JP2006184504A - Kind-discriminating device for recording material, and image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a kind-discriminating device for a recording material which automatically discriminates the recording materials of various kinds with accuracy, by precisely counting the number of rugged edges of the recording material, without receiving the influence of deterioration and distortion of a photographed image due to variation in the light amount due to light source and lens, and the variation in sensitivity in each photoelectric conversion cell of an imaging element and performs image formation under appropriate conditions. <P>SOLUTION: The interval of recessed and projecting parts of the recording material is detected accurately, and the kind of the recording material is discriminated with higher accuracy, by discriminating the image formed during the conveyance of the recording material as a threshold for binarization arithmetic processing in counting the interval of the uneveness intervals, by subjecting the imaging results during the rest time of the recording material to binarization arithmetic processing, by using an imaging sensor comprising an area sensor or a line sensor and a lens and a light-emitting light source so as to detect the uneveness intervals with higher accuracy and to discriminate the paper kind with higher accuracy. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a recording material discriminating apparatus and an image forming apparatus. More specifically, the present invention relates to a recording material discriminating apparatus that discriminates the type by detecting the amount of reflected light from the surface of the recording material, and an image using the recording material discriminating apparatus. The present invention relates to an image forming apparatus such as a copying machine or a laser printer for controlling conditions.

  An image forming apparatus such as a copying machine or a laser printer transfers an image developed on a photoreceptor to a recording medium, and fixes the image by heating and pressurizing the recording medium on which the image has been transferred under predetermined fixing processing conditions. A fixing device is provided.

  Conventionally, in such an image forming apparatus, an image on the surface of a recording medium fed and conveyed is read by an image reading unit having a line sensor and an area sensor such as a CCD sensor and a CMOS sensor, and the result is an inkjet OHT ( Means for determining whether it is an OHP sheet or laser beam OHT, and if it is determined to be OHT for inkjet, means for stopping the recording medium conveyance to the fixing device and stopping the image forming operation of the image forming apparatus, or By stopping the temperature control of the fixing device without stopping the conveyance of the recording medium to the fixing device, or by providing a control means for setting a temperature lower than the normal temperature, the user accidentally goes out of the specified sheet. OHT wrapping around the fixing roller or on the recording medium that occurs when a certain inkjet OHT is passed How to solve the adverse problem of image degradation or the like is known (e.g., see Patent Document 1).

  In addition to the OHT, the type of recording medium such as glossy paper, plain paper, rough paper, and OHT is determined by calculating the depth of unevenness and the unevenness interval on the surface of the recording medium from the reading result obtained by reading the surface image of the recording medium. In addition, a method for optimally setting image forming conditions such as print density, transfer bias setting, fixing temperature, and process speed is also known (see, for example, Patent Document 2).

  In a configuration using an image sensor and a lens of a line sensor or area sensor such as a CCD sensor or a CMOS sensor used in these cases, light reflected from an object to be photographed is incident on the image sensor via an imaging lens or the like, There is known an image reading apparatus that obtains image data of a photographing object by A / D converting a signal output from the image sensor. In such an image reading apparatus, there are many cases in which a captured image is deteriorated due to a light amount variation caused by a light source or a lens. There is also a sensitivity variation in each photoelectric conversion cell of the image sensor.

JP 2003-228256 A JP 2003-302208 A

However, the conventional recording material discriminating apparatus and image forming apparatus have the following problems.
In recent years, although the types of recording materials have been diversified, the demand for print quality has been increasing, and accordingly, it is required to accurately discriminate a wide variety of recording materials. However, all the paper types cannot be discriminated only with the setting mode prepared in advance for discriminating the paper type, and as a result, there is a problem that the setting of the fixing process condition may not be optimized.
With respect to such a problem, in the conventional method, the image information of the pixels in the specific pixel region is binarized from the image information captured by the reading unit, and the number of edges of the binarized image is counted. There is a recording material discriminating device provided with a calculation means for quantitatively judging the unevenness on the surface of the recording material.

  However, in the recording material discriminating apparatus, an average value is obtained in advance from an image captured at the previous sampling timing, and the image information captured at the next sampling timing is binarized using the average value as a threshold value. Therefore, it is difficult to accurately count the number of edges due to the influence of deterioration and distortion of the photographed image due to variations in the amount of light caused by the light source and lens, and sensitivity variations in each photoelectric conversion cell of the image sensor. There was a problem.

  The present invention has been made in view of such problems, and can accurately count the number of edges of a recording material, automatically determine various types of recording materials with high accuracy, and perform image formation under appropriate conditions. An object of the present invention is to provide a recording material discriminating apparatus and an image forming apparatus.

In order to achieve such an object, a light irradiation means for irradiating light on the surface of the recording medium, an image reading means for reading and outputting the light irradiation area of the recording material irradiated by the light irradiation means as an image, A binarizing unit that binarizes the image information on the surface of the recording medium using a predetermined threshold; and an arithmetic unit that counts the number of edges of the binarized image to calculate the unevenness on the surface of the recording medium. Recording material discriminating apparatus,
According to a first aspect of the present invention, there is provided a calibration image photographed when the recording medium is moved by the light irradiation means and the image reading means as the threshold value, and the recording medium photographed by the light irradiation means and the image reading means. A still image is binarized by the binarizing means.

  According to a second aspect of the present invention, in the recording material discriminating apparatus, when the recording medium is stationary, the calibration image is captured a plurality of times, and a predetermined calculation is performed on the plurality of imaging results. The captured image is binarized by the binarizing means.

  According to a third aspect of the present invention, in the recording material discriminating apparatus, the predetermined calculation is an average for each pixel at the same position in each image of the plurality of imaging results.

  According to a fourth aspect of the present invention, in the recording material discriminating apparatus, a binarized image is binarized by the binarizing means with the threshold value obtained by adding or subtracting a predetermined value to the calibration image. It is characterized by that.

In addition, an image processing unit that performs predetermined image processing on the input original image, a latent image carrier that carries a latent image, and the latent image carrier is exposed and scanned based on the image data that has been subjected to the image processing. An exposure unit that forms a latent image, a developing unit that visualizes the latent image as a developer image by applying a developer to the latent image carrier, and a recording material conveyed in a predetermined direction by the developing unit. Transfer means for transferring the developer image, and fixing for fixing the developer image to the recording material by heating and pressurizing the recording material onto which the developer image has been transferred by the transfer means under predetermined fixing processing conditions. An image forming apparatus comprising:
A fifth invention further comprises the recording material discriminating device according to any one of the first to fourth inventions, and corresponding to the type of the recording material discriminated by the recording material discriminating device, the image processing means, Predetermined printing conditions such as processing, output, and speed in the exposure unit, the developing unit, the transfer unit, and the fixing unit are variably controlled.

  According to a sixth aspect of the present invention, in the image forming apparatus, after the start of printing, only the first recording medium is photographed when the calibration image is moved, and for the second and subsequent sheets, the first calibration image is the second image. It is used as the threshold value in the value converting means.

According to the present invention, there is provided image reading means for reading and outputting the light irradiation area of the recording material as an image, and binarization means for binarizing the image information on the surface of the recording medium using a certain threshold value; In a recording material discriminating apparatus, comprising: an arithmetic unit that counts the number of edges of a binarized image and calculates the unevenness of the recording medium surface;
In the first invention, a calibration image is captured when the recording medium is moved, and the calibration image is used as a threshold value, and the captured image while the recording medium is stationary is binarized. It is possible to accurately count the number of edges without being affected by deterioration and distortion of the captured image due to variations in the amount of light to be emitted and sensitivity variations in each photoelectric conversion cell of the image sensor. Realize automatic discrimination.

  In the second and third inventions, the calibration image is taken a plurality of times, and the recording medium is stationary with a threshold value obtained by performing a predetermined calculation (averaging) on the plurality of times of imaging results. By binarizing the captured image, it is possible to accurately count the number of edges by further reducing variations in the amount of light and sensitivity, and to realize automatic discrimination of various types of recording agents with high accuracy. .

  In a fourth aspect of the invention, only an edge having a large peak value of the reflected light amount is selected by binarizing the captured image while the recording medium is stationary with a threshold value obtained by adding or subtracting a predetermined value to the calibration image. It is possible to automatically detect various types of recording materials with high accuracy by counting the number of desired edges without being affected by noise or the like.

In addition, an image processing unit that performs predetermined image processing on the input original image, a latent image carrier that carries a latent image, and the latent image carrier is exposed and scanned based on the image data that has been subjected to the image processing. An exposure unit that forms a latent image, a developing unit that visualizes the latent image as a developer image by applying a developer to the latent image carrier, and a recording material conveyed in a predetermined direction by the developing unit. Transfer means for transferring the developer image, and fixing for fixing the developer image to the recording material by heating and pressurizing the recording material onto which the developer image has been transferred by the transfer means under predetermined fixing processing conditions. An image forming apparatus comprising:
In the fifth aspect of the invention, the printing conditions such as processing, output, speed, etc. in the image processing means, exposure means, developing means, transfer means, fixing means, corresponding to the type of recording material discriminated by the recording material discrimination device. Since appropriate variable control is performed, image formation can be performed under appropriate conditions.

  In the sixth invention, the measurement time associated with the calculation of counting the number of edges after the second sheet can be omitted, and the usability can be improved by shortening the time until the end of printing.

  Hereinafter, a recording material discriminating apparatus and an image forming apparatus according to the present invention will be described with reference to the drawings.

[Example 1]
The recording material discriminating apparatus of the present invention is used in a general image forming apparatus as shown in FIG. In FIG. 1, an image forming apparatus 101 includes a paper cassette 102, a paper feed roller 103, a transfer belt driving roller 104, a transfer belt 105, yellow, magenta, cyan, and black photosensitive drums 106 to 109, yellow, magenta, and cyan. , Black color transfer rollers 110 to 113, yellow, magenta, cyan, and black color cartridges 114 to 117, yellow, magenta, cyan, and black color optical units 118 to 121, and a fixing unit 122. .

  The image forming apparatus 101 generally uses an electrophotographic process, and superimposes and transfers yellow, magenta, cyan, and black images on a recording material, and controls the temperature of the toner image transferred by a fixing unit 122 including a fixing roller. Heat fixing. The optical units 118 to 121 for each color are configured to form a latent image by exposing and scanning the surfaces of the photosensitive drums 106 to 109 with a laser beam, and these series of image forming operations are performed on the recording material to be conveyed. Synchronization is performed so that the image is transferred from a predetermined position.

  Further, the image forming apparatus 101 includes a paper feed motor that feeds and transports recording paper, which is a recording material, and the fed recording paper is transferred onto the transfer belt 105 and the fixing roller while being desired on the surface thereof. Form an image of

  The image reading sensor 123 is arranged so that the image can be read before the recording paper is conveyed to the transfer belt, and irradiates the surface of the conveyed recording material with light and collects the reflected light to form an image. Thus, an image of a specific area on the surface of the recording material is read out.

Next, the operation of the control CPU in an embodiment of the image forming apparatus using the recording material discrimination device of the present invention will be described with reference to FIG.
FIG. 2 is a diagram illustrating a configuration of each unit controlled by the control CPU 210.

  In FIG. 2, the control CPU 210 is connected to the CMOS area sensor 211 and the polygon mirrors, motors, and lasers 212 to 215 included in the optical units 118 to 121 for the respective colors via the ASIC 223, and scans the laser on the photosensitive drum surface. Then, the optical units 118 to 121 for drawing a desired latent image are controlled. Similarly, a paper feed motor 216 for transporting the recording material, a paper feed solenoid 217 used to start driving the paper feed roller 103 for feeding the recording material, and whether or not the recording material is set at a predetermined position. Paper presence / absence sensor 218 for detecting the color, primary charging necessary for the electrophotographic process, development, primary transfer, high voltage power source 219 for controlling the secondary transfer bias, photosensitive drums 106 to 109, and drums for driving the transfer rollers 110 to 113 A belt driving motor 221, a fixing unit 122, and a low-voltage power source 222 for driving the driving motor 220, the transfer belt 105, and the rollers of the fixing unit 122 are controlled. Further, the control CPU 210 monitors the temperature with a thermistor (not shown) and controls to keep the fixing temperature constant.

  The control CPU 210 is connected to the memory 224 by a bus or the like (not shown), and the memory 224 stores all of the above control and processing performed by the control CPU 210 in each embodiment described in this specification. A program and data for executing a part are stored. That is, the control CPU 210 executes the operation of each embodiment of the present invention using the program and data stored in the memory 224.

  The ASIC 223 performs motor speed control inside the CMOS area sensor 211 and the optical units 212 to 215 and speed control of the paper feed motor 216 based on instructions from the control CPU 210. The speed control of the motor is performed by detecting a tack signal from a motor (not shown) and outputting an acceleration signal or a deceleration signal to the motor so that the tack signal interval becomes a predetermined time interval. Speed control is performed. For this reason, it is more advantageous that the control circuit is composed of a circuit using hardware of the ASIC 223 so that the control load of the control CPU 210 can be reduced.

  When receiving a command print command from a host computer (not shown), the control CPU 210 determines the presence / absence of a recording material by a paper presence sensor 218, and if there is paper, the paper feed motor 216, drum drive motor 220, The belt driving motor 221 is driven, and the sheet feeding solenoid 217 is driven to convey the recording material to a predetermined position.

  When the recording material is conveyed to the position of the CMOS area sensor 211, the control CPU 210 instructs the ASIC 223 to cause the CMOS area sensor 211 to image, and the CMOS area sensor 211 captures the surface image of the recording material. At this time, the ASIC 223 activates Sl_select, then outputs SYSCLK of a predetermined pulse at a predetermined timing, and captures imaging data output from the CMOS area sensor 211 via Sl_out.

  On the other hand, the gain setting of the CMOS area sensor 211 is performed by setting a value determined in advance by the control CPU 210 in a register in the ASIC 223 so that the ASIC 223 activates Sl_select and then outputs SYSCLK of a predetermined pulse at a predetermined timing. The gain is set for the CMOS area sensor 211 via Sl_in.

  The ASIC 223 includes a circuit that performs a calculation based on a convex / concave amount calculation method and a calculation based on a convex / concave interval calculation method, which will be described later, in order to realize the recording material determination device of the present invention described below. Stored in the register. Then, the control CPU 210 reads the register in the ASIC 223, determines the type of the fed recording material, and controls to change the developing bias condition of the high voltage power source 219 according to the result. For example, in the case of so-called rough paper where the surface fibers of the recording material are rough, control is performed to prevent toner scattering by lowering the developing bias than plain paper and suppressing the amount of toner adhering to the surface of the recording material. This is because the amount of toner adhering to the surface of the recording material is large especially in the case of rough paper, so that the problem that the image quality deteriorates due to the scattering of the toner due to the paper fibers is solved.

  Further, the control CPU 210 controls to change the temperature condition of the fixing unit 122 according to the determination result of the type of the fed recording material. For example, in the case of the rough paper, since the surface fibers are rough, the toner is poorly fused, and optimization is performed by changing the fixing temperature. In particular, when the recording material is OHT, there is an effect on the problem that the permeability of the OHT deteriorates if the fixing property of the toner adhering to the surface of the recording material is poor.

  Further, the control CPU 210 controls to change the conveyance speed of the recording material in accordance with the determination result of the type of the recording material fed. The control of the conveyance speed is realized by resetting the speed control register value of the ASIC 223 that actually controls the speed by the control CPU 210. Change the fixing temperature conditions for recording materials with different basis weights. For example, recording materials with a relatively large thickness have a large heat capacity, so the fixing temperature is controlled to be high, while recording with a relatively small thickness, that is, a small heat capacity. The material is fixed at a lower fixing temperature.

  Alternatively, the recording material conveyance speed can be changed and controlled according to the basis weight of the recording material. Further, in the case of OHT or glossy paper, it is possible to improve the image quality by discriminating these and improving the fixability of the toner adhering to the surface of the recording material and increasing the gloss.

  As described above, in the present embodiment, from the surface image of the recording material 304 imaged by the CMOS area sensor 211, the hardware circuit by the ASIC 223 performs the calculation based on the convex / concave amount calculation method and the calculation based on the convex / concave interval calculation method described later, In accordance with the result, the control CPU 210 can control to change the developing condition of the high voltage power source 219, the control temperature condition of the fixing unit 122, or the recording material conveyance speed.

  Next, a recording material discrimination device according to an embodiment of the present invention will be described.

  As shown in FIG. 3, the image reading sensor 123 includes a reflection LED 301 that is an irradiation unit, a CMOS area sensor 211 that is a reading unit, and an imaging lens 303. Here, the sensor 211 may be a CCD sensor, or a line sensor may be used instead of the area sensor. When the line sensor is used, an image obtained by capturing a predetermined area for each line is accumulated in a memory (for example, the memory 224) to obtain an image of the predetermined area.

  Light using the reflective LED 301 as a light source is irradiated toward the surface of the recording material 304. In this embodiment, the light source is an LED, but a xenon tube, a halogen lamp, or the like can also be used. The reflected light from the recording material 304 is condensed through the lens 303 and forms an image on the CMOS area sensor 211. As a result, an image on the surface of the recording material 304 can be read. In the present embodiment, the LED 301 is arranged so that the LED light irradiates the recording material 304 with light at an angle as shown in FIG.

  FIG. 4 is a diagram showing a comparison between an analog image of the surface of the recording material 304 read by the CMOS area sensor 211 of the image reading sensor 123 and a digital image obtained by digitally processing the output from the CMOS area sensor 211 into 8 × 8 pixels. is there. Here, the digital processing is performed by converting the analog output from the CMOS area sensor 211 into 8-bit pixel data by A / D conversion.

  In FIG. 4, the recording material A of the image 40 is so-called rough paper in which the fibers of the paper on the surface are relatively sandwiched, the recording material B of the image 41 is so-called plain paper that is generally used, and the recording material C of the image 42 is paper. This is a gloss paper in which the fibers are sufficiently compressed, and is an enlarged image of each surface. These images 40 to 42 read into the CMOS area sensor 211 are digitally processed into images 43 to 45 shown in FIG. Thus, the image on the surface varies depending on the type of recording material. This is a phenomenon that occurs mainly because the fiber state on the paper surface is different.

  At this time, the amount of reflected light of the recording material is generally calculated from the total or average value of the light input to each pixel. In some embodiments, only the result of one light-receiving pixel can be used. As described above, the surface state of the paper fiber of the recording material can be identified by an image obtained by digitally processing the image obtained by reading the surface of the recording material by the CMOS area sensor 211. Discrimination becomes possible.

  The recording material surface is identified by reading images at a plurality of locations, detecting the pixel density Dmax and the pixel density Dmin having the lowest density in each image, and averaging the values obtained at the plurality of locations. . That is, when the paper fiber on the surface is rough like the recording material A, many shadows of the fiber are generated. As a result, the difference between the bright part and the dark part is greatly increased, so that Dmax−Dmin (unevenness) increases. On the other hand, the image of the surface of the recording material having a high smoothness with sufficiently compressed fibers, such as the recording material C, has less fiber shadow and Dmax−Dmin becomes small. The paper type of the recording material is determined based on the difference in the unevenness amount (Dmax−Dmin).

  In this way, the recording material can be determined based on the unevenness amount of the recording material. Of course, the unevenness interval (unevenness edge amount) on the surface of the recording material calculated based on the uneven edge amount calculation method described later is used. It is also possible to determine the recording material by using it. Furthermore, it is possible to improve the discrimination accuracy of the recording material by combining both. For such recording material discrimination, for example, a recording material discrimination threshold value is stored in an EEPROM (not shown) for each of the unevenness amount and the unevenness interval, and the above-described discrimination threshold value is compared with the unevenness amount and unevenness interval calculated by the ASIC 223. Thus, the control CPU 210 can perform this.

  Here, a control circuit of the CMOS area sensor 211 for performing the above operation will be described with reference to FIG.

  FIG. 5 is a block diagram showing a circuit for controlling the CMOS area sensor 211. The control CPU 210, the control circuit 702, the CMOS area sensor 211, the interface control circuit 704, the arithmetic circuit 705, and the amount of unevenness on the surface of the recording material are judgment units. The register A 706 stores the calculation result, the register B 707 stores the uneven edge amount calculation result on the surface of the recording material, and the control register 708.

Next, the operation of this circuit will be described.
When the control CPU 210 gives an operation instruction for the CMOS area sensor 211 to the control register 708, the CMOS area sensor 211 starts to capture a recording material surface image. That is, charge accumulation in the CMOS area sensor 211 is started. When the CMOS area sensor 211 is selected by Sl_select from the interface circuit 704 and SYSCLK is generated at a predetermined timing, the captured digital image data is transmitted from the CMOS area sensor 211 via the Sl_out signal.

  The imaging data received via the interface circuit 704 is calculated by the control circuit 702 based on the above-described unevenness amount calculation method, and the result is stored in the register A 706 as the unevenness amount calculation result on the surface of the recording material. On the other hand, the image data received via the interface circuit 704 is calculated by the control circuit 702 based on the uneven edge amount calculation method described later, and the result is the register B 707 as the uneven edge amount calculation result on the surface of the recording material. Stored in The control CPU 210 determines the surface smoothness of the recording material from the values of the two registers.

Next, a circuit block diagram of the CMOS area sensor will be described with reference to FIG.
FIG. 6 is a circuit block diagram of the CMOS area sensor.

  In FIG. 6, a CMOS area sensor 211 includes a CMOS sensor portion 801, and, for example, sensors for 8 × 8 pixels are arranged in an area. The CMOS area sensor 211 further includes vertical shift registers 802 and 803, an output buffer 804, a horizontal shift register 805, a system clock 806, and a timing generator 807.

Next, the operation of this sensor circuit block will be described.
When the Sl_select signal 813 is activated, the CMOS sensor unit 801 starts accumulating charges based on the received light. Next, when the system clock 806 is applied, the vertical shift registers 802 and 803 sequentially select the pixel columns to be read out by the timing generator 807 and the data is sequentially stored in the output buffer 804.

Data stored in the output buffer 804 is transferred to the A / D converter 808 by the horizontal shift register 805. The pixel data digitally converted by the A / D converter 808 is output-controlled by the output interface circuit 809 at a predetermined timing, and is output as the Sl_out signal 810 while the Sl_select signal 813 is active.
On the other hand, the control circuit 811 can be controlled to change the A / D conversion gain from the Sl_in signal 812. For example, when the contrast of the captured image cannot be obtained, the control CPU 210 can always capture with the best contrast by changing the gain.

  Next, with reference to FIG. 7, description will be given of the detection of the concave / convex spacing (the concave / convex edge amount) on the surface of the recording material by the concave / convex spacing calculating means.

  An image 80 is an image obtained by digitally processing the surface of the recording material. The image 81 is obtained as a result of obtaining an average value of the density from an image 80 previously captured at the previous sampling timing, and binarizing 8 × 8 pixels captured at the next sampling timing using the average value as a threshold value. FIG.

  The number of edges indicated by reference numeral 82 is the number of edges (black-and-white boundaries in the figure) in the first line as a result of binarization, and in this example is' 05'h. The number of edges indicated by reference numeral 83 is the number of edges in the second line, and is' 03'h in this example. Similarly, the number of edges indicated by reference numeral 84 is the number of edges in the eighth line, which is' 03'h in this example. A value obtained by counting the number of edges for each line and adding all the lines is defined as a result of calculating the uneven edge amount on the surface of the recording material by the uneven distance calculating means.

  By the way, in the calculation of the uneven edge amount detection, when binarizing each pixel imaged while the recording material is stationary, the average value of the image 80 imaged at the previous sampling timing is used as a threshold value. In addition, by using an image (shading data) captured during conveyance of the recording material as a threshold value, it is possible to prevent a decrease in accuracy of the uneven edge amount detection due to unevenness in the imaging region. Note that the image captured during the conveyance of the recording material is stored in a memory (not shown) included in the ASIC 223 and used as the threshold value. Further, this memory may not be included in the ASIC 223 and is not particularly limited. For example, a memory that is internal to the control CPU 210 or that is externally connected by a bus (not shown) may be used.

  FIG. 8 is a diagram for explaining the operation of the present invention, and shows data for one line in the result of imaging the surface of the recording material when stationary by the area sensor. If an image captured while the recording material is stationary is to be binarized with a fixed threshold, the deterioration and distortion of the captured image due to variations in the amount of light caused by the light source and the lens, and the effect of sensitivity variations in each photoelectric conversion cell of the image sensor Therefore, it is difficult to accurately count the number of edges of the recording material.

  In FIG. 8, the broken line represents the fixed threshold value, and in the region near the left end in the figure, the difference between the threshold value and the actual imaging result is particularly large, and fine edge detection omission occurs. Therefore, in this embodiment, an image captured during conveyance of the recording material, that is, a solid curve in the figure (because it is based on an image captured during conveyance rather than at rest, the density at each position for one line is the conveyance direction. The optimum threshold value is set for each paper position by using as a threshold value the shading data shown in FIG. As a result, it becomes possible to discriminate edges that could not be detected with the fixed threshold in the region near the left end in the figure, and it is possible to prevent edge counting leakage and improve detection accuracy.

  As described above, by using an image captured during conveyance of the recording material as a threshold, the number of edges of the recording material can be accurately detected without being affected by unevenness in the imaging region or element variation, and the paper type of the recording material Can be discriminated with higher accuracy.

[Example 2]
Since the basic configuration of this embodiment is the same as that of the first embodiment except that a predetermined value (offset) is added to or subtracted from the threshold value, a detailed description in common is omitted.
In this embodiment, when binarizing each pixel imaged while the recording material is stationary in the above-described calculation of the uneven edge amount detection, the average value of the image 80 imaged at the previous sampling timing is used as a threshold value. Rather than making the threshold value the value obtained by adding or subtracting an appropriate offset amount to the image (shading data) captured during conveyance of the recording material, in addition to unevenness in the imaging region, It is possible to prevent a decrease in accuracy of detecting the uneven edge amount due to the influence.

FIG. 9 is a diagram for schematically explaining the operation of this embodiment. An edge having a large peak can be selectively detected by setting an appropriate offset amount to an image captured during conveyance of the recording material. This can prevent erroneous detection of noise in the imaging region.
As described above, according to the present exemplary embodiment, the threshold value is obtained by adding or subtracting an appropriate offset amount to an image captured during conveyance of the recording material, so that unevenness in the imaging region, element variation, and fine noise existing in the region are detected. Therefore, it is possible to detect the desired number of edges in the recording material without being affected by the above, and to determine the paper type of the recording material with higher accuracy.

[Example 3]
Since the basic configuration of the present embodiment is the same as that of the first embodiment except for the operation during continuous printing, the detailed description in common is omitted.
In this embodiment, an image is taken while only the first recording material is conveyed after printing is started, and the contents (calibration image) are held in a memory (not shown) included in the ASIC 223 until the end of the printing operation. The second and subsequent sheets are characterized in that the first calibration image is used as a threshold value in the above-described calculation of the uneven edge amount detection. The memory does not have to be included in the ASIC 223 and is not particularly limited. For example, a memory that is internal to the control CPU 210 or that is externally connected by a bus (not shown) may be used.
As described above, compared to the first embodiment, the measurement time required for the calculation of the load reduction of the control CPU 210 and the detection of the unevenness of the second and subsequent sheets can be omitted, and the usability is improved by reducing the time until the end of printing. It becomes possible to make it.

[Example 4]
Since the basic configuration of the present embodiment is the same as that of the first embodiment except for the number of times of image shooting during conveyance of the recording material, the detailed description in common is omitted.
In this embodiment, an image (shading data) of the surface of the recording material is captured a plurality of times during conveyance of the recording material, and averaged for each pixel at the same position in each image of the imaging result is used to detect the uneven edge amount. It is characterized by a threshold value in the calculation. The contents of the plurality of times of imaging are sequentially held in a memory (not shown) included in the ASIC 223 and averaged by the arithmetic circuit 705 as described above. The memory does not have to be included in the ASIC 223 and is not particularly limited. For example, a memory that is internal to the control CPU 210 or that is externally connected by a bus (not shown) may be used. Further, the averaging calculation is not limited to being performed by the arithmetic circuit 705, and may be performed by the control CPU 210.
As described above, the number of edges of the recording material can be accurately detected without being affected by random variations or noise that cannot be removed by a single imaging operation, and the paper type of the recording material can be determined with higher accuracy. It becomes.

1 is a schematic view showing an image forming apparatus used in an embodiment of the present invention. It is a figure which shows the structure of each unit which control CPU by one Embodiment of this invention controls. It is a schematic diagram which shows schematic structure of an image reading sensor. It is a figure which shows contrast with the analog image of the recording material surface read by an image reading sensor, and the digital image which digitally processed the analog output to 8x8 pixel. It is a block diagram which shows the control circuit of the CMOS area sensor in Example 1 of this invention. It is a figure which shows the circuit block diagram of the CMOS area sensor in Example 1 of this invention. It is a figure for demonstrating the uneven | corrugated space | interval (irregularity edge amount) detection in Example 1 of this invention. It is a figure which shows the relationship between the imaging data for 1 line in Example 1 of this invention, and a threshold value. It is a figure which shows the relationship between the imaging data for 1 line in Example 2 of this invention, and a threshold value.

Explanation of symbols

DESCRIPTION OF SYMBOLS 101 Image forming apparatus 102 Paper cassette 103 Paper feed roller 104 Transfer belt drive roller 105 Transfer belt 106-109 Photosensitive drums for yellow, magenta, cyan, and black colors 110-113 Transfer rollers for yellow, magenta, cyan, and black colors 114 -117 Yellow, magenta, cyan, and black color cartridges 118-121 Yellow, magenta, cyan, and black color optical units 122 Fixing unit 123 Image reading sensor 210 Control CPU
211 CMOS area sensor 212 to 215 Polygon mirror, motor and laser (optical unit)
216 Paper feed motor 217 Paper feed solenoid 218 Paper presence sensor 219 High voltage power supply 220 Drum drive motor 221 Belt drive motor 222 Low voltage power supply 223 ASIC
224 memory 301 LED for reflection
303 Lens 304 Recording Material 702 Control Circuit 704 Interface Control Circuit 705 Arithmetic Circuit 706 Register A
707 Register B
708 Control register 801 CMOS sensor unit 802, 803 Vertical shift register 804 Output buffer 805 Horizontal shift register 806 System clock 807 Timing generator 808 A / D converter 809 Output interface circuit 810 Sl_out signal 811 Control circuit 812 Sl_in signal 813 Sl_select signal

Claims (6)

Light irradiating means for irradiating light on the surface of the recording medium, image reading means for reading and outputting the light irradiation area of the recording material irradiated by the light irradiating means, and image information on the surface of the recording medium In a recording material discriminating apparatus comprising: binarizing means for binarizing using a predetermined threshold value; and calculating means for calculating the unevenness of the surface of the recording medium by counting the number of edges of the binarized image.
Using the calibration image taken when the recording medium is moved by the light irradiating means and the image reading means as the threshold, the image at rest of the recording medium taken by the light irradiating means and the image reading means, The recording material discriminating apparatus characterized in that binarization is performed by the binarizing means.   2. The recording material discriminating apparatus according to claim 1, wherein the calibration image is shot a plurality of times, and the threshold value is a value obtained by performing a predetermined calculation on the plurality of times of imaging results. A recording material discriminating apparatus characterized in that an image is binarized by the binarizing means.   3. The recording material discriminating apparatus according to claim 2, wherein the predetermined calculation is an arithmetic operation for averaging pixels at the same position in each image of the plurality of imaging results.   4. The recording material discriminating apparatus according to claim 1, wherein an image obtained when the recording medium is stationary is obtained by the binarizing unit with the threshold value obtained by adding or subtracting a predetermined value to the calibration image. A recording material discriminating apparatus characterized by binarization. An image processing means for performing predetermined image processing on the input original image, a latent image carrier for carrying a latent image, and exposing and scanning the latent image carrier on the basis of the image data on which the image processing has been performed. An exposure means for forming an image; a developing means for visualizing the latent image as a developer image by applying a developer to the latent image carrier; and the development by the developing means on a recording material conveyed in a predetermined direction. A transfer unit that transfers the developer image; and a fixing unit that fixes the developer image on the recording material by heating and pressing the recording material onto which the developer image has been transferred by the transfer unit under predetermined fixing processing conditions. In an image forming apparatus comprising:
5. The recording material discriminating apparatus according to claim 1, further comprising: the image processing unit, the exposing unit, the developing unit, corresponding to the type of the recording material discriminated by the recording material discriminating apparatus. An image forming apparatus characterized by variably controlling printing conditions such as processing, output, and speed in the transfer unit and the fixing unit.   6. The image forming apparatus according to claim 5, wherein after the start of printing, only the first recording medium is photographed when the calibration image is moved, and for the second and subsequent sheets, the first calibration image is binarized. An image forming apparatus used as the threshold value in a unit.