paper jam according to the time when the paper reaches the registration sensor, and the paper conveyance speed. And a conveyance control unit that controls the sheet conveyance speed from the feedout sensor to the registration sensor according to the time from the instruction to start conveying the sheet until the sheet reaches the feedout sensor. At the same time, the time for paper jam detection by the paper jam detection means is adjusted according to the paper transport speed. Is shall.

  In the present invention, since the sheet conveyance speed to the registration sensor is controlled according to the time until the sheet is conveyed from the paper feed tray and reaches the feedout sensor, the sheet can be conveyed to the registration sensor at a fixed timing. . In addition, since the time for determining a paper jam is adjusted according to the paper transport speed, an optimal paper jam determination time can be set according to the paper transport speed.

  Therefore, according to the present invention, since the JAM timer is set according to the arrival time of a certain section on the paper conveyance path, the margin for JAM can be set to the maximum, and there is no misjudgment of JAM and the reliability is high. Paper conveyance can be realized. As a result, it is possible to sufficiently cope with an increase in speed in image formation.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a schematic diagram illustrating an image forming apparatus according to the present embodiment. That is, the image forming apparatus 1 according to the present embodiment includes a copier or a printer that conveys a sheet from the sheet feeding tray 10 to the image processing unit 11, prints an image on the sheet by the image processing unit 11, and outputs the image. Thus, it is possible to realize optimum control for the conveyance speed and JAM (paper jam) of the sheet conveyed from the sheet feeding tray 10.

  In order to control the sheet conveyance timing, the image forming apparatus 1 of the present embodiment is provided with a feedout sensor S1 disposed immediately after the sheet feed tray 10 and a lower side in the sheet conveyance direction than the feedout sensor S1. And a registration sensor S2 for adjusting the image forming timing in the image processing unit 11. Each sensor can output a predetermined signal when the leading edge or the trailing edge of the sheet passes.

  In the operation of the image forming apparatus 1, first, sheets are sent out from the sheet feeding tray 10 one by one based on an image forming instruction. The paper sent out from the paper feed tray 10 is detected by a feed-out sensor S1 immediately after the paper feed tray 10, and then sent to the image processing unit 11. The image processing unit 11 is provided with a registration sensor S2. The operation of the image processing unit 11 is synchronized with the timing at which the registration sensor S2 detects the sheet, and the image processing unit 11 is positioned at an accurate position of the sheet being conveyed. Transfer the image.

  FIG. 2 is a functional block diagram of the image forming apparatus according to the present embodiment. In order to perform paper conveyance and JAM determination, the image forming apparatus is provided with the sensor S including the feed-out sensor and the registration sensor described above, conveyance control means 21, paper jam determination means 22, and table data 23. It has been.

  The conveyance control unit 21 is a part that controls the rotation speed of the conveyance roller based on a sheet detection signal output from the feedout sensor S1 or the registration sensor S2. Further, the paper jam determination means 22 uses the time until the paper reaches the registration sensor S2 from the feedout sensor S1 and the preset reference time (JAM timer) to reach the paper arrival time JAM. Judgment is made as to whether or not the timer is within the allowable range (allowance time), and if it does, JAM is not generated, and if it is not, JAM is determined to have occurred.

  The table data 23 is data indicating the correspondence between the time from the sheet conveyance start instruction (activation signal) to the feedout sensor S1, and the subsequent sheet conveyance speed and the set time of the JAM timer. .

  In the present embodiment, in the sheet conveyance control by the conveyance control unit 21, the arrival time from the instruction (start signal) for starting sheet conveyance from the sheet feed tray 10 to the sheet passing through the feedout sensor S1 is calculated. Measure and refer to the table data 23 according to the arrival time to adjust the conveyance speed for conveying the paper to the registration sensor S2.

  For example, if it takes a long time for the paper to reach the feedout sensor S1 from the activation signal indicating the start of paper conveyance, it is assumed that there is a conveyance delay, and the rotational speed of the TA (Take Away) roll immediately after the feedout sensor S1 And the paper conveyance speed from there to the registration sensor S2 is increased. On the other hand, if the time from the instruction signal for starting the conveyance of the paper to the feedout sensor S1 is short, it is assumed that the conveyance has progressed, and the rotation speed of the TA roll is slowed down, and the paper conveyance speed from there to the registration sensor S2 is set. Try to be late. By such a conveyance speed control, even when the conveyance timing of the sheet fed from the paper feed tray varies, the timing to finally reach the registration sensor S2 can be adjusted so that the image processing unit 11 can accurately Processing can be performed.

  In the image forming apparatus 1 according to the present embodiment, in addition to the sheet conveyance speed control, the setting time of the JAM timer used by the paper jam determination unit 22 is adjusted according to the sheet conveyance speed controlled by the conveyance control unit 21. There is a feature in the point.

  FIG. 3 is a chart for explaining sheet conveyance timing in the image forming apparatus according to the present embodiment. FIG. 4 is a diagram illustrating an example of table data for conveyance control and a JAM timer. In other words, the sheet conveying unit 21 in the image forming apparatus 1 of the present embodiment has a variation in the arrival time of the sheet that occurs due to variations in the leading end position of the sheet in the sheet feeding tray 10 or due to the heavy running of the sheet due to the slip. The subsequent conveyance speed is controlled and the set time of the JAM timer is adjusted according to the set conveyance speed.

  In the example shown in FIG. 3, when the average arrival time from the paper feed tray to the feedout sensor is reached (graphs (a) to (A) in the figure), the average arrival time is later. The case ((b)-(B) graph in the figure) and the case where it is earlier than the average arrival time ((c)-(C) graph in the figure) are shown.

  When the average arrival time from the paper feed tray to the feedout sensor is slower than the average arrival time, the TA roll rotation speed is increased to control the paper conveyance speed. If it is faster, control is performed to lower the paper transport speed by lowering the rotational speed of the TA roll. Thereby, the timing at which the paper reaches the registration sensor can be adjusted. Actually, the adjustment of the sheet conveyance speed is completed before the registration sensor (position from the TA roll to the distance T), and from there to the registration sensor, all are set to a constant conveyance speed.

  In the table data shown in FIG. 4, the arrival time from the conveyance start instruction to the feedout sensor is divided into, for example, five, and the conveyance speed to the registration sensor is set in advance according to this division. The conveyance control unit 21 calculates the arrival time from the sheet conveyance start instruction to the feedout sensor, and obtains the conveyance speed corresponding to the calculated arrival time from the table data shown in FIG. Then, the rotational speed of the TA roll is controlled based on the obtained transport speed.

  Further, the transport control means 21 refers to the set time of the JAM timer from the table data shown in FIG. 4 based on the determined paper transport speed. Since the JAM timer differs depending on the paper quality, the JAM timer setting time corresponding to the paper quality of the paper to be transported is referred to. Then, by sending the set time to the paper jam determination unit 22, the paper jam determination unit 22 detects the occurrence of JAM on the basis of the sent set time.

  The paper jam determining means 22 may directly refer to the set time of the JAM timer from the table data. In this case, the conveyance control means 21 sends the calculated arrival time or information on the conveyance speed obtained from the table data to the paper jam determination means 22, and based on this information, the paper jam determination means 22 refers to the table data and sets the JAM timer. The set time may be determined.

  The setting time of the JAM timer is so long that the time to reach the paper feed-out sensor is short and the subsequent paper conveyance speed is set to be slow. That is, when the paper reaches the feedout sensor quickly from the paper feed tray, the arrival time becomes longer because the conveyance speed from the detection of the paper by the feedout sensor to the arrival of the registration sensor is reduced. Therefore, the setting time of the JAM timer is increased accordingly.

  On the other hand, the time to reach the paper feedout sensor is longer, and the setting time for the JAM timer is shorter as the subsequent paper transport speed is set to be faster. That is, when the paper arrives from the paper feed tray to the feedout sensor with a delay, the arrival time is shortened because the transport speed from the detection of the paper by the feedout sensor to the arrival of the registration sensor is increased. Therefore, the setting time of the JAM timer is shortened accordingly.

  The set time of the JAM timer in the table data 23 is provided for each paper quality corresponding to the five categories of arrival time from the conveyance start instruction to the feedout sensor, similarly to the conveyance speed.

  With this JAM timer setting, the standard paper arrival time at the controlled paper transport speed (arrival time from the feedout sensor to the registration sensor) can be approximately the center of the allowable range of the JAM timer. Thus, a sufficient margin of the JAM timer can be provided, and JAM misjudgment can be reduced even if there is some variation in paper conveyance.

  In the above embodiment, the conveyance speed and the set time of the JAM timer are obtained according to the arrival time classification based on the table data 23. However, instead of the table data 23, it may be obtained by calculation using a predetermined function. .

1 is a schematic diagram illustrating an image forming apparatus according to an embodiment. 1 is a functional block diagram of an image forming apparatus according to an embodiment. 6 is a chart for explaining sheet conveyance timing in the image forming apparatus according to the embodiment. It is a figure which shows the example of the table data of conveyance control and a JAM timer.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Image forming apparatus, 10 ... Paper feed tray, 11 ... Image processing part, 21 ... Conveyance control means, 22 ... Paper jam determination means, 23 ... Table data, S1 ... Feedout sensor, S2 ... Registration sensor

Claims (3)

In the image forming apparatus having a function of controlling the conveyance speed of the paper on the conveyance path of the paper sent from the paper feed tray,
A feedout sensor disposed immediately after the paper feed tray;
A registration sensor provided on the lower side in the paper conveyance direction from the feed-out sensor, and for matching the timing of image formation;
A paper jam judging means for judging a paper jam of the paper according to a time required for the paper to reach the registration sensor;
A conveyance control means for controlling the conveyance speed of the paper,
The transport control unit controls a paper transport speed from the feedout sensor to the registration sensor according to a time from the instruction to start transporting the paper until the paper reaches the feedout sensor. An image forming apparatus, wherein a time for paper jam determination by the paper jam determination unit is adjusted according to speed. The image forming apparatus according to claim 1, wherein the conveyance control unit obtains the paper conveyance speed and the time for determining the paper jam based on preset table data. The image formation according to claim 1, wherein the time for determining the paper jam is set to a shorter value as the time until the paper reaches the feedout sensor from an instruction to start transporting the paper is longer. apparatus.

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