JP2006292952A - Image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image forming apparatus shortening measurement time, achieving reduced size of the body without deteriorating recording medium discrimination accuracy, and optimizing printing conditions, according to the kind of a recording medium from the printing operation standby state, by completing the recording medium discrimination, prior to the starting of supply of paper. <P>SOLUTION: Image data are acquired, when the recording medium is stopped under first imaging conditions. The kind is discriminated, on the basis of the characteristics of the recording medium determined therefrom. A correction data for acquiring shading data for each kind of recording medium and a second imaging condition are selected, on the basis of the kind of the recording medium discriminated; the image data are acquired, when the recording medium is stopped with a second imaging condition; recording medium surface data are generated, on the basis of the image data acquired with the first imaging condition, the image data acquired with the second imaging condition, and the correction data; and the detailed kinds of the recording media are discriminated from the characteristics. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a method for detecting the surface smoothness of a recording medium, and an image forming apparatus such as a copying machine or a laser printer that controls image forming conditions from the detection result of the surface smoothness of the recording medium.

  Image forming apparatuses such as copying machines and laser printers transfer an image developed on a photoreceptor to a recording medium, and fix the image by heating and pressurizing the recording medium on which the image has been transferred under predetermined fixing processing conditions. A fixing device is provided.

  Conventionally, in such an image forming apparatus, a surface image of a recording medium fed and conveyed is read by a video reading unit having a line sensor and an area sensor such as a CCD sensor and a CMOS sensor, and the result is an inkjet OHT (OHP). And a means for determining whether the laser beam is OHT. When the inkjet OHT is determined, the fixing device stops the conveyance of the recording medium to the fixing device and stops the image forming operation of the image forming apparatus or the recording medium conveyance to the fixing device. By providing a means for stopping the temperature control of the printer, or a control means for setting the temperature to a temperature lower than the normal temperature, it is possible to prevent the fixing roller from being generated when the user accidentally passes the OHT for ink jet outside the specified paper. A method for solving inconvenient problems such as OHT wrapping and image deterioration on a recording medium is known (see, for example, Patent Document 1).

  Also, not only OHT, but also the depth of unevenness and unevenness interval of the surface of the recording medium are calculated from the result of reading the surface image of the recording medium, and the type of the recording medium such as gloss paper, plain paper, rough paper, and OHT is discriminated. A method for optimally setting image forming conditions such as print density, transfer bias setting, fixing temperature, and process speed is known (see, for example, Patent Document 2).

  In order to read a surface image of a recording medium, a configuration using an image sensor and a lens of a line sensor such as a CCD sensor or a CMOS sensor or an area sensor is used. 2. Description of the Related Art A video reading device that obtains image data of an imaging object by causing light reflected from the imaging object to enter the imaging element via an imaging lens and A / D-converting a signal output from the imaging element is known. ing. In such a video reading apparatus, a captured image is deteriorated due to a light amount variation caused by a light source or a lens. There is also image degradation due to sensitivity variation in each photoelectric conversion cell of the image sensor. For this reason, in order to accurately read an object and obtain an accurate imaging result, the recording medium is moved, the imaging for shading measurement is performed a plurality of times, and the imaging result is averaged to obtain the shading correction data. Thus, a method of correcting the imaging result using the correction data is performed.

JP 2003-228256 A JP2003-302208A

In the above conventional example, imaging for shading measurement is performed a plurality of times during conveyance of the recording medium. In addition, every time the medium is determined, the surface of the recording medium in a stopped state and the surface of the moving recording medium (shading measurement) are captured.
For this reason, the conventional example has any of the following drawbacks.
(1) In shading measurement, since imaging is performed a plurality of times in one measurement, it takes time for normal imaging. As a result, the time required to determine the recording medium becomes longer.
(2) In order to perform imaging for shading measurement, it is necessary to secure a certain transport distance in the paper feeding unit. Therefore, it is difficult to reduce the size of the image forming apparatus main body.
(3) Imaging for shading measurement must be performed while the recording medium is being transported. For this reason, a sensor must be installed on the conveyance path of the recording medium, and the degree of freedom of the sensor installation location is low.
(4) It is necessary to perform imaging for shading measurement while transporting the recording medium. Therefore, the recording medium can be determined only after the recording medium conveyance is started.

  The present invention has been made in view of such problems, and a first object of the present invention is to shorten the time required for discriminating a recording medium and to facilitate downsizing of the image forming apparatus main body. is there.

  A second object of the present invention is to enable discrimination of a recording medium before starting to convey the recording medium.

  In order to achieve the above object, according to a first aspect of the present invention, in the image forming apparatus, an imaging unit that captures an image of a predetermined area on a recording medium and outputs image information, and an imaging condition by the imaging unit are arbitrarily changed. A plurality of possible imaging condition changing means, a plurality of correction data for obtaining shading data for each type of recording medium, a storage means for storing a plurality of imaging conditions for each type of recording medium, and the selected first First image acquisition means for acquiring image data captured while the recording medium is stopped by the imaging means under the imaging condition, and the recording based on the characteristics of the recording medium determined from the image data acquired under the first imaging condition Based on the first recording medium discriminating means for discriminating the type of medium and the type of the recording medium discriminated by the first recording medium discriminating means, A condition determining unit that selects the imaging condition, a second image acquiring unit that acquires image data captured by the imaging unit while the recording medium is stopped under the second imaging condition, and a first imaging condition. Recording medium surface data generating means for generating recording medium surface data based on the acquired image data, the image data acquired under the second imaging condition, and the correction data selected by the condition determining means; And second recording medium determining means for determining the type of the recording medium based on the characteristics of the recording medium determined from the recording medium surface data.

  According to a second aspect of the present invention, in the image forming apparatus according to the first aspect, for the preferential recording medium selected in advance, the first image acquisition unit captures an image corresponding to the preferential recording medium. Image data captured using the first imaging condition as a condition is acquired, and the condition determination unit determines the correction data stored in the storage unit based on the type of the recording medium determined by the first recording medium determination unit. And the recording medium surface data generation means calculates the shading data based on the image data acquired under the first imaging condition and the correction data, the calculated shading data, and the first The recording medium surface data is generated from the image data acquired under the second imaging condition.

  According to a third aspect of the present invention, in the image forming apparatus according to the first or second aspect, the acquisition of the image data under the first imaging condition is such that the imaging time is a minimum time. It is characterized by performing.

  According to a fourth aspect of the present invention, there is provided the image forming apparatus according to any one of the first to third aspects, wherein the image is determined according to the type of the recording medium determined by the second recording medium determining unit. The formation control is variably controlled.

  According to a fifth aspect of the present invention, in the image forming apparatus according to any one of the first to fourth aspects, the surface of the recording medium is imaged by the imaging means before the conveyance of the recording medium is started, and the surface of the recording medium The recording medium surface data is generated by the data generating means before the recording medium conveyance is started.

  According to a sixth aspect of the present invention, in the image forming apparatus according to the fifth aspect, the imaging unit is installed in a paper feed cassette.

  According to a seventh aspect of the present invention, there is provided a control method for an image forming apparatus, wherein an imaging process for imaging a predetermined area on a recording medium and outputting image information, and imaging conditions in the imaging process are arbitrarily changed. A step of enabling, a step of acquiring image data captured while the recording medium is stopped in the imaging step with the selected first imaging condition, and a recording determined from the image data acquired with the first imaging condition A first discriminating step for discriminating the type of the recording medium based on the characteristics of the medium, and shading data for each type of the recording medium based on the type of the recording medium discriminated by the first discriminating step. A condition determination step of selecting correction data and second imaging conditions from a storage means for storing a plurality of correction data and storing a plurality of imaging conditions for each type of recording medium; and the second imaging conditions Acquiring image data captured while the recording medium is stopped in the imaging step; image data acquired under the first imaging condition; the image data acquired under the second imaging condition; and the condition determining step. And generating the recording medium surface data based on the correction data selected by the step of determining the type of the recording medium based on the characteristics of the recording medium determined from the recording medium surface data. It is characterized by that.

  According to an eighth aspect of the present invention, in the method according to the seventh aspect, the step of acquiring image data captured under the first imaging condition with respect to a preselected priority recording medium is the priority. Image data captured using the imaging condition corresponding to the recording medium as the first imaging condition is acquired, and the condition determining step is based on the type of the recording medium determined by the first determining step. The step of selecting the optimum correction data from the means and generating the recording medium surface data calculates the shading data based on the image data acquired under the first imaging condition and the correction data. The recording medium surface data is generated from the calculated shading data and the image data acquired under the second imaging condition.

  The invention according to claim 9 is the method according to claim 7 or 8, wherein the acquisition of the image data under the first imaging condition is performed so that the imaging time is a minimum time. It is characterized by.

  According to a tenth aspect of the present invention, in the method according to any one of the seventh to ninth aspects, the control for image formation is variably controlled according to the detailed type of the determined recording medium. It is characterized by doing.

  According to an eleventh aspect of the present invention, in the method according to any one of the seventh to tenth aspects, the recording medium surface is imaged to generate the recording medium surface data before starting the conveyance of the recording medium. Features.

According to the present invention, it is not necessary to perform the shading basic data (shading component) acquisition operation that has been performed every time a recording medium is detected. Further, the time required for discriminating the recording medium can be greatly reduced as compared with the conventional case. In addition, since it is not necessary to secure the recording medium conveyance distance that was conventionally necessary for acquiring basic shading data, the image forming apparatus main body can be downsized.
Further, according to the present invention, it is possible to determine the recording medium before starting the conveyance of the recording medium. For this reason, the printing operation can be optimized in advance according to the type of the recording medium before printing is started.

[First Embodiment]
First, the configuration of the image forming apparatus according to the first embodiment of the present invention will be described with reference to FIGS.

  FIG. 1 shows a schematic configuration of an image forming apparatus 100 of the present embodiment. Here, a tandem type color image forming apparatus is taken as an example. The recording medium fed from the paper feed cassette 102 by the pickup roller 103 is discriminated by the image sensor 30, and image processing, development bias, and the like are performed according to various characteristics such as surface smoothness of the recording medium. An optimal image can be obtained by variably controlling the temperature control value of the fixing unit or the recording medium conveyance speed.

  Reference numeral 104 denotes a transfer belt driving roller, 105 denotes a transfer belt, 106 to 109 denote yellow, magenta, cyan, and black color photosensitive drums, 110 to 113 denote yellow, magenta, cyan, and black color transfer rollers, 114. ˜117 are cartridges for each color of yellow, magenta, cyan, and black, 118 to 121 are optical units for each color of yellow, magenta, cyan, and black, 122 is a fixing roller, and 123 is for confirming the presence of a recording medium in the conveyance path. This is a cash register sensor.

  Here, FIG. 2 shows a schematic diagram when detecting the surface smoothness of the recording medium. In the present embodiment, the imaging sensor 30 is used to capture a surface image of the recording medium 101 and detect surface smoothness.

  FIG. 3 shows the configuration of the image sensor 30 in the present embodiment. As shown in FIG. 3, the image sensor 30 includes a reflective LED 32 as a light irradiation unit, a CMOS area sensor 31 as an image unit, and a lens 33 as an imaging lens (the sensor 31 may be a CCD sensor). Yes. Under the control of the issuance control unit 1000, the light having the reflection LED 32 as a light source is applied to the surface of the recording medium 101. The reflected light from the recording medium 101 is condensed through the lens 33 and imaged on the CMOS area sensor 31. As a result, an image on the surface of the recording medium 101 is read. In the present embodiment, the reflecting LED 32 is arranged so that the LED light is irradiated obliquely at a predetermined angle with respect to the surface of the recording medium 101 as shown in FIG.

  FIG. 4 is a diagram showing the relationship between the surface of the recording medium 101 read by the CMOS area sensor 31 of the image sensor 30 and an example in which the output from the CMOS area sensor 31 is digitally processed to 8 × 8 pixels. The digital processing is performed by converting the analog output from the CMOS area sensor 31 into 8-bit pixel data by A / D conversion (FIG. 6, 608) as conversion means.

  In FIG. 4, 40 is an enlarged image of the surface of the recording medium A of so-called rough paper, which is relatively rough with respect to the surface smoothness of the paper and the unevenness due to the paper fibers is easy to distinguish. 41 is an enlarged image of the surface of a so-called plain paper recording medium B that is normally used in a general office, and 42 is a glossy paper (hereinafter referred to as gloss paper) in which paper fibers are sufficiently compressed. 2 is an enlarged image of the surface of a recording medium C.

These images 40, 41, 42 read into the CMOS sensor 31 are digitally processed to become images 43, 44, 45 shown in FIG. As shown by 43, 44, and 45 in FIG. 4, the surface image differs depending on the type of the recording medium. These differences are mainly due to the different fiber conditions at the paper surface.
The amount of reflected light from the recording medium is detected by obtaining the total or average value of the light input to each pixel of the CMOS sensor 31. Note that the detection of the amount of reflected light may use only the result of one light receiving pixel.

  As described above, by digitally processing the surface image of the recording medium read by the CMOS area sensor 31, it is possible to determine the recording medium by knowing the surface state of the recording medium and the amount of reflected light. In the image comparison calculation of the digitally processed image, the recording medium surface data is divided into a plurality of blocks, and the maximum density pixel Dmax and the minimum density pixel Dmin are derived for each of the divided data. This is executed for each divided block to calculate Dmax-Dmin (this is referred to as the unevenness amount) to derive Dmax-Dmin of the entire recording medium.

  That is, when the paper fibers on the surface are rough like the recording medium A, many shadows of the fibers are generated. As a result, the difference between the bright part and the dark part is large, and Dmax−Dmin becomes large. On the other hand, on the surface like the recording medium C, there are few shadows of a fiber and Dmax-Dmin becomes small. The paper type of the recording medium is determined by comparing the unevenness.

  In the recording medium detection according to the present embodiment, the type of the recording medium is determined once only by the average amount of reflected light from the surface of the recording medium. OHT, plain paper, and super glossy paper differ greatly in the amount of reflected light when the recording medium surface is irradiated with light. The amount of reflected light from the recording medium surface of super glossy paper is significantly higher than that of plain paper. Conversely, in the case of OHT, the amount of reflected light from the surface of the recording medium is significantly lower than that of ordinary media. Therefore, it is possible to determine the type of the recording medium only with the average amount of reflected light from the recording medium surface. However, the type determination based on the average amount of reflected light from the surface of the recording medium is not as accurate as the method for obtaining Dmax−Dmin by the above calculation, and is used as an auxiliary determination means.

  Further, the control processor needs to process the video sampling processing, gain and filter calculation processing from the CMOS area sensor 31 in real time. Thus, for example, it is desirable to use a digital signal processor or gate array or a high speed CPU.

Next, a control circuit block diagram of the image sensor 30 will be described with reference to FIG.
In the figure, 501 is a CPU for determining a recording medium, 502 is a control circuit, 30 is an image sensor, 504 is an interface control circuit, 505 is an arithmetic circuit A, 510 is an arithmetic circuit B that generates basic shading data, and 509 is a correction. A RAM for storing data, 506 is a register A in which the unevenness amount calculation result on the recording medium surface is set, 507 is a register B in which the unevenness edge amount calculation result on the recording medium surface is set, and 508 is a control register.

  The uneven edge amount is a value obtained by counting the number of edges for each line on the surface of the imaged recording medium and adding all the lines. As described above, the recording material can be determined based on the unevenness amount of the recording medium, but the recording medium can also be determined using the uneven edge amount. Furthermore, it is possible to improve the discrimination accuracy of the recording material by combining both.

Next, the operation of the control circuit of the image sensor 30 will be described.
When the CPU 501 gives an operation instruction for the imaging sensor 30 to the control register 508, the imaging sensor 30 starts imaging the recording medium surface image. That is, charge accumulation is started in the CMOS area sensor of the image sensor 30. When the image sensor 30 is selected by Sl_select from the interface control circuit 504, and SYSCLK is generated and supplied to the image sensor 30 at a predetermined timing, digital image data captured by the Sl_out signal from the image sensor 30 is synchronized with this. Sent.

  Imaging data received via the interface control circuit 504 is transmitted to the arithmetic circuit A505. The average amount of reflected light of the recording medium calculated by the arithmetic circuit A505 based on the arithmetic method described above is transmitted from the arithmetic circuit A505 to the arithmetic circuit B510. The arithmetic circuit B510 generates basic shading data (shading component) from the correction data stored in the RAM 509 based on the average reflected light amount data of the recording medium (described later), and transmits it to the arithmetic circuit A505. Based on the shading component transmitted from the arithmetic circuit B510 and the imaging data received via the interface circuit control circuit 504, the arithmetic circuit A505 calculates Dmax-Dmin based on the above-described arithmetic method, and the result is the surface of the recording medium. Is set in the register A 506 as the result of the calculation of the unevenness.

Next, the image sensor circuit will be described with reference to FIG.
FIG. 6 is a circuit block diagram of the image sensor 30. In the figure, reference numeral 601 denotes a CMOS area sensor portion, for example, sensors of 8 × 8 pixels are arranged in an area. Reference numerals 602 and 603 are vertical shift registers, 604 is an output buffer, 605 is a horizontal shift register, 606 is a system clock (SYSCLK), and 607 is a timing generator.

Next, the operation of the image sensor circuit will be described.
When the Sl_select signal 613 is activated, the CMOS area sensor 601 starts to accumulate charges based on the received light. Next, when the system clock 606 is applied, when the column of pixels read by the vertical shift registers 602 and 603 is sequentially selected by the control signal from the timing generator 607, data is sequentially output from the CMOS area sensor 601 and the output buffer 604 is output. Set to

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

  On the other hand, the A / D conversion gain can be variably controlled from the Sl_in signal 612 by the control circuit 611. For example, if the contrast of the captured image cannot be obtained, the CPU can change the gain and always capture with the best contrast.

Next, the shading component removal method will be described with reference to FIG.
FIG. 7 shows an image (8 × 8 pixels) captured by the image sensor 30 when detecting the surface smoothness of the recording medium of FIG. The captured image includes the letter “A” of the target image and a shading component by an optical system, an illumination system, or the like. An actually captured image shown as a two-dimensional image is shown as 1-1, and a three-dimensional image shown as 1-4. Next, an image obtained by extracting only a shading component by an optical system or an illumination system is shown as a two-dimensional image 1-2, and an image shown as a three-dimensional image is shown 1-5. When only the shading component is removed from the captured image by digital processing, the image images 1-3 (two-dimensional) and 1-6 (three-dimensional) shown in FIG. 7 are obtained, and the character “A” that is an image to be obtained is obtained. Is clearly obtained.

Next, digital processing for removing shading components will be described.
In the graphs 1-7, 1-8, and 1-9 shown in FIG. 7, only one line is extracted from each of the three-dimensional image images (8 × 8 pixels) 1-4, 1-5, and 1-6. FIG. By subtracting 1-8 data from 1-7 data, 1-9 data is obtained. This is done for all 8 lines.

  In the recording medium surface smoothness detection of the present embodiment, the shading component is not extracted every time. The measurement time is shortened by preparing correction data in advance. A shading component is generated by the shading component generation means of the arithmetic circuit B510 shown in FIG. The shading component generation means calculates correction data stored in advance in the RAM 509 shown in FIG. 5 according to the average light quantity measurement result, and converts it into a shading component (shading basic data). In actual calculation, for example, when processing an image of 8 × 8 pixels, the ratio of the average value of the light amount of all 8 × 8 pixels and the average value of the correction data is obtained, and this is multiplied by the light amount of each pixel of the correction data. It is obtained by calculating the value. This calculation process is expressed by the following equation.

  Correction data acquisition is performed at the time of factory shipment using a reference plate having a predetermined smoothness. The shading component data extracted using the reference plate is stored as correction data in the RAM 509 in FIG. However, since the amount of reflected light on the surface of the recording medium differs greatly between OHT, plain paper, and super glossy paper, the appearance of unevenness in the amount of reflected light by the optical system and illumination system differs as shown in FIG.

  (A) and (b) in FIG. 8 show the amount of reflected light (zigzag solid line) of each pixel on one line when images of different recording media (for example, OHT, plain paper, super glossy paper) are taken. This is a graph of correction data (smooth solid line). Note that the horizontal axis corresponds to a row of pixels on one line, and the vertical axis represents the amount of reflected light of the corresponding pixel. The two zigzag lines in FIGS. 8A and 8B indicate that the recording medium of the same type (for example, plain paper) can be judged (primary judgment) from the average amount of reflected light from the surface of the recording medium. (For example, the group judged to be plain paper in the primary judgment includes rough paper, gloss paper, gloss film, etc. in addition to plain paper). Then two kinds).

  As shown in the figure, the actual reflected light level varies depending on the type of recording medium, but the appearance of unevenness in the reflected light quantity of the recording medium that is judged to be the same kind by the primary judgment is similar, and common correction It can be seen that the shading component can be corrected using the data. On the other hand, different groups require different correction data. Therefore, in order to accurately determine the recording medium, it is necessary to prepare different correction data for OHT, plain paper, and super glossy paper that can be determined by primary determination. When extracting the shading component, the shading component is extracted with three different types of dedicated reference papers prepared for OHT, plain paper, and super glossy paper, and stored in the memory as separate correction data.

  FIG. 9 shows a flowchart of the recording medium surface smoothness detection process during the printing operation in the present embodiment.

  First, when a print command is issued and the image forming apparatus 100 can perform a printing operation (YES in S001), it is determined whether the recording medium (paper) is not at the position of the registration sensor 123 (S001). (S003) The conveyance of the recording medium is started (S004). If there is, a predetermined error process is performed because the recording medium remains at the registration sensor position. Next, when the recording medium is conveyed to the registration sensor position (YES in S005), the recording medium conveyance is once stopped (S006). After the recording medium is stopped, the recording medium is determined (S007).

  When the recording medium discrimination is completed, the recording medium is transported again (S008). However, if a non-guaranteed OHT or non-guaranteed super glossy paper is detected as a result of the recording discrimination, the user is notified as a warning that a recording medium that cannot be printed is set, or the printing operation is automatically stopped. In addition, for printable recording media, image formation is started (S009) with the temperature of the fixing device, the recording medium conveyance conditions, etc. as the optimum conditions according to the recording medium discrimination result.

FIG. 10 shows a detailed flowchart of the S007 recording medium determination in FIG.
First, the surface of the recording medium is imaged and the average amount of reflected light from the surface of the recording medium is measured (primary measurement S201). However, the measurement conditions at this time are such that the imaging time is the minimum time, and the light quantity of the reflective LED and the gain at the time of digital conversion are the optimum conditions that can discriminate between OHT media, plain paper media, and super glossy paper media. Next, based on the amount of light reflected from the surface of the recording medium at the time of primary measurement, the recording medium is determined to be OHT, plain paper, or super glossy paper (primary determination S202).

  When the result of the primary determination is OHT (S203), the measurement condition is set to the OHT measurement condition (measurement condition A), and imaging is performed again (secondary measurement S204). At this time, the amount of reflected light from the surface of the OHT is significantly lower than that of plain paper, so that the optimum contrast can be obtained by adjusting the amount of reflected LED light, the gain during digital conversion, or the imaging time of the recording medium surface. To do. Next, after the actual imaging is completed, the average amount of reflected light from the surface of the recording medium at the time of the secondary measurement and the shading component calculated from the correction data dedicated to OHT are removed from the surface imaging data for the secondary measurement. The unevenness amount is determined, and printable OHT and non-guaranteed OHT are determined (secondary determination S205).

  On the other hand, when the result of the primary determination is plain paper (S206), the measurement condition is changed to the plain paper measurement condition (measurement condition B), and imaging is performed again (secondary measurement S207). At this time, the amount of light of the reflective LED, the gain at the time of digital conversion, or the imaging time of the surface of the recording medium is adjusted so that the amount of reflected light from the surface of the recording medium has an optimum contrast. Next, after the actual imaging is completed, the average amount of reflected light from the surface of the recording medium at the time of the secondary measurement and the shading component calculated from the correction data dedicated to plain paper are removed from the surface imaging data of the secondary measurement. Then, plain paper, gloss paper, and gloss film are discriminated (secondary determination S207).

  On the other hand, when the result of the primary determination is super glossy paper (S209), the measurement condition is changed to the super gloss paper measurement condition (measurement condition C), and the main imaging is performed again (secondary measurement S210). At this time, since the amount of reflected light from the surface of the recording medium is significantly higher than that of plain paper, the optimum contrast can be obtained by adjusting the amount of light from the reflected LED, the gain at the time of digital conversion, or the imaging time of the surface of the recording medium. It is made a condition to be able to. Next, after the actual imaging is completed, the average amount of reflected light from the surface of the recording medium at the time of secondary measurement and the shading component calculated from the correction data dedicated to super glossy paper are removed from the secondary imaging surface imaging data, and printing is performed. The possible super glossy paper and the non-guaranteed super glossy paper are discriminated (secondary determination S211).

The fixing temperature condition, transfer bias, and recording medium conveyance speed are optimized in accordance with the recording medium that is determined to have completed the recording medium determination as described above, and image formation is started (FIG. 9: S008 and S009). If the determination result is a non-guaranteed recording medium, the user is warned that it is a non-guaranteed recording medium before starting image formation, and the user can select whether to continue printing. If the user chooses to cancel printing, the printing operation is terminated. If he chooses to continue printing, image formation is started.
The imaging conditions such as the OHT measurement condition, the plain paper measurement condition, and the super glossy paper measurement condition are stored in the memory together with the correction data described above, and are used during the measurement.

[Second Embodiment]
Next, the second embodiment will be described.
Since the basic configuration is the same as that of the first embodiment, a detailed description of the common configuration is omitted, and only differences from the first embodiment will be described.

  In the first embodiment, primary measurement (determining the average amount of reflected light from the surface of the recording medium is OHT, plain paper, or super glossy paper) and secondary measurement (OHT, plain paper, super glossy paper are imaged under optimum conditions, respectively. More detailed determination is performed on the entire recording medium based on the amount of unevenness at the time. However, the present embodiment is characterized by preferentially shortening the determination time of the recording medium used by the user most frequently as follows.

The user can select the type of recording medium (OHT, plain paper, super glossy paper) most frequently used at the time of printer purchase or periodically. The default setting is plain paper that is most likely to be used most frequently.
Since the flowchart of the recording medium surface smoothness detection process is the same as that in the first embodiment (FIG. 9), detailed description thereof is omitted.

11 and 12 show detailed flowcharts of recording medium discrimination in the present embodiment.
In the present embodiment, detection of a recording medium is started on the assumption of a recording medium (OHT, plain paper, super glossy paper) selected by the user and used frequently. Only when there is a contradiction during the recording medium detection, the other recording medium is determined.

  First, FIG. 11 shows a flowchart when the recording medium selected by the user and used frequently is OHT.

  Here, first, the measurement condition is set to the OHT measurement condition (measurement condition A), and the surface of the recording medium is imaged. At this time, the amount of reflected light from the surface of the recording medium is significantly lower than that of plain paper, so that the optimal contrast can be obtained by adjusting the amount of reflected LED light, the gain during digital conversion, or the imaging time of the surface of the recording medium. (Primary measurement S301). When the average amount of reflected light at the time of primary measurement is significantly higher than the normal value, it is determined that the recording medium is other than OHT, and that the normal value is OHT (primary determination S302).

  If the result of the primary determination is OHT (S303), the average amount of reflected light from the recording medium surface at the time of the primary determination and the shading component (shading basic data A) calculated from the correction data dedicated to OHT are obtained from the surface imaging data of the primary measurement. An operation for removal is performed to determine the amount of unevenness of the recording medium, and to determine printable OHT and non-guaranteed OHT (secondary determination S304).

  If the result of the primary determination is other than OHT, the recording time is set to the minimum time, the light quantity of the reflective LED, and the gain at the time of digital conversion are again the recording medium under the optimum conditions that can distinguish the types of OHT, plain paper, and super glossy paper. The surface is imaged (re-primary measurement S305).

  If the result of the re-primary determination (S306) is plain paper (S307), the measurement condition is changed to the plain paper measurement condition (measurement condition B), and imaging is performed again (secondary measurement S308). At this time, the amount of light of the reflective LED, the gain at the time of digital conversion, or the imaging time of the surface of the recording medium is adjusted so that the amount of reflected light from the surface of the recording medium has an optimum contrast. Next, after the actual imaging is completed, the average amount of reflected light from the surface of the recording medium at the time of the secondary measurement and the shading component (shading basic data B) calculated from the correction data dedicated to plain paper are removed from the surface imaging data of the secondary measurement. An arithmetic operation is performed to determine rough paper, plain paper, gloss paper, and gloss film (secondary determination S309).

  If the result of the re-primary determination is super glossy paper (S310), the measurement condition is changed to the super glossy paper measurement condition (measurement condition C), and imaging is performed again (secondary measurement S311). At this time, since the amount of reflected light from the surface of the recording medium is significantly higher than that of plain paper, the optimum contrast can be obtained by adjusting the amount of light from the reflected LED, the gain at the time of digital conversion, or the imaging time of the surface of the recording medium. It is made a condition to be able to. Next, after the actual imaging is completed, the average amount of reflected light from the surface of the recording medium at the time of secondary measurement and the shading component (shading basic data C) calculated from correction data dedicated to super glossy paper are removed from the secondary imaging surface imaging data. The calculation is performed to discriminate between printable super glossy paper and non-guaranteed super glossy paper (secondary determination S312).

  Next, FIG. 12 shows a flowchart when the recording medium selected by the user and used frequently is plain paper.

  Here, imaging of the surface of the recording medium is performed first under the plain paper measurement condition (measurement condition B). At this time, the light amount of the reflective LED, the gain at the time of digital conversion, or the imaging time on the surface of the recording medium is adjusted so that the amount of light reflected from the surface of the recording medium has an optimum contrast (primary measurement S401). When the average amount of reflected light at the time of primary measurement is significantly lower than the normal value, it is determined that the recording medium is OHT, and when it is significantly higher than the normal value, it is super glossy paper (primary determination S402).

  When the result of the primary determination is plain paper (S406), the average of the amount of reflected light from the surface of the recording medium at the time of the primary determination and the shading component (shading basic data B) calculated from the correction data dedicated to the normal recording medium are the surface of the primary measurement. An operation to remove from the imaged data is performed, the unevenness amount of the recording medium is determined, and rough paper, plain paper, gloss paper, and gloss film paper are determined (secondary determination S407).

  When the result of the primary determination is OHT (S403), the measurement condition is changed to the OHT measurement condition (measurement condition A), and imaging is performed again (secondary measurement S404). At this time, the amount of reflected light from the surface of the recording medium is significantly lower than that of plain paper, so that the optimal contrast can be obtained by adjusting the amount of reflected LED light, the gain during digital conversion, or the imaging time of the surface of the recording medium. To. Next, after the main imaging is completed, an operation for removing the average amount of reflected light from the surface of the recording medium at the time of secondary measurement and the shading component (shading basic data A) calculated from correction data dedicated to OHT from the surface imaging data of secondary measurement. The amount of unevenness of the recording medium is determined, and printable OHT and non-guaranteed OHT are determined (secondary determination S405).

  If the result of the primary determination is super glossy paper (S408), the measurement condition is changed to the super glossy paper measurement condition (measurement condition C), and imaging is performed again (secondary measurement S409). At this time, since the amount of reflected light from the surface of the recording medium is significantly higher than that of plain paper, the optimum contrast can be obtained by adjusting the amount of light from the reflected LED, the gain at the time of digital conversion, or the imaging time of the surface of the recording medium. It is made a condition to be able to. Next, after the actual imaging is completed, the average amount of reflected light from the surface of the recording medium at the time of secondary measurement and the shading component (shading basic data C) calculated from correction data dedicated to super glossy paper are removed from the secondary imaging surface imaging data. The calculation is performed to distinguish printable super glossy paper and non-guaranteed super glossy paper (secondary determination S410).

  Next, FIG. 13 shows a flowchart when the recording medium selected by the user and used frequently is super glossy paper.

Here, first, the measurement condition is set to the super glossy paper measurement condition (measurement condition C), and the surface of the recording medium is imaged. At this time, since the amount of reflected light from the surface of the recording medium is significantly higher than that of plain paper, the optimum contrast can be obtained by adjusting the amount of reflected LED light, the gain at the time of digital conversion, or the imaging time of the surface of the recording medium. (Primary measurement S501). When the average amount of reflected light at the time of primary measurement is significantly lower than the normal value, it is determined that the recording medium is other than super glossy paper. (Primary judgment S502)
If the result of the primary determination is super glossy paper (S503), the average of the amount of reflected light from the surface of the recording medium at the time of the primary determination and the shading component (shading basic data C) calculated from the correction data dedicated to super glossy paper are subjected to primary measurement. An operation to remove from the surface imaging data is performed, the unevenness amount of the recording medium is determined, and guaranteed super glossy paper and non-guaranteed super glossy paper are determined (secondary determination S504).

  If the result of the primary determination is other than super glossy paper, the imaging time is set to the minimum time, and the light quantity of the reflective LED and the gain at the time of digital conversion are again adjusted under the optimum conditions that can distinguish the type of OHT and plain paper. Imaging is performed (re-primary measurement S505).

  When the result of the primary determination (S506) is plain paper (S507), the measurement condition is changed to the plain paper measurement condition (measurement condition B), and imaging is performed again (secondary measurement S508). At this time, the amount of light of the reflective LED, the gain at the time of digital conversion, or the imaging time of the surface of the recording medium is adjusted so that the amount of reflected light from the surface of the recording medium has an optimum contrast. Next, after the actual imaging is completed, the average amount of reflected light from the surface of the recording medium at the time of the secondary measurement and the shading component (shading basic data B) calculated from the correction data dedicated to plain paper are removed from the surface imaging data of the secondary measurement. An arithmetic operation is performed to determine rough paper, plain paper, gloss paper, and gloss film (secondary determination S509).

  When the result of the re-primary judgment (S506) is OHT (S510), the measurement condition is set to the OHT measurement condition (measurement condition A), and imaging is performed again (secondary measurement S511). At this time, the amount of reflected light from the surface of the recording medium is significantly lower than that of plain paper, so that the optimal contrast can be obtained by adjusting the amount of reflected LED light, the gain during digital conversion, or the imaging time of the surface of the recording medium. To. Next, after the actual imaging, the average amount of reflected light from the surface of the recording medium at the time of secondary measurement and the shading component (shading basic data A) calculated from correction data dedicated to super glossy paper are removed from the secondary imaging surface imaging data. The guarantee OHT that can be printed and the non-guaranteed OHT are discriminated (secondary judgment S512).

  The fixing temperature condition, transfer bias, and recording medium conveyance speed are optimized in accordance with the recording medium that is determined to have completed the recording medium determination as described above, and image formation is started (FIG. 9: S008 and S009). If the determination result is a non-guaranteed recording medium, the user is warned that the recording medium is not guaranteed before starting image formation, and the user can select whether to continue printing. If the user chooses to cancel printing, the printing operation is terminated. If he chooses to continue printing, image formation is started.

[Third Embodiment]
Next, a third embodiment will be described.
Since the basic configuration is the same as that of the first embodiment, a detailed description of the common configuration is omitted, and only differences from the first embodiment will be described.

  In the first embodiment, as shown in FIG. 1, the image sensor 30 is installed on the recording medium conveyance path, and the recording medium is determined while the recording medium is being conveyed. In this embodiment, the image sensor 30 is installed in the paper feed cassette 102. Actually, as shown in 51 in FIG. 14, the image sensor 30 is installed by pressing it against the recording medium from above with a spring or the like from the upper part of the paper feed cassette 102 in which the recording medium is stored. Ensure that the distance between them is always constant. Alternatively, an image sensor 30 is installed at the lower part of the paper feed cassette 102 as shown in FIG. 52 so that the distance between the bottom surface of the recording medium bundle and the sensor is always constant.

  Here, FIG. 15 shows an operation flowchart of the present embodiment.

  First, it is detected that there is a recording medium in the paper feed cassette 102 in accordance with the recording medium determination request (S101). When there is a recording medium in the paper feed cassette 102, the recording medium is determined, and the type of the recording medium placed in the paper feed cassette 102 is determined (S102). If there is no recording medium in the paper cassette, processing error processing is performed. Next, after waiting for a print execution command to be issued and issuing a print execution command (YES in S103), whether the printing operation is possible (S104), and if the printing operation is possible, whether there is a recording medium at the registration sensor position. Determination is made (S105). If there is a recording medium at the registration sensor position, the recording medium remains at the registration sensor position, so that a predetermined error process is performed. If the printing operation is possible and there is no recording medium at the registration sensor position, the recording medium is fed under the optimum image forming conditions according to the type of the recording medium in the paper feeding cassette 102 (S106), and the conveyance is started. (S107) Image formation is started (S108).

The detailed operation of the recording medium discrimination according to the present embodiment is the same as that in the flowchart of FIG.
In the present embodiment, the recording medium installed in the paper feed cassette 102 can be specified before starting the printing operation. Therefore, it is possible to easily give a warning when a user sets a non-guaranteed recording medium in the paper feed cassette 102. Also for printable recording media, the image forming conditions such as the temperature of the fixing device and the recording medium conveyance conditions can be optimized in advance according to the type of the recording medium before printing starts. In particular, a time-consuming operation such as control of the fixing temperature can be controlled in a wider range by starting the control in advance before the start of printing.

1 is a diagram illustrating an outline of an image forming apparatus. It is a schematic diagram when detecting the surface smoothness of the recording medium. It is a figure which shows schematic structure of an imaging sensor. It is a figure which shows contrast with the digital image which digitally processed the analog image of the recording-medium surface read by an imaging sensor, and the analog output into 8x8 pixel. It is a control circuit block diagram of an image sensor. It is a figure which shows an imaging sensor circuit. It is a figure explaining the shading component removal method. It is a figure which shows the relationship between how the unevenness of the reflected light amount by an optical system or an illumination system looks, and correction data. 6 is a flowchart of a recording medium surface smoothness detection process during a printing operation. FIG. 9 is a detailed flowchart of S007 recording medium determination. 10 is a detailed flowchart of recording medium determination according to the second embodiment. 10 is a detailed flowchart of recording medium determination according to the second embodiment. 10 is a detailed flowchart of recording medium determination according to the second embodiment. It is a figure which shows arrangement | positioning of the imaging sensor in 3rd Embodiment. It is an operation | movement flowchart in 3rd Embodiment.

Explanation of symbols

30 ... Imaging sensor 31 ... CMOS area sensor 32 ... Reflecting LED
DESCRIPTION OF SYMBOLS 33 ... Lens 100 ... Image processing apparatus 101 ... Recording medium 102 ... Paper feed cassette 103 ... Pickup roller 104 ... Transfer belt drive roller 105 ... Transfer belt 106, 107, 108, 109 ... Photosensitive drum 110, 111, 112, 113 ... Transfer Rollers 114, 115, 116, 117 ... cartridge 118, 119, 120, 121 ... optical unit 122 ... fixing roller 123 ... registration sensor 501 ... CPU
502 ... Control circuit 504 ... Interface control circuit 505, 510 ... Arithmetic circuit 506, 507 ... Register 508 ... Control register 509 ... RAM
DESCRIPTION OF SYMBOLS 601 ... CMOS area sensor 602, 603, 605 ... Shift register 604 ... Output buffer 607 ... Timing generator 608 ... A / D converter 609 ... Output interface 611 ... Control circuit

Claims (11)

Imaging means for imaging a predetermined area on the recording medium and outputting image information;
Imaging condition changing means capable of arbitrarily changing the imaging condition by the imaging means;
Storage means for storing a plurality of correction data for obtaining shading data for each type of recording medium, and storing a plurality of imaging conditions for each type of recording medium;
First image acquisition means for acquiring image data captured while the recording medium is stopped by the imaging means under the selected first imaging condition;
First recording medium determining means for determining the type of the recording medium based on the characteristics of the recording medium determined from the image data acquired under the first imaging condition;
Condition determining means for selecting the correction data and the second imaging condition of the storage means based on the type of the recording medium determined by the first recording medium determining means;
Second image acquisition means for acquiring image data captured while the recording medium is stopped by the imaging means under the second imaging condition;
Recording medium surface data is generated based on the image data acquired under the first imaging condition, the image data acquired under the second imaging condition, and the correction data selected by the condition determining means. Recording medium surface data generating means;
An image forming apparatus comprising: a second recording medium determining unit that determines a type of the recording medium based on characteristics of the recording medium determined from the recording medium surface data.   For the preferentially selected priority recording medium, the first image acquisition unit acquires image data captured using the imaging condition corresponding to the priority recording medium as the first imaging condition, and the condition determination unit Selects the correction data of the storage means based on the type of the recording medium determined by the first recording medium determination means, and the recording medium surface data generation means is acquired under the first imaging condition The shading data is calculated based on the image data and the correction data, and the recording medium surface data is generated from the calculated shading data and the image data acquired under the second imaging condition. The image forming apparatus according to claim 1.   The image forming apparatus according to claim 1, wherein the acquisition of the image data under the first imaging condition is performed so that an imaging time becomes a minimum time.   4. The image formation according to claim 1, wherein control for image formation is variably controlled according to a type of the recording medium determined by the second recording medium determination unit. 5. apparatus.   5. The recording medium surface is imaged before the start of conveyance of the recording medium by the imaging unit, and the recording medium surface data is generated by the recording medium surface data generation unit before the conveyance of the recording medium is started. The image forming apparatus according to any one of the above.   6. The image forming apparatus according to claim 5, wherein the image pickup unit is installed in a paper feed cassette. An image forming apparatus control method comprising:
An imaging step of imaging a predetermined area on the recording medium and outputting image information;
A step of arbitrarily changing the imaging condition in the imaging step;
Acquiring image data captured while the recording medium is stopped in the imaging step under the selected first imaging condition;
A first determination step of determining the type of the recording medium based on the characteristics of the recording medium determined from the image data acquired under the first imaging condition;
A plurality of correction data for obtaining shading data for each type of recording medium based on the type of recording medium determined in the first determination step, and a plurality of imaging conditions for each type of recording medium A condition determining step of selecting correction data and second imaging conditions from the means;
Acquiring image data captured while the recording medium is stopped in the imaging step under the second imaging condition;
Recording medium surface data is generated based on the image data acquired under the first imaging condition, the image data acquired under the second imaging condition, and the correction data selected in the condition determination step. Process,
Determining the type of the recording medium based on the characteristics of the recording medium determined from the recording medium surface data.   The step of acquiring image data captured under the first imaging condition with respect to a pre-selected priority recording medium is the image data captured using the imaging condition corresponding to the priority recording medium as the first imaging condition. The condition determining step selects optimum correction data from the storage unit based on the type of the recording medium determined by the first determining step, and generates the recording medium surface data. The step calculates the shading data based on the image data acquired under the first imaging condition and the correction data, the calculated shading data, and the image data acquired under the second imaging condition. The method according to claim 7, wherein the recording medium surface data is generated.   The method according to claim 7 or 8, wherein the acquisition of the image data under the first imaging condition is performed so that an imaging time becomes a minimum time.   10. The method according to claim 7, wherein control for image formation is variably controlled in accordance with the detailed type of the determined recording medium. The method according to any one of claims 7 to 10, wherein the recording medium surface data is generated by imaging the recording medium surface before starting the recording medium conveyance.

Images