JP2005330028A - Image forming device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image forming device capable of stably and automatically distinguishing various kinds of recording papers and detecting a tip position of the recording paper precisely while improving usability and cost performance to set process conditions for various recording papers automatically and control a tip blank precisely. <P>SOLUTION: This image forming device is provided with a light irradiation means for irradiating light on a surface of recording paper, and a reading means for reading the inside of a light irradiation region on the surface of recording paper by the light irradiation means and outputting it as image. The reading means is provided with a paper tip detection function for detecting a tip position of the recording paper. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an image forming apparatus such as a copying machine, a laser printer, and an ink jet printer.

  Conventionally, for example, the size and type (hereinafter also referred to as paper type) of recording paper as a recording material is set by a user on an operation panel or the like provided in the image forming apparatus main body, and process conditions (for example, thermal fixing) are set according to the setting. Control is performed to set the fixing temperature in the image forming apparatus using the method. When the recording paper is an OHT sheet, a transmission type sensor provided inside the image forming apparatus automatically detects whether the recording paper is an OHT sheet, and when light is transmitted through the recording paper, If the recording paper does not transmit light, it is determined as plain paper, and control is performed so as to set the process conditions according to the determination result.

Also, in order to adjust the leading edge margin of the recording paper, the leading edge position of the recording paper is adjusted by detecting the leading edge position of the conveyed recording paper by a sensor and controlling the rotation of a registration roller that conveys the recording paper by a clutch. Control is done.
JP 2004-59192 A

  However, the above-described conventional image forming apparatus has the following problems.

  (1) Since the user needs to set the paper type in the image forming apparatus or the PC, there is a problem that the burden on the user is large and the operability of the image forming apparatus is poor.

  (2) In recent years, the number of paper types handled has increased, and it has become impossible to cover all paper types only with the setting mode prepared in advance. As a result, there is a problem that the setting of process conditions is not well determined and the quality of the output image is degraded.

  (3) In the transmission type sensor for automatic detection of the OHT sheet, other paper types cannot be determined, and the sensor is dedicated to the OHT. As a result, there is a problem that the cost performance of the apparatus is lowered and miniaturization of the apparatus system is hindered.

  (4) In a sensor that may be erroneously detected due to dirt, such as a transmission type sensor for automatic detection of an OHT sheet, control is required to correctly detect even if the sensor output decreases due to dirt. Thus, there is a problem that the cost performance of the device system is bad.

  (5) Since it is necessary to dispose the registration sensor and the OHT sensor at a timing before the image is formed on the recording paper, there is a problem that miniaturization of the apparatus is hindered.

  (6) When the clutch that drives the registration roller is turned on / off, the recording paper stop position and the paper conveyance start timing are shifted due to inertia, so that it is difficult to accurately control the leading edge of the recording paper. is there.

  In view of this, the present invention provides an image which can stably and automatically discriminate various types of recording paper and can accurately control the leading end position of the recording paper while improving usability and cost performance and downsizing the apparatus. An object of the present invention is to provide a forming apparatus, and as a result, it is possible to automatically set process condition settings for various recording papers and to accurately control the leading margins of the recording papers.

  According to the present application, the object is to contact the light irradiation means for irradiating the surface of the recording paper, the reading means for reading and outputting the light irradiation area by the light irradiation means as an image, and the leading edge of the recording paper. According to the first aspect of the present invention, the conveyance position of the recording paper is detected by a movable lever that operates in the above.

  According to the present application, the above object is achieved by the second invention in which the movable lever is provided with a cleaning device for the reading device in the first invention.

  According to the present application, the above object is the invention according to any one of the first and second aspects, wherein the recording paper conveyance start timing is detected from the time change of the image read by the reading means. Achieved by:

  According to the first invention of the present application, the paper type is discriminated from the image read by the reading unit and the stop position of the recording paper is detected, thereby improving usability and cost performance and reducing the size of the apparatus. However, it is possible to detect the paper type and control the paper edge position with high accuracy.

  Further, according to the second invention of the present application, by providing the movable lever with the cleaning brush, it is possible to prevent dirt from adhering to the reading means and to obtain a stable sensor output.

  Further, according to the third invention of the present application, by detecting the recording paper conveyance start timing from the image change obtained by the reading means, the paper leading edge margin can be obtained more accurately without adding new parts. Can be controlled.

  Hereinafter, the best mode for carrying out the present invention will be described in detail with reference to examples.

  Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

  FIG. 3 is a schematic cross-sectional view of a color laser printer (hereinafter referred to as a printer) which is an image forming apparatus according to the present embodiment. The printer 100 includes a deck 101 that stores recording paper P, a deck paper presence sensor 102 that detects the presence or absence of the recording paper P in the deck 101, a pickup roller 103 that feeds the recording paper P from the deck 101, and the pickup roller 103. A deck paper feed roller 104 for transporting the fed recording paper P, and a retard roller 105 for preventing the recording paper P from being double fed are provided.

  Further, a registration roller pair 107 for synchronously conveying the recording paper P is disposed downstream of the deck paper supply roller 104, and an image reading sensor 106 is provided immediately before the registration roller pair 107. The image reading sensor 106 adjusts the registration of the recording paper P using a movable lever, which will be described later, and detects the stop position of the recording paper P from the time change of the continuously detected video. Further, the paper type of the recording paper P is detected from the surface image of the recording paper P. Further, the conveyance start timing of the recording paper P is detected from the time change of the continuously detected video. Details of the image reading sensor 106 will be described later.

  Further, an intermediate transfer belt (hereinafter referred to as ITB) 109 is disposed downstream of the registration roller pair 107, and processes for four colors (yellow Y, magenta M, cyan C, and black B) are provided on the ITB. A color image is formed by sequentially superimposing images formed by an image forming unit including the cartridges 110, 111, 112, 113 and the scanner units 114, 115, 116, 117 by the primary transfer rollers 118, 119, 120, 121. Is further transferred onto the recording paper P by the secondary transfer roller 122.

  Further, downstream of the secondary transfer roller 122, a fixing roller 124 having a heating heater 123 therein and a pressure roller 125 pair in order to thermally fix the toner image transferred onto the recording paper P, from the fixing roller A pair of fixing paper discharge rollers 126 for conveying the recording paper P, a fixing paper discharge sensor 127 for detecting the conveyance state from the fixing unit, a pair of conveyance rollers 128 for conveying the recording paper from the fixing unit, and paper discharge A paper discharge sensor 129 that detects the conveyance state of the recording paper and a paper discharge roller pair 130 that discharges the recording paper P are provided.

  Each scanner unit includes a laser unit (not shown) that emits a laser beam modulated based on each image signal sent from a video controller 131 described later, and a laser beam from each laser unit to each photosensitive drum. It comprises a polygon mirror (not shown) for scanning on 132, 133, 134, 135, a scanner motor (not shown), and an imaging lens group (not shown).

  Each process cartridge includes photosensitive drums 132, 133, 134, 135 charging rollers (not shown) and a developing roller (not shown) necessary for a known electrophotographic process.

  Further, when the video controller 131 receives image data sent from an external device 136 such as a personal computer, the video controller 131 expands the image data into bitmap data and generates an image signal for image formation.

  Reference numeral 137 denotes a DC controller which is a control unit of the laser printer. The MPU (microcomputer) 138 having a RAM 138a, a ROM 138b, a timer 138c, a digital input / output port 138d, various input / output control circuits (not shown), etc. It consists of

  Reference numeral 139 denotes a main motor, which rotates and conveys each transport system roller such as the ITB 109, the photosensitive drums 132, 133, 134, 135, and the fixing roller 124 via a drive transmission system (not shown) and also via a clutch 140. Thus, the registration roller pair 107 is driven to rotate. Reference numeral 141 denotes a stepping motor that rotates the pickup roller 103 and the deck paper discharge roller 104.

  Next, the image reading sensor 106 will be described with reference to FIGS. 1 and 2.

  FIG. 2 is a schematic cross-sectional view relating to the image reading function of the image reading sensor 106. The image reading sensor 106 includes an LED 33 serving as a light irradiation unit, a CMOS sensor 34 serving as a reading unit, and lenses 35 and 36 serving as condensing / imaging lenses. Light having the LED 33 as a light source is applied to the surface of the recording paper transport guide 31 or the surface of the recording paper P on the recording paper transport guide 31 through the lens 35. The reflected light from the recording paper P is collected through the lens 36 and imaged on the CMOS sensor 34. Thereby, the surface image of the recording paper conveyance guide 31 or the recording paper P is read. In the present embodiment, the LED 33 is arranged so that the LED light irradiates the recording paper P surface obliquely at a predetermined angle as shown in FIG.

  FIG. 1 is a schematic cross-sectional view relating to a movable lever provided in the image reading sensor 106. As shown in FIG. 1A, when the recording paper P is not conveyed under the image reading sensor 106, the movable lever 300 is stationary at a position crossing the recording paper conveyance guide. When the recording paper P is conveyed, the movable lever 300 moves out of the reading area of the image reading sensor 106 as shown in FIG. 1B, and the operation of the movable lever 300 is detected by the photosensor 301, thereby recording. The conveyance timing of the paper P is detected. Here, the photosensor 301 is configured to react after the leading end of the recording paper P and the movable lever 300 have moved out of the image area of the video reading sensor 106.

  Next, stop position detection control of the recording paper P by the video reading sensor 106 will be described using the flowchart of FIG. When conveyance of the recording paper P is detected by the movable lever 300 provided in the video reading sensor 106, the DC controller 137 is notified of the conveyance of the recording paper (S210) and moves from there until the recording paper P stops. Start quantity detection. First, a constant cycle interrupt for each detected sampling is monitored (S211), and the surface image of the recording paper P is read at the time of the interrupt (S212). Next, filter processing is performed on the read image (S213). By this filtering process, for example, 8-bit 256 gradation data is reduced to 16 gradations, and components due to noise and the like are removed. Here, it is determined whether the first image reading (S212) is the first reading (S214), and if it is the first reading, a comparison image to be compared with the next sample image is detected from the acquired sample image. (S217), the comparison image is stored in an image memory (not shown) (S218), and the process returns to the monitoring of a constant cycle interrupt (S211). When the first image reading (S212) is performed for the second time or later, the number of moving pixels of the image pattern is detected by comparing the acquired sample image with a comparison image stored in an image memory (not shown). (S215). Here, if it is determined that the recording paper P is moving, the total movement amount from the start of detection is calculated and stored in the memory (S218). Then, a comparison image to be compared with the next sample image is created (S217), the comparison image is stored in an image memory (not shown) (S218), and then the process returns to the constant cycle interruption (S211). If it is determined that the recording paper P has stopped, the total moving distance is output (S219), and the tip position detection control is terminated. The DC controller 137 finely adjusts the timing of the conveyance start signal of the recording paper P based on the detected moving distance, and controls the leading edge margin of the recording paper.

  Next, a paper type detection method by the image reading sensor 106 will be described with reference to FIGS.

  FIG. 5 shows the relationship between the surface of the recording material read by the CMOS sensor 34 and an example in which the output from the CMOS sensor 34 is digitally processed to 8 × 8 pixels. The digital processing is performed by converting the analog output from the CMOS sensor 34 into 8-bit pixel data by A / D conversion (not shown) as conversion means. In FIG. 5, 40 is an enlarged image of the surface of the recording paper A, which is a so-called rough paper, on which the fibers of the paper on the surface are relatively loose, and 41 is a recording paper B, which is a so-called plain paper that is generally used. 42 is an enlarged image of the surface, and 42 is an enlarged image of the surface of the recording paper C, which is a glossy paper in which the fibers of the paper are sufficiently compressed. These images 40 to 42 read into the CMOS sensor 34 are digitally processed into images 43 to 45 shown in FIG. Thus, the image on the surface varies depending on the type of recording paper. This is a phenomenon that occurs mainly because the fiber state on the paper surface is different. As described above, the image obtained by reading the recording paper surface by the CMOS sensor 34 and digitally processing it can be discriminated by the surface state of the paper fiber of the recording paper.

  FIG. 6 is a paper type detection control flow by the MPU 163 provided in the DC controller 162 which is a read recording paper conveyance control means. First, the recording paper P is conveyed to the registration roller pair 107 and waits until the conveyance is temporarily stopped for the leading edge margin adjustment (S101). When the standby state is reached, the CMOS sensor 34 reads the image of the recording paper P (S102). Then, it is determined again that the recording paper P is waiting (S103). This is because the video is read again when the recording paper P is transported during image reading and a good video cannot be read. If it is in the standby state, the video comparison calculation described later is performed (S104), and the paper type is determined based on the video comparison calculation result (S105).

  Here, the above-described video comparison calculation method will be described. In the video comparison calculation, the maximum density pixel Dmax and the minimum density pixel Dmin are derived from the result of reading the video at a plurality of locations on the surface of the recording paper. This is executed for each read video and averaged. That is, when the paper fiber on the surface is rough like the recording paper A, many shadows of the fiber are generated. As a result, the difference between the bright part and the dark part is large, and Dmax−Dmin becomes large. On the other hand, on the surface such as the recording paper C, the shadow of the fiber is small and Dmax−Dmin is small. Based on this comparison, the paper type of the recording paper is determined.

  Since the above-mentioned video comparison calculation needs to process the video sampling processing, gain and filter calculation processing from the CMOS sensor 34 in real time, it is desirable to use a digital signal processor.

  Next, the conveyance start timing detection control of the recording paper P by the video reading sensor 106 will be described using the flowchart of FIG. When the conveyance of the recording paper P is stopped by the registration roller and the detection of the paper type is completed, the detection is started (S301), and a constant cycle interrupt for each detection sampling is monitored (S302). Is read (S303). Next, filter processing is performed on the read image (S305). By this filtering process, for example, 8-bit 256 gradation data is reduced to 16 gradations, and components due to noise and the like are removed. Here, it is determined whether the first image reading (S303) is the first reading (S306). If it is the first reading, a comparison image to be compared with the next sample image is obtained from the acquired sample image. It detects and creates (S308), this comparison image is memorize | stored in an image memory (not shown) (S309), and it returns to monitoring of a fixed period interruption (S302). If the first image reading (S303) is performed for the second time or later, the acquired sample image is compared with the comparison image stored in the image memory (not shown) (S307) and moved. Judgment is made. If it is determined that the image has not moved, a comparison image to be compared with the next sample image is detected and created from the acquired sample image (S308), and this comparison image is stored in an image memory (not shown). (S309), the process returns to the monitoring of the fixed period interrupt (S302). If it is determined that the movement has occurred, a movement start signal is output (S316), and the conveyance start detection control is terminated. The above-described detection of the conveyance start timing of the recording paper P is performed for each fixed number of printings, and the control signal output timing of the clutch 140 that controls the conveyance of the recording paper P by the DC controller 173 is determined based on the detected timing of the movement start signal. Make fine adjustments.

  Next, a second embodiment of the present invention will be described.

  FIG. 8 is a schematic cross-sectional view of the image reading sensor 106 according to the present embodiment.

  The difference from the first embodiment is that the movable lever 300 includes a cleaning brush 302 on the reading surface of the image reading sensor 106. According to this configuration, as shown in FIG. 8A, when the recording paper P is not conveyed under the image reading sensor 106, the cleaning brush 302 stops at a position covering the surfaces of the lenses 35 and 36. When the recording paper P is conveyed as shown in FIG. 8B, the cleaning brush 302 moves away from the surfaces of the lenses 35 and 36 together with the operation of the movable lever 300. At that time, the surfaces of the lenses 35 and 36 are cleaned. It is configured like this.

  With this configuration, dirt and fibers scattered from the recording paper P, or dirt such as toner scattered from the process cartridges 110, 111, 112, 113 and ITB 109 as developing / transfer devices are prevented from adhering to the lenses 35, 36. I can do it.

1 is a schematic cross-sectional view relating to a video reading sensor according to Embodiment 1 of the present invention. Schematic sectional view relating to the image reading function of the image reading sensor according to the present invention. 1 is a schematic cross-sectional view of a color laser printer according to Embodiment 1 of the present invention. Recording paper stop distance detection control flow according to the present invention The figure which shows the relationship between the surface image of the recording paper read by the optical sensor which concerns on this invention, and the example which digitally processed this Paper type detection control flow according to the present invention Recording paper conveyance start timing detection control flow according to the present invention Typical sectional drawing regarding the image reading sensor which concerns on Example 2 of this invention.

Explanation of symbols

P Recording paper 33 LED
34 CMOS sensor 35, 36 Lens 100 Color laser printer 106 Image reading sensor 300 Movable lever 302 Cleaning means (cleaning brush)

Claims (3)

  In an image forming apparatus that temporarily stops conveyance of recording paper at a timing prior to forming an image on recording paper, light irradiation means for irradiating light on the surface of the recording paper, and light irradiation means on the surface of the recording paper Reading means for reading and outputting the inside of the light irradiation area as an image, and further including a movable lever that operates by contacting the leading end of the recording paper, and detecting the conveyance timing of the recording paper by the movable lever An image forming apparatus.   The said movable lever is equipped with the cleaning means with respect to the reading surface of the said reading means, The reading surface of the said reading means was cleaned in response to operation | movement of the said movable lever. Image forming apparatus.   The image forming apparatus according to claim 1, wherein the conveyance start timing of the recording paper is detected from a time change of the video read by the reading unit.

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