JP4638773B2 - Recording medium remaining amount detection device - Google Patents

Description

The present invention relates to a recording medium level detecting unit, and more particularly to a recording medium residual amount detection device for detecting the remaining amount of the sheet-shaped recording medium on the mounting table in low cost and high accuracy.

  In image forming apparatuses such as electrophotographic systems, ink jet systems, and other recording systems such as copying machines, printers, facsimile machines, and composite machines, sheet-like recording such as sheet-like paper, film, etc., one by one from the paper feed unit The medium is conveyed to the image forming unit, and the image forming unit sequentially forms images on the conveyed sheet-like recording medium.

  In the conventional image forming apparatus, the first transmitted light amount detecting means for detecting the transmitted light amount of the sheet passing on the sheet conveyance path and the second transmitted light amount of the sheet placed on the sheet tray are detected. The remaining amount of paper in the paper tray is determined from the detected transmitted light amount value of the transmitted light amount detection means (see Patent Document 1).

  In this case, for example, as the first transmitted light amount detecting unit and the second transmitted light amount detecting unit, the light emitting unit and the light receiving unit are disposed with the detection target sheet sandwiched in the thickness direction of the sheet, and the first transmitted light amount detecting unit receives light. By simply performing a comparison operation between the detection voltage or detection current as the detection value output from the means and the detection voltage or detection current as the detection value output from the light receiving means of the second transmitted light amount detection means, the remaining paper in the paper tray Judging the number of sheets.

Japanese Patent Laid-Open No. 2003-159859

  However, the prior art described in the above publication requires improvement in detecting the number of recording media remaining at low cost and high accuracy.

That is, in the above prior art, the detection value output from the light receiving means of the first transmitted light amount detecting means and the detection value output from the light receiving means of the second transmitted light amount detecting means are simply compared and calculated, so that the paper tray because it determines the residual amount of paper as the recording medium of the inner, for instance, it is a specification of the same light emitting means of the light receiving means and the second transmitted light quantity detecting means of the first transmitted light detecting means, first transmission When the light detection means and the second transmitted light amount detection means have different arrangement conditions such as the distance and angle between the light emitting means and the light receiving means in the thickness direction of the recording medium, the remaining amount of the recording medium can be accurately detected. could not. In this case, in order to improve the accuracy, if dedicated light emitting means and light receiving means are used, there is a problem that the cost becomes high and it is not economical.

The present invention aims to provide a recording medium residual amount detection device for detecting inexpensively and accurately the remaining amount of the recording medium on the table.

To achieve the above object, the first means, the device was irradiated with light from a light emitting element in the thickness direction for a sheet-like recording medium to be loaded, receiving the light transmitted through the recording medium by the light receiving element, and placing the recording medium detecting means for outputting an output value that corresponds to the received light amount from the light receiving element, transmitted through the one recording medium is irradiated with light from the light emitting element in the thickness direction for the one recording medium The received light is received by the light receiving element, and an output value corresponding to the amount of received light is output from the light receiving element, and the light receiving elements of both the above-described placement recording medium detecting means and the transported recording medium detecting means receiving the remaining amount detecting means for comparing the output values for detecting the remaining amount of the recording medium, both with the placement recording medium detection means in a state where record medium is not present between the transfer recording medium detecting means The larger output value of the element output values is the reference value. And a correction means for amplifying the smaller output value to the reference value, and a recording medium remaining amount detecting device.
The second means is characterized in that in the first means, there is provided an amplification factor adjusting means for adjusting an amplification factor when the correction means performs the amplification.
Further, the third means is characterized by an image forming apparatus provided with the recording medium remaining amount detecting apparatus according to the first or second means.

According to the onset bright, it can be detected inexpensively and accurately the residual amount of record medium.

  Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. In addition, since the Example described below is a suitable Example of this invention, various technically preferable restrictions are attached | subjected, However, The scope of the present invention limits this invention especially in the following description. As long as there is no description of the effect, it is not restricted to these aspects.

  1 to 7 are diagrams showing an embodiment of a recording medium remaining amount detecting device according to the present invention. FIG. 1 is an image forming apparatus 1 to which an embodiment of a recording medium remaining amount detecting device according to the present invention is applied. FIG.

  In FIG. 1, the image forming apparatus 1 has an image forming unit 100 disposed at the center, a paper feeding unit 200 disposed below the image forming unit 100, and a reading unit 300 above the image forming unit 100. Further, an ADF (Auto Document Feeder) 310 is disposed on the upper portion of the reading unit 300.

  In FIG. 1, a plurality of sheet feeding units 200, four sheet feeding trays 201 a to 201 d are arranged in the vertical direction, and each sheet feeding tray 201 a to 201 d has a plurality of sheets as shown in FIG. 2. A sheet-like recording medium P is accommodated, and bottom plates (mounting bases) 202a to 202d on which the recording medium P is placed with the leading end side in the feeding direction inclined upward are accommodated. The paper feed unit 200 is provided with feed rollers 203a to 203d and separation rollers 204a to 204d provided in the paper feed trays 201a to 201d, and the recording medium P sent from the paper feed trays 201a to 201d. The image forming unit 100 includes a plurality of conveying rollers 205 and the like, and the sheet feeding unit 200 is provided with an additional sheet feeding unit 210 and a manual sheet feeding unit 211 as necessary.

  The paper feed unit 200 feeds the uppermost recording medium P from the selected paper feed trays 201a to 201d by the feed rollers 203a to 203d, and separates the recording medium P sent by the feed rollers 203a to 203d from the separation rollers 204a to 204. Are separated one by one and sent to the conveying roller 205. The conveyance roller 205 conveys the recording medium P separated and fed one by one from the paper feed trays 201 a to 201 d to the image forming unit 100.

  The reading unit 300 reads and reads an image of a document set on the document table 301 by performing main scanning and sub-scanning. The ADF 310 sequentially transports the set plurality of documents one by one to the reading position of the reading unit 300, and the reading unit 300 sequentially reads the images of the documents conveyed to the reading position by the ADF 310.

  The image forming unit 100 includes a transfer belt mechanism unit 110, and image forming units 111 of yellow (Y), magenta (M), cyan (C), and black (K) colors arranged along the transfer belt mechanism unit 110. , An optical writing unit 112, a secondary transfer unit 113, a fixing unit 114, a reversing unit 115, a registration roller 116, and the like. A drive mechanism unit for transmitting

  The image forming unit 100 is based on image data of each color such as image data of a document read by the reading unit 300 or image data received from a host device such as a personal computer via a network (not shown) or image data received by facsimile. Laser light modulated by the optical writing unit 112 is irradiated to the photoconductor of the image forming unit 111 of each color, and an electrostatic latent image for each color is formed on the photoconductor. The image forming unit 100 develops the electrostatic latent image on the photoreceptor of the image forming unit 111 of each color by attaching the toner of each color in the developing unit of the image forming unit 111 to form a toner image of each color, The toner images of the respective colors are sequentially superimposed and transferred onto a transfer belt 117 that is rotationally driven clockwise by the transfer mechanism unit 110 to form a color toner image on the transfer belt 117. The image forming unit 100 transfers the toner image on the transfer belt 117 to the recording medium P conveyed from the paper feeding unit 200 by the secondary transfer unit 113. That is, as shown in FIG. 2, the recording medium P from the paper feeding unit 200 is conveyed to the registration roller 116, and the registration roller 116 adjusts the timing with the toner image on the transfer belt 117, thereby performing the secondary transfer. Sent between the portion 113 and the transfer belt 117.

  The image forming unit 100 transfers the toner image on the transfer belt 117 to the recording medium P by the secondary transfer unit 113, conveys the recording medium P to which the toner image has been transferred to the fixing unit 114, and heats / The toner image on the recording medium is fixed to the recording medium P by being conveyed while being pressurized. The image forming unit 100 discharges the recording medium P on which the toner image has been fixed onto a paper discharge tray 118 outside the apparatus, and, if necessary, the recording medium P on which the toner image has been fixed on the reversing unit 115. Then, the toner image is transferred again between the secondary transfer unit 113 and the transfer belt 117 via the registration roller 116 and transferred onto the back surface. The image forming unit 100 discharges the recording medium P on which the toner image has been transferred onto the back surface onto the paper discharge tray I118 after the toner image is fixed by the fixing unit 114 as described above.

  As shown in FIG. 3, the image forming apparatus 1 according to the present exemplary embodiment detects the recording medium P stored in each of the paper feed trays 201a to 201d with respect to the paper feed tray 201a. (Loaded recording medium detection means) 220 and a conveyance recording medium detection section (conveyance recording medium detection means) 221 for detecting the recording medium P sent out from the paper feed trays 201a to 201d onto the conveyance path are provided. .

  The mounted recording medium detection unit 220 includes a light emitting unit 220a that projects detection light in the thickness direction of the recording medium P that is attached to the bottom plates 202a to 202d of the paper feed trays 201a to 201d, and the light emitting unit 220a. A light receiving unit 220b that receives the detection light from the light and photoelectrically converts it to output a detection signal (output value). That is, the mounted recording medium detection unit 220 detects the transmitted light in the thickness direction of the recording medium P mounted on the bottom plates 202a to 202d of the paper feed trays 201a to 201d by the light receiving unit 220b, and detects the detected light. Output a signal. As shown in FIG. 4, in the mounted recording medium detection unit 220, the light receiving unit 220b is disposed on the bottom plates 202a to 202d on which the recording medium P is mounted, and the light emitting unit 220a is mounted on the bottom plates 202a to 202d. Above the recording medium P to be placed, the angle (medium) formed between the detection light directed from the light emitting unit 220a to the light receiving unit 220b and the surface of the recording medium P to be detected is arranged at a predetermined distance C1 from the light receiving unit 220b. Angle) E1 is a predetermined medium angle. That is, the thickness direction of the recording medium P and the direction of the detection light are inclined by the medium angle E1. In FIG. 4, the distance D1 is the distance between the light receiving unit 220b and the surface of the recording medium P. The mounted recording medium detection unit 220 transmits the transmitted light in the thickness direction of the recording medium P placed on the bottom plates 202a to 202d of the paper feed trays 201a to 201d to the recording medium P with a predetermined medium. Detection is performed in a state inclined by an angle E1, and a detection signal is output.

  The transport recording medium detection unit 221 is a light emitting unit disposed in a state of being opposed to each other in the thickness direction of the transported recording medium P across the transport path of the recording medium P sent out from each of the paper feed trays 201a to 201d. 221a and a light receiving unit 221b, the light emitting unit 221a projects detection light in the thickness direction of the transported recording medium P, and the light receiving unit 221b is projected from the light emitting unit 221a and transmitted through the recording medium P. Is received and photoelectrically converted to output a detection signal. That is, as shown in FIG. 5, the conveyance recording medium detection unit 221 has a predetermined distance between the light emitting unit 221a and the light receiving unit 221b across the conveyance path of the recording medium P sent out from each of the paper feed trays 201a to 201d. The recording medium P is transported in a state of approximately 90 ° (right angle) with respect to the detection light from the light emitting unit 221a to the light receiving unit 221b. That is, the thickness direction of the recording medium P matches the direction of the detection light. In FIG. 5, the distance D2 is the distance between the light receiving unit 221b and the surface of the recording medium P. The transport recording medium detection unit 221 detects the transmitted light in the thickness direction of the recording medium P sent from each of the paper feed trays 201a to 201d at a medium angle E2 perpendicular to the recording medium P, and detects the detection signal. Is output.

  The above-described recording medium detection unit 220 and transport recording medium detection unit 221 have the same specifications of the light emitting unit 220a and the light emitting unit 221a, and the light receiving unit 220b and the light receiving unit 221b, respectively. For example, in consideration of miniaturization, an LED (Light Emitting Diode) element, a semiconductor laser, or the like can be used as the light emitting unit 221a, but other light emitters such as an incandescent lamp and a fluorescent lamp may be used. As the light receiving portions 220b and 221b, for example, a phototransistor, a photodiode, or the like can be used. Any detection element can be used as long as it can detect received light by converting it into some value. Good. Further, the mounted recording medium detection unit 220 and the transported recording medium detection unit 221 have the light emitting unit 220a, the light receiving unit 220b, and the light emitting unit 221a, as shown in FIG. 4 and FIG. And the arrangement conditions of the light receiving unit 221b (distances C1, C2, medium angles E1, E2 between the recording medium P and the detection light, distances D1, D2 between the light receiving units 220b, 221b and the recording medium P, etc.) may be different. It may be the same or the same.

  As shown in FIG. 6, the image forming apparatus 1 is provided with an amplification circuit unit (correction means) 10 in an internal control circuit (not shown). The amplification circuit unit 10 has a light receiving unit with a smaller output. 220b, 221b, in this embodiment, an amplification circuit (amplifying means) 11 connected to the light receiving part 220b of the mounted recording medium detection unit 220 and an amplification factor control unit (amplification factor adjusting means) for controlling the amplification factor of the amplification circuit 11 ) 12 etc. Various amplifier circuits 11 can be used. For example, when the output of the light receiving unit 220b is a voltage, a non-inverting amplifier circuit using an operational amplifier can be used. The placement recording medium detection unit 220, the transport recording medium detection unit 221, and the amplification circuit unit 11 function as a recording medium remaining amount detection device 230 as a whole.

The amplifying circuit unit 10 outputs the output value of the light receiving unit 220b or 221b having the smaller output value out of the light receiving unit 220b of the loaded recording medium detecting unit 220 and the light receiving unit 221b of the transported recording medium detecting unit 221. Using the output value as a reference value, the amplifier circuit 11 amplifies (corrects) the output value so that it matches the larger output value, which is the reference value, so that the light emitting unit 220a, the light receiving unit 220b, the light emitting unit 221a, and the light receiving unit 221b. In the state where the recording medium P does not exist between them (there is no interposition), the output values of the light receiving unit 220b and the light receiving unit 221b under different arrangement conditions are matched, and the light receiving units 220b and 221b with smaller outputs are matched. by amplifying the output, and wide dynamic range, improve the detection accuracy of the remaining amount of the recording medium P. Further, the amplification factor control unit 12 can adjust the amplification factor of the amplification circuit 11 to easily and more appropriately match the outputs of the light receiving unit 220b and the light receiving unit 221b without the recording medium P interposed.

Next, the operation of this embodiment will be described. The image forming apparatus 1 of this embodiment, the transport records remaining amount of the recording medium P placed on the bottom plate 202a~202d of each paper feed tray 201 a to 201 d, the detection result of the mounting recording medium detecting unit 220 and Based on the detection result of the medium detector 221, the detection is inexpensive and highly accurate.

  That is, the image forming apparatus 1 conveys the recording medium P from the selected paper feed trays 201a to 201d among the plurality of paper feed trays 201a to 201d of the paper feed unit 200 to the image forming unit 100 one by one, and reads the reading unit. Based on the image data of the document read in 300 or the image data received from the outside, the image forming unit 100 creates a toner image and transfers it to the recording medium P conveyed from the paper feeding unit 200. The toner image on P is fixed by the fixing unit 114 and discharged onto the paper discharge tray 118 to form an image.

Then, in the image forming operation, or the remaining amount of the recording medium P in the paper feed tray 201a~201d is many pieces is important.

In view of this, the image forming apparatus 1 according to the present exemplary embodiment includes the mounted recording medium detection unit 220 in each of the paper feed trays 201 a to 201 d and transports the recording medium P from each of the paper feed trays 201 a to 201 d to the image forming unit 100. A conveyance recording medium detection unit 221 is provided on the path, and the inside of the paper feed trays 201a to 201d is based on the detection result of the transmitted light of the recording medium P of the loaded recording medium detection unit 220 and the detection result of the conveyance recording medium detection unit 221. and it calculates the remaining amount of the recording medium P.

That is, when one sheet-like recording medium P is transported on the transport path, the light transmission section 221a and the light receiving section 221b of the transport recording medium detection section 221 detect the amount of light transmitted through the recording medium P, and the recording On the bottom plates 202a to 202d of the paper feed trays 201a to 201d by the light emitting unit 220a and the light receiving unit 220b of the loaded recording medium detection unit 220 disposed in the paper feed trays 201a to 201d in which the medium P is stored. The amount of transmitted light that has passed through a plurality of recording media P is detected, and the paper feed tray is determined based on the amount of transmitted light detected by the transported recording medium detection unit 221 and the amount of transmitted light detected by the loaded recording medium detection unit 220. and it calculates the remaining amount of the recording medium P in the 201 a to 201 d.

  Now, the specifications of the light emitting unit 220a of the mounted recording medium detecting unit 220, the light emitting unit 221a of the transported recording medium detecting unit 221, the light receiving unit 220b of the transported recording medium detecting unit 221, and the light receiving unit 221b of the transported recording medium detecting unit 221 are described. Are the same, and the arrangement conditions of the light emitting section 220a and the light receiving section 220b of the loaded recording medium detection section 220 and the arrangement conditions of the light emitting section 221a and the light receiving section 221b of the transport recording medium detection section 221, ie, the light emitting section 220a and the light receiving section. If the arrangement conditions such as the distance between the portion 220b and the light emitting portion 221a and the light receiving portion 221b, the distance between the recording medium P and the light receiving portion 220a or the light receiving portion 221a, the inclination angle of the recording medium P with respect to the optical axis of the detection light are different. The output of the light receiving unit 220b of the recording medium detection unit 220 and the output of the light receiving unit 221b of the conveyance recording medium detection unit 221 are different. When the output of the light receiving portion 220b of the recording medium detecting unit 220 is small, the output dynamic range of the narrows, the detection accuracy becomes lowered.

  Therefore, if the outputs of the light receiving unit 220b and the light receiving unit 221b when the recording medium P does not exist between the light emitting unit 220a and the light receiving unit 220b and between the light emitting unit 221a and the light receiving unit 221b, one sheet is obtained. Output when the detection light is transmitted through the recording medium P (hereinafter, the outputs of the light receiving unit 220b and the light receiving unit 221b when the detection light is transmitted through the recording medium P) coincide with each other. The outputs of the light receiving unit 220b and the light receiving unit 221b have the same ratio as in the case where the arrangement conditions of the light emitting unit 220a and the light emitting unit 221a are the same, and the light receiving unit 220b when compared with the output (transmission output) of one recording medium P1. The transmission output dynamic range can be effectively used, and the remaining amount of the recording medium P can be detected with higher accuracy.

  Further, in order to obtain the same output, if the arrangement conditions of the light emitting unit 220a and the light receiving unit 220b of the mounted recording medium detection unit 220 and the arrangement conditions of the light emitting unit 221a and the light receiving unit 221b of the transport recording medium detection unit 221 are the same, The size of the image forming apparatus 1 may increase, or the layout of the image forming apparatus 1 may cause inconveniences such as being unable to mount the light emitting units 220a and 221a and the light receiving units 220b and 221b. In many cases, it is difficult to make the condition. As a result, the arrangement conditions of the light emitting section 220a and the light receiving section 220b of the loaded recording medium detection section 220 and the arrangement conditions of the light emitting section 221a and the light receiving section 221b of the transport recording medium detection section 221 are different.

  Now, for example, as shown in FIGS. 4 and 5, the distance C1 between the light emitting unit 220a and the light receiving unit 220b of the loaded recording medium detecting unit 220> the light emitting unit 221a and the light receiving unit 221b of the transported recording medium detecting unit 221. The distance C2 between the recording medium P and the light receiving unit 220b> the distance D2 between the recording medium P and the light receiving unit 221b, and the medium angle E1 between the optical axis of the loaded recording medium detecting unit 220 and the recording medium P is predetermined. When the medium angle E2 formed by the optical axis of the transport recording medium detection unit 221 and the recording medium P is a right angle, specifically, distance C1 = 30 mm> distance C2 = 14 mm, distance D1 = 8. When 5 mm> distance D2 = 2 mm, medium angle E1 = 55 °, and medium angle E2 = 90 °, here, the light emitted from the light emitting unit 220a and the light emitted from the light emitting unit 221a are equivalent. The amount of light is the distance C 1, C 2, angles E 1, E 2, distances D 1, D 2, and the like. In the above example, the amount of light received by the light receiving unit 220 b is smaller than the amount of light received by the light receiving unit 221 b due to these arrangement conditions. As a result, if the output of the light receiving unit 220b is used as it is, the dynamic range becomes narrow, and the detection accuracy of the remaining amount detection of the recording medium P in the paper feed trays 201a to 201d is lowered.

  When light emitting diodes are used as the light emitting portions 220a and 221a and phototransistors are used as the light receiving portions 220b and 221b, the relationship between the current flowing through the light emitting diodes and the voltage output from the phototransistor is as shown in FIG. FIG. 7 shows the relationship between the light emitting diode current of the mounted recording medium detector 220 and the phototransistor output in FIG. 4 as output F, and the relationship between the light emitting diode current of the carrier recording medium detector 221 and the phototransistor output in FIG. The relationship is output G. As can be seen from FIG. 7, the amount of light emitted from the light emitting diode increases as the amount of current flowing increases, and the amount of light received by the phototransistor increases as the current of the light emitting diode increases and the amount of emitted light increases. growing. Therefore, in order to increase the phototransistor output, it is conceivable to increase the light amount of the light emitting diode.

  However, since the light emitting diode has an absolute maximum rating, the current that can be passed is limited, and there is a limit to the increase in the output of the phototransistor due to the increase in the light emission amount of the light emitting diode. That is, in FIG. 7, in order to obtain the phototransistor output I1, a light emitting diode current of H1 is required for the output G and H2 is required for the output F, but when H2 exceeds the absolute maximum rating of the light emitting diode, The phototransistor output I1 cannot be obtained.

  However, if the phototransistor output of output F is amplified (corrected) to the level of output G so that output F matches output G, phototransistor output I1 can be obtained with light emitting diode current H1.

  Therefore, the image forming apparatus 1 is provided with an amplification circuit unit 10 in an internal control circuit (not shown) as shown in FIG. 6, and the amplification circuit unit 10 receives light receiving units 220b and 221b having a smaller output. In this embodiment, the output of the light receiving unit 220b of the loaded recording medium detection unit 220 is amplified (corrected) so as to match the output value of the larger light receiving unit 220b, 221b.

That is, as described above, the amplification circuit unit 10 outputs the light receiving units 220b and 221b having a smaller output among the light receiving unit 220b of the loaded recording medium detection unit 220 and the light receiving unit 221b of the transport recording medium detection unit 221. By amplifying (correcting) the amplification circuit 11 so that the value matches the output value of the larger light receiving unit 220b, 221b, light reception without the recording medium P intervening even if the arrangement conditions are different. parts 220b and to match the output of the light receiving portion 221b, also, the smaller the light receiving portion 220b of the output, by amplifying the output of the 221b, and wider dynamic range, improving the detection accuracy of the remaining amount of the recording medium P Let In addition, the amplification circuit unit 10 can change the amplification factor of the amplification circuit 11 by the amplification factor control unit 12, and easily and more appropriately equalize the outputs of the light receiving unit 220b and the light receiving unit 221b under different arrangement conditions, The detection accuracy can be further improved.

  Note that the amplification circuit unit 10 may be configured such that the amplification circuit 11 amplifies at a constant magnification without connecting the amplification factor control unit 12.

Now, when the output voltage of the light receiving unit 220b of the mounted recording medium detection unit 220 is 0.8V and the output voltage of the light receiving unit 221b of the transport recording medium detection unit 221 is 4.0V, the output of the light receiving unit 220b receives light. For example, a non-inverting amplifier circuit using an operational amplifier with a magnification of 5 is connected to the light receiving unit 220b as the amplification circuit 11 so that the output is 4.0V equivalent to that of the unit 221b, and the output of the light receiving unit 220b is amplified five times. Thus, even if the arrangement conditions of the light emitting part 220a and the light receiving part 220b of the loaded recording medium detecting part 220 and the transported recording medium detecting part 221 are different, the recording medium P is not interposed. the output voltage can be made equal, it is possible to improve the detection accuracy of the remaining amount of the recording medium P in each of the paper feeding tray 201 a to 201 d.

In addition, when the output voltage of the light receiving unit 221b is smaller than the output voltage of the light receiving unit 220b, the light receiving unit without the recording medium P interposed by connecting the amplifier circuit 11 such as a non-inverting amplifier circuit to the light receiving unit 221b. the output voltage of 221b by amplifying the output voltage to match the output voltage of the light receiving portion 220b, it is possible to improve the detection accuracy of the remaining amount of the recording medium P in each of the paper feeding tray 201 a to 201 d.

Further, the image forming apparatus 1 of this embodiment, the amplification factor control unit 12 provided in the amplifier circuit portion 10, since the adjusted amplification factor of the amplifying circuit 11, more the detection accuracy of the remaining amount of the recording medium P This can be further improved.

  That is, in the case of FIG. 6, the amplifier circuit 11 is connected to the light receiving unit 220b, and amplification is performed so that the output of the light receiving unit 220b in the state where the recording medium P is not present coincides with the output of the light receiving unit 221b. For example, when the photo-transistors 221b are phototransistors, the sensitivities are not necessarily the same, so even if the light-receiving elements have the same specifications, all outputs do not always match.

  Therefore, the amplification circuit unit 10 connects the amplification factor control unit 12 to the amplification circuit 11, and the amplification factor control unit 12 adjusts the amplification factor of the amplification circuit 11 in accordance with the sensitivity of the light receiving unit 220b.

  Therefore, the output of the light receiving unit 220b in the state where the recording medium P is not interposed can be corrected with high accuracy so as to coincide with the light receiving unit 221b, and the light emission of the mounted recording medium detection unit 220 and the conveyance recording medium detection unit 221. The specifications of the unit 220a, the light emitting unit 221a, the light receiving unit 220b, and the light receiving unit 221b are the same, and the light receiving unit 220a, the light receiving unit 220b, and the light emitting unit 221a of the mounted recording medium detecting unit 220 and the transported recording medium detecting unit 221 receive light. Even if the arrangement condition with the part 221b is different, the detection accuracy of the recording medium P can be further improved.

  In addition, when the output of the light receiving unit 220b or the light receiving unit 221b is amplified by the amplifier circuit 11 of the amplifier circuit unit 10, a correction value for the variation of the amplifier circuit 11 is acquired in advance, and this correction value is used as the output of the amplifier circuit 11. On the other hand, arithmetic processing may be performed.

  That is, for example, in FIG. 6, when the output voltage of the light receiving unit 220b of the loaded recording medium detection unit 220 is 0.8V and the output voltage of the light receiving unit 221b of the transport recording medium detection unit 221 is 4.0V, The voltage is adjusted to 0.8 V without connecting the amplifier circuit 11 to the light receiving unit 220b. After that, the amplifier circuit 11 that multiplies the output obtained by the light receiving unit 220b of the loaded recording medium detection unit 220 arranged in the paper feed trays 201a to 201d is connected, and the obtained voltage is Va. Here, if there is no variation in the elements such as resistors used in the amplifier circuit 11 or the influence of an offset input voltage when using an operational amplifier as the amplifier circuit 11, the output of the light receiving unit 220b is accurately set to 0.8V. A voltage 4.0V multiplied by 5 can be obtained as an output of the amplifier circuit 11.

  However, for example, when the amplification of the amplifier circuit 11 is affected only by the input offset voltage and the input offset voltage is 0.1 V, the output voltage after amplification by the amplifier circuit 11 is (0.8 −0.1) × 5 = 3.5V. When the amplification of the amplifier circuit 11 is affected only by the resistance, the non-inverting amplifier circuit sets the magnification to 5 times with the resistance of 1 kΩ and 4 kΩ, and the error of the resistance of 1 kΩ is + 10% and 4 kΩ. If the resistance error is −10%, the actual resistance magnitudes are 1.1 kΩ and 3.6 kΩ, and the magnification of the non-inverting amplifier circuit is (3.6 / 1.1) + 1≈5. .27 times, and the output of the amplifier circuit 11 is about 4.2V. Therefore, as in the above example, 4.0 V cannot be obtained if there is a variation in magnification due to factors such as the resistance of the amplifier circuit 11 and the offset input voltage of the operational amplifier.

Therefore, in the case of the above example, the voltage to be corrected is calculated by 0.8−Va / 5 = Vb. Each time an output voltage is obtained from the amplifier circuit 11, 5 × Vb is added to the voltage obtained from the amplifier circuit 11, so that it cannot be amplified five times due to variations in elements of the amplifier circuit 11. may also be able to obtain a corrected value to be 5 times, to detect the more the remaining amount of accurately recording medium P.

In the above description, with reference to the amplifier circuit portion 10, by amplifying the output of the light receiving section 220b or the light receiving portion 221b, but to improve the detection accuracy of the remaining amount of the recording medium P, to improve the detection accuracy The method is not limited to the above method. For example, although not shown, by providing an arithmetic processing unit (arithmetic processing means) that converts the outputs of the light receiving unit 220b and the light receiving unit 221b into digital values and performs arithmetic processing. The detection accuracy may be improved.

  That is, for example, the output (for example, output voltage) of the light receiving unit 220b of the loaded recording medium detecting unit 220 and the light receiving unit 221b of the transported recording medium detecting unit 221 is converted into a digital value by an A / D converter or the like, and digitally converted. The output value is matched with a predetermined reference value, or on the other hand, for example, the larger output value is used as a reference value, and the smaller output value is matched with the larger output value. In this case, when the smaller output value is matched with the larger output value, they may be matched by multiplying by a predetermined fixed magnification.

  In this way, the light emitting unit 220a of the loaded recording medium detection unit 220, the light emitting unit 221a of the transport recording medium detection unit 221, the light receiving unit 220b of the transport recording medium detection unit 221, and the light receiving unit of the transport recording medium detection unit 221. The specifications of 221b are the same, and the arrangement conditions of the light emitting unit 220a and the light receiving unit 220b of the loaded recording medium detecting unit 220 and the arrangement conditions of the light emitting unit 221a and the light receiving unit 221b of the transported recording medium detecting unit 221 are different. In addition, the output values of the light receiving unit 220b and the light receiving unit 221b without the recording medium P can be corrected with high accuracy, and the detection accuracy of the recording medium P can be further improved.

  In the above description, the case where the recording medium remaining amount detecting device 230 is applied to the image forming apparatus 1 has been described. However, the recording medium remaining amount detecting device 230 can also be applied to a single sheet feeding device.

As described above, the image forming apparatus 1 according to the present exemplary embodiment includes the placement recording medium detection unit 220 that detects the amount of light transmitted through the recording medium P on the bottom plates 202a to 202d of the paper feed trays 201a to 201d, and one recording medium P. both of the light receiving portion 220b of the conveying recording medium detecting unit 221 for detecting the amount of transmitted light, when comparing the output value of 221b detects the remaining amount of the recording medium P on the bottom plate 202a~202d of the paper feed tray 201a~201d The output values of the light receiving units 220b and 221b whose output values deviate from a predetermined reference value at the timing when the recording medium P does not exist in both the mounted recording medium detection unit 220 and the conveyance recording medium detection unit 221 are By correcting to the reference value, the output values of both the light receiving units 220b and 221b are matched with the reference value.

Accordingly, the arrangement conditions such as the distance and the angle sandwiched in the thickness direction of the recording medium P by the light emitting units 220a and 221a and the light receiving units 220b and 221b, and the light emitting units of the loaded recording medium detection unit 220 and the conveyance recording medium detection unit 221 220a, 221a and the light receiving portion 220b, the light receiving portion 220b due to the difference or the like 221b specifications, can be inexpensively compensate for changes in the output value of 221b, be detected inexpensively and accurately the remaining amount of the recording medium P Can do.

  The image forming apparatus 1 according to the present exemplary embodiment uses the larger output value of the output values of the mounted recording medium detection unit 220 and the light receiving units 220b and 221b of the transport recording medium detection unit 221 as a reference value. The output value is amplified to the reference value by the amplifier circuit 11.

Accordingly, the output values of the light receiving units 220b and 221b of both the loaded recording medium detection unit 220 and the conveyance recording medium detection unit 221 when the recording medium P is not interposed are corrected more inexpensively and easily. it can, it is possible to detect the remaining amount of the recording medium P to more expensive and high precision.

  Further, in the image forming apparatus 1 of this embodiment, the amplification factor of the amplifier circuit 11 is adjusted by the amplification factor controller 12.

Therefore, even if there is variation in the amplifier circuit 11 or variations in the light receiving portions 220b and 221b, the output values of the light receiving portions 220b and 221b can be corrected with higher accuracy, and the recording medium P it is possible to detect the remaining amount even more accurately.

  Further, the image forming apparatus 1 according to the present embodiment digitally converts the output values of the light receiving unit 220b of the loaded recording medium detecting unit 220 and the light receiving unit 221b of the transported recording medium detecting unit 221, and then the output value is determined from the reference value. The output values of the light receiving units 220b and 221b that are out of place are processed into the reference value, and both output values are made to match the reference value.

  Accordingly, the specifications of the light emitting unit 220a of the loaded recording medium detection unit 220, the light emitting unit 221a of the transport recording medium detection unit 221, the light receiving unit 220b of the transport recording medium detection unit 221, and the light receiving unit 221b of the transport recording medium detection unit 221 are the same. Even if the arrangement conditions of the light emitting unit 220a and the light receiving unit 220b of the placed recording medium detection unit 220 and the arrangement conditions of the light emitting unit 221a and the light receiving unit 221b of the transport recording medium detection unit 221 are different, the recording medium The outputs of the light receiving unit 220b and the light receiving unit 221b without any intervening can be corrected with high accuracy equally, and the detection accuracy of the recording medium P can be further improved.

  The invention made by the present inventor has been specifically described based on the preferred embodiments. However, the present invention is not limited to the above, and various modifications can be made without departing from the scope of the invention. Needless to say.

Recording medium level detecting unit and the recording medium to detect the remaining amount of the placed on it are recording media of a sheet-like recording medium to be conveyed one by one while being placed on top a plurality of sheets in low cost and high precision The present invention can be applied to a paper feeding device or an image forming apparatus using a remaining amount detection device.

1 is a schematic front view of an image forming apparatus to which an embodiment of a recording medium remaining amount detection apparatus of the present invention is applied. FIG. 2 is a schematic front view of a main part of an uppermost sheet feed tray and an image forming unit of the sheet feeding unit of the image forming apparatus in FIG. 1. FIG. 2 is a schematic front view of a main part illustrating a loaded recording medium detection unit and a conveyance recording medium detection unit of a top sheet feeding tray portion of a sheet feeding unit of the image forming apparatus of FIG. 1. FIG. 4 is a diagram showing an arrangement of the mounted recording medium detection unit in FIG. 3. FIG. 4 is a diagram illustrating an arrangement of a conveyance recording medium detection unit in FIG. 3. The circuit block diagram of the amplifier circuit part connected to the light-receiving part of the mounting recording medium detection part of FIG.3 and FIG.4. FIG. 6 is a diagram showing a current-voltage relationship when a phototransistor and a light emitting diode are used as the mounted recording medium detection unit of FIGS. 4 and 5 and the transported recording medium detection unit of FIG. 3.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Image forming apparatus 10 Amplifying circuit part 11 Amplifying circuit 12 Amplification rate control part 100 Image forming part 110 Transfer belt mechanism part 111 Image forming part 112 Optical writing part 113 Secondary transfer part 114 Fixing part 115 Reversing part 116 Registration roller 117 Transfer Belt 200 Paper feed unit 201a-201d Paper feed tray 202a-202d Bottom plate 203a-203d Feed roller 204a-204d Separation roller 205 Transport roller 210 Additional paper feed unit 211 Manual paper feed unit 220 Mounted recording medium detection unit 220a Light emission unit 220b Light reception Unit 221 conveying recording medium detection unit 221a light emitting unit 221b light receiving unit 230 recording medium remaining amount detection device 300 reading unit 301 document table 310 ADF
P Recording medium

Claims (3)

For the sheet-like recording medium to be mounted is irradiated with light from the light emitting element in the thickness direction, receives light transmitted through the recording medium by the light receiving element, outputs an output value corresponding to an amount of light received from the light receiving element A mounted recording medium detecting means ;
The light transmitted through the one recording medium is irradiated with light from the light emitting element in the thickness direction for the one recording medium is received by the light receiving element, it outputs an output value corresponding to an amount of light received from the light receiving element and conveying the recording medium detecting means for,
Remaining amount detection means for detecting the remaining amount of the recording medium by comparing the output value of the light receiving elements of both the the placement recording medium detecting means and the conveying recording medium detecting means,
Record medium as a reference value an output value of the larger one of the output values of both the light receiving elements with the placement recording medium detecting means and the conveying recording medium detection means in the absence, the output value of the smaller Correction means for amplifying to the reference value;
A recording medium remaining amount detection device comprising: 2. The recording medium remaining amount detection apparatus according to claim 1, wherein the correction means includes an amplification factor adjustment unit that adjusts an amplification factor at the time of amplification. An image forming apparatus comprising the recording medium remaining amount detecting device according to claim 1.

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