JP4801403B2 - Sheet remaining amount detection device, sheet feeding device, and image forming apparatus - Google Patents

Description

  The present invention relates to a sheet remaining amount detection device that detects the number of remaining sheets of sheet-like medium, a sheet feeding device using the same, and an image forming apparatus using them.

  In recent years, with the increase in color and speed of copying machines and printers, it has become necessary to accurately detect the number of sheet-like media remaining in the paper feed tray. This is because with the increase in the size of the intermediate transfer belt, the number of images that can be formed on the intermediate transfer belt has increased, but the number of sheets that can be stocked from the paper feed tray to the transfer device has decreased.

  For example, an image forming apparatus that can form an image that can be transferred onto five sheets on an intermediate transfer belt, but can store only three sheets between the paper feed tray and the transfer device is taken as an example. explain. In this image forming apparatus, when an image that can be transferred onto five sheets is formed on the intermediate transfer belt and no sheet is fed from the sheet feeding tray (the number of sheets is insufficient), 5 is placed on the intermediate transfer belt. −3 = 2 There are remaining images that can be transferred to two sheets, and the remaining images are erased by the intermediate transfer cleaning device. As described above, in the image forming apparatus as described above, if the number of sheets that can be stocked from the paper feed tray to the transfer apparatus is insufficient, wasteful image formation may be performed and toner may be wastefully consumed. .

  Therefore, in order to eliminate such waste, it is only necessary to accurately detect the number of remaining sheets on the sheet feeding tray and prevent image formation beyond the remaining number. For example, in Patent Document 1, a first light-emitting unit and a light-receiving unit are provided at positions sandwiched in the thickness direction of the stacked sheet-like media, the conveyance path through which the sheet-like medium passes, and the thickness of the medium on the conveyance path. Second light emitting means and light receiving means are provided at positions sandwiched in the vertical direction. Then, the amount of transmitted light emitted from the second light emitting means and transmitted through the medium and obtained by the light receiving means, and the amount of transmitted light obtained from the first light emitting means and transmitted through the stacked sheet-like medium and obtained by the light receiving means, A transmitted light amount detection device that detects the number of stacked sheet-like media by calculating the above is disclosed.

JP 2004-269233 A

  However, in Patent Document 1, two sets of light emitting means and light receiving means are required to detect the remaining amount of the sheet, and the remaining amount cannot be detected with only one set of light emitting means and light receiving means. Therefore, there was a problem that the cost was expensive and it was not economical.

  The present invention has been made in view of the above, and a remaining sheet amount detecting device, a sheet feeding device, and a sheet remaining amount detecting device that can detect the remaining amount of a sheet-like medium with low cost and high accuracy using a light emitting unit and a light receiving unit, and An object is to provide an image forming apparatus.

In order to solve the above-described problems and achieve the object, the invention according to claim 1 is a light-emitting unit and a light-receiving unit that are arranged to face each other in a thickness direction of a plurality of sheet-like media, and the plurality of sheets. A first storage means for storing a first light quantity obtained by the light receiving means receiving light emitted from the light emitting means that has passed through the sheet-like medium, and the plurality of sheet-like media having the first light quantity. A second storage means for storing an increase in the amount of light that is a difference between the second light quantity obtained by the light receiving means when the number of the light receiving means is reduced by one from the time of acquisition, and the first light quantity; A third storage unit that stores a range in which the relationship between the increase amount of the light amount and the second light amount can be taken for each number of sheets at the second light amount, and a range stored in the third storage unit If, increase of the light intensity, and based on the second light quantity, the plurality of Calculating means for calculating the remaining amount of over preparative like medium, characterized in that Ru comprising a.

The invention according to claim 2, in the sheet residual amount detecting apparatus according to claim 1, wherein the light receiving means includes an amplifier circuit for amplifying the light amount obtained by receiving, based on the amplified light amount and performing by that operation to the arithmetic unit Te.

According to a third aspect of the present invention, in the sheet remaining amount detecting device according to the first aspect, the calculation unit performs a calculation process of multiplying a light amount obtained by receiving the light by the light receiving unit by a predetermined magnification, The output of the light receiving means is corrected.

  According to a fourth aspect of the present invention, in the remaining sheet amount detecting device according to the second aspect, the calculation means calculates in advance a correction value for variations in the amplifier circuit, and uses the correction value to calculate the amplifier circuit. The obtained output is processed.

According to a fifth aspect of the present invention, in the sheet remaining amount detecting device according to any one of the first to fourth aspects, the calculating means has a relationship between the increase amount of the light amount and the second light amount. The third storage means that stores the possible range for each type of sheet-like medium is used to perform arithmetic processing by switching the expression of the boundary line according to the sheet-like medium to be used.

According to a sixth aspect of the present invention, in the sheet remaining amount detecting device according to any one of the first to fifth aspects, the calculation unit is responsive to the second light amount obtained from the light receiving unit. It is characterized by changing the method of arithmetic processing.

According to a seventh aspect of the present invention, there is provided a paper feeding device using the remaining sheet amount detecting device according to any one of the first to sixth aspects, wherein the first light amount of the sheet-like medium It is characterized in that the number of sheet-like media is detected by obtaining the second light quantity of the sheet-like media whose number has decreased after paper and performing arithmetic processing.

  According to an eighth aspect of the present invention, the remaining sheet amount detecting device according to any one of the first to sixth aspects is provided as a remaining amount detecting unit for recording paper on which image formation is performed. An image forming apparatus.

  According to a ninth aspect of the present invention, there is provided an image forming apparatus comprising the paper feeding device according to the seventh aspect.

Sheet residual amount detecting apparatus according to the present invention, a plurality of sheet-like medium having a thickness of the light emitting means in a position sandwiched by the direction and the light receiving means are opposed, the emission light of the transmitted light emitting means a plurality of sheet-like medium, the light receiving The first light quantity obtained when the means receives light is stored in the first storage means, and the second light quantity and the second light quantity obtained when the plurality of sheet-like media are decreased by one sheet from the time when the first light quantity is obtained. The amount of increase in the amount of light, which is the difference from the amount of one light, is stored in the second storage means, and the range in which the relationship between the amount of increase in the amount of light for each number of sheets and the second amount of light at the second light amount can be taken. The remaining amount of the plurality of sheet-like media is calculated by the calculation means based on the range stored in the third storage means, the increase amount of the light amount, and the second light amount . For this reason, the remaining amount of the sheet-like medium can be calculated with low cost and high accuracy regardless of the thickness of the paper by using the light emitting means and the light receiving means.

  Hereinafter, embodiments of a remaining sheet amount detecting device, a sheet feeding device, and an image forming apparatus according to the present invention will be described in detail with reference to the drawings. Note that the present invention is not limited to the embodiments.

  FIG. 1 is a cross-sectional view illustrating a schematic configuration of an image forming apparatus including a remaining sheet amount detecting device according to the present invention. In the image forming apparatus 1 shown in FIG. 1, an image forming unit 2 is disposed at the center of the apparatus, and a paper feeding unit 3 is disposed below the image forming unit 2. The paper feed unit 3 includes a paper feed tray 31 that accommodates a sheet-like medium (transfer paper) at each stage, and a paper feed device 32 can be added as necessary. A reading unit 4 for reading a document is disposed above the image forming unit 2, and a paper discharge storage unit 5 is formed on the left side of the image forming unit 2 to discharge and store the recording paper on which the image is formed.

  In the image forming unit 2, a plurality of image forming units 7 are arranged in parallel on a belt-like intermediate transfer belt 6, and each image forming unit 7 has a photoconductor 71 around a drum-shaped photoconductor 71. A charging device 72 that charges the surface of the photosensitive member 71, an exposure device 8 that irradiates the surface of the photosensitive member 71 with laser light, and a developing device that visualizes the electrostatic latent image formed by exposing the surface of the photosensitive member 71 to light. 73 and a cleaning device 74 that removes and collects toner remaining on the photoreceptor 71 is disposed.

  As an image forming process, the intermediate transfer belt 6 rotates to form one color image. That is, first, yellow (Y) toner is developed and transferred to the intermediate transfer belt 6 in the yellow (Y) image forming section. Next, the magenta (M) toner is developed in the magenta (M) image forming section and transferred to the intermediate transfer belt 6. Next, cyan (C) toner is developed and transferred to the intermediate transfer belt 6 at the cyan (C) image forming section, and finally, black (K) toner is developed and transferred to the intermediate transfer belt 6. To do.

  A transfer device 61 that transfers the four color toner images developed on the intermediate transfer belt 6 to a sheet, and an intermediate transfer cleaning device 62 that removes and collects toner remaining on the surface of the intermediate transfer belt 6 after transfer are arranged. .

  A fixing device 9 for fixing the toner on the paper on which the toner image has been obtained is disposed downstream of the image forming apparatus 1 (downstream in the paper conveyance path). The sheet that has passed through the fixing device 9 is discharged and stored in the discharge storage section 5 by a discharge roller.

  In the paper supply unit 3, unused recording paper is stored in the paper supply tray 31, and the bottom plate supported rotatably is raised to a position where it can come into contact with the uppermost pickup roller. The uppermost paper is fed out from the paper feed tray 31 by the rotation of the paper feed rollers 36 and 37, and is conveyed to the registration roller 33.

  The registration roller 33 is controlled so as to start rotating at a timing so that the conveyance of the recording paper is temporarily stopped and the positional relationship between the toner image on the surface of the photosensitive member 71 and the leading edge of the recording paper becomes a predetermined position. .

  The reading unit 4 reads the document by scanning the document placed on the contact glass. The scanned image information is read as an image signal into the CCD through the lens. The read image signal is digitized and subjected to image processing. Then, an electrostatic latent image is formed on the surface of the photoreceptor 71 by light emission of a laser diode LD (not shown) in the exposure device 8 based on the image-processed signal. The optical signal from the laser diode LD reaches the photosensitive member 71 via a known polygon mirror or lens. Above the reading unit 4, an automatic document feeder (ADF) 41 for automatically feeding the document onto the contact glass is attached.

  The image forming apparatus of the present embodiment scans an original as described above, reads the image, digitizes it, and copies it onto a sheet of paper. It also has a facsimile function for transferring image information to and from a remote place, and a so-called printer function for printing image information handled by a computer on paper.

  FIG. 2 is an enlarged view of the periphery of the paper feed tray and the transfer device of FIG. As shown in FIG. 2, the feature of the present invention is that color (YMCK) photoconductors 71Y, 71M, 71C, 71K are arranged by colorization and speedup, and these color images are superimposed on the intermediate transfer belt 6. Here, the image is enlarged so that five images can be formed by transferring. In this manner, the number of sheets 20a, 20b, and 20c that can be stocked between the paper feed tray 31 and the transfer device 61 (three sheets) is smaller than the number of images that can be formed on the intermediate transfer belt 6 (five sheets). It has become.

  Therefore, after 5 sheets of images have been formed on the intermediate transfer belt 6, if there are no sheets in the sheet feed tray 31 and sheets are not fed, 5-3 = 2 images that can be transferred to 2 sheets. Is left on the intermediate transfer belt 6 and is erased by the intermediate transfer cleaning device 62 and is wasted.

  Therefore, according to the present invention, the remaining number of sheets stocked in the sheet feed tray 31 is accurately detected, so that no image formation exceeding the remaining amount is performed and waste is eliminated. When the present invention is used in the image forming apparatus, the remaining amount of the sheet-like medium 20 remaining in the sheet feeding tray 31 can be accurately detected. Control processing according to the remaining amount of the sheet-like medium 20 can be performed.

  FIG. 3 is a conceptual diagram showing an embodiment of a paper feeding device according to the present invention. The light emitting unit 100 and the light receiving unit are positioned at a position where a bundle of sheet-like media 20 is sandwiched in the thickness direction on the bottom plate 34 of the paper feeding tray 31. Part 101 is provided. The light emitted from the light emitting unit 100 is transmitted through the bundle of sheet-like media 20, and the amount of transmitted light is detected by the light receiving unit 101. The light emitting unit 100 may be an LED element, a semiconductor laser, or the like, but may be other light emitting means such as an incandescent lamp or a fluorescent lamp. As for the wavelength, not only visible light but also infrared light and ultraviolet light can be considered.

  The light receiving unit 101 may be a phototransistor, a photodiode, or the like. However, any light receiving unit may be used as long as a certain value corresponding to the amount of received light can be obtained.

  Here, the light receiving unit 101 obtains a first light amount emitted from the light emitting unit 100 and transmitted through the bundle of sheet-like media 20, and the sheet-like media 20 is fed out by the pickup roller 38 and fed by the paper feed rollers 36 and 37. The second light quantity transmitted through the bundle of sheet-like media 20 with the reduced number of sheets is obtained by paper, and the remaining light of the sheet-like media left in the paper feed tray 31 is obtained by calculating them. The number of sheets is detected.

  As described above, in the present embodiment, the remaining number of sheets of the sheet-like medium 20 can be accurately detected by only one set of the light emitting unit 100 and the light receiving unit 101, and the determination of 0 can be performed. A paper end sensor that determines that the sheet-like medium 20 in the paper tray 31 is zero is not necessary. In addition to the cost of the light emitting unit 100 and the light receiving unit 101, the cost of the paper end sensor can be reduced compared to the conventional remaining amount detection device that requires two sets of the light emitting unit 100 and the light receiving unit 101. Cost can be reduced.

  FIG. 4 is a block diagram showing the configuration of the remaining sheet amount detecting device of the present invention. As shown in FIG. 4, the sheet remaining amount detection apparatus includes a control unit 110 that controls the light emitting unit 100 and the light receiving unit 101, converts the transmitted light amount obtained from the light receiving unit 101 into a voltage value, and calculates the calculation unit 111. An arithmetic process is performed at. Further, the control unit 110 controls the sheet feeding of the sheet feeding tray (sheet feeding unit) 31 to convert the transmitted light amount obtained from the light receiving unit 101 into a voltage value in a state where the number of the sheet-like media 20 is reduced. can do. The memory 112 stores various parameters necessary for arithmetic processing, the detected transmitted light amount, and the like.

  FIG. 5 is a conceptual diagram showing the distance and positional relationship between the light emitting unit and the light receiving unit provided in the paper feed tray of FIG. In FIG. 5, a distance C1 is a distance between the light emitting unit 100 and the light receiving unit 101, an angle E1 is an angle formed by an optical axis (broken line) connecting the light emitting unit 100 and the light receiving unit 101 and a medium (sheet-like medium), A distance D1 is a distance between the medium and the light receiving unit 101. Here, when there is a bundle of sheet-like media 20, the output from the light receiving unit 101 increases as the number of sheets decreases.

  For example, the distance C1 between the light emitting unit 100 and the light receiving unit 101 is 30 mm, the angle E1 formed by the optical axis connecting the light emitting unit 100 and the light receiving unit 101 and the medium is 55 °, and the distance D1 between the medium and the light receiving unit is 8. 5 mm. The output of the light receiving unit 101 is a voltage value, and here, it is assumed that there are four sheet-like media 20. At this time, the output voltage of the light receiving unit 101 is 0.1855V. Next, when the sheet-like medium 20 is reduced by 1 sheet to 3 sheets, the output voltage of the light receiving unit 101 is 0.2563V. Thus, since the amount of transmitted light increases when the number of the sheet-like medium 20 decreases, the output voltage of the light receiving unit 101 increases.

(First embodiment)
Next, in the sheet remaining amount detection apparatus according to the present embodiment, a case where the transmitted light amount obtained from the light receiving unit 101 is converted into a voltage to obtain the transmitted light amount will be described. First, the light emitting unit 100 and the light receiving unit 101 are arranged at a position where the sheet medium 20 is sandwiched in the thickness direction, and when the light amount emitted from the light emitting unit 100 and transmitted through the sheet medium 20 is received by the light receiving unit 101, the voltage is Obtain Va. Then, after the number of sheet-like media 20 is reduced by a paper feeding operation or the like, when the light amount emitted from the light emitting unit 100 and transmitted through the medium is received by the light receiving unit 101, the voltage Vb is obtained. The relationship between the voltages Va and Vb is Vb> Va because the output voltage of the light receiving unit 101 increases as the number of transmitted sheets of the sheet-like medium 20 decreases. Therefore, an increase amount of voltage Vb−Va = Vc is obtained. The remaining amount is determined by the relational expression of Vc and Vb obtained in this way.

  FIG. 6 shows the relationship between the output voltage of the light receiving unit 101 and the amount of increase by measuring the output voltage of the light receiving unit 101 when 5 sheets of plain paper are changed from 4 sheets → 3 sheets → 2 sheets → 1 sheet. FIG. FIG. 7 is a diagram in which boundary lines of the respective numbers are drawn with respect to the respective number of points in FIG.

The formula for the boundary line between one and two shown in FIG.
−0.0287 × light receiving means output voltage × light receiving means output voltage + 0.4592 × light receiving means output voltage + 0.06088
It is. The formula for the border between the two and three is
−0.0433 × light receiving means output voltage × light receiving means output voltage + 0.3529 × light receiving means output voltage + 0.0396
It is. The equation for the boundary line between 3 and 4 is
−0.0677 × light receiving means output voltage × light receiving means output voltage + 0.3075 × light receiving means output voltage + 0.0271
It is. Further, as described above, Vb is the output voltage of the light receiving unit 101, and the remaining number of media can be determined by comparing this boundary line with the increase amount of the sensor output voltage, that is, Vc.

  FIG. 8 is a flowchart for explaining a calculation processing procedure in the calculation unit. In this calculation process, it is possible to determine the number of sheets of 0, 1, 2, 3, 4 or more. In the figure, the number data is the number from 0 to 4 sheets, the sensor output voltage is the current sensor output voltage, the previous sensor output voltage is the previous sensor output voltage, and the increment of the sensor output voltage is the previous sensor output voltage. A difference in sensor output voltage shall be entered. The determination formula is “sensor output voltage increase−boundary formula”.

  As shown in FIG. 8, the sensor measurement is performed before paper feeding, and stored in the front sensor output voltage (step S100). Subsequently, a sheet feeding operation is performed by the sheet feeding tray (sheet feeding unit) 31 (step S101), the sensor measurement is performed immediately after sheet feeding, the sensor output voltage is stored (step S102), and the process proceeds to step S103. .

  In step S103, it is determined whether or not the sensor output voltage is 0.02 V or more. If the sensor output voltage is 0.02 V or more, the difference between the sensor output voltage and the previous sensor output voltage is stored in the increase amount of the sensor output voltage (step S104). The output voltage is stored in the previous sensor output voltage (step S105), and the process proceeds to step S106.

  In step S106, if the increase amount of the sensor output voltage is smaller than 0, the process ends abnormally. If the increase amount of the sensor output voltage is greater than 0, it is determined in step S107 whether or not the 0 sheet determination formula is greater than 0. If “NO” in the step S107, it is determined whether or not the three-sheet determination formula is smaller than 0 (step S108). If “NO” in the step S108, it is determined whether or not the two-sheet determination formula is smaller than 0 (step S109). If “NO” in the step S109, it is determined whether or not the one-sheet determination formula is smaller than 0 (step S110). If “NO” in the step S110, it is determined that the remaining number is one (step S111).

  If YES in step S107, it is determined that the remaining number is 0 (step S112). If YES in step S108, the remaining number is determined to be 4 (step S113). If YES in step S109, the remaining number is determined to be 3 (step S114). If YES in step S110 described above, it is determined that the remaining number is two (step S115). Furthermore, if the sensor output voltage is smaller than 0.02 V in step S103, it is determined that the remaining number is 4 or more (step S117).

  As described above, after the remaining number of sheets is determined in steps S111, S112, S113, S114, S115, and S117, the sheet number data is updated (step S116), the process returns to step S102, and the above process is repeated.

In other words, the determination formula is greater than or equal to the number if the result of substituting the value is positive, and less than or equal to the number if negative. For example, if the calculation result of the three-sheet determination formula and the two-sheet determination formula is positive and the calculation result of the one-sheet determination formula is negative, the number is determined to be two. Although the determination equation is of plain paper, since performing the number determined by the formula of increment and border of the sensor output voltage, and wherein can be applied regardless of the sheet thickness.

  As described above, according to the first embodiment, the remaining number of sheet-like media 20 can be accurately detected by only one set of the light emitting unit 100 and the light receiving unit 101, so that no image formation is wasted. Cost can be increased.

  In the first embodiment, the method of accurately determining up to three sheets has been described, but any number of sheets may be determined.

(Second Embodiment)
FIG. 9 is a conceptual diagram illustrating a configuration in which an amplifier circuit is connected to the light receiving unit. The circuit shown in FIG. 9 includes a light receiving unit 51, an amplifier circuit 52, an amplification factor control unit 53, and a power supply 54. The amplification factor control unit 53 can change the amplification factor of the amplification circuit 52. Further, it may be configured to amplify at a constant magnification without connecting the amplification factor control unit 53. Then, by amplifying the output of the light receiving unit 51 by the amplifier circuit 52, the dynamic range can be widened, so that the remaining amount can be detected with high accuracy.

  As described above, according to the second embodiment, the amplifier circuit 52 that amplifies the transmitted light amount received by the light receiving unit 51 is provided, and the arithmetic unit 111 performs arithmetic processing based on the amplified output. The remaining amount of the sheet-like medium can be accurately detected.

  Note that the light receiving unit 51 in FIG. 9 outputs the obtained light amount as a voltage. Therefore, a non-inverting amplifier circuit using an operational amplifier can be considered as the amplifier circuit 52. However, this amplifier circuit does not necessarily have to use an operational amplifier, and any amplifier circuit that can amplify the voltage may be used.

(Third embodiment)
Next, in the image forming apparatus 1 in which the paper feed tray 31 includes 100 light emitting units and the light receiving unit 101, the transmission obtained by the light receiving unit 101 when detecting the number of sheet-like media in the paper feed tray 31. The amount of light is converted into a voltage, and the voltage is converted into a digital value by an A / D converter or the like. However, if the voltage value is small when determining the remaining amount, the remaining amount cannot be detected with high accuracy. Therefore, the voltage value is corrected by multiplying the converted digital value by a fixed magnification. The process of multiplying the digital value by a fixed magnification can be performed by the calculation unit 111 shown in FIG. Thereby, it is possible to detect the remaining amount with high accuracy.

  As described above, according to the third embodiment, the output of the light receiving unit 101 can be corrected by performing a calculation process in which the calculation unit 111 multiplies the transmitted light amount obtained by the light receiving unit 101 by a constant magnification, thereby achieving high accuracy. In addition, the remaining amount of the sheet-like medium can be detected.

(Fourth embodiment)
In the fourth embodiment, a case where the transmitted light amount obtained from the light receiving unit is converted into a voltage value will be described. First, the output of the light receiving unit 51 shown in FIG. 9 is adjusted to 0.8 V without being connected to the amplifier circuit 52. Thereafter, an amplifying circuit 52 for connecting the output obtained by the light receiving unit 51 arranged on the sheet-like medium 20 to 5 times is connected, and the obtained voltage is set to Vd. Here, if there is no variation in the elements such as resistors used in the amplifier circuit 52 or the influence of the offset input voltage when the operational amplifier is used in the amplifier circuit 52, the voltage 4.0V accurately obtained is obtained. be able to.

  However, for example, when there is an influence of only the input offset voltage and the input offset voltage is 0.1V, the output voltage after amplification is (0.8−0.1) × 5 = 3.5V.

  In addition, when there is an influence of only the resistance, the magnification is set to 5 times with the resistance of 1 kΩ and 4 kΩ in the non-inverting amplifier circuit, the error of the resistance of 1 kΩ is + 10%, and the error of the resistance of 4 kΩ is −10%. If so, the actual resistance magnitude is 1.1 kΩ and 3.6 kΩ, respectively, so the magnification of the non-inverting amplifier circuit is (3.6 / 1.1) + 1≈5.27 times and the output of the amplifier circuit is It becomes about 4.2V. For this reason, 4.0 V cannot be obtained when there is variation in magnification due to the influence of elements such as the resistance of the amplifier circuit and the offset input voltage of the operational amplifier as in the above example.

  Therefore, the calculation unit 111 calculates a voltage to be corrected by 0.8−Vd / 5 = Ve. Then, every time a voltage is obtained from the amplifier circuit 52, 5 × Ve is added to the voltage obtained from the amplifier circuit 52, so that even if it cannot be amplified five times due to variations in the elements of the amplifier circuit 52, etc. Since the corrected value can be obtained, the remaining amount can be detected with higher accuracy.

  As described above, according to the fourth embodiment, the correction value for the variation of the amplifier circuit 52 and the like is calculated in advance by the calculation unit 111, and the output obtained from the amplifier circuit 52 is calculated using the correction value. Since processing is performed, variations in the amplifier circuit 52 are corrected, and the remaining amount of the sheet-like medium can be detected with high accuracy.

(Fifth embodiment)
In the fifth embodiment, a case where the transmitted light amount obtained from the light receiving unit is converted into a voltage to obtain the transmitted light amount will be described. Depending on the type of the sheet-like medium, the relationship between the output voltage of the light receiving unit 101 and the amount of increase is different. Therefore, for example, if only plain paper and the second original drawing are fed, there are only two types of boundary line expressions for determining the number of sheets.

  However, when the OHP sheet is fed in addition to the plain paper and the second original drawing, three types of boundary line formulas for determining the number of sheets including the OHP sheet are required. Therefore, the sheet remaining amount detection apparatus according to the fifth embodiment includes boundary line formulas for determining the number of types of sheets, and determines the number of sheets according to the type of the sheet-like medium 20 from among them. Therefore, the calculation process is performed by switching the expression of the boundary line. Thereby, the remaining amount can be accurately detected.

  For example, FIG. 10 is a graph showing the relationship between the output voltage of the light receiving unit and the increase amount of the light receiving unit on the TA paper of the second original diagram, and the boundary between the number of each point with respect to each number of points. It is the figure which drew the line. As shown in FIG. 10, when the type of the sheet-like medium 20 is different, a graph corresponding to the sheet-like medium is created, and an arithmetic process corresponding to the type of the sheet-like medium is performed by deriving a boundary line expression. This makes it possible to detect the remaining amount with high accuracy.

  As described above, according to the fifth embodiment, the calculation unit 111 has a boundary line expression for determining the number of sheets of sheet-like medium for each type of sheet-like medium, and according to the sheet-like medium to be used. Since the calculation process is performed by switching the expression of the boundary line, the remaining amount of the sheet-like medium can be detected with high accuracy.

(Sixth embodiment)
In the sixth embodiment, a case where the transmitted light amount obtained from the light receiving unit is converted into a voltage to obtain the transmitted light amount will be described. Here, even if the same sheet-like medium 20 is used, if the number of sheets is determined using one boundary line expression, the determination may be severe. Therefore, for example, the boundary line expression of the two and three sheets is switched as follows according to the case where the output voltage of the light receiving unit 101 is 0 V or more, less than 1 V, or 1 V or more. The plurality of boundary line expressions are stored in advance in the memory 112 of FIG. 4, for example, and the control unit 110 reads the corresponding boundary line expressions from the memory 112 in accordance with the output voltage from the light receiving unit 101. Thus, calculation processing is performed by the calculation unit 111.

[0V or more and less than 1V]
-0.1279 x light receiving means output voltage x light receiving means output voltage +0.4379 x light receiving means output voltage +0.022
[In case of 1V or more]
−0.0433 × light receiving means output voltage × light receiving means output voltage + 0.3529 × light receiving means output voltage + 0.0396

  As described above, according to the sixth embodiment, even in the same sheet-like medium 20, the boundary line expression used for determining the number of sheets is switched in accordance with the output voltage of the light receiving unit, so that the sheet-like shape is more accurately obtained. The remaining amount of the medium can be detected.

  The above example is merely an example, and the method of dividing the output voltage or the expression of the boundary line to be used is not limited to the above example.

  The sheet remaining amount detection device described in the above embodiment can be detected in the sheet feeding medium 31 as shown in FIGS. 2 and 3 to detect the remaining amount of the sheet-like medium with low cost and high accuracy. It can be implemented as a paper feeding device.

  In addition, the sheet remaining amount detection device described in the above embodiment is mounted in a sheet feed tray 31 as shown in FIG. It can be implemented as an image forming apparatus capable of detecting the remaining amount of the medium.

  In addition, the sheet feeding device described in the above embodiment can be detected at low cost and with high accuracy in the remaining amount of sheet-like medium by being incorporated in the image forming apparatus 1 as a sheet feeding tray 31 as shown in FIG. It can be implemented as an image forming apparatus.

  As described above, the remaining sheet amount detecting device, the sheet feeding device, and the image forming apparatus according to the present invention are a remaining sheet amount detecting device that detects the remaining amount of a sheet-like medium using a light emitting unit and a light receiving unit, Is suitable for an image forming apparatus such as a color digital copying machine and the like.

1 is a cross-sectional view illustrating a schematic configuration of an image forming apparatus including a remaining sheet amount detecting device according to the present invention. FIG. 2 is an enlarged view of a periphery of a sheet feeding tray and a transfer device in FIG. 1. It is a conceptual diagram which shows one Embodiment of the paper feeder which concerns on this invention. FIG. 3 is a block diagram illustrating a configuration of a sheet remaining amount detection device according to the present invention. FIG. 4 is a conceptual diagram illustrating a distance and a positional relationship between a light emitting unit and a light receiving unit provided in the paper feed tray of FIG. 3. It is the figure which measured the output voltage of the light-receiving part when five sheets of plain paper became 4 sheets-> 3 sheets-> 2 sheets-> 1 sheet, and plotted the relationship between the output voltage of a light-receiving part, and its increase amount. . FIG. 7 is a diagram in which a boundary line for each number is drawn with respect to each number of points in FIG. 6. It is a flowchart explaining the arithmetic processing procedure in a calculating part. It is a conceptual diagram explaining the structure by which the amplifier circuit was connected to the light-receiving part. In the TA paper of the second original figure, the output voltage of the light receiving unit is measured, the relationship between the output voltage of the light receiving unit and the increase amount is graphed, and the boundary line of each number is drawn for each number of points. is there.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Image forming apparatus 2 Image forming part 20 Sheet-like medium 3 Paper feed part 31 Paper feed tray (paper feed part)
32 Paper Feeding Device 33 Registration Roller 34 Bottom Plate 36 Paper Feeding Roller 37 Paper Feeding Roller 38 Pickup Roller 4 Reading Unit 41 Automatic Document Feeder (ADF)
DESCRIPTION OF SYMBOLS 5 Discharge storage part 51 Light receiving part 52 Amplifying circuit 53 Amplification factor circuit 54 Power supply 6 Intermediate transfer belt 61 Transfer apparatus 62 Intermediate transfer cleaning apparatus 7 Image forming part 71 Photoconductor 72 Charging apparatus 73 Developing apparatus 74 Cleaning apparatus 8 Exposure apparatus 9 Fixing Device 100 Light emitting unit 101 Light receiving unit 110 Control unit 111 Calculation unit 112 Memory

Claims (9)

A light emitting means and a light receiving means that are arranged opposite to each other at positions sandwiched in the thickness direction of a plurality of sheet-like media;
First storage means for storing a first light quantity obtained by the light receiving means receiving light emitted from the light emitting means that has passed through the plurality of sheet-like media;
A light amount increase amount that is a difference between the second light amount obtained by the light receiving unit and the first light amount when the plurality of sheet-like media are decreased by one sheet from the time when the first light amount is acquired. Second storage means for storing
Third storage means for storing in advance a range in which the relationship between the increase amount of the light amount and the second light amount can be taken for each number of sheets at the second light amount;
A calculation unit that calculates the remaining amount of the plurality of sheet-like media based on the range stored in the third storage unit, the increase amount of the light amount, and the second light amount ;
Sheet residual amount detecting device characterized by Ru with a. It said light receiving means, the sheet remaining in claim 1, wherein the performing by that operation on the operation means on the basis of the light quantity provided an amplifier circuit to amplify to amplify the amount of light obtained by receiving Quantity detection device. The sheet remaining amount detection according to claim 1, wherein the calculating unit corrects an output of the light receiving unit by performing a calculation process of multiplying a light amount obtained by receiving the light by the light receiving unit by a predetermined magnification. apparatus.   The sheet remaining amount according to claim 2, wherein the calculation means calculates a correction value for variations in the amplifier circuit in advance, and uses the correction value to calculate an output obtained from the amplifier circuit. Detection device. The calculation means uses the third storage means that stores, for each type of sheet-like medium, a range in which the relationship between the amount of increase in the light quantity and the second light quantity can be taken , according to the sheet-like medium to be used. 5. The sheet remaining amount detecting apparatus according to claim 1, wherein the arithmetic processing is performed by switching the expression of the boundary line. The sheet remaining amount detection apparatus according to claim 1, wherein the calculation unit changes a method of calculation processing according to the second light amount obtained from the light receiving unit. A sheet feeding device using the sheet remaining amount detection device according to any one of claims 1 to 6, wherein the first light amount of the sheet-like medium and the number of sheet-like media whose number of sheets has decreased after feeding. A sheet feeding device that detects the number of sheet-like media by obtaining the second light amount and performing arithmetic processing.   An image forming apparatus comprising the sheet remaining amount detecting device according to any one of claims 1 to 6 as recording sheet remaining amount detecting means for performing image formation.   An image forming apparatus comprising the sheet feeding device according to claim 7.

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