JP6173497B2 - Recording medium imaging device and image forming apparatus - Google Patents

Description

  The present invention relates to a recording medium imaging apparatus that images a recording medium, and an image forming apparatus.

  2. Description of the Related Art Conventionally, in an image forming apparatus, in order to determine the type of recording medium used for image formation (whether it is plain paper or glossy paper), a recording medium imaging apparatus that captures the surface of the recording medium has been introduced. Sometimes. Specifically, as proposed in Patent Document 1 and Patent Document 2, the surface of the recording medium is imaged by a CMOS sensor, and the surface smoothness is detected from the captured image to determine the type of the recording medium. There is something. Then, conditions for image formation and the like are determined using the determination result of the type of the recording medium.

  As described above, in an apparatus for imaging the surface of a recording medium, it is necessary to correct the light amount of the irradiation unit in order to capture a surface image with high accuracy. As an example of correcting the light amount of the irradiating means, Patent Document 3 proposes a configuration in which a reference plate is provided that reflects light from the irradiating means to the imaging means in the absence of a recording medium. The amount of light is corrected using the reflected light from the reference plate.

JP 2002-182518 A JP 2004-038879 A JP 7-131952

  However, in the conventional configuration, the amount of light emitted from the irradiation unit can be corrected only when there is no recording medium. Therefore, the correction of the amount of light and the imaging of the surface image of the recording medium should be performed at different timings. It becomes. For this reason, when performing continuous printing, it is necessary to secure a period during which the recording medium is not conveyed in order to perform light amount correction, and throughput may be reduced.

  The invention according to the present application has been made in view of the above situation, and an object thereof is to perform light amount correction without reducing the throughput.

In order to achieve the above object, a recording medium discriminating apparatus according to the present invention includes a reference plate for reflecting light, a recording medium, irradiation means for irradiating the reference plate with light, and first reflected light from the recording medium. A light receiving means for receiving the reflected light from the reference plate by the second light receiving section, and the type of the recording medium based on the reflected light from the recording medium received by the light receiving means. And a discriminating unit for discriminating, from the reference plate received by the second light receiving unit while the recording medium is transported and passed through an area irradiated with light by the irradiating unit. The reflected light is used to adjust the amount of light from the irradiating means , and at least a part of the reference plate is conveyed by the recording medium when viewed from a direction perpendicular to the light reflection surface of the reference plate. Overlapped with the passing area And wherein the Rukoto.
In order to achieve the above object, an image forming apparatus of the present invention includes an image forming unit that forms an image, a reference plate that reflects light, a recording medium, and an irradiation unit that irradiates the reference plate with light. Light reflected from the recording medium is received by the first light receiving unit, and light reflected from the reference plate is received by the second light receiving unit, and reflected light from the recording medium received by the light receiving unit. And a control means for controlling the image forming conditions of the image forming means, while the recording medium is transported and passed through the area irradiated with light by the irradiating means . light reflected from the reference plate which is received by the second light receiving portion is used for the control means to adjust the amount of light from the irradiation unit, a reflecting surface perpendicular to the direction of light of the reference plate Look, at least of the reference plate Some are characterized by overlapping the region in which the recording medium passes through is conveyed.
In order to achieve the above object, a recording medium detection apparatus of the present invention includes a reference plate that reflects light, a recording medium, an irradiation unit that irradiates light to the reference plate, and reflected light from the recording medium. is received by the first light receiving portion, the recording medium detecting device having a light receiving means for receiving light reflected by the second light receiving portion from the reference plate, the recording areas where light is irradiated by the irradiation unit light reflected from said second of said reference plate, which is received by the light receiving portion while the medium passes through is conveyed, the used to adjust the amount of light from the illumination means, the light of the reference plate When viewed from a direction perpendicular to the reflecting surface, at least a part of the reference plate overlaps with an area through which the recording medium is conveyed.

  According to the configuration of the present invention, it is possible to perform light amount correction without reducing the throughput.

1 is a schematic diagram showing the configuration of an image forming apparatus according to the present invention. FIG. 2 is an oblique view and a cross-sectional view showing a configuration of a recording medium imaging apparatus according to the present invention. FIG. 4 is a top sectional view showing the configuration of the recording medium imaging device according to the present invention. The block diagram which shows control of the recording medium imaging device in this invention The flowchart which acquires the data for correction | amendment of the recording-medium imaging device in 1st Embodiment Lightness distribution chart of correction data of the recording medium imaging apparatus according to the first embodiment Correction data, surface image, and surface image after shading correction of recording medium imaging apparatus according to first embodiment 6 is a flowchart for determining the type of a recording medium in the recording medium imaging apparatus according to the first embodiment. The figure which shows the change of the brightness when the shading correction | amendment in 1st Embodiment is performed. FIG. 3 is a cross-sectional view illustrating a configuration of a recording medium imaging device in which the arrangement of the inner surface reference plate in the first embodiment is different. 1 is an oblique view showing a configuration of a recording medium imaging apparatus in which a plurality of LEDs are arranged in the first embodiment. FIG. 3 is an upper cross-sectional view illustrating a configuration of a recording medium imaging device in which a plurality of LEDs are arranged in the first embodiment. 7 is a flowchart showing control of light amount correction of the recording medium imaging apparatus according to the second embodiment. 6 is a flowchart showing control of surface image acquisition of the recording medium imaging apparatus according to the second embodiment. 10 is a flowchart showing control of surface image acquisition of the recording medium imaging apparatus according to the third embodiment.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. The following embodiments do not limit the invention according to the claims, and all combinations of features described in the embodiments are not necessarily essential to the solution means of the invention.

(First embodiment)
The recording medium imaging apparatus of this embodiment can be used in an image forming apparatus such as a copying machine or a printer. FIG. 1 is a configuration diagram showing an image forming apparatus that employs an intermediate transfer belt and has a plurality of image forming units arranged in parallel as an image forming apparatus equipped with a recording medium imaging device.

  Each configuration of the image forming apparatus 1 in FIG. 1 is as follows. Reference numeral 2 denotes a paper feed cassette 2 that stores the recording medium P. Reference numeral 3 denotes a paper feed tray on which the recording medium P is stacked. A paper feed roller 4 feeds the recording medium P from the paper feed cassette 2 or the paper feed tray 3. Reference numeral 4 ′ denotes a paper feed roller that feeds the recording medium P from the paper feed cassette 2 or the paper feed tray 3. Reference numeral 5 denotes a conveyance roller that conveys the fed recording medium P, and reference numeral 6 denotes a conveyance counter roller that faces the conveyance roller 5. Reference numerals 11Y, 11M, 11C, and 11K denote photosensitive drums that carry developers of yellow, magenta, cyan, and black, respectively. Reference numerals 12Y, 12M, 12C, and 12K denote charging rollers as primary charging units for the respective colors for uniformly charging the photosensitive drums 11Y, 11M, 11C, and 11K to a predetermined potential. 13Y, 13M, 13C, and 13K irradiate laser beams corresponding to the image data of the respective colors onto the photosensitive drums 11Y, 11M, 11C, and 11K charged by the primary charging unit to form an electrostatic latent image. Is a unit.

  Reference numerals 14Y, 14M, 14C, and 14K denote developing devices for visualizing the electrostatic latent images formed on the photosensitive drums 11Y, 11M, 11C, and 11K. Reference numerals 15Y, 15M, 15C, and 15K denote developer conveying rollers for sending the developer in the developing units 14Y, 14M, 14C, and 14K to a portion facing the photosensitive drums 11Y, 11M, 11C, and 11K. Reference numerals 16Y, 16M, 16C, and 16K denote primary transfer rollers for respective colors that primarily transfer images formed on the photosensitive drums 11Y, 11M, 11C, and 11K. Reference numeral 17 denotes an intermediate transfer belt that carries the primary transferred image. A drive roller 18 drives the intermediate transfer belt 17. Reference numeral 19 denotes a secondary transfer roller for transferring an image formed on the intermediate transfer belt 17 to the recording medium P, and reference numeral 20 denotes a secondary transfer counter roller facing the secondary transfer roller 19. A fixing unit 21 melts and fixes the developer image transferred to the recording medium P while conveying the recording medium P. A discharge roller 22 discharges the recording medium P that has been fixed by the fixing unit 21.

  The photosensitive drums 11Y, 11M, 11C, and 11K, the charging rollers 12Y, 12M, 12C, and 12K, the developing devices 14Y, 14M, 14C, and 14K, and the developer transport rollers 15Y, 15M, 15C, and 15K are respectively provided for each color. Is integrated. As described above, a unit in which the photosensitive drum, the charging roller, and the developing unit are integrated is referred to as a cartridge, and the cartridges for each color are configured to be easily detachable from the image forming apparatus 1.

  Next, an image forming operation of the image forming apparatus 1 will be described. Print data including a print command and image information is input to the image forming apparatus 1 from a host computer (not shown) or the like. Then, the image forming apparatus 1 starts a printing operation, and the recording medium P is fed from the paper feed cassette 2 or the paper feed tray 3 by the paper feed roller 4 or the paper feed roller 4 ′ and sent out to the conveyance path. In order to synchronize the operation of forming the image formed on the intermediate transfer belt 17 and the conveyance timing, the recording medium P temporarily stops at the conveyance roller 5 and the conveyance counter roller 6 and waits until image formation is performed. The photosensitive drums 11Y, 11M, 11C, and 11K are charged to a constant potential by the charging rollers 12Y, 12M, 12C, and 12K as an image forming operation together with the operation of feeding the recording medium P. In accordance with the input print data, the optical units 13Y, 13M, 13C, and 13K expose and scan the surfaces of the charged photosensitive drums 11Y, 11M, 11C, and 11K with a laser beam to form an electrostatic latent image. In order to visualize the formed electrostatic latent image, development is performed by the developing devices 14Y, 14M, 14C, and 14K and the developer transport rollers 15Y, 15M, 15C, and 15K. The electrostatic latent images formed on the surfaces of the photosensitive drums 11Y, 11M, 11C, and 11K are developed as images in respective colors by the developing devices 14Y, 14M, 14C, and 14K. The photosensitive drums 11Y, 11M, 11C, and 11K are in contact with the intermediate transfer belt 17, and rotate in synchronization with the rotation of the intermediate transfer belt 17. Each developed image is successively multiplex-transferred onto the intermediate transfer belt 17 by the primary transfer rollers 16Y, 16M, 16C, and 16K. Then, the toner image is secondarily transferred onto the recording medium P by the secondary transfer roller 19 and the secondary transfer counter roller 20.

  Thereafter, in order to perform secondary transfer on the recording medium P in synchronization with the image forming operation, the recording medium P is conveyed to the secondary transfer unit. The image formed on the intermediate transfer belt 17 is transferred to the recording medium P by the secondary transfer roller 19 and the secondary transfer counter roller 20. The developer image transferred to the recording medium P is fixed by a fixing unit 21 including a fixing roller. The fixed recording medium P is discharged to a discharge tray (not shown) by a discharge roller 22 and the image forming operation is finished.

  In the image forming apparatus of FIG. 1, the recording medium imaging device 40 of the present invention is disposed upstream of the transport roller 5 and the transport counter roller 6, and the surface of the recording medium P transported from the paper feed cassette 2 or the like is smoothed. It is possible to detect information reflecting the sex. In this embodiment, the determination by the recording medium imaging device 40 is performed when the recording medium P is sent out from the paper feed cassette 2 or the like into the image forming apparatus and is transported before being sandwiched between the transport roller 5 and the transport counter roller 6. Alternatively, it is performed when the sheet is nipped between the conveyance roller 5 and the conveyance counter roller 6 and conveyed. This is because the recording medium imaging device 40 of the present invention uses a line sensor. Since the conventional image pickup apparatus picks up an image by stopping the recording medium P with an area sensor, the image pickup range is determined in advance. The recording medium imaging apparatus 40 according to the present embodiment can capture an image by appropriately changing the range of the surface image necessary for determining the recording medium P by capturing the recording medium P being conveyed by the line sensor. .

  Next, a recording medium imaging device 40 according to an embodiment of the present invention will be described with reference to FIGS. FIG. 2A shows a configuration of the recording medium imaging device 40 for obtaining a surface image reflecting the surface smoothness. 2 (b) is a cross-sectional view of FIG. 2 (a), and FIG. 3 is a top view of FIG. 2 (a).

  The recording medium imaging device 40 shown in FIG. 2 includes the following. Reference numeral 41 denotes an LED which is an irradiation means for irradiating the surface of the recording medium P with light. An imaging lens 42 is an imaging unit that forms an image of reflected light reflected from the surface of the recording medium P by light irradiated from the irradiation unit. Reference numeral 43 denotes a CMOS line sensor which is an image pickup means for picking up the light imaged by the image forming means. The light irradiated from the LED 41 strikes the recording medium P, where the light is reflected is a reflecting portion, and the reflected light reflected by the reflecting portion is captured as a surface image by the CMOS line sensor 43. Reference numerals 46a and 46b are reference plates (hereinafter referred to as an inner surface reference plate 46a and an inner surface reference plate 46b) that are positioned on the imaging unit side of the reflecting portion at the end of the region where the light of the irradiation unit can be irradiated. A protective member 47 protects the imaging lens 42 and the LED 41. The inner surface reference plates 46a and 46b are arranged on the surface of the protective member 47 on the imaging lens 42 side at the end of the region where the light of the irradiation means can be irradiated. The mechanism for transporting the recording medium P includes a transport roller 5 for transporting the recording medium P, a transport counter roller 6 provided opposite to the transport roller 5, and a transport guide (not shown) that forms a transport path for the recording medium P. . Here, the inner surface reference plates 46a and 46b are disposed on the surface of the protective member 47. However, for example, when the protective member 47 is not provided, the inner surface reference plates 46a and 46b may be disposed on the mold member of the image forming apparatus main body. is there.

  As shown in FIG. 2B, the imaging lens 42 and the CMOS line sensor 43 are arranged so as to be orthogonal to the conveyance direction of the recording medium P. Thereby, the reflected light reflected from the surface of the recording medium P and the reflected light reflected from the inner surface reference plates 46a and 46b can be simultaneously imaged by the light emitted from the LED 41. The LED 41 is arranged so that light can be irradiated at an angle of 10 degrees with respect to the surface of the recording medium P. In that case, LED41 is arrange | positioned so that inner surface reference | standard board 46a, 46b may also be irradiated. Note that this angle is an example, and the angle is not necessarily limited to 10 degrees as long as an image sufficient for determining the recording medium P can be obtained. Moreover, although white LED was used as an irradiation means, if it can irradiate the recording medium P, it will not be limited to white LED. Further, although the CMOS line sensor 43 is used as the imaging means, the present invention is not limited to this, and a two-dimensional area sensor or the like can also be used.

  As shown in FIG. 3, the LED 41 is arranged as an ideal mounting position so that the optical axis is perpendicular to the central portion of the CMOS line sensor 43. However, in consideration of the mounting accuracy of the LED 41, it is not necessarily required to be vertical, and it is sufficient that the inner surface reference plates 46a and 46b are irradiated with light. The recording medium irradiation range represents an area in which the surface information of the recording medium P is acquired, and the recording medium effective image range is used to determine the type of the recording medium P based on the lightness distribution of the light irradiated from the LED 41. This shows the range of the surface image. In this lightness distribution, the lightness range exceeding the threshold value is set as a recording medium effective image range. The threshold value here may be any value that satisfies the discrimination accuracy of the recording medium P, and can be appropriately set according to the type of the LED 41, the distance between the LED 41 and the CMOS line sensor 43, and the like. In the present embodiment, as an example of the threshold value, the lightness is set to 180 (the lightness intensity is set to 256 gradations (0 (dark) to 255 (light)) by taking into account the shortest time for capturing the image of the CMOS line sensor 43 and the diffuse reflectance. The surface image within the effective image range of the recording medium is used for discriminating the type of the recording medium P. Further, the inner surface reference plate irradiation ranges a and b of the inner surface reference plates 46a and 46b are respectively the inner surface reference. The area | region which acquires the surface information of board 46a, 46b is represented.The inner surface reference board effective image range a, b is an area | region used in order to calculate the reflected light amount from each inner surface reference board 46a, 46b.

  FIG. 4 is an example of an operation control block diagram of the recording medium imaging device 40. Light is emitted from the LED 41 to the surface of the recording medium P being conveyed. A surface image is captured by the CMOS line sensor 43 through the imaging lens 42 with the reflected light from the recording medium P. The surface image of the recording medium P imaged by the CMOS line sensor 43 is output to the discrimination processing unit 45.

  The discrimination processing unit 45 performs A / D conversion on the received surface image of the recording medium P in an A / D conversion 451 to obtain an image on the same straight line perpendicular to the conveyance direction of the recording medium P. In this embodiment, an 8-bit A / D conversion IC is used, and the A / D conversion 451 outputs a value from 0 to 255. In the image extraction 452 and the storage area 455, the received surface image of the recording medium P is connected in the transport direction to obtain a two-dimensional surface image. In this embodiment, the conveyance speed of the recording medium P is 80 mm / second, and the resolution of the CMOS line sensor 43 is 600 dpi for one line (about 42 μm per dot). Therefore, the image size is 118 dots × 118 dots, and an area corresponding to 5 mm × 5 mm of the recording medium P can be imaged. Imaging of the CMOS line sensor 43 is performed at 42 μm / (80 mm / second) and at intervals of about 530 μsec or more. Thereby, it is possible to capture images without overlapping the imaging areas on the recording medium P.

  Based on information such as the optical axis and effective image range stored in the storage area 455 from the obtained two-dimensional surface image, a surface image used for discrimination of the type of the recording medium P is extracted. At this time, in order to determine the type of the recording medium P, the surface image is subjected to shading correction. In the feature amount calculation 453, the feature amount is calculated from the extracted surface image. In the paper type discrimination 454, the paper type is discriminated based on the result calculated in the feature amount calculation 453. The result of the paper type determination 454 is output to the image forming condition control unit 101 of the control unit 10, and the image forming condition is controlled based on the determined result. The image forming conditions are conditions such as a transfer voltage, a conveyance speed of the recording medium P, and a fixing device temperature. For example, if the paper type is determined to be rough paper as a result of the paper type determination, the fixing property is not as good as the image forming conditions for plain paper, so the conveyance speed of the recording medium P is decreased and the fixing time in the fixing unit 21 is increased. And control such as raising the fixing temperature. In the storage area 455, a current value for controlling the light emission of the LED 41, a light amount target value necessary for light amount adjustment described later, dark current data when the LED 41 is turned OFF used for correcting light amount unevenness described later, and when the LED 41 is turned ON. Is stored. In addition, among the light amount unevenness data when the LED 41 is ON, the pixel range of the data corresponding to the output of the inner surface reference plates 46a and 46b, the light amount value thereof, and the pixel range of the data corresponding to the optical axis of the LED 41 and the light amount value thereof are also stored. doing.

  In order to acquire the surface image of the recording medium P, a method of adjusting the light amount of the LED 41 and acquiring light amount unevenness data will be described with reference to the flowchart of FIG. The reason for adjusting the amount of light of the LED 41 is that if the amount of light is excessive, the reflected light from the recording medium P increases, the acquired surface image becomes too bright, and the image feature amount may not be obtained correctly. It is. In addition, when the amount of light is insufficient, the acquired surface image becomes too dark, and the feature amount of the image may not be obtained correctly. Further, the amount of light emitted from the LED 41 decreases with time. For this reason, it adjusts so that LED41 may be light-emitted with the light quantity suitable for imaging of a surface image.

  In order to finely control the decrease in the amount of light, for example, it is ideal to correct the amount of light every time one image of the recording medium P is captured. In the conventional example, since the light amount correction and the imaging of the surface image are performed at different timings, it is necessary to secure a period during which the recording medium is not conveyed every time the light amount correction is performed, and thus the throughput is reduced. In the present embodiment, the inner surface reference plates 46a and 46b are disposed between the recording medium P and the CMOS line sensor 43, so that the inner surface reference plates 46a and 46b are within the period for capturing the surface image of the recording medium P. A surface image can also be captured. Thus, even when the interval between sheets is short during continuous printing, it is possible to perform light amount correction without reducing the throughput based on the surface images of the inner surface reference plates 46a and 46b. Here, the light amount correction is performed for imaging one recording medium P, but the timing for performing the light amount correction can be set as appropriate. In addition, here, imaging is performed using the light amount corrected from imaging of the next recording medium P that has been subjected to light amount correction, but the timing for reflecting the result of light amount correction can be set as appropriate.

  Further, the reason for obtaining the light amount unevenness data and performing the shading correction is that it is difficult to irradiate the effective image range with a uniform light amount even if the light amount of the LED 41 is appropriately adjusted. For this reason, a light amount difference occurs within the effective image range, and the surface image for each portion within the effective image range varies due to the light amount difference. Shading correction is performed to reduce this effect. In the present embodiment, initial data for shading correction is acquired by a reference recording medium or a reference reference plate at the time of factory shipment or the like.

  In the sequence 100, acquisition of correction data is started. By the sequence 101, a surface image is acquired using the CMOS line sensor 43 with the LED 41 turned off, and is output to the arrays B [0] to B [i_max] as dark current data. This dark current data is lightness information for removing noise such as ambient light, and is used as a black (dark part) reference in shading correction described later. The dark current data is obtained by imaging multiple times with the CMOS line sensor 43 and calculating an average value for each pixel. In this embodiment, since the CMOS line sensor 43 has 468 pixels at 600 dpi, i_max = 468-1 and the number of measurements is five. If the outputs obtained in each measurement are expressed as B1 to B5, respectively, (B1 + B2 + B3 + B4 + B5) / 5 = B.

  In the sequence 102, the light amount of the LED 41 is corrected. First, a light emission current value (hereinafter referred to as I_led) of the LED 41 is set to emit light. The value LED_current stored in the storage area 455 is used as the value of I_led. LED_current uses 0 or a predetermined default value. In the present embodiment, as an example, the LED 41 is caused to emit light by PWM (Pulse Width Modulation) control, and the PWM value to be controlled has a default value of DUTY 50%.

  In sequence 103, the LED 41 is caused to emit light and an image is acquired using the CMOS line sensor 43. Here, a reference plate serving as a reference for initial data is arranged in the effective image range of the recording medium, and light is applied to the surfaces of the reference plate and the inner surface reference plates 46a and 46b. Each reflected light is imaged by the CMOS line sensor 43, brightness information is acquired from the surface image of the reference plate, and is output to the arrays W [0] to W [i_max], so that one line in the direction of the CMOS line sensor 43 is obtained. Find the lightness information for the minute. i_max is set to i_max = 468-1 described above.

  In sequence 104, the optical axis is detected from the surface image of the obtained reference plate. This is to select a recording medium effective image range for determining the type of the recording medium P described later. The optical axis is a pixel having the highest brightness (brightness) in the brightness distribution for one line in the image area of the reference plate. In the present embodiment, the optical axis T is the moving average WA (WA [i] = (W [i−1] + W [i] + W [i + 1]) / 3 of the lightness distributions W [0] to W [i_max], i. = 1 to 466), and the i pixel with the maximum WA is taken as the optical axis T.

  In the sequence 105, the effective image range of the recording medium is obtained from the pixel of the obtained optical axis. The effective image range of the recording medium is a pixel having a lightness equal to or higher than a certain threshold in the lightness distribution. Then, the necessary number of pixels dot_w in the sensor direction used for the discrimination stored in advance with the optical axis obtained in the center as the center is set as the recording medium effective image range. When the pixel of the optical axis is T, the effective image range of the recording medium is T-dot_w / 2 to T + dot_w / 2-1. However, the recording medium effective image range is a natural number, and there is a condition that it is within the recording medium irradiation range.

  In the sequence 106, the light amount correction amount calculation 456 calculates the average value of the brightness of the entire surface image in the recording medium effective image range. In this embodiment, the average value of W [T-dot_w / 2] to W [T + dot_w / 2-1] is used. In the sequence 107, the value of I_led of the LED 41 is adjusted so that the calculated value becomes a desired light amount correction value stored in the storage area 455. If it is determined that the calculated value is less than the desired value, adjustment is performed by increasing the value of I_led of the LED 41. By repeating the measurement several times, it approaches the desired value. Adjustment is performed, and the process ends when the average value of brightness reaches a desired value. In this embodiment, the light amount correction value on the reference plate serving as a reference for the initial data takes into account the shortest time for capturing the image of the CMOS line sensor 43 and the diffuse reflectance, and is 192 (the lightness intensity is 256 gradations (0 (dark)). ~ 255 (bright))). If the calculated average brightness value does not change, the light quantity of the LED 41 is determined to be maximum, and the adjustment is terminated.

  The output of the CMOS line sensor 43 when the sequence 107 is satisfied is shown in FIG. FIG. 7A shows a surface image when the number of effective pixels in the transport direction is 42. The outputs at both ends represent the surface images of the inner reference plates 46a and 46b, and the output at the center represents the surface image of the initial reference plate. At this time, the optical axis is the pixel position 232, and the effective image range of the recording medium is the pixel position 173 to 290. The recording medium effective image range was selected as a range having a brightness greater than the threshold value. Here, the threshold value is 180, but this can be set as appropriate according to the discrimination accuracy of the type of the recording medium P. At this time, in the graph of FIG. 6, the brightness is high in the range of the pixel positions 65 to 90 and the pixel positions 380 to 405. In the present embodiment, this range is a portion corresponding to the end of the inner surface reference plates 46 a and 46 b, and the inner surface reference plates 46 a and 46 b are in contact with the glass as the protective member 47. For this reason, the light from the LED 41 is reflected at the ends of the protective member 47 and the inner surface reference plates 46a and 46b, and further reflected toward the CMOS line sensor 43, so that the brightness is high. Also in FIG. 7A, it can be seen that high brightness portions are imaged at both ends. Therefore, although this range is also a range that exceeds the threshold value of the recording medium effective image range, it can be determined that the number of pixels exceeding the threshold value is small and the brightness is only locally increased. Do not use as.

  In the sequence 108, the light emission current value I_led of the LED 41 when the condition of the sequence 107 is satisfied is stored as LED_current. In the sequence 109, the pixel T of the optical axis and the pixel Rdot (= T-dot_w / 2) of the recording medium effective image range are stored. In the sequence 110, the light amount value LVr (average value of W [Rdot] to W [Rdot + dot_w−1]) of the effective image range of the recording medium, and the surface information (W [Rdot] to W [Rdot + dot_w−1] of the effective image range of the recording medium. ) Are stored in arrays DW [0] to DW [dot_w−1]. Then, dark current data (B [Rdot] to B [Rdot + dot_w−1]) of the effective image range of the recording medium is stored in the arrays DB [0] to DB [dot_w−1]. In the sequence 111, the pixels ref_a1 to ref_a2 and the light amount value LVra (average value of the inner surface reference plate effective image range W [ref_a1] to W [ref_a2]) and the pixels of the inner surface reference plate effective image range b in the inner surface reference plate effective image range a. The ref_b1 to ref_b2 and the light amount value LVrb (average value of the inner surface reference plate effective image range W [ref_b1] to W [ref_b2]) are stored in the storage area 455. The pixels used as the inner surface reference plate effective image ranges a and b have a lightness range of 50 to 100 in consideration of the reflectance of the inner surface reference plate, the irradiation angle of the LED 41, the arrangement configuration, and the like. The brightness of the inner surface reference plates 46a and 46b is the average value of the brightness in the inner surface reference plate effective image range of FIG. In this embodiment, since the inner surface reference plates 46a and 46b are arranged at both ends of the CMOS line sensor 43, two light quantity values are calculated. These data are stored in the storage area 455 as one correction data. The surface images of the inner surface reference plate effective image ranges a and b represent the light amount of the LED 41. By making this light amount constant, fluctuations in the light amount of the LED 41 can be corrected.

  Next, control for acquiring the surface image of the recording medium P will be described. Based on the LED light emission current value stored in the storage area 455, the LED 41 irradiates the recording medium P being conveyed with light. The reflected light from the recording medium P is imaged by the CMOS line sensor 43, and the surface image of the recording medium P is output to the discrimination processing unit 45. When the discrimination processing unit 45 receives the surface image of the recording medium P from the CMOS line sensor 43, the voltage signal is A / D converted to obtain an image on the same straight line orthogonal to the conveyance direction of the recording medium P. As for the surface image of the recording medium P received by the discrimination processing unit 45, the surface images of the inner surface reference plates 46a and 46b arranged at both ends are also acquired at the same time. Since the amount of light emitted from the LED 41 to the recording medium P can be calculated from the surface images of the inner surface reference plates 46a and 46b, the amount of light when the recording medium P is imaged can be detected. For this reason, it has become possible to perform light amount correction, which is conventionally performed in a state where the recording medium P is not transported before the recording medium P is imaged, while the surface image of the recording medium P is captured. Therefore, it is possible to detect the light amount of the LED 41 that is capturing the surface image of the recording medium P and correct it to an appropriate light amount.

  Next, a method for determining the type of the recording medium P based on the imaged surface image of the recording medium P will be described with reference to the flowchart of FIG. In sequence 200, image acquisition is started. In the sequence 201, based on the LED light emission current value LED_current stored in advance, the LED 41 irradiates light to the recording medium P and the inner surface reference plates 46a and 46b being conveyed.

  In the sequence 202, reflected light from the recording medium P and the inner surface reference plates 46a and 46b is imaged by the CMOS line sensor 43, and the surface images of the recording medium P and the inner surface reference plates 46a and 46b are output to the discrimination processing unit 45. . The brightness of the surface image of the recording medium P is output to the arrays POj [0] to POj [i_max]. The discrimination processing unit 45 acquires a two-dimensional surface image by joining the received surface images of the recording medium P in the transport direction. Note that j in the array represents a pixel position in the transport direction.

  In the sequence 203, the light quantity values LVa and LVb of the LED 41 are calculated based on the obtained surface images of the inner surface reference plates 46a and 46b. LVa is an average value of POj [ref_a1] to POj [ref_a2] that are outputs of the pixels ref_a1 to ref_a2 of the inner surface reference plate effective image range a. LVb is an average value of the outputs POj [ref_b1] to POj [ref_b2] of the pixels ref_b1 to ref_b2 in the inner surface reference plate effective image range b. In the sequence 204, the calculated light quantity values LVa and LVb are compared with the light quantity values LVra and LVrb of the inner surface reference plates 46a and 46b stored in advance, respectively, and I_led is corrected. As a result of the comparison, for example, when the calculated light amount value LVa is smaller than the prestored light amount value LVra, control is performed to increase the LED light emission current value and increase the light amount value of the LED 41. Further, based on the result of the large light amount difference between the calculated light amount value LVa and the pre-stored light amount value LVra and the light amount difference between the calculated light amount value LVb and the pre-stored light amount value LVrb, the LED light emission current value Control. Further, when the difference between the calculated light quantity values LVa and LVb and the stored light quantity values LVra and LVrb is within ± 3%, the process is terminated.

  In the sequence 205, the sequences 202 to 204 are repeated until the necessary number of pixels dot_h in the transport direction stored in advance is acquired. In the sequence 206, I_led when the surface image of the recording medium P is finally captured is stored. Since this is used when acquiring the surface image of the next recording medium P, the surface image can be captured without controlling the light amount correction at the time of the next imaging. Further, it is possible to correct the amount of light of the LED 41 while capturing the surface image of the recording medium P by using the surface images of the inner surface reference plates 46a and 46b, and it is more accurate even when the interval between sheets is short during continuous printing. A surface image of the recording medium P can be obtained. FIG. 7B is an image obtained by capturing the surface images of the inner surface reference plates 46 a and 46 b and the surface image of the recording medium P. The central portion of the image is the surface image of the recording medium P, and the images at both ends are the surface images of the inner surface reference plates 46a and 46b. Among these surface images, the type of the recording medium P is discriminated using the surface image of the recording medium P, and the light amount of the LED 41 is corrected using the surface images of the inner surface reference plates 46a and 46b.

  In sequence 207, shading correction is performed to correct unevenness in the amount of light on the surface image of the obtained recording medium P. The shading correction is performed based on the dark current data DB when the LED 41 is OFF and the initial reference plate data DW. The light quantity unevenness of the LED 41 is the brightness distribution of FIG. FIG. 9 shows the relationship of output values in the shading correction operation. (A) is the lightness distribution of the reference data, (b) is the lightness distribution before the shading correction, and (c) is the lightness distribution after the shading correction. The reference data is correction data for light amount unevenness stored in advance. Based on this brightness distribution, the ratio of the output values of each pixel is calculated so that the value of each pixel in the recording medium effective image range is close to 192. Shading correction is performed by multiplying the calculated ratio of each pixel to each pixel of the surface image of the recording medium P. Then, as shown in FIG. 9C, the light amount unevenness is reduced in the surface image of the recording medium P after the shading correction.

  Since the shading correction method can be performed by a conventionally known method, detailed description thereof is omitted. A method of correcting the light amount unevenness of the i-th pixel in the j-th line, assuming that the data after shading correction is Dj [0] to Dj [dot_w−1]. First, POj [i] -DB [i] is performed to remove the influence of dark current noise. Next, in order to remove the influence of the unevenness of the light amount, the light amount value is matched with a predetermined light amount correction value (here, 192) with respect to the obtained result. Then, Dj [i] = (POj [i] −DB [i]) × 192 / DW [i] is performed. FIG. 7C shows a surface image subjected to shading correction. The central portion of the image is the surface image of the recording medium P, and the images at both ends are the surface images of the inner surface reference plates 46a and 46b. From the image after the shading correction, it can be seen that the light amount unevenness is corrected as compared with the surface image of FIG.

  In the sequence 208, the feature amount of the surface unevenness is calculated from the surface image subjected to the shading correction. As a calculation method, the brightness of each pixel of the surface image is made into a histogram and used as a standard deviation of the brightness distribution. When the average value of all data (i = 0 to dot_w−1, j = 0 to dot_h−1) of the correction data Dj [i] is DA, the standard deviation is (((Dj [i] −DA) The square root of the sum of the square of 2) divided by the number of pieces). In sequence 209, the type of the recording medium P is determined based on the obtained feature amount, and the determination result is output to the image forming condition control unit 101 in the control unit 10. The obtained feature amount is compared with an output value for specifying the type of the recording medium P stored in advance, and the type of the recording medium P is determined. The image forming condition control unit 101 controls the image forming conditions based on the type of the obtained recording medium P. Although an example in which shading correction is performed after acquiring the surface image of the recording medium P is shown here, shading correction may be performed after acquiring the surface image for each line.

  Up to this point, the configuration in which the inner surface reference plates 46a and 46b are in contact with the protection member 47 has been described. However, the inner surface reference plates 46a and 46b may be disposed on the surface of the protection member 47 as shown in FIG. Moreover, the structure of the inner surface reference | standard board 46a, 46b in the case of having a some light source as an irradiation means is shown in FIG.11 and FIG.12. FIG. 11 is a perspective view in the case of having a plurality of light sources. The difference from the perspective view of FIG. 2A is that there are a plurality of LEDs 41a and 41b as irradiation means and the light emitted from the LEDs 41a and 41b. That is, a slit structure member 44 that leads in an arbitrary direction is arranged. FIG. 12 is a cross-sectional view, and the difference from the cross-sectional view of FIG. 3 is that the number of LEDs 41 and the slit structure member 44 are arranged as in FIG. The optical axis of the LED 41a is arranged to be 45 degrees (+45 degrees) counterclockwise with respect to the conveyance direction of the recording medium P, and the optical axis of the LED 41b is 45 degrees clockwise with respect to the conveyance direction of the recording medium P. It arrange | positions so that it may become (-45 degree | times). The slit structure member 44 prevents the light from the LED 41a and the light from the LED 41b from irradiating the same area, and irradiates the surface of the recording medium P with light with high accuracy. , 41b is limited. The inner surface reference plates 46a and 46b correspond to the LEDs 41a and 41b, respectively, and are arranged outside the optical axes of the LEDs 41a and 41b (on the end side of the CMOS line sensor). Arranged on the outer side is that when the inner surface reference plates 46a and 46b are arranged on the inner side (center side of the CMOS line sensor), the irradiation to the recording medium P is shielded, and the surface image of the recording medium P is shielded. This is because it appears as a shadow.

  As described above, even when a plurality of light sources are used as the irradiating means, the inner surface reference plates 46 a and 46 b are arranged between the recording medium P and the CMOS line sensor 43, so that the surface image of the recording medium P can be captured. The surface images of the inner surface reference plates 46a and 46b can be taken within the period to be performed. This makes it possible to perform light amount correction based on the surface images of the inner reference plates 46a and 46b even when the interval between sheets is short during continuous printing.

(Second Embodiment)
Since the configuration of this embodiment can be implemented in FIGS. 1 to 4 described in the first embodiment, description thereof is omitted here. In the present embodiment, when performing light amount correction, instead of changing the light amounts of the LEDs 41a and 41b, light amount unevenness data for performing shading correction is appropriately selected in accordance with the light amount, so that an accurate surface image can be obtained. The image is taken.

  The light quantity correction operation in this embodiment will be described with reference to the flowchart of FIG. In sequence 300, light quantity correction is started. In sequence 301, a surface image is acquired using the CMOS line sensor 43 with the LED 41 turned off, and is output to the arrays B [0] to B [i_max] as dark current data. In the sequence 302, the LED 41 irradiates the inner surface reference plates 46a and 46b with light based on I_led stored in advance. The value LED_current stored in the storage area 455 is used as the value of I_led. When the light amount correction is performed once or more, since the value is stored in the LED_current, it is possible to reduce the number of loop control times of the sequences 303 to 305 shown below.

  In sequence 303, the reflected light from the inner surface reference plates 46a and 46b is imaged by the CMOS line sensor 43 to obtain surface information of the inner surface reference plates 46a and 46b. The obtained data is output to the arrays PO [ref_a1] to PO [ref_a2] and PO [ref_b1] to PO [ref_b2], respectively. In the sequence 304, the light quantity value of the LED 41 is calculated based on the obtained surface images of the inner surface reference plates 46a and 46b. The light amount value is calculated as the average value of the surface image of the inner surface reference plate 46 as described above.

  In sequence 305, the calculated light quantity values LVa and LVb are compared with the light quantity values LVra and LVrb of the inner surface reference plates 46a and 46b stored in advance, respectively, and I_led is corrected. The comparison between the calculated light amount values LVa and LVb and the light amount values LVra and LVrb stored in advance is the same as that in the sequence 204 in FIG. 8, and the description thereof is omitted here. In sequence 306, the value is updated with LED_current as I_led when the conditions of sequence 305 are satisfied, and the surface image of the recording medium P is acquired based on this value.

  Next, the acquisition of the surface image of the recording medium P and a method for correcting the shading of the acquired surface image will be described with reference to the flowchart of FIG. In sequence 400, acquisition of a surface image is started. In the sequence 401, the LED 41 irradiates the recording medium P and the inner surface reference plates 46a and 46b being transported based on the LED_current obtained by the light amount correction described above. In sequence 402, the CMOS line sensor 43 images reflected light from the recording medium P and the inner surface reference plates 46a and 46b, and surface images POj [0] to POj [i_max] of the recording medium P and the inner surface reference plates 46a and 46b. Get.

  In sequence 403, the light quantity values LVa and LBb of the LED 41 are calculated based on the obtained surface images of the inner surface reference plates 46a and 46b. Here, in this embodiment, the light amount correction of the light amount values LVa and LBb of the LED 41 is not performed using the light amount value calculated from the surface information of the inner surface reference plates 46a and 46b. According to the light quantity values LVa and LBb of the LED 41, the light quantity unevenness data of the optimum recording medium effective image range is selected, and the surface image of the recording medium P is acquired by performing the shading correction of the surface image. Here, irradiation with a plurality of different LED light emission current values is performed on the recording medium for initial adjustment or the reference plate for initial adjustment so that optimum light intensity unevenness data corresponding to the light intensity values LVa and LBb of the LED 41 can be selected. In this case, the light amount unevenness data is stored in the storage area 455 in advance. In this embodiment, the light amount unevenness data is stored when the light amount value of the effective image range of the recording medium is 160, 176, 192, 208, and 224. However, the present invention is not limited to this light amount. At this time, simultaneously with the acquisition of the light amount unevenness data, the light amount values LVa and LVb of the inner surface reference plates 46a and 46b are also stored in correspondence with the light amount unevenness data. As described above, in this embodiment, by performing shading correction using the light amount unevenness data corresponding to the light amount values LVa and LBb of the LED 41, the surface image of the recording medium P with high accuracy without performing the light amount correction of the LED 41. Can be obtained.

  In sequence 404, the optimum shading correction data is selected from a plurality of light quantity unevenness data acquired by irradiation with a plurality of different LED light emission current values stored in advance. As a selection method, the stored light amount values of the plurality of inner surface reference plates 46 a and 46 b are compared with the light amount values of LVa and LVb calculated in the sequence 403. Then, the light quantity values LVra and LVrb of the inner surface reference plates 46a and 46b whose light quantity values match or are closest to each other are selected. The light amount unevenness data DW [Rdot] to DW [Rdot + dot_w−1] of the effective image range of the recording medium stored in the selected light amount values LVra and LVrb are used for shading correction.

  In a sequence 405, shading correction is performed on the surface image of the recording medium P based on the dark current data DB when the LED 41 is OFF and the selected correction data DW. Since the shading correction method is the same as that of the first embodiment, description thereof is omitted here. In the sequence 406, the sequences 402 to 405 are repeated until the necessary number of pixels “dot_h” in the transport direction stored in advance is acquired. Thereby, since the shading correction can be performed using the light amount unevenness data corresponding to the light amount value of the LED 41, the surface image of the recording medium P with high accuracy can be obtained.

  Here, a method of acquiring shading unevenness data in the case of irradiation with light of a plurality of LED light emission current values in advance and performing shading correction according to the light amount values LVa and LBb of the LED 41 is shown. As described above, as another method for performing shading correction without performing light amount correction, the distribution of light amount values and light amount unevenness in the effective image range of the recording medium based on the light amount values and light amount unevenness of the surface images of the inner surface reference plates 46a and 46b. It is also possible to calculate shading and perform shading correction. This method eliminates the need to store a plurality of light amount unevenness data in advance, so that the storage area can be reduced.

(Third embodiment)
Since the configuration of this embodiment can be implemented in FIGS. 1 to 4 described in the first embodiment, description thereof is omitted here. In the present embodiment, when performing light amount correction, an accurate surface image is captured by adjusting the light amount in accordance with the whiteness of the recording medium P. By using the inner surface reference plates 46a and 46b, the brightness can be determined based on the surface image of the recording medium P, and thus the whiteness of the recording medium P can be detected. For example, paper with low whiteness, such as recycled paper, has a low output from the CMOS line sensor 43 as a whole, so that the unevenness of the surface image may be crushed, and the paper type may be determined to be smoother than the actual. Even in such a case, when the whiteness of the recording medium P being conveyed is detected and determined to be lower or higher than the preset whiteness, the light emission current value of the LED 41 is changed, and the light intensity value is changed. To change. By irradiating the recording medium P with low whiteness such as recycled paper or the recording medium P with high regular reflection by increasing the light amount value of the LED 41, the surface image of the recording medium P can be accurately captured.

  The acquisition of the surface image of the recording medium P in the present embodiment will be described with reference to the flowchart of FIG. Since the sequence 500 to the sequence 502 are the same as the sequence 300 to the sequence 302 of FIG. 13 in the second embodiment, description thereof is omitted here.

  In the sequence 503, the reflected light from the recording medium P is imaged by the CMOS line sensor 43, and surface images PO [Rdot] to PO [Rdot + dot_w−1] of the recording medium P are obtained. In the sequence 504, the light amount value LV of the effective image range of the recording medium is calculated based on the obtained surface image of the recording medium P. LV is calculated as the average value of the surface images in the effective image range of the recording medium P as described above.

  In sequence 505, LV is compared with a light amount value LVr stored in advance, and if the condition is not satisfied, I_led is changed and measurement is performed again. The value is updated by setting I_led when the condition of the sequence 505 is satisfied as LED_current, and the surface image of the recording medium P is acquired based on this value. Further, since the updated LED_current corresponds to the whiteness of the recording medium P, the type of the recording medium P can be determined based on the LED_current.

  In the sequence 506, the LED 41 irradiates the recording medium P and the inner surface reference plates 46a and 46b with light based on the updated LED_current. Reflected light from the recording medium P and the inner surface reference plates 46a and 46b is imaged by the CMOS line sensor 43 to obtain surface information POj [0] to POj [i_max] of the recording medium P and the inner surface reference plates 46a and 46b. In sequence 507, the light quantity values LVa and LVb are calculated based on the obtained surface images of the inner surface reference plates 46a and 46b. The light quantity values LVa and LVb are calculated as an average value of the surface images POj [ref_a1] to POj [ref_a2] of the inner surface reference plates 46a and 46b and an average value of POj [ref_b1] to POj [ref_b2].

  In the sequence 508, the optimum correction data is selected from correction data irradiated with light of a plurality of LED_currents stored in advance. As a selection method, the stored light amount values of the plurality of inner surface reference plates 46 a and 46 b are compared with the light amount values of LVa and LVb calculated in the sequence 507. Then, the light quantity values LVra and LVrb of the inner surface reference plates 46a and 46b whose light quantity values match or are closest to each other are selected. The light amount unevenness data DW [Rdot] to DW [Rdot + dot_w−1] of the effective image range of the recording medium stored in the selected light amount values LVra and LVrb are used for shading correction.

  In the sequence 509, shading correction is performed on the surface image of the recording medium P based on the dark current data DB when the LED 41 is OFF and the selected correction data. Since the shading correction method is the same as that of the first embodiment described above, description thereof is omitted here. In the sequence 510, the sequences 506 to 508 are repeated until the necessary number of pixels “dot_h” in the transport direction stored in advance is acquired. Thereby, since the shading correction can be performed using the light amount unevenness data corresponding to the light amount value of the LED 41, the surface image of the recording medium P with high accuracy can be obtained.

  As described above, the type of the recording medium P can be determined based on the two parameters of the LED_current obtained from the surface image and the surface image of the recording medium P. By determining the type of the recording medium based on the two feature quantities of the surface image and the whiteness, the recording medium P can be determined with high accuracy.

DESCRIPTION OF SYMBOLS 1 Image forming apparatus 40 Recording medium imaging device 41 LED
42 Imaging lens 43 CMOS line sensor 44 Slit structure member 45 Discrimination processing part 46a, 46b Inner surface reference plate 47 Protection member

Claims (38)

A reference plate that reflects light;
Irradiating means for irradiating the recording medium and the reference plate with light;
Light receiving means for receiving reflected light from the recording medium with a first light receiving unit and receiving reflected light from the reference plate with a second light receiving unit;
A discriminating unit for discriminating the type of the recording medium based on the reflected light from the recording medium received by the light receiving unit;
The reflected light from the reference plate received by the second light receiving unit while the recording medium is transported and passed through the region irradiated with light by the irradiating means is the amount of light from the irradiating means. It is used for adjustment, and when viewed from a direction perpendicular to the light reflection surface of the reference plate, at least a part of the reference plate overlaps with a region through which the recording medium is conveyed. Recording medium discrimination device. 2. The recording medium discriminating apparatus according to claim 1, wherein the light receiving means is an image pickup means for picking up reflected light from the recording medium received by the first light receiving section as a surface image of the recording medium. . The recording medium determination apparatus according to claim 2, wherein the determination unit determines a surface state of the recording medium based on a surface image of the recording medium imaged by the imaging unit. The amount of light reflected from the reference plate which is received by the second light receiving portion while the first light receiving portion for receiving reflected light from the recording medium, adjusting the light quantity of light from the irradiation unit The recording medium discriminating apparatus according to claim 1, wherein the recording medium discriminating apparatus is used to perform the recording . The light receiving means is an imaging means for picking up the reflected light from the reference plate received by the second light receiving section as a surface image of the reference plate, and the amount of reflected light from the reference plate is the imaging 5. The recording medium discriminating apparatus according to claim 4, wherein the recording medium discriminating apparatus is obtained from data of a surface image of the reference plate imaged by means. The amount of reflected light from the reference plate is the data obtained by receiving the light through the end of the reference plate in the direction orthogonal to the recording medium conveyance direction among the data of the surface image of the reference plate. 6. The recording medium discriminating apparatus according to claim 5, wherein the recording medium discriminating apparatus is obtained from the excluded data. A reference plate that reflects light;
Irradiating means for irradiating the recording medium and the reference plate with light;
Reflected light from the recording medium is received by a first light receiving unit, reflected light from the recording medium received by the first light receiving unit is captured as a surface image of the recording medium, and reflected from the reference plate Imaging means for receiving light by the second light receiving unit;
Discriminating means for discriminating the surface state of the recording medium based on the surface image of the recording medium imaged by the imaging means;
In the recording medium discrimination apparatus having a storage means for storing a plurality of correction data for the imaging means to correct the data of the surface image of the recording medium captured,
The light reflected from the reference plate which is received by the second light receiving portion while the recording medium region where light is irradiated passes conveyed by irradiation means, a plurality of which are stored in the storage means It is used to select one correction data from among the correction data , and when viewed from a direction perpendicular to the light reflection surface of the reference plate, at least a part of the reference plate is transported by the recording medium. it characterized in that overlaps the region record medium discriminating device. The amount of reflected light from the reference plate received by the second light receiving unit while the first light receiving unit receives reflected light from the recording medium is a plurality of corrections stored in the storage unit. 8. The recording medium discriminating apparatus according to claim 7, wherein the recording medium discriminating apparatus is used for selecting one correction data from the data. In accordance with the amount of reflected light from the recording medium obtained from the surface image data of the recording medium, the amount of light from the irradiation unit is adjusted, and after the amount of light from the irradiation unit is adjusted, One correction data is selected from among a plurality of correction data stored in the storage means in accordance with the amount of reflected light from the reference plate received by the second light receiving unit. Item 9. The recording medium discrimination device according to Item 8 . Recording medium detecting device according to any one of claims 1 to 9, characterized in that the reference plate is fixed. The light receiving means is an image pickup means for simultaneously picking up reflected light from the recording medium received by the first light receiving section and reflected light from the reference plate received by the second light receiving section as surface images. recording medium detecting device according to any one of claims 1 to 10, characterized in that. When viewed from the reflecting surface perpendicular to the direction of light of the reference plate, any all parts of the reference plate of claims 1 to 11, characterized in that overlaps with a region where the recording medium passes through is conveyed The recording medium discriminating apparatus according to claim 1. An image forming means for forming an image;
A reference plate that reflects light;
Irradiating means for irradiating the recording medium and the reference plate with light;
Light receiving means for receiving reflected light from the recording medium with a first light receiving unit and receiving reflected light from the reference plate with a second light receiving unit;
An image forming apparatus comprising: a control unit that controls image forming conditions of the image forming unit based on reflected light from the recording medium received by the light receiving unit;
The reflected light from the reference plate received by the second light receiving unit while the recording medium is transported and passed through the region irradiated with light by the irradiating means is reflected by the control means from the irradiating means. It is used to adjust the amount of light, and at least a part of the reference plate overlaps the area through which the recording medium is transported when viewed from the direction perpendicular to the light reflection surface of the reference plate. An image forming apparatus. The image forming apparatus according to claim 13 , wherein the light receiving unit is an imaging unit that captures reflected light from the recording medium received by the first light receiving unit as a surface image of the recording medium. The image forming apparatus according to claim 14 , wherein the control unit controls the image forming condition based on a surface image of the recording medium imaged by the imaging unit. The amount of the reflected light from the reference plate received by the second light receiving unit while the first light receiving unit receives the reflected light from the recording medium is determined by the control unit using light from the irradiation unit. the image forming apparatus according to any one of claims 13 to 15, characterized in that it is used to adjust the amount of light. The light receiving means is an imaging means for picking up the reflected light from the reference plate received by the second light receiving section as a surface image of the reference plate, and the amount of reflected light from the reference plate is the imaging The image forming apparatus according to claim 16 , wherein the image forming apparatus is obtained from data of a surface image of the reference plate imaged by a means. The amount of reflected light from the reference plate is the data obtained by receiving the light through the end of the reference plate in the direction orthogonal to the recording medium conveyance direction among the data of the surface image of the reference plate. The image forming apparatus according to claim 17 , wherein the image forming apparatus is obtained from the excluded data. An image forming means for forming an image;
A reference plate that reflects light;
Irradiating means for irradiating the recording medium and the reference plate with light;
Reflected light from the recording medium is received by a first light receiving unit, reflected light from the recording medium received by the first light receiving unit is captured as a surface image of the recording medium, and reflected from the reference plate Imaging means for receiving light by the second light receiving unit;
Control means for controlling image forming conditions of the image forming means based on a surface image of the recording medium imaged by the imaging means;
In the image forming apparatus to have a storage means for storing a plurality of correction data for the imaging means to correct the data of the surface image of the recording medium captured,
The light reflected from the reference plate which is received by the second light receiving portion while the recording medium region where light is irradiated passes conveyed by illumination means, said control means stores in the memory means Used to select one correction data from the plurality of correction data, and the recording medium conveys at least a part of the reference plate when viewed from a direction perpendicular to the light reflection surface of the reference plate. has been images forming device you characterized in that overlaps the region to pass. The amount of reflected light from the reference plate received by the second light receiving unit while the first light receiving unit receives reflected light from the recording medium is a plurality of corrections stored in the storage unit. The image forming apparatus according to claim 19, wherein the image forming apparatus is used to select one correction data from the data. The control unit adjusts the amount of light from the irradiation unit according to the amount of reflected light from the recording medium obtained from the surface image data of the recording medium, and the amount of light from the irradiation unit is adjusted. After that, the control means selects one correction data from the plurality of correction data stored in the storage means according to the amount of reflected light from the reference plate received by the second light receiving unit. The image forming apparatus according to claim 20 , wherein the image forming apparatus is an image forming apparatus. The image forming apparatus according to any one of claims 13 to 21, wherein the reference plate is fixed. The light receiving means is an image pickup means for simultaneously picking up reflected light from the recording medium received by the first light receiving section and reflected light from the reference plate received by the second light receiving section as surface images. an apparatus according to any of claims 13 to 22, characterized in that. 24. Any one of claims 13 to 23 , wherein when viewed from a direction perpendicular to the light reflection surface of the reference plate, all portions of the reference plate overlap with a region through which the recording medium is conveyed. The image forming apparatus according to claim 1. The image forming condition is a recording medium conveyance speed, a transfer voltage when transferring the image formed on the image carrier to the recording medium, or a fixing temperature when fixing the image transferred to the recording medium. The image forming apparatus according to any one of claims 13 to 24 . A reference plate that reflects light;
Irradiating means for irradiating the recording medium and the reference plate with light;
In a recording medium detection device having light receiving means for receiving reflected light from the recording medium with a first light receiving unit and receiving reflected light from the reference plate with a second light receiving unit,
The reflected light from the reference plate received by the second light receiving unit while the recording medium is transported and passed through the region irradiated with light by the irradiating means is the amount of light from the irradiating means. It is used for adjustment, and when viewed from a direction perpendicular to the light reflection surface of the reference plate, at least a part of the reference plate overlaps with a region through which the recording medium is conveyed. Recording medium detection device. 27. The recording medium detection device according to claim 26 , wherein the light receiving unit is an imaging unit that captures reflected light from the recording medium received by the first light receiving unit as a surface image of the recording medium. . 28. The recording medium detection apparatus according to claim 27 , wherein a type of the recording medium is determined based on a surface image of the recording medium imaged by the imaging unit. 29. The recording medium detection device according to claim 28 , wherein a surface state of the recording medium is determined based on a surface image of the recording medium imaged by the imaging unit. The amount of light reflected from the reference plate which is received by the second light receiving portion while the first light receiving portion for receiving reflected light from the recording medium, adjusting the light quantity of light from the irradiation unit recording medium detection device according to any one of claims 26 to 29 characterized in that it is used for. The light receiving means is an imaging means for picking up the reflected light from the reference plate received by the second light receiving section as a surface image of the reference plate, and the amount of reflected light from the reference plate is the imaging 31. The recording medium detection device according to claim 30 , wherein the recording medium detection device is obtained from data of a surface image of the reference plate imaged by a means. The amount of reflected light from the reference plate is obtained by removing the data obtained by receiving the edge of the reference plate in the direction orthogonal to the recording medium conveyance direction from the surface image data of the reference plate. 32. The recording medium detection device according to claim 31 , wherein the recording medium detection device is obtained. A reference plate that reflects light;
Irradiating means for irradiating the recording medium and the reference plate with light;
Reflected light from the recording medium is received by a first light receiving unit, reflected light from the recording medium received by the first light receiving unit is captured as a surface image of the recording medium, and reflected from the reference plate In a recording medium detection device having imaging means for receiving light at a second light receiving unit,
The light reflected from the reference plate which is received by the second light receiving portion while the recording medium region where light is irradiated by the irradiation means passes is conveyed, the recording captured by the image pickup means It used to select one of the correction data from a plurality of correction data for correcting the data of the surface image of the medium, viewed from the reflective surface perpendicular to the direction of light of the reference plate, the reference plate At least some of you, characterized in that overlaps with a region where the recording medium passes through is conveyed record medium detector. The amount of reflected light from the reference plate received by the second light receiving unit while the first light receiving unit receives reflected light from the recording medium is one of a plurality of correction data. 34. The recording medium detection device according to claim 33, wherein the recording medium detection device is used to select correction data. In accordance with the amount of reflected light from the recording medium obtained from the surface image data of the recording medium, the amount of light from the irradiation unit is adjusted, and after the amount of light from the irradiation unit is adjusted, 35. The recording according to claim 34 , wherein one correction data is selected from a plurality of the correction data based on the amount of reflected light from the reference plate received by the second light receiving unit. Medium detection device. Recording medium detection device according to any one of claims 26 to 35, wherein the reference plate is fixed. The light receiving means is an image pickup means for simultaneously picking up reflected light from the recording medium received by the first light receiving section and reflected light from the reference plate received by the second light receiving section as surface images. recording medium detection device according to any one of claims 26 to 36, characterized in that. 38. Any one of claims 26 to 37 , wherein when viewed from a direction perpendicular to the light reflection surface of the reference plate, all portions of the reference plate overlap with an area through which the recording medium is conveyed. The recording medium detection device according to claim 1.