JP2007025567A - Image forming apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To achieve appropriate fixing conditions, transfer conditions, and conveying conditions for various types of recording materials by performing optimum correction even if the sensor is contaminated with toner or paper dust while improving usability and cost performance And an image forming apparatus capable of obtaining a good image.
A reflection LED 1111 for irradiating light on the surface of a recording material 1114 before fixing, a transmission LED 1112 for irradiating light on the back surface of the recording material 1114 before fixing, and a reflection LED 1111 or transmission of the recording material 1114 A CMOS sensor 1110 that reads and outputs the image of the light irradiation area of the LED 1112 as an image, and an image forming condition setting unit that controls to set a fixing condition, a transfer condition, and a conveying condition corresponding to an output value from the CMOS sensor 1110 In the image forming apparatus, it is possible to detect the contamination of the sensor by irradiating the recording material with light without moving the recording material, and to easily determine the paper type of the recording material.
[Selection] Figure 1

Description

  The present invention relates to a detection apparatus for detecting the surface smoothness of a recording material and an image forming apparatus such as an ink jet printer, a copying machine, and a laser printer for controlling image forming conditions from the detection result of the surface smoothness of the recording material.

  An image forming apparatus such as a copying machine or a laser printer includes a latent image carrier that carries a latent image, and a developing device that visualizes the latent image as a developer image by applying a developer to the latent image carrier. A transfer unit that transfers the developer image by the developing device to a recording material conveyed in a predetermined direction; and the recording material that has received the transfer of the developer image by the transfer unit is heated under predetermined fixing processing conditions. A fixing device that fixes the developer image on the recording material by applying pressure is provided.

  Conventionally, in such an image forming apparatus, for example, the size and type (hereinafter also referred to as a paper type) of a recording material as a recording material is set by a user on an operation panel or the like provided in the main body of the image forming apparatus. Then, control is performed to change development conditions, transfer conditions, fixing processing conditions (for example, fixing temperature and conveyance speed of the recording material passing through the fixing device) or image processing. Alternatively, when the user sets the paper type at the time of printing from the host computer, the image forming apparatus performs control to change the development condition, the transfer condition, the fixing processing condition, or the image processing according to the designated paper type.

  As proposed in Japanese Patent Laid-Open No. 2002-182518, a surface image of a recording material is picked up by a CMOS sensor, the type of the recording material is determined by a method of detecting the surface smoothness of the recording material, and development conditions, transfer conditions or fixing Variable control of conditions.

Further, there has been proposed an apparatus for discriminating a recording material by transmitted light by providing a light source at a position facing a sensor for discriminating the recording material and detecting transmitted light.
JP 2002-182518 A

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

  If this recording material discrimination sensor is contaminated with toner or paper dust, it blocks transmission light and reflected light from the recording material, thus preventing high-precision recording material discrimination. For this reason, development conditions, transfer conditions, fixing processing conditions, or image processing A new problem has arisen that the control to change the value cannot be performed properly.

  In view of this, the present invention proposes a configuration that can discriminate a recording material satisfactorily by performing correction even if the sensor is contaminated with toner or paper dust, and is optimal by obtaining an accurate discrimination result for any recording material. An object of the present invention is to provide an image forming apparatus capable of obtaining a good fixed image under image forming conditions.

  In order to achieve the above object, a first invention according to the present application includes: a light irradiating unit that irradiates light onto a recording medium; and an imaging lens that forms an image in a light irradiation region by the light irradiating unit on a reading unit. An image forming apparatus comprising: a video reading device including: a type of a recording medium determined from a video signal read by the video reading device; and a printing condition on the recording medium is changed based on the determination result In this case, the image reading device reads the video signal in a state where the recording medium is stopped, thereby detecting the contamination of the image reading device, and the condition for determining the type of the recording medium is changed based on the detected contamination information. It has the means to do.

  In the second invention according to the present application, the light irradiation means has means for irradiating light on the surface of the recording medium.

  Further, in a third invention according to the present application, the light irradiating means has means for irradiating light from the back surface of the recording medium.

  According to a fourth aspect of the present application, the maximum value of the contrast difference between the pixels in the specific pixel region is extracted from the video information captured by the video reader, and the depth of the unevenness on the surface of the recording material is determined. The first computing means is characterized by having means for discriminating the type of the recording medium.

  Further, in the fifth invention according to the present application, the video information of the pixels in the specific pixel region is binarized from the video information captured by the video reader, and the number of edges of the binarized image is counted. Judging the unevenness on the surface of the recording material from the result is the second calculation means, and has means for discriminating the type of the recording medium.

  In the sixth invention according to the present application, binarization is performed by adding or subtracting a predetermined threshold value for binarization to the video information imaged from the video reader, and from the result, the height of the unevenness is calculated. Alternatively, the image processing device includes a third calculation unit that determines whether the image reading device is dirty by extracting a portion having a depth greater than or equal to a predetermined amount, and changes or invalidates pixel information of the extracted region. To do.

  Furthermore, in the seventh invention according to the present application, the irradiation light amount of the light irradiation means is changed, and a place where the amount of change in the received light amount of the image reading device accompanying the change amount is equal to or less than a predetermined amount is extracted as dirt, It has a means for changing or invalidating information of pixels in the extracted area.

  In the eighth invention according to the present application, the first detection result of light reception by the first light irradiation means for irradiating the surface of the recording medium and the light reception by the second light irradiation means for irradiation from the back surface of the recording medium. A fourth calculation means for comparing the second detection result with the first detection result and the second detection result; and a video reading device that indicates that the difference is equal to or less than a predetermined amount from the result of the fourth calculation means. And a means for changing or invalidating pixel information of the extracted area.

  Further, in the seventh invention according to the present application, when the amount of contamination of the obtained image reading apparatus does not exceed a predetermined value, the difference of the recording material is determined as the depth of the unevenness on the surface of the recording material which is the first computing means. When the amount of contamination of the obtained image reading device exceeds a predetermined value, there is a means for discriminating the difference of the recording material by using the concave / convex interval on the surface of the recording material, which is the second computing means. An image forming apparatus.

  As described above, the present invention irradiates the recording material with the first light irradiating unit for irradiating the recording material surface with light or the second light irradiating unit for irradiating the recording material back surface with light. In a recording material smoothness detecting apparatus provided with a reading means for reading the first or second light irradiation area as an image, the reading means detects the reflectance or transmittance of the recording material without moving the recording material. Thus, it is possible to easily detect the contamination of the image reading means. In this configuration, by changing the method for discriminating the recording material according to the contamination detection result, the entire system can be simplified and the accuracy can be improved. As a result, even if the recording material discrimination sensor is soiled by paper dust or toner, various recording materials can be discriminated.

  An image forming apparatus using the present invention variably controls image processing, a developing bias, a temperature control value of a fixing unit, or a recording material conveyance speed according to various characteristics such as the surface property of the recording material and the thickness of the recording material. Thus, there is an effect that a stable image quality independent of the recording material can be obtained.

Example 1
FIG. 1 is a schematic cross-sectional view showing a schematic configuration of an apparatus for performing surface smoothness of a recording material and detecting a reflected light amount or a transmitted light amount.

  As shown in FIG. 1, the image reading sensor 123 includes a reflection LED 1111 as a first light irradiation means, an LED 1112 as a second light irradiation means for detecting a transmitted light amount installed on the opposite side of the recording material 1114, CMOS area sensor 1110 serving as reading means At this time, the sensor 1110 includes a lens 1113 serving as an imaging lens, which may be a CCD sensor.

  Light that uses the LED 1111 for reflection as a light source is applied to the surface of the recording material 1114.

  The reflected light from the recording material 1114 is collected through the lens 1113 and imaged on the CMOS area sensor 1110. Thereby, the surface image of the recording material 1114 is read.

  In the present embodiment, the LED 1111 is arranged so that the LED light irradiates the recording material 1114 surface obliquely at a predetermined angle as shown in FIG.

  FIG. 2 is a diagram showing the relationship between the surface of the recording material 1114 read by the CMOS area sensor 1110 of the video reading sensor 123 and an example in which the output from the CMOS area sensor 1110 is digitally processed to 8 × 8 pixels.

  The digital processing is performed by converting the analog output from the CMOS area sensor 1110 into 8-bit pixel data by A / D conversion (not shown) as conversion means.

  In FIG. 2, 40 is a photograph showing an enlarged image of the surface of the recording material A of so-called rough paper, which is relatively rough in the surface property of the recording material and is easy to distinguish irregularities due to the fibers of the recording material. 41 is a photograph showing an enlarged image of the surface of a so-called plain paper recording material B normally used in a general office, and 42 is a glossy paper (hereinafter referred to as gloss paper) in which the fibers of the paper are sufficiently compressed. This is a photograph showing an enlarged image of the surface of the recording material C.

  These images 40 to 42 read into the CMOS sensor 1110 are digitally processed into the 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 detected from the total or average value of the light input to each pixel. At this time, only the result of one light receiving pixel may be used.

  As described above, the image of the recording material read by the CMOS area sensor 1110 and digitally processed can receive the amount of reflected light corresponding to the surface state of the paper fiber of the recording material, and can determine the paper type of the recording material. It becomes.

  As a method for performing the image comparison calculation, the pixel Dmax having the maximum density and the pixel Dmin having the minimum density are derived from the result of reading the images of a plurality of locations on the surface of the recording material. This is executed for each read video and averaged.

  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 becomes large, and Dmax-Dmin becomes large.

  On the other hand, on the surface such as the recording material C, the shadow of the fiber is small and Dmax−Dmin is small.

  This comparison determines the paper type of the recording material.

  Next, a method for measuring the transmittance of the recording material 1114 will be described. The light having the transmission LED 1112 as the second light irradiating means as the light source irradiates the reading area of the image reading sensor 123 on the recording material from the opposite side of the image reading sensor 123 to the recording material 1114.

  FIG. 3 shows the relationship between the surface of the recording material 1114 read by the CMOS area sensor 1110 of the image reading sensor 123 and the example in which the output from the CMOS area sensor 1110 is digitally processed to 8 × 8 pixels using the LED 1112 for transmission. FIG.

  The transmitted light of the recording material 1114 is collected through the lens 1113 and irradiated to the CMOS area sensor 1110. At this time, the amount of transmitted light is determined from the total value or average value of light input to the entire area of the sensor or each pixel in a predetermined range. At this time, only one result among the plurality of light receiving pixels may be used.

FIG. 4 shows the relationship between basis weight and transmitted light. The horizontal axis represents the basis weight [g / m ² ] of the recording material. The vertical axis indicates an output value corresponding to the total incident light amount of the image reading device, and the sensor output increases as the incident light amount increases. From this figure, it can be seen that a recording material with a large basis weight such as thick paper has a small amount of transmitted light, while a recording material with a low basis weight such as thin paper has a large amount of transmitted light.

  Next, a control circuit block diagram of the CMOS area sensor 1110 will be described with reference to FIG.

  In the figure, 701 is a CPU which is a determination unit, 702 is a control circuit, 1110 is a CMOS area sensor, 704 is an interface control circuit, 705 is an arithmetic circuit, and 706 is a first arithmetic means, which is a calculation result of the surface roughness of the recording material Are set as registers A and 707, and registers B and 708 are set as the second calculation means for setting the calculation result of the uneven edge amount on the surface of the recording material.

  Next, the operation will be described. When the CPU 701 gives an operation instruction for the CMOS area sensor 1110 to the control register 708, the CMOS area sensor 1110 starts capturing a recording material surface image. That is, charge accumulation is started in the CMOS area sensor.

  When the CMOS area sensor 1110 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 1110 via the Sl_out signal.

  The imaging data received via the interface circuit 704 is calculated by a calculation circuit 705 based on a first calculation method to be described later, and the result is set in the register A 706 as a calculation result of the unevenness on the recording material surface.

  On the other hand, the result calculated from the image data received via the interface circuit 704 by the arithmetic circuit 705 based on the second calculation method described later is set in the register B 707 as the uneven edge amount calculation result on the surface of the recording material. The The CPU 701 determines the surface smoothness of the recording material from the values of the two registers.

  The above-described CPU 701 may use a digital signal processor because it is necessary to perform video sampling processing, gain and filter calculation processing from the CMOS area sensor 1110 in real time.

  Next, a sensor circuit block diagram will be described with reference to FIG.

  The figure shows a circuit block diagram of the CMOS area sensor.

  In the figure, reference numeral 601 denotes a CMOS sensor portion. For example, sensors for 8 × 8 pixels are arranged in an area. 602 and 603 are vertical shift registers, 604 is an output buffer, 605 is a horizontal shift register, 606 is a system clock, and 607 is a timing generator.

  Next, the operation will be described.

  When the Sl_select signal 613 is activated, the CMOS sensor unit 601 starts to accumulate charges based on the received light. Next, when the system clock 606 is applied, the timing generator 607 causes the vertical shift registers 602 and 603 to sequentially select the pixel columns to be read, and sequentially set the data in the output buffer 604.

  The data set in the output buffer 604 is transferred to the A / D converter 608 by the horizontal shift register 605. The pixel data digitally converted by the A / D converter 608 is controlled at a predetermined timing by the output interface circuit 609, and is output to the Sl_out signal 610 while the Sl_select signal 613 is active.

  On the other hand, the A / D conversion gain can be variably controlled from the Sl_in signal 612 by the control circuit 611.

  For example, if the contrast of the captured image cannot be obtained, the CPU can change the gain and always capture with the best contrast.

  Next, a method for detecting the unevenness on the surface of the recording material, which is the first calculation means, will be described with reference to FIG. In FIG. 7, an image 70 is an image of 8 rows × 8 columns obtained by digitally processing the image of the surface of the recording material. Here, the vertical direction is a column and the horizontal direction is a row.

  The analog output from the sensor unit of the CCD area sensor is A / D converted into 8-bit pixel data, and 8-bit data is determined in proportion to the brightness of the image.

  At that time, the maximum contrast 71 in the first column is the darkest part in one line of the first row. In the example in the figure, 80h (h indicates hexadecimal notation, the same applies hereinafter), and the minimum contrast 72 is 1. The brightest part in the line, which is 10h in the example in the figure. At this time, the difference between the two values is 80h-10h = 70h.

  That is, the difference between the maximum contrast value and the minimum value in the first row is 70h.

  Similarly, the maximum contrast 73 in the second row is 80h, the darkest part of the second column, and the minimum contrast 74 is the brightest part of the first column, 20h, and the difference is 80h-20h = 60h.

  Similarly, the maximum contrast 75 in the eighth row is 80h which is the darkest part of the seventh column, and the minimum contrast 76 is 10h which is the brightest part of the second column, and the difference is 80h-10h = 70h. .

  In this way, a value obtained by adding the differences between the maximum value and the minimum value for each line for each line is defined as the unevenness calculation result value on the surface of the recording material, which is the first calculation means.

  Next, a method for detecting the uneven edge amount on the surface of the recording material, which is the second calculation means, will be described with reference to FIG.

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

  The number of edges 82 is the number changed from white to black or from black to white in the first line as a result of binarization, and is 05h in this example. The number of edges 83 is the number of edges in the second line, and is 03h in this example.

  Similarly, the number of edges 84 is the number of edges in the eighth line, which is 03h 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, which is the second calculation means.

  Next, a control flow by the CPU 701 as fixing processing condition control means provided in the image forming apparatus 123 will be described with reference to FIG.

  First, the reflecting LED 1111 is turned on in S01, and the detection result of the video reading device at that time is stored. Next, the transmitting LED 1112 is turned on in S02, and the detection result of the video reader at that time is stored. In S03, by using the data of the two storage results, a dirt determination, which will be described in detail later, is performed to identify any dirty pixels and extract the dirty parts. In S04, instead of the measurement data stored as the value of the extracted pixel, a value averaged in the vicinity thereof, for example, every 2 pixels × 2 pixels, is used as a substitute. In S05, the paper type is determined using the reflected light and transmitted light data corrected in S04. For example, the pixel Dmax having the highest density and the pixel Dmin having the lowest density are derived from the result of reading the video at a plurality of locations on the surface of the recording material. This is executed for each read video and averaged. 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 becomes large, and Dmax-Dmin becomes large. On the other hand, on the surface such as the recording material C, the shadow of the fiber is small and Dmax−Dmin is small. This comparison determines the paper type of the recording material. In S06, the fixing process condition is changed according to the determined paper type.

  As the image forming apparatus is used, foreign matter such as scattered toner and paper dust adheres to the image reading apparatus, and the amount of adhesion gradually increases. If this is left as it is, the amount of light greatly changes by a part of the light incident on the image reading apparatus, and the surface property of the recording material cannot be detected correctly. When the image reading apparatus is not contaminated, the surface property of the recording material can be detected with high accuracy as seen in FIG. However, when dirt adheres to the image reading apparatus shown in FIG. 10, it is difficult to detect the surface property of the dirt (portion A). For this reason, the detection performance which detects the kind of recording material from the surface property of a recording material falls.

  11 and 12 are diagrams for explaining the operation of this embodiment. FIG. 11 shows an output signal of the image reading apparatus when a stationary recording material is imaged using the reflecting LED 1111 in the image reading apparatus with dirt as shown in FIG. A decrease in the amount of light due to contamination occurs in some of the pixels of the image reading apparatus.

  Therefore, a representative value in the vicinity of each pixel is calculated from the detected received light quantity. Here, the representative value is, for example, an average value of squares divided into 2 pixels × 2 pixels, or a value of light emission distribution unevenness of the LED stored in the initial stage. Here, description will be made using an average value of squares divided into 2 pixels × 2 pixels. The thick line “representative value in the vicinity” in FIG. 12 is an example. This representative value is compared with the detected received light amount data, and the received light data is binarized according to the magnitude relationship. FIG. 14 shows the binarization performed on FIG. This result is used to determine the type of recording material. However, the contamination of the image reading apparatus cannot be determined from this result. Therefore, a value smaller than the representative value between the representative value and the minimum value of the received light amount data is determined as the threshold value. FIG. 15 shows an example in which a threshold value obtained by subtracting 20% from the representative value is set. By performing binarization with this threshold value, it is possible to extract the pixel of the lowered portion due to dirt as shown in FIG. 16 from the received light amount data of FIG. The image reading apparatus is not reflected in the paper type discrimination by using, as a substitute, a representative value in the vicinity thereof, for example, a value averaged every 2 pixels × 2 pixels, instead of storing measurement data for the pixels with dirt attached. It is possible to suppress a decrease in detection accuracy due to dirt. Here, the threshold is set to 20%. It is obvious that this threshold value may be other than 20% multiplication as long as it is in a range in which dirt can be detected, and may be addition or subtraction of a predetermined amount, for example. Thereby, it is possible to prevent a decrease in accuracy of recording material determination due to contamination of the video reading apparatus, and it is possible to provide a high-quality image by applying optimum image forming conditions regardless of the type of recording material.

(Example 2)
Since the basic configuration and determination method of the second embodiment are the same as those of the first embodiment, detailed description thereof is omitted.

  FIG. 21 is a flowchart for explaining the second embodiment. In the same manner as in the first embodiment, light is emitted from the LED 1111 for surface property detection in S11, and the amount of reflected light from the recording material is detected by the image reading device. At this time, the light quantity of the LED 1111 is changed stepwise. In step S12, the light amount of the transmitting LED 1112 is changed stepwise. In S13, when the image reading apparatus is dirty, the corresponding pixel has a low incident light amount and a small change amount. Further, the incident light quantity of the pixel without dirt increases in accordance with the light emission quantity of the LED 1111 and the LED 1112. An example is shown in FIG. In the figure, three levels of low light, standard light, and high light are described as an example. By extracting a region with a small amount of change from the received light data, it is possible to specify a pixel that is affected by dirt.

  Further, FIG. 18 shows an example of detection data by the LED 1111 for surface property detection and a detection result by the LED 1112 for transparency detection. As shown in this figure, it can be seen that the pixel having the contamination has low data of received light amount for both transmitted light and reflected light, and the same level. In this way, by extracting pixels in which the amounts of light received by the two types of LEDs are both small and the difference between the two types is small, it is possible to identify a pixel that is affected by contamination.

  In S14, a pixel with dirt is extracted. Instead of the measurement data stored as the value of the extracted pixel, a value averaged in the vicinity thereof, for example, every 2 pixels × 2 pixels, is used as a substitute. In S15, the paper type is determined using the reflected light and transmitted light data corrected in S14. In S16, the fixing process condition is changed according to the determined paper type.

  By not reflecting the detection result of dirty pixels, it is possible to improve the accuracy of the calculation result of the first calculation means for determining the depth of the unevenness. Thereby, it is possible to prevent a decrease in accuracy of recording material determination due to contamination of the video reading apparatus, and it is possible to provide a high-quality image by applying optimum image forming conditions regardless of the type of recording material.

(Example 3)
Since the basic configuration and determination method of the third embodiment are the same as those of the first embodiment, detailed description thereof is omitted.

  FIG. 22 shows a flowchart for explaining the third embodiment. In the same manner as in the first embodiment, light is emitted from the surface detection LED 1111 in S21, and the amount of reflected light from the recording material is detected by the video reader. In step S22, light is emitted from the transmission LED 1112, and the amount of transmitted light from the recording material is detected by the video reader. A representative value in the vicinity of each pixel is calculated from the detected amount of received light. Here, the representative value is, for example, an average value of squares divided into 2 pixels × 2 pixels, or a value of light emission distribution unevenness of the LED stored in the initial stage. Here, description will be made using an average value of squares divided into 2 pixels × 2 pixels. Binarization is performed using the representative value as a threshold value for edge determination of the amount of received light. At this time, the threshold value is slid and continuously changed from a value less than the received minimum light amount (−offset) to a value greater than the maximum light amount (+ offset). FIG. 19 shows the image. Binarization is performed on the offset threshold values, and the number of edges at each threshold value is obtained (S23). An example is shown in FIG. A solid line indicates a case where the image reading apparatus is dirty, and a dotted line indicates a case where the image reading apparatus is not dirty. When there is no dirt, the number of edges is rapidly reduced to 0 by decreasing the threshold value for edge determination. When there is dirt, the decrease in the number of edges is gradual, resulting in a graph with a long tail. From this, it is possible to determine the degree of contamination of the image reading apparatus based on the gradient of the number of edges with respect to the change in the threshold value for edge determination. Alternatively, the degree of contamination can be obtained from the area at this low edge determination threshold.

  In S24, when the amount of contamination of the image reading apparatus is equal to or less than a certain value (small contamination), the paper type of the recording material is determined by the normal paper type determination unit 1. When the degree of contamination of the image reading device exceeds a certain level (large contamination), there is a high risk of misidentification by the normal paper type determination means, so the determination standard is changed from the paper type determination means 1 to the paper type determination means 2. The risk of misjudgment is reduced by switching. The paper type determination method will not be described in detail here. For example, in the paper type determination 1, the detected amount of unevenness on the surface of the recording material, which is the first calculation means, is used, and in the paper type determination 2, the surface of the recording material, which is the second calculation means, is used. There is a method using the detected uneven edge amount.

  The fixing process conditions, transfer conditions, and development conditions are changed according to the determined paper type. Depending on the paper type, the transport speed may be changed. Thereby, it is possible to prevent a decrease in accuracy of recording material determination due to contamination of the video reading apparatus, and it is possible to provide a high-quality image by applying optimum image forming conditions regardless of the type of recording material.

1 is a schematic cross-sectional view illustrating a schematic configuration in Example 1. FIG. The figure which shows the surface enlarged video photograph of a recording material, and its determination result. The figure which shows an example of a recording material discrimination | determination result. The relationship figure of transmitted light amount and basic weight. CMOS area sensor circuit block diagram. The sensor circuit block diagram. The figure for demonstrating the 1st calculating means of this invention. The figure for demonstrating the 2nd calculating means of this invention. Imaging results captured with a clean video reader. Imaging results captured with a dirty video reader. The figure which shows the light-receiving light quantity of the specific pixel in a dirty image reading apparatus. The figure which shows the relationship between the edge determination value used for a 2nd calculating means, and dirt. The flowchart for demonstrating the control in 1st embodiment of this invention. The figure for demonstrating the conventional determination method. The figure for demonstrating 1st embodiment of this invention. The figure which shows the stain | pollution | contamination determination result in 1st embodiment of this invention. The figure for demonstrating 2nd embodiment of this invention. The figure for demonstrating 2nd embodiment of this invention. The figure for demonstrating 3rd embodiment of this invention. The figure for demonstrating the determination result of 3rd embodiment of this invention. The flowchart for demonstrating the control in 2nd embodiment of this invention. The flowchart for demonstrating the control in 3rd embodiment of this invention.

Claims (9)

  A video reading device comprising: a light irradiating unit that irradiates light onto the recording medium; and an imaging lens that forms an image in a light irradiation region by the light irradiating unit on the reading unit; In the image forming apparatus, the type of the recording medium is determined from the received video signal, and the printing condition on the recording medium is changed based on the determined result. An image forming apparatus comprising: means for detecting contamination of a video reading device by reading a signal; and means for changing a condition for determining the type of the recording medium based on the detected contamination information.   2. The image forming apparatus according to claim 1, further comprising a first light irradiating unit that irradiates the surface of the recording medium with light as the light irradiating unit.   The image forming apparatus according to claim 1, further comprising a second light irradiation unit configured to irradiate light from the back surface of the recording medium as the light irradiation unit.   The image forming apparatus according to claim 1, wherein a maximum value of a contrast difference between pixels in a specific pixel region is extracted from video information captured by the video reader to determine a depth of unevenness on the surface of the recording material. An image forming apparatus comprising: a first calculation unit; and a unit that determines a type of a recording medium from a result of the first calculation unit.   2. The image forming apparatus according to claim 1, wherein the image information of the pixels in the specific pixel region is binarized from the image information captured by the image reading device, and the number of edges of the binarized image is counted. An image forming apparatus comprising: a second computing unit that determines the unevenness of the recording material surface from the second computing unit; and a unit that discriminates a type of the recording medium from a result of the second computing unit.   2. The image forming apparatus according to claim 1, wherein a predetermined threshold value for binarization is added to or subtracted from the video information captured by the video reader to binarize the video information. It has third operation means for judging the contamination of the image reading device by extracting a place where the height or depth is a predetermined amount or more, and changing or invalidating the information of the pixels in the extracted region. An image forming apparatus.   The image forming apparatus according to claim 1, wherein the irradiation light quantity of the light irradiation unit is changed, and a portion where the change amount of the received light quantity of the image reading device according to the change amount is equal to or less than a predetermined amount is extracted and extracted. An image forming apparatus comprising: means for changing or invalidating pixel information of the area.   2. The image forming apparatus according to claim 1, wherein a first detection result of light reception by the first light irradiation means for irradiating the surface of the recording medium and a first light reception result by the second light irradiation means for irradiation from the back surface of the recording medium. The fourth calculation means for comparing the second detection result, the first detection result and the second detection result, and the difference between the results of the fourth calculation means is less than or equal to a predetermined amount. An image forming apparatus comprising means for extracting as dirt and changing or invalidating pixel information of the extracted area.   2. The image forming apparatus according to claim 1, wherein when the amount of dirt of the obtained image reading device does not exceed a predetermined value, the depth of the unevenness on the surface of the recording material, which is the first computing means, is determined as the difference between the recording materials. When the amount of contamination of the obtained image reading device exceeds a predetermined value, there is a means for discriminating the difference of the recording material by using the concave / convex spacing on the surface of the recording material, which is the second computing means. An image forming apparatus.

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