JP4412009B2 - Sheet feeding device - Google Patents

Description

  The present invention relates to a sheet feeding apparatus for feeding a recording sheet such as a sheet or an OHP film to an image forming apparatus such as a copying machine or a printer using, for example, an electrophotographic system or an inkjet system. Relates to an improvement for detecting various types of information such as thickness and type of recording sheets set as a bundle in a supply tray.

JP2001-144452 JP-A-10-310284 JP 05-000744 A JP 04-303350 A Japanese Patent Laid-Open No. 08-217290

  In an image forming apparatus such as a copying machine or a printer using an electrophotographic method or an ink jet method, in order to form a high-quality recorded image on a recording sheet such as paper, the thickness or material of the recording sheet depends on the recording sheet. It is necessary to form a recorded image with appropriate parameters. For example, in the electrophotographic system, in order to transfer a toner image formed on a photoreceptor to a recording sheet satisfactorily, it is necessary to set a transfer bias having a strength corresponding to the thickness and material of the recording sheet. Further, in the ink jet system, the thickness and material of the recording sheet directly affect the image quality, and it is necessary to change the ink ejection pattern in accordance with these.

  In general, the recording sheets are set on a supply tray in a state where a plurality of stacked sheets are stacked, and the sheet bundle is separated into individual recording sheets, and then an electrophotographic or inkjet image forming unit. Need to be fed to. At that time, in order to prevent so-called double feeding in which two recording sheets are fed due to a separation error, the position of the retard roll relative to the feed roll is adjusted according to the thickness of the fed recording sheet, etc. A method of adjusting detailed parameters when separating the recording sheets according to the thickness of the recording sheet is effective. In order to prevent skew or jam of the recording sheet during conveyance, it is also effective to adjust the pressure contact force of the conveyance roll that holds the recording sheet according to the thickness of the recording sheet.

  Therefore, it is extremely important to detect the thickness and material of the recording sheet fed to the image forming unit of the copying machine or printer prior to the image forming operation.

  Conventionally, as a means for measuring the thickness of the recording sheet, after the recording sheet is sent out from the supply tray, the displacement amount of the transport roll when the recording sheet passes is measured, and the thickness of the recording sheet is calculated from the displacement amount. The ones that presume this are known (Japanese Patent Laid-Open Nos. 04-303350, 05-000744, and 08-217290). In addition, the height of the sheet bundle in the supply tray is measured in advance, and the height of the sheet bundle in the supply tray is measured again after feeding several recording sheets. There is also known a method for grasping the thickness of one recording sheet from the number of sheets fed (Japanese Patent Laid-Open Nos. 10-310284 and 2000-114452).

  However, in these conventional measuring methods, the thickness of the recording sheet cannot be grasped unless the recording sheet is actually fed from the supply tray. That is, when the type of the sheet bundle set in the supply tray is exchanged, the parameters relating to image formation and the parameters relating to feeding of the recording sheet cannot be changed from the time when the first recording sheet is conveyed, There was no guarantee that a high-quality recorded image could be formed from the beginning of a copy job or print job.

  In addition, if the thickness of the recording sheet set in the supply tray is grasped, the difference between the kinds of recording sheets set using the grasped thickness as a clue, such as plain paper, cardboard, OHP film, etc. Although it is possible to make an image forming apparatus such as a printer automatically discriminate, in the above-described prior art, since the recording sheet cannot be grasped unless the recording sheet is actually conveyed, it is set in the supply tray. Immediately after replacing the recording sheet, the type of the recording sheet could not be automatically determined. For this reason, there are many cases where a mistake in selecting a recording sheet is noticed after the start of a print job or a copy job. When printing or copying a special recording sheet, it is placed in the supply tray prior to these jobs. The set recording sheet had to be confirmed, and the workability was poor.

  The present invention has been made in view of such problems, and an object of the present invention is to supply various information regarding the thickness and material of the recording sheet set in the supply tray from the supply tray. In addition to providing a sheet supply device that can be detected before printing, an image forming device capable of performing an optimum image forming operation from the beginning of a print job or a copy job using information of the detected recording sheet is provided. There is to do.

  That is, the present invention is a sheet supply apparatus that stores a sheet bundle in which a plurality of recording sheets are aligned in a supply tray, separates the recording sheets one by one from the sheet bundle, and feeds the sheet from the supply tray. And a means for imaging the sheet bundle set in the supply tray from the side end direction, and an information extracting means for detecting information relating to the recording sheet from the image data obtained from the imaging means. It is what.

  According to such technical means, in the state where the sheet bundle is set on the supply tray, various information on the recording sheet is detected from the image data on the side surface of the sheet bundle, so that the recording sheet is fed from the supply tray. Therefore, the thickness and material of the recording sheet can be grasped.

  If various information such as the thickness of the recording sheet set in the supply tray can be grasped without actually transporting the recording sheet, the type of the recording sheet set in the supply tray using such information as a clue, for example, Differences between plain paper, cardboard, OHP film, etc., can be automatically discriminated by image forming apparatuses such as copiers and printers. Depending on the type of recording sheet thus determined, parameters and images necessary for transporting the recording sheet can be used. Parameters necessary for formation can be optimized, and a high-quality recorded image can be formed from the beginning of a copy job or print job.

  If the printer is provided with a plurality of supply trays, the supply tray that stores the recording sheet specified in the print job or copy job is automatically selected. If it is not set in the supply tray, it is possible to display a warning message on the computer screen instructing the print job or the operation panel of the copier, thereby preventing unnecessary copying and printing and It is possible to improve the performance.

  In such technical means, as the imaging means, if the sheet bundle set in the supply tray can be imaged from the side end direction and the image data of the side surface of the sheet bundle can be collected, its specific The general configuration can be changed as appropriate. For example, imaging can be performed using a CCD sensor. As such a CCD sensor, a plurality of image sensors are arranged in a line (one-dimensional) along the thickness direction of the sheet bundle as long as image data can be collected with respect to a predetermined region along the thickness direction of the sheet bundle. It may also be one that has been arranged, or a plurality of imaging elements arranged in a planar shape (two-dimensional). Further, a CCD sensor that can collect image data for a very small area may be provided, and the image data may be collected while moving the CCD sensor in the thickness direction of the sheet bundle. When a CCD sensor with an image sensor arranged in a line is used, only one line of image data along the thickness direction of the sheet bundle can be collected in one shooting, but the image sensor is arranged in a plane. By using the CCD sensor thus obtained, it is possible to collect image data for a plurality of lines along the thickness direction of the sheet bundle in one shooting, and by comparing these image data, the thickness of the recording sheet can be obtained. It is possible to improve the accuracy of information extraction regarding the safety.

  Further, when collecting the image data of the side end surfaces of the sheet bundle, it is not always necessary to move the imaging unit up and down in the thickness direction of the sheet bundle, and the sheet bundle is configured to move up and down with respect to the imaging unit. Also good. In the first place, in this type of sheet supply apparatus, a bottom fume plate that can be moved up and down in the supply tray for the purpose of bringing the uppermost recording sheet of the sheet bundle into contact with a pickup roll or feed roll provided above the supply tray. For example, when the sheet bundle set in the supply tray is exchanged, the bottom plate is raised so that the sheet bundle is brought into contact with a pickup roll or the like. Therefore, the bottom plate mechanism may be used to move the sheet bundle in the thickness direction relative to the imaging means.

  The bottom plate is lowered when the supply tray is pulled out from the casing of the image forming apparatus such as a copying machine or a printer for replenishing or replacing the recording sheet, and the supply tray is remounted on the casing of the image forming apparatus. In general, the recording sheet is set so as to collect the density data of the sheet bundle side end surface using the vertical movement of the bottom plate as described above. It is possible to detect the thickness of the recording sheet set in the supply tray every time the ink is replenished or replaced. As a result, it is possible to start a print job or a copy job with the thickness of the recording sheet set in the supply tray being always grasped, preventing the occurrence of miscopying or misprinting and producing a high-quality recorded image. It can be formed on a recording sheet.

  On the other hand, as the information of the recording sheet that can be extracted from the image data, the thickness of the recording sheet can be considered. In a state where a plurality of recording sheets are overlapped to form a sheet bundle, when the sheet bundle is imaged from the side end direction and image data is collected, a striped pattern in which shading is repeated in the thickness direction of the sheet bundle This is because the thickness data of the recording sheet can be detected by analyzing the density data. As a specific method for extracting the thickness of the recording sheet from the image data, after extracting one line of data along the thickness direction of the sheet bundle from the image data, the line data is converted into density data. It is conceivable to calculate the frequency characteristic of the density data and detect the thickness of the recording sheet from the frequency characteristic.

  Also, when imaging the sheet bundle in the supply tray from the side end direction, air supply means for blowing air to the sheet bundle is provided, and a gap is formed between the overlapping recording sheets by blowing air. It is preferable to do this. With this configuration, when the sheet bundle is imaged, the contrast of the stripe pattern appearing in the density data can be made stronger than the state in which the overlapping recording sheets are in close contact with each other, and the frequency characteristics described above can be obtained. It is possible to detect the thickness of the recording sheet directly from the captured image without calculation.

  In addition, if air can be blown against the sheet bundle in the supply tray to form a gap between the overlapping recording sheets, the recording sheets can be removed when the recording sheets are fed by a pickup roll or a feed roll. It becomes easy to separate the sheets one by one, and it is possible to prevent double feeding of recording sheets. In particular, glossy recording sheets called art paper and coated paper frequently used in color copiers and color printers have high surface smoothness and high adhesion between the recording sheets. If a gap is formed between the overlapping recording sheets as a front stage of the paper, it is possible to reduce or eliminate the adhesion between the recording sheets and prevent double feeding.

  The air supply means that blows air against the sheet bundle may be anywhere on the supply tray in which the sheet bundle is accommodated, but the contrast of the density data collected by the imaging means is increased. From a viewpoint, it is preferable to be provided at a position where air is blown against an imaging region by the imaging means. Also, from the viewpoint of facilitating separation during sheet feeding by weakening the adhesion between the recording sheets in the supply tray, it is preferable to blow air against the front end surface of the sheet bundle in the sheet feeding direction.

  When air is blown against the sheet bundle in the supply tray in this way, a gap serving as an air passage is formed between the overlapping recording sheets, and the recording sheet located above the gap is in a floating state. When the image data obtained by the imaging means is analyzed, the floating state of the recording sheet, for example, the floating height, floating range, and floating posture of the recording sheet can be grasped, but the recording accumulated in the supply tray If the environmental conditions such as the amount of the sheet, the strength of the air flow to be blown, and the temperature and humidity are substantially the same, it can be considered that the floating state depends on the type of the recording sheet. Therefore, the information extraction unit can detect the floating state of the recording sheet in the supply tray from the image data of the imaging unit, and can detect information on the thickness and material of the recording sheet from the floating state.

In addition, when detecting information related to the physical properties of the recording sheet from the floating state of the recording sheet in the supply tray, the recording sheet that has been stably floated may be imaged and the image data analyzed. You may comprise so that an image analysis may be carried out about the transition of the recording sheet after starting spraying until it reaches a stable floating state. There is a short time until the recording sheet actually starts to float after the air flow starts to be blown up, and the floating state is stabilized. For example, a light recording with a basis weight of about 50 to 100 g / m ^2. In the sheet, the levitation state is stabilized within 1 second from the start of levitation. On the other hand, for thick paper having a basis weight of 200 g / m ² or more, a longer time is required until the floating state is stabilized. Therefore, the physical properties of the recording sheet can also be detected by analyzing the transitional movement of the recording sheet from the image data.

  Further, when air is blown to the sheet bundle in the supply tray to promote separation of the recording sheets, the uppermost recording sheet of the sheet bundle is levitated with respect to the second recording sheet, It is preferable that a gap is formed between them. For example, in the case of a lightweight recording sheet having a small basis weight, a plurality of recording sheets including the uppermost recording sheet are grouped with respect to the recording sheet below the recording sheet. The recording sheet may not be sufficiently promoted.

  Therefore, from this point of view, the air supply means is controlled using information on the thickness of the recording sheets obtained by imaging the sheet bundle in the supply tray, and the air flow blown against the sheet bundle It is preferable that the optimum gap is always formed between the uppermost recording sheet and the second recording sheet by changing the strength of the nozzle, the height of the blowing nozzle, and the blowing direction. Further, by analyzing the image data obtained from the image pickup means, it is possible to grasp the floating state of the uppermost recording sheet in the supply tray with respect to the second recording sheet. You may comprise so that an air supply means may be feedback-controlled.

  As described above, according to the sheet supply apparatus of the present invention, the sheet bundle set on the supply tray is imaged from the side end direction to obtain density data, thereby extracting various information about the recording sheet from the density data. It is possible to detect information on the thickness and material of the recording sheet before feeding the recording sheet from the supply tray, and use the detected information to optimize the print job or copy job from the beginning. Image forming operation can be performed.

Hereinafter, the sheet feeding apparatus of the present invention will be described in detail with reference to the accompanying drawings.
FIG. 1 shows an example of a digital color copying machine to which the sheet feeding apparatus of the present invention is applied. The copying machine includes an image input unit 1 that optically reads image information of a document 11 placed on a platen glass 10 and converts the image information into electrical image data by a CCD sensor 12. The image output unit 2 is configured to form an image on the recording sheet P based on the transferred image data.

  The image output unit 2 forms a toner image on the photosensitive drum 20 based on the image data transferred from the image input unit 1, and then primarily transfers the toner image to the endless transfer belt 3. 3 is secondarily transferred to the recording sheet P to form a recording image on the recording sheet P. The recording sheet P onto which the toner image has been secondarily transferred passes through the fixing device 4 and is discharged to the discharge tray 50. It is supposed to be discharged to the top.

  The photosensitive drum 20 is rotated in the direction of the arrow at a predetermined process speed, and a charging corotron 21 around the surface of the photosensitive drum 20 is uniformly charged to a predetermined background potential. And a laser beam scanner 22 that exposes the photosensitive drum 20 with a laser beam modulated based on the image data, and forms an electrostatic latent image on the photosensitive drum 20, and each color development of black, yellow, magenta, and cyan A rotary developing unit 23 that develops the electrostatic latent image on the photosensitive drum with any of the developing units, and removes the potential on the photosensitive drum 20 prior to the primary transfer of the toner image to the transfer belt 3. A transfer pretreatment corotron 24 and a cleaner 25 for removing residual toner on the photosensitive drum 20 after the primary transfer of the toner image is completed.

  On the other hand, the transfer belt 3 is wound around a plurality of rolls and rotated in the direction of the arrow, and the respective color toner images sequentially formed on the photosensitive drum 20 are transferred onto the transfer belt 3 in a multiple transfer manner. Secondary transfer is performed collectively from the transfer belt 3 to the recording sheet P. A primary transfer roll 30 that forms a transfer electric field with the photosensitive drum 20 is disposed at a position facing the photosensitive drum 20 across the transfer belt 3, while a toner image secondary transfer position is provided. The secondary transfer roll 31 and the counter electrode roll 32 are disposed with the transfer belt 3 interposed therebetween, and the recording sheet P is inserted between the secondary transfer roll 31 and the transfer belt 3 to transfer the toner image. It is configured to receive. In addition, a belt cleaner 33 that removes paper dust and residual toner from the surface of the transfer belt 3 where the secondary transfer is completed is between the secondary transfer position and the primary transfer position in the rotation path of the transfer belt 3. Is provided.

  Further, below the image output unit 2, four-stage sheet supply trays 5 a to 5 d that contain recording sheets P of different sizes are provided, and appropriate according to the document size detected by the image input unit 1. The recording sheet P having a size is sent from one of the sheet supply trays to the image output unit 2 by the rotation of the pickup roll 51. A plurality of sheet conveyance rolls 52 are disposed on the conveyance path of the recording sheet P from each of the sheet supply trays 5a to 5d to the secondary transfer position of the toner image, and a registration roll immediately before the secondary transfer position. 53 is provided, and the registration roll 53 performs the secondary transfer of the recording sheet P sent out from the sheet supply trays 5a to 5d at a predetermined timing synchronized with the writing timing of the electrostatic latent image on the photosensitive drum 20. Feed into position.

  In FIG. 1, reference numeral 13 denotes a platen cover, and reference numeral 26 denotes image data transferred from the image input unit 1 to the image output unit 2 according to the content of the copying operation and then supplied to the laser beam scanner 22. Reference numeral 54 denotes a manual tray used for manual feeding of the recording sheet P. Reference numeral 55 denotes a sheet conveying belt for feeding the recording sheet P onto which the toner image has been secondarily transferred to the fixing device 4, reference numeral 56. Is an inverter path for reversing the recording sheet P and feeding it from the fixing device 4 to the secondary transfer position during double-sided copying of the recording sheet P.

  In the color copying machine of the present embodiment configured as described above, the laser beam scanner 22 exposes the photosensitive drum 20 based on the image information of the original captured by the image input unit 1, and first, the photosensitive drum 20 is exposed. On the upper side, an electrostatic latent image corresponding to black is written. On the other hand, in the rotary developing unit 23, the black toner developing device is set at a position facing the photosensitive drum 20, and the electrostatic latent image is developed by the black developing device with a slight delay from the writing timing. The black toner image thus formed is primarily transferred onto the transfer belt 3 by the primary transfer roll 30, and the transfer belt 3 rotates while carrying the toner image. When the developing process by the black developing device is completed, the developing device is replaced until the transfer belt 3 completes one rotation cycle, and the yellow toner developing device is exposed to light by rotating the rotary developing unit 23 by 90 °. It is set at a position facing the body drum 20.

  Thereafter, these operations are repeated for each rotation cycle of the transfer belt 3, and each time, yellow, magenta, and cyan toner images are transferred from the photosensitive drum 20 to the transfer belt 3. A superimposed toner image is formed by the color toner images. The full-color multiple transfer toner image thus formed is secondarily transferred to the recording sheet P sent from the registration roll 53 at a predetermined timing, and the recording sheet P to which the unfixed toner image is transferred is It is discharged to the discharge tray 50 through the fixing device 4.

FIG. 2 is a schematic view showing a specific configuration of each sheet supply tray 5 (5a to 5d).
The sheet supply tray 5 is provided with a storage space for the recording sheet P and is formed in a substantially rectangular shape. The sheet supply tray 5 is inserted from the front side (the front side in FIG. 1) into the copier casing constituting the paper feeding unit. It is configured to be able to. A recording sheet P is mounted inside the sheet supply tray 5, and a bottom plate 60 that pushes the recording sheet P upward is provided.

  Further, on the housing side of the copying machine in which the sheet supply tray 5 is inserted, the above-described pickup roll 51 is provided corresponding to the leading end of the recording sheet P positioned in the sheet supply tray 5, and the bottom plate When the recording sheet P is lifted by the lift of 60, the leading end of the recording sheet P positioned at the uppermost position in the sheet supply tray 5 comes into pressure contact with the pickup roll 51. Accordingly, when the pickup roll 51 rotates, a predetermined frictional force acts between the recording sheet P and the pickup roll 51, and the uppermost recording sheet P is pulled out from the sheet supply tray 5. On the other hand, in order to prevent so-called double feeding in which a large number of recording sheets P pulled out from the sheet supply tray 5 are conveyed in a stacked state, a feed roll 63 and a roll adjacent to the pickup roll 51 are provided on the side of the copying machine casing. A retard roll 64 is provided.

  As shown in FIG. 3, the feed roll 63 is fixedly provided at a predetermined height, while the retard roll 64 is supported by an arm 65a provided so as to be swingable about a fulcrum 65. The arm 65a It is pressed against the feed roll 63 by the urging force of the elastic member 66 connected to one end of the feed roller 63. Further, in order to reliably prevent double feeding of the recording sheet P, the pressure contact force of the retard roll 64 against the feed roll 63 can be adjusted according to the thickness of the recording sheet P to be used. That is, an actuator rod 67 is coupled to one end of the elastic member 66. When the adjustment motor 68 is rotated to move the actuator rod 67, the urging force exerted by the elastic member 66 is changed, and the feed roll The pressure contact force of the retard roll 64 with respect to 63 can be freely adjusted. The recording sheets P drawn from the sheet supply tray 5 are separated one by one when passing through the nip formed by the feed roll 63 and the retard roll 64. The feed roll 63 and the pickup roll 51 are rotationally driven by a common feed motor (not shown), while the retard roll 64 is rotated via a torque limiter so as to rotate only when a predetermined torque or more is applied. It is supported.

  FIG. 4 shows a mechanism for moving the bottom plate 60 up and down. A wire 69 that is wound around a pulley 62 is connected to the bottom plate 60. When the wire 69 is taken up by a take-up pulley 71 connected to a lift-up motor 70, the bottom plate 60 is moved into the sheet supply tray 5. The uppermost recording sheet P comes into contact with the pickup roll 51. The take-up pulley 71 is connected to the lift-up motor 70 when the sheet supply tray 5 is pushed into the copying machine casing, and is separated from the lift-up motor 70 when the sheet supply tray 5 is pulled out from the copying machine casing. It is configured to be. For this reason, when the sheet supply tray 5 is extracted from the apparatus housing, the bottom plate 60 is lowered to the bottom surface of the sheet supply tray 5 by its own weight, so that the user can easily replenish the recording sheet P. When it is confirmed by a sensor (not shown) that the sheet supply tray 5 has been completely pushed into the copying machine casing, the lift-up motor 70 is driven as a preparatory operation for feeding the recording sheet P. Then, the wire 69 is wound up, and the bottom plate 60 is raised until the uppermost recording sheet P of the sheet bundle stacked on the bottom plate 60 comes into contact with the pickup roll 51.

  Further, the pick-up roll 51 is arranged so as to be movable up and down, and gradually descends as the number of recording sheets P stacked on the bottom plate 60 decreases due to paper feeding. In order to maintain the pickup roll 51 at substantially the same height level as the feed roll 63, when the pickup roll 51 is lowered to a predetermined height level by continuous paper feeding, the illustrated sensor detects this, The lift-up motor 70 is configured to be driven for a predetermined time using a change in the output signal of the sensor as a trigger. As a result, the bottom plate 60 is raised by an amount corresponding to the thickness of the fed recording sheet P, and the uppermost recording sheet P in the sheet supply tray 5 is always in contact with the pickup roll 51 at a predetermined height. It is like that.

  On the other hand, in this type of electrophotographic copying machine, particularly a color copying machine that multi-transfers toner images of a plurality of colors onto the recording sheet P, an optimum value corresponding to the thickness of the recording sheet P with respect to the secondary transfer roll 31 is obtained. If it is necessary to apply a transfer bias, and if the applied transfer bias is inappropriate, toner image transfer failure and retransfer due to toner polarity reversal will occur, making it impossible to form a high-quality recorded image. It becomes possible. Further, when feeding the recording sheet P from the sheet supply tray 5, in order to prevent double feeding of the recording sheet P, the pressure contact force of the retard roll 64 with respect to the feed roll 63 depends on the thickness of the recording sheet P. It is important to optimize. For this reason, in the color copying machine of this embodiment, the thickness of the recording sheet P set on the sheet supply tray 5 is automatically grasped, and the secondary image of the toner image is determined according to the grasped thickness of the recording sheet P. The transfer bias and the pressure contact force of the retard roll 64 can be optimized.

  In order to grasp the thickness of the recording sheet P without conveying it toward the image output unit 2, in the color copying machine of this embodiment, a CCD sensor using the sheet bundle Ps set on the sheet supply tray 5 as an imaging means. And the thickness of the recording sheet P is detected from the density data of the photographed image. Specifically, as shown in FIG. 5, a CCD sensor 75 is attached at a position facing the side end surface of the sheet bundle in the sheet supply tray 5, and the CCD sensor 75 images the side end surface of the sheet bundle Ps. It is supposed to be.

  As the mounting position of the CCD sensor 75, the side end face of the sheet bundle Ps can be photographed irrespective of the size of the recording sheet P set in the sheet supply tray 5, and for example, as shown in FIG. If the recording sheet P is set in the supply tray 5 by so-called side registration, it is set as a reference side wall for aligning the sheet bundle Ps and close to the rotating shaft 51a of the pickup roll 51. Is preferred. As shown in FIG. 7, if the recording sheet P is set by so-called center registration in the sheet supply tray 5, the CCD sensor 75 is preferably provided near the center of the front end wall of the sheet supply tray 5. .

  FIG. 8 is a block diagram showing a processing system for detecting the thickness of the recording sheet P from an image photographed by the CCD sensor 75 and a control system for transfer bias and the like using the detected thickness of the recording sheet P. . When the side end surface of the sheet bundle Ps is photographed by the CCD sensor 75, image data as shown in FIG. 9 can be obtained. The vertical direction in the figure is the thickness direction of the sheet bundle Ps, in other words, the direction in which the recording sheets P are stacked, and the density is repeated along the direction in the image data. This repetition interval corresponds to the thickness of one recording sheet P. The image data obtained from the CCD sensor 75 in this way is input to the information extraction unit 76 that is a computer system. The information extraction unit 76 extracts one line along the thickness direction of the sheet bundle Ps from the image data shown in FIG. 9, and calculates density data for each pixel in the line. FIG. 10 shows the calculated density data. The horizontal axis represents the pixel position along the thickness direction of the sheet bundle Ps, and the vertical axis represents the density data of each pixel expressed in 256 gradations. It can be seen that the density of each pixel repeats along the Ps thickness direction. Next, the information extraction unit performs frequency analysis such as fast Fourier transform (FFT processing) on the calculated density data, and calculates a grayscale period. FIG. 11 is a graph showing the result of converting the grayscale period obtained from the result of frequency analysis into the unit of distance based on the imaging magnification by the CCD sensor 75 and the arrangement pitch of the image sensors in the CCD sensor 75. Represents the repetition distance of the light and shade period, and the vertical axis represents the density difference. From this result, the repetition distance having a steep peak with respect to the density difference is the thickness of the recording sheet P set in the sheet supply tray 5.

  In the copying machine shown in FIG. 1, since the sheet supply tray 5 is provided in four stages, the thickness of the recording sheet P set for each sheet supply tray 5 is detected. Information regarding the thickness of the recording sheet P grasped by the information extraction unit 76 is sent to the main control unit 77 of the copying machine, and is stored in the main control unit 77 in correspondence with the sheet supply trays 5a to 5d.

  When the thickness of the recording sheet P is ascertained in this way, the main controller 77 optimizes the pressure contact force of the retard roll 64 against the feed roll 63 according to the thickness of the recording sheet P. The adjustment motor 68 provided for each tray is driven to change the urging force of the elastic member 66 described above. As a result, the separation operation of the recording sheet P by the cooperation of the feed roll 63 and the retard roll 64 can be optimized according to the thickness of the recording sheet P set on the sheet supply tray 5. Further, the pressure contact force of the pickup roll 51 with respect to the recording sheet P can be changed according to the detected thickness of the recording sheet P. In this way, by optimizing the pressure contact force of the pick-up roll 51 and the pressure contact force of the retard roll 63 using the grasped thickness of the recording sheet P, the recording sheet P from the sheet supply tray 5 to the image output unit 2 is optimized. Can be performed stably.

  Further, when the user performs a copy job, if the sheet supply tray 5 used in the job is selected automatically or manually, the main control unit 77 sets the thickness of the recording sheet P used in the job to a non-volatile state. The transfer bias corresponding to the thickness of the recording sheet P is set in the transfer bias power supply 78. As a result, when the toner image is secondarily transferred from the intermediate transfer belt 3 to the recording sheet P, a transfer bias having an optimum intensity according to the thickness of the recording sheet P can be applied. Transfer can be prevented.

  When the side edge surface of the sheet bundle Ps was actually imaged by the CCD sensor 75 and the thickness of the recording sheet P was calculated by the above-described method, the thickness of the recording sheet P having a peak density difference was 66.8 μm. . When the thickness of the recording sheet P constituting the sheet bundle Ps was directly measured, the thickness was 65.2 μm. Therefore, even if the thickness of the recording sheet P is calculated based on the captured image. The error was found to be within 3%. The difference in the thickness of the recording sheet P affects the sheet feeding operation to the image output unit 2 and the transfer of the toner image. The thickness of the recording sheet P is ± 10 to 20 μm with respect to the expected thickness. The sheet thickness extracted from the captured image is sufficiently close to the actual recording sheet P thickness, and the thickness of the recording sheet P extracted from the captured image is used. Even if the paper feed parameter and the toner image transfer parameter are determined, there is no practical problem. That is, according to the present invention, it is possible to detect the thickness of the recording sheet P set in the sheet supply tray 5 with an accuracy that is not problematic in practice.

  The CCD sensor 75 can image the side end face of the sheet bundle Ps every time the opening / closing of the sheet supply tray 5 is detected by a sensor not shown. As a result, when the type of the recording sheet set in the sheet supply tray 5 is changed, it can be detected immediately, and the thickness of the recording sheet P is determined from the beginning of the next copy job. It is possible to perform an optimum image forming operation. In addition, since there is a case where the type of the recording sheet P in the sheet supply tray 5 is changed in a state where the main power of the copying machine is cut off, the main power of the copying machine is turned on as a trigger. You may make it image the side end surface of the sheet bundle Ps by the CCD sensor 75.

  On the other hand, even if the sheet supply tray 5 is not opened and closed, if the sheet jam of the recording sheet P occurs continuously several times, the retard roll 64 and the pick-up roll 51 with respect to the thickness of the recording sheet P are used. Since it is considered that the pressure contact force is not optimized, the recording sheet P thickness detection operation described above is performed using a predetermined number of jams as a trigger, and the thickness of the recording sheet P stored in the main control unit 77 is detected. You may make it rewrite the data regarding length.

  With such a configuration, the main control unit 77 of the copying machine always holds information regarding the thickness of the recording sheet P set in the sheet supply tray 5, and the image forming operation is always performed on the recording sheet P. In addition, the information regarding the recording sheet P can be presented to the user through a user interface such as a control panel. Further, when the present invention is applied to a sheet supply apparatus of a printer instead of a copying machine, the main control unit 77 is set in the sheet supply tray 5 with respect to a computer connected to the printer. Information on the thickness of the sheet P can also be transmitted, and the user can monitor this information on a printer management screen or the like displayed on his / her PC.

  When the density data is extracted from the image data captured by the CCD sensor 75 and the frequency analysis of the density data is further performed, it is preferable that the image data does not include an image other than the side end face of the sheet bundle Ps. This is because noise is not included in frequency analysis, and the thickness of the recording sheet P can be accurately detected. Therefore, from this point of view, the mounting position in the height direction of the CCD sensor 75 in the sheet supply tray 5 is lower than the recording sheet P in contact with the pickup roll 51 as shown in FIG. A position where the upper end of the region is slightly lower than the uppermost recording sheet P of the sheet bundle Ps is preferable. Thereby, immediately after the recording sheet P is replenished to the sheet supply tray 5, a sufficient amount of the recording sheet P exists in the sheet supply tray 5, so that the bottom plate 60 is provided in the imaging region of the CCD sensor 75. Therefore, the CCD sensor 75 can photograph only the side end face of the sheet bundle Ps.

  On the other hand, as the recording sheet P in the sheet supply tray 5 is consumed, the bottom plate 60 in the sheet supply tray 5 gradually rises as shown in FIG. End faces are included. In this case, when the image data sent from the CCD sensor 75 is processed by the information extraction unit 76, it is recognized that the image data includes an image clearly different from the side end face of the sheet bundle Ps. When it is recognized that such an image is clearly included in the image of the CCD sensor 75, the information extraction unit 76 can detect the recording sheet P set in the sheet supply tray 5. It is determined that the remaining amount has become small, and information regarding the empty state of the recording sheet P is displayed to the user through a control panel or the like. In the case of the sheet supply tray 5 of the printer, it is also possible to display it on a PC connected to the printer. Further, even when the remaining amount of the recording sheet P in the sheet supply tray 5 is small as described above, the image recognized as clearly different from the side end surface of the sheet bundle Ps from the image data captured by the CCD sensor 75. It is also possible to remove the data and determine the thickness of the recording sheet P using other image data.

  From the viewpoint of increasing the detection accuracy of the thickness of the recording sheet P, several lines of line data along the thickness direction of the sheet bundle Ps are extracted from the image data captured by the CCD sensor 75, and the above-described line data is extracted from each line data. After detecting the thickness of the recording sheet P by this method, it is preferable to average the detection results for all line data. For this purpose, the imaging range of the CCD sensor 75 is preferably a surface area that extends in the thickness direction of the sheet bundle Ps and the surface direction of the recording sheet P, and a plurality of imaging elements of the CCD sensor 75 are two-dimensionally arranged. It is preferable.

  However, in practicing the present invention, it is sufficient that only one line of image data along the thickness direction of the sheet bundle Ps can be extracted from the image captured by the CCD sensor 75. From this point of view, the CCD sensor 75 The plurality of image pickup elements included in may be arranged in a line (one-dimensional) along the thickness direction of the sheet bundle Ps.

  Further, when the sheet supply tray 5 is mounted on the copying machine casing as described above, the bottom plate 60 in the sheet supply tray 5 rises to lift the sheet bundle Ps. It is also possible to obtain image data by scanning the side end face of the sheet bundle Ps in the thickness direction. That is, the CCD sensor 75 includes only a single image sensor or image sensors corresponding to two or three recording sheets, and as shown in FIG. 14, the bottom plate 60 is lifted after the sheet supply tray 5 is mounted. At the same time, image data is collected from the image sensor in time series. By adjusting the rising speed of the bottom plate 60 and the sampling speed of the image data output from the CCD sensor 75, it is possible to calculate density data similar to that shown in FIG. By taking the rising speed of 60 into consideration, it is possible to create data relating to the repetition cycle of the density difference similar to that shown in FIG. 11, and to detect the thickness of the recording sheet P therefrom. According to such a configuration, an extremely inexpensive CCD sensor 75 can be used, and the configuration for raising the sheet bundle Ps is a configuration conventionally provided in the sheet supply tray 5, so that it is extremely simple. The present invention can be implemented with the configuration.

  In the example shown in FIG. 14, the CCD sensor 75 is fixed to the side wall of the sheet supply tray 5, and the bottom plate 60 on which the sheet bundle Ps is stacked is moved with respect to the CCD sensor 75. It is also possible to perform imaging while moving the sensor 75 itself in the thickness direction of the sheet bundle Ps by moving means such as an actuator.

  On the other hand, when photographing the side end surface of the sheet bundle Ps set in the sheet supply tray 5 by the CCD sensor 75, the inside of the sheet supply tray 5 housed in the casing of the copying machine is dark, so that a clear captured image is obtained. In order to obtain this, it is preferable to provide illumination means for illuminating the imaging region on the side end face of the sheet bundle Ps. As this illumination means, an LED element or the like can be used, and it is preferable to turn on only during imaging of the side end face of the sheet bundle Ps by the CCD sensor 75 and to turn off immediately after the imaging is completed. Further, as shown in FIG. 15, the illumination unit 80 is preferably attached to a position where the side end surface of the sheet bundle Ps is illuminated obliquely upward or obliquely below the optical axis of the CCD sensor 75. Since the edge portions of the recording sheets P form subtle irregularities on the side end surfaces of the sheet bundle Ps, the illumination unit 80 is arranged on the sheet bundle Ps obliquely upward or obliquely downward with respect to the optical axis of the CCD sensor 75. If the side end face is illuminated, the shadow between the recording sheets P that are in contact with each other can be emphasized. The density data is extracted from the image data captured by the CCD sensor 75, and the density data is analyzed. At this time, such an analysis can be easily performed, and the thickness detection accuracy of the recording sheet P can be increased.

  FIG. 16 shows another example of a method for photographing the sheet bundle Ps by the CCD sensor 75. In the example shown in FIG. 5, the side end face of the sheet bundle Ps set in the sheet supply tray 5 is photographed as it is with the CCD sensor 75, but in the example shown in FIG. 16, the air nozzle is positioned at a position facing the side end face of the sheet bundle Ps. 82 is provided, and photographing is performed while blowing air to the sheet bundle Ps. By blowing air between the stacked recording sheets P, each recording sheet P floats slightly with respect to the recording sheets P adjacent to each other in the vertical direction, and the recording sheets P and the recording sheets are simply stacked rather than being stacked. A gap with P can be increased. As a result, in the image photographed by the CCD sensor 75, the contrast of light and dark becomes large between the portion showing the edge of the recording sheet P and the portion showing the gap between the recording sheets P, and this image data By using this, it becomes possible to detect the recording sheet P more easily and accurately.

  The arrangement position of the air nozzle in the sheet supply tray 5 is such that air is blown against the side end surface of the sheet bundle Ps and each recording sheet P constituting the sheet bundle Ps is set in a slightly floating state. Any position can be used, but from the standpoint of more prominently producing contrast in the captured image, it may be disposed at a position where air is directly blown to the imaging area of the CCD sensor 75. preferable.

  In addition, if the density contrast in the captured image can be detected by blowing air on the side end surface of the sheet bundle Ps in this way, after the density data is extracted from the image data, the density data Without performing frequency analysis, the thickness of the recording sheet P can be detected directly from the density data. That is, in the image data of the CCD sensor 75, since the edge portion of the recording sheet P appears whitish or pale, the width of the corresponding color is directly detected from the extracted density data and recorded from the photographing magnification of the CCD sensor 75. It becomes possible to detect the thickness of the sheet P. If there are a plurality of floating recording sheets P in the imaging area of the CCD sensor 75, the detection accuracy can be further improved by using the average value of the thicknesses directly detected with respect to these recording sheets P. Is possible.

  In this case, the information extraction unit 76 that has captured the image data from the CCD sensor 75 considers the floating state of the recording sheet P in the sheet supply trays 5a to 5d in determining physical properties such as the thickness and material of the recording sheet P. can do. That is, a gap is formed between the recording sheets P that are overlapped with each other by blowing air, and the recording sheets P constituting the sheet bundle Ps are in a floating state as shown in FIG. The height, levitation width, number of floating recording sheets P, and temporal changes in the floating state in the initial stage of airflow blowing are analyzed from the image data, and the analysis results are stored in the information extraction unit 76 in advance. By comparing with each data, the thickness and material of the recording sheet P stored in the sheet supply trays 5a to 5d can be determined.

  The pick-up roll 51 is pressed against the sheet bundle Ps in the sheet supply trays 5a to 5d from above, and as described above, the elevation of the bottom plate 60 is controlled so that the height thereof is substantially constant. In detecting the flying height of the recording sheet P, the flying height can be defined based on the contact surface between the pickup roll 51 and the sheet bundle Ps. Further, regarding the floating width of the recording sheet P, it is assumed that the floating width of the recording sheet P generated by the blowing of air is wider than the shooting range by the CD sensor 75, but the recording sheet P within the shooting range is assumed. It is possible to calculate by analogy with the curved shape.

  If the physical properties of the recording sheets P stored in the sheet supply trays 5a to 5d are grasped in this way, as described above, the pressure contact force of the retard roll 64 against the feed roll 63 according to the thickness of the recording sheet P, By optimizing the pressure contact force of the pickup roll 51 with respect to the sheet bundle Ps, the operation of feeding the recording sheet P to the image output unit 2 can be stabilized. Further, if the recording sheet P is separated by applying a rotational torque in the direction opposite to the rotational direction of the feed roll 63 to the retard roll 64, the magnitude of the reverse rotational torque applied to the retard roll 64. It is also possible to stabilize the separation operation of the recording sheet P by adjusting.

  In addition, if the information extraction unit 76 takes into account the floating state of the recording sheets P in the sheet supply trays 5a to 5d, that is, how much gap is formed between the recording sheets P that overlap each other. Therefore, when the recording sheet P in the sheet supply trays 5a to 5d is sent to the image output unit 2 by the pickup roll 51 as it is, it is determined whether or not a recording sheet feeding error or double feeding is likely to occur. I can grasp it. For example, when air is blown into the sheet bundle Ps in which the light recording sheets P are stacked, as shown in FIG. 18, a plurality of recording sheets P may be floated together. Since the recording sheet P floated as a group enters the nip portion between the feed roll 63 and the retard roll 64 as it is, double feeding is likely to occur during feeding to the image output unit 2. Further, when air is blown into the sheet bundle Ps on which the heavy recording sheets P are stacked, as shown in FIG. 19, the floating range of the recording sheets P is not sufficient, and the sheet bundle Ps is formed in the sheet supply trays 5a to 5d. Since the recording sheet P is not sufficiently burned, the recording sheet P is likely to be mistakenly fed or double fed. Therefore, it is not limited to simply grasping the physical properties such as the thickness of the recording sheet set in the sheet supply tray and optimizing the separation parameters such as the pressure contact force of the retard roll 64 and the pressure contact force of the pickup roll 51, By grasping the floating state of the recording sheet in the sheet supply trays 5a to 5d and optimizing the separation parameter in consideration of the floating state, it is possible to reliably prevent the recording sheet from being mistakenly fed and double feeding.

  On the other hand, from the viewpoint of making the recording sheet P to be satisfactorily blown by blowing an air flow on the sheet bundle Ps in the sheet supply trays 5a to 5d, the information extracting unit 76 records the recording sheet. The levitation state of P is grasped, and when the levitation state is inferior as shown in FIG. 18 or FIG. 19, the strength of the air flow blown from the air nozzle 82 and the direction and height of the air nozzle 82 are changed. Thus, the floating state of the recording sheet can be optimized.

  FIG. 20 is a flowchart showing a processing procedure for blowing an air flow to the sheet bundle Ps set in the sheet supply trays 5a to 5d and optimizing the condition of the sheet bundle Ps. For example, when the main power of the copying machine is turned on, a blower (not shown) starts from this point, and the air flow blown from the air nozzle 82 blows into the sheet bundle Ps set in the sheet supply trays 5a to 5d. (ST1). As a result, the recording sheets P that overlap each other and form the sheet bundles 5a to 5d start floating, and therefore, a floating state detection mode for grasping the floating state after a predetermined time has elapsed since turning on the main power supply. Is started (ST11). When the floating state detection mode is started, the information extraction unit 76 takes in the image data of the side end face of the sheet bundle Ps photographed by the CCD sensor 75 (ST12), and this image data is converted into, for example, density data of 256 gray scales. Conversion is performed and image information is calculated (ST13). Then, the contour of the recording sheet P being floated is grasped from the density data, and the floating height and the floating width of the recording sheet P are calculated based on the contour, and the contour of the image quality is floated. The number of recording sheets P and the size of gaps formed between the recording sheets P are calculated (ST14). For example, when the recording sheet P is transiently moved during levitation and good image data cannot be obtained, various parameters relating to the levitation state of the recording sheet P (the levitation height, the levitation width, the number of levitation, the gap Therefore, the information extraction unit 76 checks whether or not these parameters have been calculated normally (ST15). If it is determined that the parameters have not been calculated normally, the CCD sensor The captured 75 image data is captured again (ST16), and the above-mentioned ST13 and ST14 are repeated.

  Next, in order to confirm whether or not the floating state of the recording sheets P in the sheet supply trays 5a to 5d is desirable, in other words, whether or not the sheet bundle Ps can be satisfactorily cut by blowing air. The information extraction unit 76 compares the calculated parameter relating to the floating state of the recording sheet P with the data in the reference table stored in advance (ST17), and checks whether or not the current floating state is optimal (ST18). If it is determined that the levitation state is optimum, the blowing intensity of the air amount by the air nozzle 82, the blowing direction, and the set position of the air nozzle 82 are maintained in the state at the time of photographing by the CCD sensor 75 (ST19). On the other hand, if it is determined that the levitation state is defective, the airflow blowing strength, the blowing direction, and the setting position of the air nozzle 82 are set according to the error between the calculated parameter and the parameter stored in the reference table. Is changed (ST20). The intensity of air blown by the air nozzle 82 can be enhanced or reduced by adjusting the applied current and applied voltage of the blower. Further, a movable regulating blade may be provided on the front surface of the air nozzle 82, and the direction of the regulating blade may be changed to adjust the blowing direction and blowing strength of the air flow. Thereby, the detection mode of the levitation state ends (ST21).

  As described above, the state in which the sheet bundle Ps is blown when the air flow is blown into the sheet bundle Ps in the sheet supply trays 5a to 5d is grasped from the image data photographed by the CCD sensor 75, and the state in which the sheet bundle Ps is optimal. If the method of blowing the air flow is adjusted so that the recording sheet P is fed by rotating the pickup roll 51, only the uppermost recording sheet P of the sheet bundle Ps is reliably fed. Therefore, the recording sheet P can be fed to the nip portion of the retard roll 64, so that the recording sheet P can be prevented from being mistakenly fed or double fed.

  In the embodiment described with reference to FIGS. 5 to 20, physical properties such as the thickness of the recording sheet P set in the sheet supply tray 5 are detected using the image data captured by the CCD sensor 75. In addition to detecting the thickness, various information displayed on the recording sheet P is photographed by the CCD sensor 75, and the information is read from the image data, and the image forming apparatus such as a copying machine or a printer is used. It can be configured to be used for control.

  For example, a mark area that is discolored by heating is provided for a specific area of the edge portion of the recording sheet P. When the recording sheet P passes through the heating and fixing device 4 of a copying machine or a laser beam printer, heating is performed. The mark area is discolored by heat propagated from the fixing device 4. When the recording sheet P is set again on the sheet supply tray 5 as a one-side printed recording sheet, the mark area 81 can be imaged by the CCD sensor 75 as shown in FIG. By determining with the information extraction unit 76, it is possible to determine whether the recording sheet P set in the sheet supply tray 5 is a single-side printed recording sheet, in other words, a backing paper. If the information extraction unit 76 determines that the recording sheet P has been printed on one side, the main control unit 77 of the copying machine determines the sheet feeding parameters for the image output unit 2 of the recording sheet P based on the result. The setting of image forming parameters in the image output unit 2 can be changed, the fact that the back paper is set in the sheet supply tray 5 is displayed on the control panel of the copying machine, or the printer management screen of the client computer It is possible to display on the top.

  The extent to which the size of the mark area 81 should be set depends on conditions such as brightness difference and color difference between the color of the recording sheet P itself and the color of the mark area 81, but the results of experiments by the inventors According to the above, when the mark area 81 is set to change to orange, if the width of the mark area 81 is about 3 mm, the mark area 81 can be visually recognized, and an imaging means such as a CCD sensor 75 is used. For example, discoloration can be detected sufficiently even if it is set to a smaller value. As materials that change color, it is possible to divert materials that are commonly used as surface temperature thermosensitive labels (irreversible) and thermo labels, and there are orange, red, black, etc. To do. As for the principle of discoloration, for example, in the case of a type in which a wax layer and a dye layer are laminated, when the wax layer reaches a predetermined temperature or higher, it dissolves and soaks into the lower dye layer, and the dye layer changes color. In this case, the pigment is a pigment or a dye, and the wax is a paraffinic wax.

1 is a schematic diagram illustrating an example of a digital color copying machine to which a sheet supply apparatus of the present invention can be applied. It is the schematic which shows the structure of a sheet supply apparatus. It is an enlarged view which shows the mechanism around a feed roll and a retard roll. It is the schematic which shows the lift-up mechanism of a bottom plate. It is a schematic perspective view which shows the structure which extract | collects the image data of the side end surface of a sheet | seat bundle using a CCD sensor. FIG. 4 is a plan view showing a mounting position of a CCD sensor when a recording sheet is set in a sheet supply tray by a side registration method. FIG. 6 is a plan view showing a mounting position of a CCD sensor when a recording sheet is set in a sheet supply tray by a center registration method. FIG. 4 is a block diagram showing a processing system for detecting the thickness of a recording sheet from image data output from a CCD sensor, and a control system using the detected recording sheet thickness data. It is a figure which shows an example of the image data imaged by the CCD sensor. It is a graph which shows an example of the density data along the thickness direction of a sheet bundle. It is a graph which shows distribution of thickness estimation of the recording sheet obtained by carrying out frequency analysis of density data. It is a figure which shows the attachment height of the CCD sensor in a sheet supply tray, and has shown the case where sufficient quantity of recording sheets exist in a sheet supply tray. It is a figure which shows the attachment height of the CCD sensor in a sheet supply tray, The recording sheet in a sheet supply tray is consumed, and the state which the bottom plate approached into the imaging | photography range of the CCD sensor is shown. FIG. 4 is a schematic diagram illustrating a configuration in which image data of a side end face of a sheet bundle is collected using a CCD sensor having a small photographing range, where a part a shows a state where the bottom plate is lowered, and a part b shows a state where the bottom plate is raised. Is shown. FIG. 6 is an enlarged view showing an example of an arrangement position of illumination means in a sheet supply tray. It is a schematic perspective view which shows the example which images this side end surface with a CCD sensor, blowing air with respect to the side end surface of a sheet | seat bundle. It is a figure which shows an example of the definition of the floating height of the recording sheet which floated by blowing of air. FIG. 6 is a diagram illustrating a problem in which a plurality of recording sheets are floated together when air is blown on a sheet bundle. FIG. 10 is a diagram illustrating an example in which the recording sheet is not sufficiently floated when air is blown onto the sheet bundle. It is a flowchart which shows the process sequence for optimizing the rolling condition of sheet bundle Ps, blowing air with respect to the side end surface of a sheet bundle. FIG. 5 is a perspective view illustrating a configuration for determining whether or not a recording sheet set on a sheet supply tray is a single-side printed sheet by providing a mark area that changes color by heating in a specific area of an edge portion of the recording sheet. .

Explanation of symbols

  DESCRIPTION OF SYMBOLS 5 ... Sheet supply tray, 51 ... Pickup roll, 60 ... Bottom plate, 63 ... Feed roll, 64 ... Retard roll, 75 ... CCD sensor (imaging means), 76 ... Information extraction part, P ... Recording sheet, Ps ... Sheet bundle

Claims (14)

A supply tray for storing a sheet bundle in which a plurality of recording sheets are aligned;
A separation paper feeding means for separating and feeding the recording sheets in the supply tray one by one;
Imaging means for imaging the sheet bundle set in the supply tray from the side end direction;
Information extracting means for detecting information relating to the recording sheet from image data obtained from the imaging means ;
A bottom plate that relatively moves the image pickup unit and the sheet bundle in a recording sheet stacking direction ,
The image pickup means is disposed below the recording sheet that is in contact with the separation paper feed means, collects the image data while operating the bottom plate, and the information extraction means includes an image When it is determined that the image of the bottom plate is included in the data, the thickness information of the recording sheet is detected using image data other than the image of the bottom plate .   The sheet feeding apparatus according to claim 1, wherein the information extracting unit detects thickness information of the recording sheet.   The information extracting means extracts density data from the image data, calculates a frequency characteristic of density data in the thickness direction of the sheet bundle, and detects the thickness of the recording sheet from the frequency characteristic. 2. The sheet supply apparatus according to 2.   The sheet feeding apparatus according to claim 1, further comprising an illuminating unit that illuminates a side end surface of the sheet bundle in conjunction with the imaging unit.   5. The sheet feeding apparatus according to claim 4, wherein the illumination unit illuminates a side end surface of the sheet bundle from an obliquely upward direction or an obliquely downward direction of the stacking direction of the sheet bundle.   2. The sheet feeding apparatus according to claim 1, wherein the image pickup unit is a CCD sensor in which a plurality of light receiving elements are arranged one-dimensionally along a stacking direction of recording sheets.   2. The sheet feeding apparatus according to claim 1, wherein the image pickup means is a CCD sensor in which a plurality of light receiving elements are two-dimensionally arranged.   2. The sheet supply apparatus according to claim 1, wherein each time the supply tray is reattached to the apparatus housing, the image data is collected and information on the recording sheet is extracted.   2. The sheet feeding apparatus according to claim 1, wherein the information extracting unit detects information on whether or not the recording sheet set on the feeding tray is a one-side printed recording sheet.   2. The sheet feeding apparatus according to claim 1, further comprising a separation control unit that controls the separation sheet feeding unit in accordance with recording sheet information obtained from the information extraction unit.   2. A sheet supply apparatus according to claim 1, further comprising an air supply unit that blows air from a side end direction of the sheet bundle in the supply tray to form a gap between the overlapping recording sheets. . The sheet supply apparatus according to claim 11, wherein the air supply unit blows air to an imaging region of a sheet bundle by the imaging unit. 12. The sheet supply apparatus according to claim 11, wherein the air supply unit blows air toward a front end of a sheet bundle in a sheet feeding direction of the recording sheet. An image forming apparatus characterized in that the feeding of the recording sheet using a sheet feeding apparatus according to any one of claims 1 to 13.