JP4909062B2 - Recording medium discrimination device - Google Patents

Description

  The present invention relates to a recording medium discriminating apparatus, and more particularly to a recording medium discriminating apparatus that discriminates the type of a recording medium by detecting the surface property or light transmittance of the recording medium.

  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. Prepare. The image forming apparatus further includes transfer means for transferring the developer image by the developing device to a recording medium conveyed in a predetermined direction. The image forming apparatus further includes a fixing device that fixes the developer image to the recording medium by heating and pressurizing the recording medium, which has received the developer image transferred by the transfer unit, under predetermined fixing processing conditions.

  Conventionally, in such an image forming apparatus, for example, the size and type (hereinafter also referred to as paper type) of a recording medium are 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 so as to set the fixing processing conditions (for example, the fixing temperature and the conveyance speed of the recording medium passing through the fixing device) according to the setting.

  Alternatively, by using a sensor for discriminating the recording medium inside the image forming apparatus, for example, a surface image of the recording medium is captured by a CMOS sensor as proposed in Patent Document 1. Then, from the reading result of reading the surface image of the recording medium, the type of the recording medium such as gloss paper, plain paper, rough paper, and OHT is discriminated, and image formation such as print density, transfer bias setting, fixing temperature, process speed, etc. A method for optimally setting conditions is known.

  In a configuration using an image sensor and a lens of a row sensor or an area sensor such as a CCD sensor or a CMOS sensor used in these cases, the following apparatuses are known. That is, the light reflected from the object to be photographed is incident on an image sensor such as a sensor through an imaging lens or the like, and the signal output from the image sensor is A / D converted to obtain image data of the object to be photographed. Obtaining video reading devices are known.

When actually determining, the depth of the irregularities on the surface of the recording medium is calculated from the image data read in Patent Document 2, for example. Specifically, a Peak-to-Peak value that is a difference between the maximum light amount value and the minimum light amount value for each row in the obtained image is obtained. There is a method of discriminating gloss paper, plain paper, rough paper, and OHT based on the Peak-to-Peak value thus obtained based on a plurality of predetermined threshold values.
JP 2002-182518 A JP 2003-302208 A

  However, the above-described conventional recording medium discrimination device has the following problems.

  When the light amount variation due to the light transmittance variation of the light source or the lens used for the sensor is large, the Peak-to-Peak value obtained from the image obtained by photographing the same type of recording medium varies. Also, the variation in the Peak-to-Peak value becomes larger due to the sensitivity variation in each photoelectric conversion cell of the image sensor. As a result, it has become a factor that causes a decrease in discrimination accuracy. Therefore, in order to ensure discrimination accuracy, it is necessary to suppress variations in the amount of light of the LED as the light source, variations in the light transmittance of the lens, and variations in the cell sensitivity, resulting in a high-cost recording medium discrimination device. It was.

  Furthermore, the Peak-to-Peak value may change greatly depending on the light amount unevenness in the irradiation area of the light source, and the determination may not be possible. Therefore, in order to eliminate unevenness in the light amount of the light source, the surface image is taken a plurality of times while moving the recording medium in advance, and the average value of the light amount output values of all the pixels in the photographing region of the photographed image and the light amount output value of each pixel The difference value is obtained. In the determination, it is necessary to perform correction (hereinafter referred to as shading correction) by adding the previously obtained difference value to the light output value of each corresponding pixel in the surface image of the recording medium. As a result, there is a problem that the detection time becomes long and the first printout time becomes long.

  The present invention has been made paying attention to the above points, and can be made into a low-cost configuration, can ensure a discrimination accuracy without performing shading correction, and can reduce a detection time. An object is to provide an apparatus.

  The present invention is made for the purpose of solving the above-described problems in a recording medium discrimination device, and has the following configuration as one means for achieving such an object.

(1) Irradiation means for irradiating the recording medium with light, reading means for receiving light from the recording medium irradiated by the irradiation means and reading as an image having a plurality of pixels, and reading of the image read by the reading means A calculating unit that calculates a difference between output values from a plurality of pixels from an output value; a first difference that is a difference between output values of a second pixel adjacent to the first pixel calculated by the calculating unit; The integration information regarding the absolute value of the second difference is integrated in first to third pixels having different signs of the second difference, which is the difference in the output value of the third pixel adjacent to the second pixel. A recording medium discriminating apparatus comprising: an integrating unit; and a control unit that discriminates a type of the recording medium according to the integration information integrated by the integrating unit.

According to the present invention, the light quantity variation and means morphism irradiation, since less susceptible to variation in sensitivity of the reading preparative means, the light source LED light amount variations or the a, there is no need to suppress the dispersion of the cell sensitivity, inexpensive structure The type of recording medium can be discriminated.

Without performing shading correction for eliminating the light amount unevenness further can discrimination accuracy ensured, it is possible to shorten the detection time, allowing shortened first print out time.

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

  FIG. 1 is a schematic sectional view of a recording medium discriminating apparatus for discriminating the type of recording medium in this embodiment.

Imaging means 100 is provided with a reflective LED101 is irradiation morphism means you illuminate the surface of the recording medium 104 as shown in FIG. 1, an image reading unit 102 reads the irradiation area of the reflection LED101 as an image. Here, reflecting LED101 is first irradiation morphism means. The imaging unit 100 also includes an imaging lens 103 for forming an image on the image reading unit 102, a storage unit 108 that stores an image from the output of the image reading unit 102, and an image stored in the storage unit 108 for each row. And analyzing means 109 for analyzing.

  The light emitted from the reflecting LED 101 is irradiated at a certain angle on the surface of the recording medium 104. Then, the light reflected from the surface of the recording medium 104 is condensed through the imaging lens 103 and imaged on the image reading means 102. In this way, the surface image of the recording medium 104 is read.

  The light amount when the reflection LED 101 detects is controlled by the light emission control unit 1000 so that the light amount for each detection is constant.

  FIG. 2 is a diagram showing the relationship between the surface of the recording medium 104 read by the image reading means 102 inside the image pickup means 100 and an example in which a part of the output from the image reading means 102 is digitally processed to 8 × 8 pixels. is there. The digital processing is performed by converting the analog output from the image reading unit 102 into, for example, 8-bit pixel data by A / D conversion as a conversion unit.

  In FIG. 2, reference numeral 110 denotes a so-called enlarged surface of rough paper that is relatively rough in the surface property of the paper and that can easily distinguish irregularities due to paper fibers. 111 is a so-called magnified surface image of plain paper that is normally used in a general office, and 112 is a magnified surface image of glossy paper (hereinafter referred to as gloss paper) in which paper fibers are sufficiently compressed. is there.

  These images 110, 111, and 112 read by the image reading means 102 are digitally processed to become images 113, 114, and 115 shown in FIG.

  As described above, the surface image varies depending on the type of the recording medium 104. This is a phenomenon that occurs mainly because the fiber state on the paper surface is different.

  As described above, the recording medium 104 is discriminated by digitally processing the surface image of the recording medium 104 read by the image reading unit 102. As shown in FIG. 3, the surface image obtained by reading the α × β region by the image reading unit 102 is digitally processed to obtain a light amount output value for each pixel and stored in the storage unit 108. Based on the light amount output value stored in the storage unit 108, the analysis unit 109 analyzes how the light amount output value for each row changes.

  The actual analysis method by the analysis means 109 is shown below.

FIG. 4 shows an example of the light amount output value in the m-th row (1 ≦ m ≦ β) within the α × β region. The horizontal axis represents the pixel position, and the vertical axis represents the light amount output value. The amount of light output value at each pixel indicated by FIG. _{4 ···, y n-2,} m, y n-1, m, y n, m, y n + 1, m, y n + 2, m, and ... (3 ≦ n ≦ α-2). The light intensity output value y _n of the n-th pixel in the _row, the light amount output values of _m and n + 1 th pixel y _{n + 1, m} difference value a _{n of,} calculating the _m. Also _, the sign b _{n, m of the} difference value a _{n , m} is obtained.

The absolute difference value cn _{, m} between the nth pixel and the (n−1) th pixel in this row is obtained from a _{n, m} , b _{n, m} obtained from the above formula.

The difference integrated value s is obtained by integrating the absolute difference value cn _{, m} thus calculated in the α × β region read by the image reading means.

  For example, the case where the reflected light amount output value on the surface of the recording medium becomes the data shown in Table 1 will be described.

When the difference value a _{n, m} , the sign b _{n, m} , and the difference absolute value cn _{, m} are calculated for this data by the method described so far, the results shown in Table 2 are obtained. From the result of Table 2, the difference integrated value s in the detection area of this recording medium is “34”.

  Since the difference integral value s differs depending on the paper type, the recording medium is determined based on this difference.

  Table 3 shows the calculation of the difference integral value s in a raw image in which four types of plain paper, two types of glossy paper, and one type of gloss film are not subjected to shading correction using the recording medium discriminating apparatus having the configuration in this embodiment. The result is a list of data for 16 paper types. At this time, a 0.64 mm square CMOS area sensor is used as the image reading means, and a 1.28 mm square area on the recording medium is detected by a 1/2 reduction lens. Further, the CMOS area sensor has a size of 0.01 mm square per pixel, and the difference integrated value s was calculated from the light amount output values for all 4096 pixels of 64 × 64.

  FIG. 5 is a graph in which the data of Table 3 is plotted with the differential integral value s on the horizontal axis and the number of data on the vertical axis. For example, in the case of plain paper [1], the number of data having the differential integral value s in the range of 15000 to 16000 is 1 in the range of 16000 to 17000, 8 in the range of 17000 to 18000, and the range of 18000 to 19000. Then it becomes one. On the other hand, on the glossy paper [2], the number of data having the difference integral value s in the range of 8000 to 9000 is 16 of the total number of data. In the gloss film, the number of data having the difference integral value s in the range of 5000 to 6000 is 14, and the number of data in the range of 6000 to 7000 is 2.

As described above, in this configuration, the differential integral value s is 11000 to 22000 for plain paper, 8000 to 10700 for gloss paper, and 5700 to 6300 for gloss film. Therefore, as shown in FIG. 5, plain paper, gloss paper, and gloss film are discriminated by setting a threshold value p ₁ for discrimination between 10700 and 10800 and p ₂ between 6500 and 7800. can do.

The reason why such discrimination is possible is that the change in the surface property of the paper becomes finer in the order of plain paper, gloss paper, and gloss film. For this reason, plain paper with a large change in surface properties has a large absolute value of the difference when changing from increase to decrease and from decrease to increase, and there are many times when the difference changes from increase to decrease and decreases to increase. The value s increases. On the other hand, in a gloss film with a small change in surface properties, the absolute value of the difference when changing from increasing to decreasing and decreasing to increasing is small, and the number of times of decreasing to increasing and decreasing to increasing is small. The value of becomes smaller. Therefore, by setting the threshold values p ₁ and p ₂ , each paper type can be determined. That is, the differential integrated value s is determined to plain paper when the threshold value p ₁ or more. Further, the differential integrated value s is determined to glossy paper if the threshold p ₂ or p less than _1. Further, the differential integrated value s is determined to gloss film is less than p _2.

According to this embodiment as described above, LED light amount variations or the a light source, it is not necessary to suppress the dispersion of the cell sensitivity, it is possible to realize a low-cost structure. Furthermore, since the determination can be made without performing shading correction, the detection time can be shortened. Note that a CCD sensor may be used as the image reading means.

  FIG. 6 is a schematic cross-sectional view of a recording medium discriminating apparatus for discriminating the type of recording medium in this embodiment.

As a second embodiment of the present invention, the transmissive LED207 a source and name Ru irradiation morphism means to the recording medium 204, a recording medium 204 disposed to the opposite side to the image reading unit 202, the transmitted light of the transmission LED207 Was detected. Here, transmissive LED207 is a second irradiation morphism means.

  An actual analysis method when the image from the image reading unit 202 is analyzed by the analysis unit 209 will be described below. Reference numeral 203 denotes an imaging lens for forming an image on the image reading means 202, 208 denotes a storage means for storing an image from the output of the image reading means 202, and 2000 denotes light emission for controlling the light amount of the transmitting LED 207 to be constant. It is a control unit. In this embodiment, the imaging unit 200 includes an image reading unit 202, an imaging lens 203, a storage unit 208, and an analysis unit 209.

  The difference integral value s ′ is obtained from the transmission image of the recording medium 204 by the same method as in the first embodiment.

Table 4 shows an example of the transmitted light amount output value of the recording medium. When the difference value a _{n, m} , the sign b _{n, m} , and the absolute difference value cn _{, m} are calculated for this data by the same method as in the first embodiment, the result shown in Table 5 is obtained. From the results in Table 5, the differential integral value s ′ in the detection area of this recording medium is “75”.

  Since the difference integrated value s' differs depending on the paper type, the recording medium is determined based on this difference.

  Table 6 shows the calculation results of the difference integral value s ′ in the raw image that is not subjected to the shading correction of three types of plain paper and one type of thick paper using the recording medium discriminating apparatus having the configuration in this embodiment. It will be a list of minute data. At this time, a 0.64 mm square CMOS area sensor is used as the image reading means 202, and a 1.28 mm square area on the recording medium is detected by a 1/2 reduction lens. Further, the CMOS area sensor has a size of 0.01 mm square per pixel, and the difference integrated value s ′ is calculated from the light amount output values for all 4096 pixels of 64 × 64.

  FIG. 7 is a graph in which the data in Table 6 is plotted with the difference integral value s ′ plotted on the horizontal axis and the number of data plotted on the vertical axis.

In this configuration, the difference integral value s ′ is 9300 to 12100 for plain paper and 8200 to 8900 for thick paper. Therefore, as shown in Diagram 7, the threshold value q ₁ when determining that the setting between 8900-9300, it is possible to improve the determination accuracy of plain paper and thick paper.

The reason why the discrimination accuracy is improved is that the thickness of the cardboard is uniform compared to the plain paper. For this reason, a plain paper with a non-uniform paper thickness has a large difference value when decreasing from increasing and decreasing to increasing, and as a result, the difference integrated value s ′ increases. On the contrary, in the case of thick paper having a uniform thickness, the difference integrated value s ′ is small because the difference value is small when increasing and decreasing and when decreasing and increasing. By setting the threshold value q ₁ as described above therefore, it is possible to determine the respective paper type. That is, the differential integrated value s' is equal to the threshold value q ₁ or more determined to plain paper, it is determined that thick if it is less than the threshold value q _1.

According to this embodiment as described above, LED light amount variations or the a light source, it is not necessary to suppress the dispersion of the cell sensitivity, it is possible to realize a low-cost structure. Furthermore, since the determination can be made without performing shading correction, the detection time can be shortened. Note that a CCD sensor may be used as the image reading means.

  FIG. 8 is a schematic sectional view of the recording medium discriminating apparatus for discriminating the type of recording medium in this embodiment.

Differs from the embodiments 1 and 2, is irradiated with light for reflection of the first one is a source and name Ru irradiation morphism means to the recording medium 304 LED 301 (the first irradiation morphism means) from the surface of the recording medium 304 Arrange as follows. Also, arranging for transmission of the second LED307 (the second irradiation morphism means) from the rear surface of the recording medium 304 so as to irradiate light. The reflection image of the irradiation area by the reflection LED 301 and the transmission image of the irradiation area by the transmission LED 307 are read as images by the image reading unit 302. Then, the image from the image reading unit 302 is analyzed by the analyzing unit 309. Reference numeral 303 denotes an imaging lens for forming an image on the image reading unit 302, 308 denotes a storage unit for storing an image from the output of the image reading unit 302, and 3000 denotes a constant amount of light for the reflective LED 301 and the transmissive LED 307. It is a light emission control part which controls to. In this embodiment, the imaging unit 300 includes a reflection LED 301, an image reading unit 302, an imaging lens 303, a storage unit 308, and an analysis unit 309.

  A method for discriminating the recording medium in this embodiment will be described with reference to a flowchart shown in FIG.

  First, the LED 301 for reflection is turned on (step S401, hereinafter simply referred to as S401). Then, a surface image of the recording medium 304 is taken (S402). A difference integral value s for the surface image is calculated from the photographed surface image in the same manner as in the first embodiment (S403).

  Next, the transmission LED 307 is turned on in order to acquire the transmission image of the recording medium 304 at the same position where the reflection image is acquired (S404). Then, a transmission image of the recording medium 304 is taken (S405). A difference integral value s ′ for the transmission image is calculated from the captured transmission image in the same manner as in the method of the second embodiment (S406).

The paper type is determined by comparing the difference integral value s for the reflected image and the difference integral value s ′ for the transmission image thus obtained with preset threshold values p ₁ , p ₂ , q ₁ (S407 to S413). ). The thresholds p ₁ , p ₂ , and q ₁ are set by the method described in the first and second embodiments.

First compare the differential integrated value s and the threshold _{p 2} with respect to the reflection image (S407), if s _{<p 2} determines recording medium 304 and gloss film (S408). And when s ≧ _{p 2} compares the differential integrated value s and _{p 1} (S409). If s <p ₁ , the recording medium 304 is determined to be glossy paper (S410). When s ≧ p ₁ , the difference integral value s ′ is compared with q ₁ (S411). If s ′ <q ₁ , the recording medium 304 is determined to be thick paper (S412). If s ′ ≧ q ₁ , it is determined as plain paper (S413).

According to this embodiment as described above, as compared to when I was determined recording medium in their respective single image, it is possible to determine the type of finer recording medium, LED of a further light source There is no need to suppress variations in light amount and cell sensitivity, and an inexpensive configuration can be realized. Further, since the determination can be made without performing shading correction, the detection time can be shortened. Note that a CCD sensor may be used as the image reading means.

1 is a schematic cross-sectional view showing a schematic configuration of a recording medium discrimination device in Embodiment 1. The figure which shows the recording-medium detection result by the recording-medium discrimination | determination apparatus in Example 1 Explanatory drawing of the area | region which the image reading means in Example 1 reads. The figure which shows the mode of the change of the light quantity output value within m line in Example 1. FIG. The figure which shows the recording-medium discrimination | determination result in Example 1. Schematic sectional view showing a schematic configuration of a recording medium discriminating apparatus in Embodiment 2. The figure which shows the recording-medium discrimination | determination result in Example 2. Schematic sectional view showing a schematic configuration of a recording medium discriminating apparatus in Embodiment 3. Flowchart in discrimination of recording medium in embodiment 3

Explanation of symbols

100, 200, 300 imaging unit 101 and 301 reflecting LED (corresponding to the first irradiation morphism means)
102, 202, 302 image reading means 103, 203, 303 imaging lens 104, 204, 304 recording medium 108, 208, 308 storage unit 109,209,309 analyzing means 207, 307 transmissive LED (second irradiation morphism means Equivalent to
1000, 2000, 3000 Light emission control unit

Claims (3)

An irradiation means for irradiating the recording medium with light;
A reading unit that receives light from the recording medium irradiated by the irradiation unit and reads it as an image having a plurality of pixels;
A calculation unit that calculates a difference between output values of a plurality of pixels from an output value of an image read by the reading unit;
The first difference, which is the difference between the output values of the second pixels adjacent to the first pixel calculated by the calculating means, and the difference between the output values of the third pixels adjacent to the second pixel. Integrating means for integrating integration information relating to the absolute value of the second difference in the first pixel to the third pixel having different signs of the difference of 2;
Control means for determining the type of the recording medium in accordance with the integration information integrated by the integration means;
A recording medium discriminating apparatus comprising: The irradiating means irradiates light on the surface of the recording medium and irradiates light on the surface of the recording medium or the first irradiating means for reading the reflected light reflected from the surface as an image, and transmits the light transmitted through the surface. From the recording medium irradiated by either the first irradiation means or the second irradiation means. The recording medium discriminating apparatus according to claim 1, wherein the recording medium discriminating apparatus reads light as an image having a plurality of pixels. The irradiating means irradiates light on the surface of the recording medium, and first irradiating means for causing the reflected light reflected from the surface to be read as an image;
A second irradiation means for irradiating the surface of the recording medium with light and reading the transmitted light transmitted through the surface as an image;
Said reading means, said by the first irradiation means and the second irradiating means receiving the light irradiated sequentially, the recording medium discrimination apparatus according to claim 1, characterized in that reading as an image having a plurality of pixels .