JP4420029B2 - Image forming apparatus - Google Patents

Description

  The present invention relates to an image forming apparatus.

  Japanese Patent Application Laid-Open No. 2004-228561 discloses a conventional image forming apparatus. The image forming apparatus includes a storage unit that stores waste toner generated as a result of image formation as a storage object, a plurality of sensors, a determination unit, and a measurement unit.

  Specifically, the container is a substantially box-like body that is flat when viewed from the side of the image forming apparatus and extends in the lateral direction of the image forming apparatus, and conveys a photoreceptor and paper that generates waste toner. It is arranged below the mechanism or the like.

  Each sensor outputs an ON / OFF signal indicating whether or not there is waste toner by performing a detection operation toward the inside of the storage unit. In the embodiment, the type of sensor is not specified, but it is described that a piezoelectric vibration sensor is common. In addition, the sensors are sequentially arranged in a predetermined positional relationship from one side in the lateral direction to the other side of the housing portion. In the embodiment, there are two sensors, the first sensor is arranged approximately in the middle between the one side and the other side of the accommodating portion, and the second sensor is arranged on one side of the accommodating portion.

  The determination means has a determination step of determining whether or not waste toner is present at the location of each sensor based on an ON / OFF signal output by a detection operation performed independently for each sensor. Yes.

  The measuring means measures the amount of waste toner based on the determination in the determining step of the determining means.

  The image forming apparatus also includes a collection unit. The collecting means removes the toner remaining on the surface of the photosensitive member and sends the toner to one side in the storage unit. Further, the recovery unit periodically swings the storage unit in a specific direction to remove waste toner from one side in the storage unit. It is transferred to the other side.

  In the conventional image forming apparatus having such a configuration, waste toner generated in association with image formation is gradually accumulated from the other side to the one side in the storage unit. The determination unit performs the determination step as needed, and the measurement unit measures the amount of waste toner based on the determination in the determination step.

  Here, when the first sensor outputs an ON signal while the second sensor does not output an ON signal, the determination means determines whether the first sensor is disposed on the one side in the determination step. It is determined that there is no waste toner on one side where the second sensor is disposed, although waste toner is present in the middle of the other side.

  Thereafter, if the second sensor outputs an ON signal, the determination unit determines that waste toner is present on one side where the second sensor is disposed in the determination step.

  The measuring unit measures the amount of waste toner stored in the storage unit in consideration of the time difference between the outputs of the first sensor and the second sensor based on the determination in the determination step.

  Thus, the image forming apparatus can measure the amount of waste toner stored in the storage unit in a stepwise manner using a plurality of sensors.

Japanese Patent Laid-Open No. 11-38850

  By the way, the above-described conventional image forming apparatus performs detection operation for a plurality of sensors independently, and only makes a determination based on a combination of ON / OFF signals of the sensors, and therefore, more accurate measurement is performed. It was difficult.

  For example, when the image forming apparatus includes two sensors as described above, even if one or both of the sensors output an ON signal, the accumulated state (partially offset) of the waste toner at that time is output. Etc.), a large discrepancy is likely to occur between the amount measured by the measuring means and the amount of waste toner actually stored in the storage unit.

  SUMMARY An advantage of some aspects of the invention is that it provides an image forming apparatus capable of measuring the amount of an object to be accommodated in an accommodation unit with higher accuracy. .

An image forming apparatus according to the present invention includes an accommodating portion that accommodates an object whose amount increases or decreases, a light projecting portion, and a light receiving portion, and projects light emitted from the light projecting portion toward the inside of the accommodating portion. As a result of the detection operation of receiving light at the light receiving unit, a detection value corresponding to a change in the amount of received light received by the light receiving unit, and an absolute value of a current value or a voltage difference flowing according to the change in the received light amount is output. A first determination step for determining, for each sensor, a plurality of sensors and whether each of the detection values output by the detection operation performed independently for each of the sensors is equal to or less than a predetermined threshold value Vg1; A combined value of the detected values output by the detection operation performed simultaneously on the plurality of sensors, and a combined current value or an absolute value of a voltage difference that flows according to a change in the amount of light received by each light receiving unit is It is determined whether or not it is equal to or less than a predetermined threshold value Vg2. A determination unit having a second determination step, and a relative amount of the object to be stored with respect to the threshold value Vg1 and the threshold value Vg2 based on the determination of the first determination step and the second determination step of the determination unit. Measuring means,
In the first determination step, the measurement means has a case where each detected value is equal to or less than a predetermined threshold value Vg1, and in the second determination step, a combined value of the detected values is equal to or less than a predetermined threshold value Vg2. The relative amount of the object to be stored is distinguished from the case where the combined value of the detected values is not equal to or less than a predetermined threshold value Vg2 (claim 1).

  In the image forming apparatus of the present invention having such a configuration, the determination unit has a first determination step performed independently for each sensor and a second determination step performed simultaneously for a plurality of sensors. Compared with the above-described conventional technique, which includes only one determination step for each sensor, the amount of the object to be stored can be measured with higher accuracy. In particular, even when the object to be accommodated is shifted to one sensor, it can be determined more accurately by the second determination step that is simultaneously performed for a plurality of sensors.

  The “detected value according to the change in the amount of received light” is a value that changes according to the change in the amount of received light with reference to the amount of received light at the time of non-detection operation. With reference to the amount of light received when the light portion is turned off, the current value or the absolute value of the voltage difference that the light receiving portion changes according to the change in the amount of received light can be used. The absolute value of this current value or voltage difference generally decreases as the amount of received light decreases. The threshold values Vg1 and Vg2 are also set to positive values correspondingly. For this reason, even if the plus or minus of the current value or the voltage difference is inverted depending on the circuit configuration or the measurement method, the determination means is established.

  Any material may be used as long as it is contained in the image forming apparatus and the amount thereof is reduced or increased. For example, unused toner, waste toner, paper powder, and the like are included. .

  In the image forming apparatus of the present invention, it is preferable that the plurality of sensors be arranged at the same distance from the entrance of the housing portion.

  With the image forming apparatus having such a configuration, the effect of the present invention can be surely enjoyed even when the object to be accommodated is easily shifted in the accommodating portion.

  In the image forming apparatus of the present invention, it is preferable that the threshold value Vg1 and the threshold value Vg2 have a relationship of Vg1 × n> Vg2 (n is the number of sensors, n ≧ 2).

  In this case, in the first determination step, the image forming apparatus actually determines that the object to be stored is fully accumulated in the storage unit after determining that the object has been accumulated to some extent in the storage unit. Until the second determination step is either “a state in which a large amount of material is deposited in the housing portion” or “a state in which the material is accumulated in the housing portion to some extent but still has room” It can be determined that For this reason, the image forming apparatus can effectively measure the amount of the object to be accommodated.

  In the image forming apparatus of the present invention, the threshold value Vg1 and the threshold value Vg2 are preferably in a relationship of Vg1 = Vg2.

  In this case, in the first determination step, the image forming apparatus actually determines that the object to be stored is fully accumulated in the storage unit after determining that the object has been accumulated to some extent in the storage unit. In the middle of the process, the second judgment step is either “a state where a large amount of objects are accumulated in the accommodating portion” or “a certain amount of objects are accumulated in the accommodating portion, but there is still room” Can be determined. For this reason, the image forming apparatus can more effectively measure the amount of the object to be accommodated.

  In the first determination step, the image forming apparatus of the present invention may perform the determination by the second determination step when all of the detection values output for each sensor are equal to or less than the predetermined threshold value Vg1 (claim). Item 5).

  In this case, the image forming apparatus can improve the processing efficiency because the second determination step can be prevented from being performed when the second determination step is unnecessary.

The image forming apparatus of the present invention, the detected values output by the plurality of sensors may be input to one port in the determination unit (claim 6).

  In this case, since this image forming apparatus can reduce the number of ports of the determination unit, the apparatus configuration can be simplified.

The image forming apparatus of the present invention, said one port is one of the input terminals of the comparator, the threshold value Vg1 and threshold Vg2 may be inputted as a comparison value to the other input terminal of the comparator (claim 7).

  In this case, the image forming apparatus can further simplify the configuration of the apparatus and can reduce the product cost.

  DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments embodying the present invention will be described below with reference to the drawings.

  As shown in FIG. 1, a laser printer 1 as an image forming apparatus according to an embodiment uses a plurality of colors of toner to form a color image on a sheet as a recording medium, an OHP sheet, or the like (hereinafter simply referred to as a sheet). To form. As shown in FIG. 1, the laser printer 1 is installed with the upper side of the paper as the upper side in the direction of gravity, and is normally used with the right side of the paper as the front, and the interior of the substantially box-shaped (cuboid) housing 3. The control unit 40, the feeder unit 20, the transport mechanism 30, the image forming unit 10, the storage unit 110, the collection unit 100, and the like. Further, on the upper surface side of the housing 3, a paper discharge tray 5 on which a paper sheet that has finished image formation and is discharged from the housing 3 is placed. Hereinafter, each component of the laser printer 1 will be described in more detail.

1. Control Unit The control unit 40 controls the feeder unit 20, the transport mechanism 30, the image forming unit 10 and the like in order to form an image on a sheet based on image forming data transmitted from an external computer or the like. . The control unit 40 controls the collecting unit 100 in order to store waste toner as an object to be stored generated in image formation in the storage unit 110, as will be described in detail later. Furthermore, since the control unit 40 measures the amount of waste toner stored in the storage unit 110, the first sensor 111 and the second sensor 112 attached to the storage unit 110 and the control unit 40 will be described in detail later. And a determination unit built in the control unit 40.

2. As shown in FIG. 1, the feeder unit 20 includes a paper feed tray 21 housed in the lowermost portion of the housing 3, and a sheet placed on the paper feed tray 21 provided above the front end of the paper feed tray 21. A sheet feeding roller 22 that feeds (conveys) the image to the image forming unit 10 and a separation pad 23 that separates the sheets fed by the sheet feeding roller 22 by giving a predetermined conveyance resistance to the sheets. It is configured.

  Then, a portion of the paper transport path P from the paper feed tray 21 via the image forming unit 10 to the paper discharge tray 5 that turns to a substantially U-shape forward is curved in a substantially U-shape. On the other hand, conveying rollers 24 and 25 that apply a conveying force to the sheet conveyed to the image forming unit 10 are provided.

  Further, on the downstream side of the conveyance path P with respect to the conveyance roller 24, the skew of the sheet is corrected by contacting the leading edge of the sheet conveyed by the conveyance roller 24, and then the sheet is further transferred to the image forming unit 10. There are provided registration rollers 26 and 27 for conveying toward the front.

3. Conveying Mechanism The conveying mechanism 30 includes a conveying belt 33 disposed between the lower paper feed tray 21 and the upper image forming unit 10, and a discharge chute (not shown) disposed behind the image forming unit 10. And a discharge roller 91 and the like.

  The transport belt 33 is wound between a driving roller 31 that rotates in conjunction with the operation of the image forming unit 10 and a driven roller 32 that is rotatably disposed at a position separated from the driving roller 31 so that it can circulate. Has been.

  The transport mechanism 30 having such a configuration rotates the transport belt 33 in a state where the paper is placed, thereby causing the paper transported from the feeder unit 20 to have an image having four process cartridges 70K, 70Y, 70M, and 70C. It is sequentially conveyed to the forming unit 10. The paper on which image formation has been completed in the image forming unit 10 is conveyed along the conveyance path P by the discharge chute and the discharge roller 91 and is discharged from the discharge unit 7 to the paper discharge tray 5.

4). Image Forming Unit As shown in FIG. 1, the image forming unit 10 includes a scanner unit 60, process cartridges 70K, 70Y, 70M, and 70C, a fixing unit 80, and the like.

4.1. Scanner Unit The scanner unit 60 is disposed in the upper portion of the housing 3 and includes a laser light source, a polygon mirror, an fθ lens, a reflecting mirror, and the like.

  Then, the laser beam emitted from the laser light source is deflected by the polygon mirror, passes through the fθ lens, and then the optical path is folded by the reflecting mirror. Further, the optical path is bent downward by the reflecting mirror, so that 4 Irradiation is performed on the surface of the photosensitive member 71 provided in each of the two process cartridges 70K, 70Y, 70M, and 70C, and an electrostatic latent image is formed.

4.2. Process Cartridges Since the four process cartridges 70K, 70Y, 70M, and 70C are the same except for the color of the toner, and the others are the same, the process cartridge 70C will be described as an example.

  The process cartridge 70 </ b> C includes a casing 75 that houses a known photoreceptor 71, charger 72, toner cartridge 74, and the like.

  A transfer roller 73 is rotatably disposed on the side opposite to the photoreceptor 71 with the conveyance belt 33 interposed therebetween. The transfer roller 73 transfers toner adhering to the surface of the photoconductor 71 onto the paper when the paper passes near the photoconductor 71.

  The toner cartridge 74 includes a toner storage chamber 74A that stores toner, a supply roller 74B that supplies toner to the development roller 74C, a development roller 74C, and the like. The toner stored in the toner storage chamber 74A is supplied to the developing roller 74C side by the rotation of the supply roller 74B, and the toner supplied to the developing roller 74C side is carried on the surface of the developing roller 74C. At the same time, the thickness of the toner carried by the layer thickness regulating blade 74D is adjusted to be uniform at a predetermined thickness, and then supplied to the surface of the photoreceptor 71.

4.3. Fixing Unit The fixing unit 80 is disposed on the downstream side of the conveyance path P from the photoreceptor 71, and includes a known heating roller 81, pressure roller 82, and the like.

  The fixing unit 80 heats and melts the toner transferred onto the paper by the heating roller 81 and the pressure roller 82 and fixes the toner.

4.4. Outline of Image Forming Operation In the image forming unit 10 having such a configuration, an image is formed on a sheet as follows. That is, when image formation is started, the control unit 40 controls the feeder unit 20 and the conveyance mechanism 30 to convey the sheet to the image forming unit 10 and also scans the scanner of the image forming unit 10 based on the image formation data. Unit 60, process cartridges 70K, 70Y, 70M, 70C and the like. For this reason, the surface of the photoconductor 71 is uniformly positively charged by the charger 72 as it rotates, and then exposed by the laser beam emitted from the scanner unit 60. As a result, the surface of the photoconductor 71 Then, an electrostatic latent image corresponding to the image forming data is formed.

  Next, when the developing roller 74 </ b> C rotates, the positively charged toner carried on the developing roller 74 </ b> C is formed on the surface of the photoconductor 71 when contacting the photoconductor 71. It is supplied to the electrostatic latent image. As a result, the electrostatic latent image on the photoreceptor 71 is visualized, and a toner image by reversal development is carried on the surface of the photoreceptor 71.

  Thereafter, the toner image carried on the surface of the photoreceptor 71 is transferred onto the paper by a transfer bias applied to the transfer roller 73. Then, the sheet on which the toner image is transferred is conveyed to the fixing unit 80 and heated, and the toner transferred as the toner image is fixed on the sheet, and the image formation is completed.

5). Storage Unit The storage unit 110 is a so-called waste toner box, and as illustrated in FIG. 1, a vertically thin space formed between the lower paper feed tray 21 and the upper transport mechanism 30 in the housing 3. Is arranged. For this reason, the accommodating part 110 is made into the substantially box-shaped body which is flat seeing from the side surface, and extends in the horizontal direction of the laser printer 1 (the direction from the front side to the back side in FIG. 1). In addition, the storage unit 110 is detachably fixed to a frame member (not shown) provided in the housing 3, and when the waste toner is fully accumulated in the storage unit 110, the storage unit 110 is removed, Maintenance work can be performed.

  On the upper surface of the accommodating portion 110, as shown in an enlarged view in FIG. 2, an inlet 110a that is opened to a width substantially the same as the width of the conveyor belt 33 is formed. The waste toner adhering to the surface of the conveyor belt 30 is sent from the inlet 110a into the storage unit 110 by the collecting means 100 described later, and gradually accumulates from the front to the back in the storage unit 110. Yes.

6). As shown in FIG. 2, the collecting unit 100 includes a cleaning roller 101, a scraping roller 102, a peeling blade 103, an elliptical rotor 105, a reed valve 106, and the like.

  The cleaning roller 101 is a solid cylinder in which a resin sponge layer is formed on the outer surface side. The cleaning roller 101 is disposed in front of the inlet 110a and is rotatable about a pivot 101a parallel to the driving roller 31 and the driven roller 32. It is supported.

  The cleaning roller 101 is configured to come into contact with the conveyance belt 33 from below while being rotationally driven in a rotation direction D2 opposite to the circulation direction D1 of the conveyance belt 33. Therefore, the cleaning roller 101 can be removed from the conveying belt 33 by adhering the toner adhering to the surface of the conveying belt 33 to its own surface so as to scrape off.

  The scraping roller 102 is a solid metal cylinder, and is positioned behind the cleaning roller 101 in the inlet 110a and is rotatably supported by a pivot 102a parallel to the pivot 101a.

  Then, the scraping roller 102 rotates in the rotation direction D3 while being in contact with the surface of the cleaning roller 101 in a state where a charge opposite to the charge carried by the toner (in this embodiment, a negative charge) is applied. It is configured as follows. For this reason, the scraping roller 102 can electrically adsorb the toner adhering to the surface of the cleaning roller 101 and transfer it to the surface of the scraping roller 102.

  The peeling blade 103 is arranged so that the rear end side is fixed behind the inlet 110a and the front end side is in contact with the surface of the scraping roller 102 while being bent. For this reason, the peeling blade 103 can peel the toner adhering to the surface of the scraping roller 102 and drop it downward.

  The elliptical rotor 105 is a solid elliptical cylinder, and is positioned below the scraping roller 102 and the peeling blade 103 in the inlet 110a, and is rotatably supported by a pivot 105a parallel to the pivots 101a and 102a. The elliptical rotor 105 is configured to rotate in the rotation direction D4 following the rotation of the scraping roller 102. The elliptical rotor 105 is surrounded by the vertical wall surface 110 b of the housing part 110, the bottom surface of the housing part 110, and the reed valve 106.

  The reed valve 106 is disposed so as to be in contact with the elliptical rotor 105 while being bent.

  In the collecting unit 100, the toner attached to the conveying belt 33 moves to the scraping roller 102 via the cleaning roller 101. Next, when the peeling blade 103 peels off the waste toner adhering to the surface of the scraping roller 102 and scrapes it into the storage unit 110, the elliptical rotor 105 sends the waste toner to the rear of the storage unit 110. At this time, the reed valve 106 is also periodically bent in the front-rear direction along with the rotation of the elliptical rotor 105, and sends waste toner to the rear of the storage unit 110 together with the elliptical rotor 105. In this way, the collecting unit 100 can send waste toner into the storage unit 110 from the inlet 110a of the storage unit 110, and gradually accumulate the waste toner from the front to the back in the storage unit 110.

  In the laser printer 1 of the embodiment having such a configuration, when the waste toner generated during image formation accumulates in the storage unit 110 and becomes full, the storage unit 110 is removed from the housing 3 and the waste toner is removed. Maintenance work such as disposal is necessary. Therefore, in the laser printer 1, the control unit 40 includes a first sensor 111 and a second sensor 112, a determination unit, and a measurement unit in order to measure the amount of waste toner stored in the storage unit 110. ing.

  Hereinafter, the first and second sensors 111 and 112, the determination unit, and the measurement unit will be described with reference to FIGS. As will be described in advance, in the graph of FIG. 6, the horizontal axis represents the rate at which detection windows 110g and 110h of the first and second sensor recesses 110e and 110f described later are shielded by the accumulated waste toner (hereinafter referred to as “detection”). The vertical axis represents the voltage at the connection point P1 of the electric circuit shown in FIG.

  In the graph of FIG. 6, a solid line L1 indicates the voltage at the connection point P1 during the detection operation of the first sensor 111 alone or the detection operation of the second sensor 112 alone. The broken line M1 indicates that the waste toner accumulates from the front to the back in the housing portion 110 without being shifted to either side of the first sensor 111 and the second sensor 112. The voltage at the connection point P1 during the simultaneous detection operation of the two sensors 111 and 112 is shown. An alternate long and short dash line N1 indicates a voltage at a connection point P2 between the resistor R2 and the resistor R3. An alternate long and two short dashes line O indicates the voltage at the connection point P1 when the first and second sensors 111 and 112 are in the non-detecting operation and when the detection window shielding rate is 100%.

  Further, the graph shown in FIG. 7 is the same as the graph of FIG. 6 described above with respect to the voltage at the connection point P1 during the non-detection operation of the first and second sensors 111 and 112 and the detection window shielding rate of 100%. Is a reference (0V), and the difference (change amount) therefrom is expressed in absolute value. A solid line L2 corresponding to the solid line L1 indicates detection values C1 and C2, which will be described later, and is a broken line. A broken line M2 corresponding to M1 indicates a composite value C3 described later. A dashed line N2 corresponding to the dashed line N1 indicates thresholds Vg1 and Vg2 described later.

7). 1st sensor and 2nd sensor As shown in FIG.2 and FIG.3, the 1st sensor 111 and the 2nd sensor 112 are the recessed parts 110e for 1st sensors formed in two places below the rear-end side of the accommodating part 110, respectively. And a second sensor recess 110f.

  As shown in FIG. 3, the first sensor recess 110 e and the second sensor recess 110 f are located at an equal distance from the center of the housing portion 110 in the lateral direction (left-right direction in FIG. 3). For this reason, the first sensor 111 and the second sensor 112 are arranged at the same distance from the entrance 110 a of the housing part 110.

  As shown in FIGS. 2-4, the 1st sensor 111 consists of the light projection part A and the light-receiving part 111a. The light projecting part A is a light emitting diode, and the light receiving part 111a is a phototransistor. Then, the light projected from the light projecting part A toward the inside of the housing part 110 is received by the light receiving part 111a through the detection window 110g made of a light transmitting material provided in the first sensor concave part 110e. As a result of the detection operation, the collector potential changes due to a change in the current flowing through the light receiving unit 111a.

  Specifically, as indicated by the solid line L1 in the graph of FIG. 6, when the detection window shielding rate (the rate at which the detection window 110g is shielded by the waste toner accumulated) changes from 0 to 100%, the first sensor When the single detection operation 111 is performed, the collector potential of the light receiving unit 111a (the voltage at the connection point P1 shown in FIG. 4) increases as the amount of received light decreases. Here, when the first and second sensors 111 and 112 are not detected, the detection value C1 output by the first sensor according to the change in the amount of light received by the light receiving unit 111a by driving the light projecting unit A This is the absolute value of the amount of change in the collector potential caused by the change in the current flowing through the section 111a. For this reason, the detection value C1 decreases according to the decrease in the amount of light received by the light receiving unit 111a, as indicated by the solid line L2 in the graph of FIG.

  Similar to the first sensor 111, the second sensor 112 includes a light projecting unit B and a light receiving unit 112a. The light projecting unit B is a light emitting diode, and the light receiving unit 112a is a phototransistor. Then, the light projected from the light projecting unit B toward the inside of the housing unit 110 is received by the light receiving unit 112a through the detection window 110h made of a translucent material provided in the second sensor recess 110f. As a result of the detection operation, the collector potential changes due to a change in the current flowing through the light receiving unit 112a.

  Specifically, as indicated by the solid line L1 in the graph of FIG. 6, when the detection window shielding rate (the rate at which the detection window 110h is shielded by the waste toner accumulated) changes from 0 to 100%, the second sensor When the single detection operation 112 is performed, the collector potential of the light receiving unit 112a (the voltage at the connection point P1 shown in FIG. 4) increases as the amount of received light decreases. Here, the detection value C2 output from the second sensor in response to a change in the amount of light received by the light receiving unit 112a by driving the light projecting unit B with respect to the non-detecting operation of the first sensor 112 flows to the light receiving unit 112a. This is the absolute value of the amount of change in collector potential caused by the change in current. For this reason, as indicated by the solid line L2 in the graph of FIG. 7, the detection value C2 decreases according to a decrease in the amount of light received by the light receiving unit 112a.

8). Determination Unit The determination unit is built in the control unit 40 and, as shown in FIG. 4, a switching circuit 121 for turning on / off the light projecting unit A of the first sensor 111 and a light projecting unit B of the second sensor 112. Is configured to include a switching circuit 122 for turning ON / OFF the signal and a comparator circuit 123.

  The comparator circuit 123 has one operational amplifier 123 a whose output terminal is connected to the CPU input port 40 a in the control unit 40. The non-inverting input terminal of the operational amplifier 123a is connected to a connection point P1 between the collector terminal of the light receiving unit 111a and the collector terminal of the light receiving unit 112a via a resistor R4. Further, one end of a resistor R1 whose other end is connected to the power feeding side is connected to the connection point P1. For this reason, when the detection window shielding rate (the rate at which the detection windows 110g and 100h are shielded by the accumulated waste toner) varies from 0 to 100%, the detection operation is simultaneously performed for the first and second sensors 111 and 112. For example, the combined current of the current flowing through the light receiving unit 111a and the current flowing through the light receiving unit 112a flows through the resistor R1. Then, as indicated by a broken line M1 in the graph of FIG. 6, the voltage at the connection point P1 changes corresponding to this combined current. Here, the combined value C3 of the detection values of the first and second sensors 111 and 112 is driven by the light projecting parts A and B when the first and second sensors 111 and 112 are in the non-detecting operation, thereby receiving the light receiving parts 111a and 112a. Is the absolute value of the amount of voltage change at the connection point P1 caused by the change in the current flowing through. For this reason, the composite value C3 decreases as the amount of light received by the light receiving units 111a and 112a decreases, as indicated by the broken line M2 in the graph of FIG.

  The inverting input terminal of the operational amplifier 123a is connected to a connection point P2 between one end of the resistor R2 whose other end is connected to the power supply side and one end of the resistor R3 whose other end is connected to the ground side. Here, the voltage at the connection point P2 is set to about 1.73 V by adjusting the resistance values of the resistors R2 and R3 (indicated by a one-dot chain line N1 in FIG. 6). Therefore, if the voltage at the connection point P1 is larger than the voltage at the connection point P2, the maximum voltage value is output from the output terminal of the operational amplifier 123a to the CPU input port 40a. On the other hand, if the voltage at the connection point P1 is smaller than the voltage at the connection point P2, the minimum voltage value is output from the output terminal of the operational amplifier 123a to the CPU input port 40a.

  The voltage at the connection point P2 (about 1.73 V) is a threshold value Vg1 (comparison value, indicated by a one-dot chain line N2 in FIG. 7) for the detection value C1 of the first sensor 111 and the detection value C2 of the second sensor 112, and the composition This corresponds to the threshold value Vg2 for the value C3 (comparison value, indicated by the one-dot chain line N2 in FIG. 7) (Vg1 = Vg2 = about 1.57V). Hereinafter, the comparison between the voltage at the connection point P1 and the voltage at the connection point P2 by the comparator circuit 123 will be described by replacing the detection values C1, C2 and the combined value C3 with the threshold values Vg1, Vg2.

  The determination means also includes a first determination step (step S101 to step S106) and a second determination step (step S108 to step S110) in the waste toner amount measurement routine (step S100 to step S120) shown in FIG. Yes. The first determination step determines whether or not the detection values C1 and C2 output by the detection operation performed independently for each of the first and second sensors 111 and 112 are equal to or less than the threshold value Vg1. In the second determination step, it is determined whether or not the composite value C3 of the detection values output by the detection operation performed simultaneously for the first and second sensors is equal to or less than the threshold value Vg2. Details of each step will be described when a waste toner amount measurement routine is described later.

9. Measuring means The measuring means is composed of step S107 and steps S111 to S115 shown in FIG. Then, the measuring means determines the amount of waste toner based on the determination in the first determination step and the second determination step of the determination means as “a state where the waste toner is considerably accumulated in the storage unit 110. ”)”, “Waste toner has accumulated to some extent in the storage unit 110, but there is still room (hereinafter simply referred to as“ near full ”)”, “Waste toner is stored in the storage unit 110. It is measured in three stages: “not so much deposited (hereinafter simply referred to as“ low ”)”.

10. Waste Toner Amount Measurement Routine The control unit 40 performs the waste toner amount measurement routine shown in FIG. 5 when the laser printer 1 is started or during an image forming operation in order to measure the amount of waste toner stored in the storage unit 110. Implement as needed. Hereinafter, each step will be described in detail.

  First, in step S100, the process is started.

  Next, in step S <b> 101, the ON signal of the light projecting unit A of the first sensor 111 is sent from the control unit 40 to the switching circuit 121, and the switching circuit 121 lights the light projecting unit A. As a result, the light projecting unit A projects light into the first sensor recess 110e.

  Next, in step S102, a detection operation in which the light receiving unit 111a receives the light projected from the light projecting unit A is performed, and a detection value C1 that decreases according to a decrease in the amount of light received by the light receiving unit 111a is first set. The sensor 111 outputs. The detected value C1 is input to the non-inverting input terminal of the operational amplifier 123a of the comparator circuit 123, and is compared with the threshold value Vg1 set at the inverting input terminal of the operational amplifier 123a. Then, a comparison result between the detection value C1 and the threshold value Vg1 is transmitted from the output terminal of the operational amplifier 123a to the CPU input port 40a.

  Next, in step S <b> 103, the OFF signal of the light projecting unit A of the first sensor 111 is sent from the control unit 40 to the switching circuit 121, and the switching circuit 121 turns off the light projecting unit A.

  Next, in step S <b> 104, the ON signal of the light projecting unit B of the second sensor 112 is sent from the control unit 40 to the switching circuit 122, and the switching circuit 122 turns on the light projecting unit B. As a result, the light projecting unit B projects light into the second sensor recess 110e.

  Next, in step S105, a detection operation in which the light receiving unit 112a receives the light projected from the light projecting unit B is performed, and a detection value C2 that decreases with a decrease in the amount of light received by the light receiving unit 112a is set to a second value. The sensor 112 outputs. The detected value C2 is input to the non-inverting input terminal of the operational amplifier 123a of the comparator circuit 123, and is compared with the threshold value Vg1 set at the inverting input terminal of the operational amplifier 123a. Then, the comparison result between the detection value C2 and the threshold value Vg1 is transmitted from the output terminal of the operational amplifier 123a to the CPU input port 40a.

  Next, in step S <b> 106, the OFF signal of the light projecting unit B of the second sensor 112 is sent from the control unit 40 to the switching circuit 122, and the switching circuit 122 turns off the light projecting unit B.

  Next, when it is determined in step S107 that “detection value C1 ≦ threshold value Vg1 and detection value C2 ≦ threshold value Vg1” is “Yes”, the process proceeds to step S108.

  In step S108, the ON signals of the light projecting units A and B of the first and second sensors 111 and 112 are sent from the control unit 40 to the switching circuits 121 and 122, and the switching circuits 121 and 122 are transmitted to the light projecting unit A, Turn on B. As a result, the light projecting portions A and B project light into the first sensor recess 110e and the second sensor recess 110f.

  Next, in step S109, the detection operation in which the light receiving unit 111a receives the light projected from the light projecting unit A and the detection operation in which the light receiving unit 112a receives the light projected from the light projecting unit B are simultaneously performed. Then, the first and second sensors 111 and 112 output a composite value C3 of the detection values of the first and second sensors 111 and 112. Then, the combined value C3 is input to the non-inverting input terminal of the operational amplifier 123a of the comparator circuit 123, and compared with the threshold value Vg2 set at the inverting input terminal of the operational amplifier 123a. Then, the comparison result between the composite value C3 and the threshold value Vg2 is transmitted from the output terminal of the operational amplifier 123a to the CPU input port 40a.

  Next, in step S110, the OFF signals of the light projecting units A and B of the first and second sensors 111 and 112 are sent from the control unit 40 to the switching circuits 121 and 122, and the switching circuits 121 and 122 are transmitted to the light projecting unit A. , B are turned off.

  Next, when it is determined in step S111 that “detection value C3 ≦ threshold value Vg2” is “Yes”, the process proceeds to step S112. In step S112, it is determined that the amount of waste toner is “full”, the process proceeds to step S120, and the process ends.

  On the other hand, when it is determined in step S111 that “detection value C3 ≦ threshold value Vg2” is “No”, the process proceeds to step S114. In step S114, it is determined that the amount of waste toner is “near full”, the process proceeds to step S120, and the process is terminated.

  On the other hand, when it is determined in step S107 that “detection value C1 ≦ threshold value Vg1 and detection value C2 ≦ threshold value Vg1” is “No”, the process proceeds to step S113.

  When it is determined in step S113 that “detection value C1> threshold value Vg1 and detection value C2> threshold value Vg1” is “Yes”, the process proceeds to step S115. In step S115, it is determined that the amount of waste toner is “low”, the process proceeds to step S120, and the process ends.

  On the other hand, if it is determined in step S113 that “detection value C1> threshold value Vg1 and detection value C2> threshold value Vg1” is “No”, the process proceeds to step S114. In step S114, it is determined that the amount of waste toner is “near full”, the process proceeds to step S120, and the process is terminated.

  In this way, the control unit 40 measures the amount of waste toner in the storage unit 110, notifies the user of the measurement result of the waste toner amount as appropriate, and performs necessary processing such as notifying the maintenance of the storage unit 110. To do.

  Here, as shown in the graphs of FIGS. 6 and 7, the waste toner does not shift to either side of the first sensor 111 and the second sensor 112, and is evenly directed from the front to the rear in the housing portion 110. A description will be given of what processing the waste toner measurement routine performs under the condition of accumulation.

  In the graph of FIG. 7, in the area on the left side of the vertical line S1, “No” is determined in step S107 and “Yes” is determined in step S113. As a result, the amount of waste toner is “low”. It is judged. In the area on the right side of the vertical line S2, “Yes” is determined in step S107, and “Yes” is determined in step S111. As a result, the amount of waste toner is determined to be “full”. . Further, in the region from the vertical line S1 to the vertical line S2, “Yes” is determined in step S107 and “No” is determined in step S111. As a result, the amount of waste toner is determined to be “near full”. Is done.

  Here, if there is no second determination step (step S108 to step S110) and step S111, if the detection window shielding rate of the first and second sensors 111 and 112 is 80%, for example, “Yes” in step S107. ”Is determined, the waste toner amount is determined to be“ full ”.

  On the other hand, in the present embodiment, when there is a second determination step (step S108 to step S110) and step S111, when the detection window shielding rate of the first, second sensor 111, 112 is 80%, It can be determined that the amount of waste toner is “near full”. For this reason, in the present embodiment, “full” and “near full” can be distinguished more accurately.

  Further, a test example of waste toner amount measurement in the laser printer 1 of the embodiment will be described with reference to FIGS.

(Test example)
In the test example, the waste toner generated with the image formation of the laser printer 1 is accumulated from the front to the rear in the housing portion 110 while being shifted to the first sensor 111 side from the second sensor 112. The condition is set. For this reason, as shown in the graph of FIG. 8, as the number of image formations (indicated on the horizontal axis) of the laser printer 1 increases, the detection window shielding rate (indicated by the broken line X1) of the first sensor 111 increases. It rises faster than the detection window shielding ratio of 112 (indicated by the broken line X2).

  In this case, when the waste toner measurement routine is executed as needed, as shown in the graph of FIG. 9, the detection value C1 (indicated by the solid line L3), the detection value C2 (indicated by the solid line L4), and the composite value C3 (indicated by the broken line M3) Change).

  In the graph of FIG. 9, in the region on the left side of the vertical line T1, “No” is determined in step S107 and “Yes” is determined in step S113. As a result, the amount of waste toner is “low”. It is judged. In the area from the vertical line T1 to the vertical line T2, “No” is determined in step S107 and “No” is determined in step S113. As a result, the amount of waste toner is “near full”. To be judged. Further, in the region from the vertical line T2 to the vertical line T3, “Yes” is determined in step S107 and “No” is determined in step S111. As a result, the amount of waste toner is “near full”. To be judged. In the area on the right side of the vertical line T3, “Yes” is determined in Step S107 and “Yes” is determined in Step S111. As a result, it is determined that the amount of waste toner is “Full”. .

  If there is no second determination step (steps S108 to S110) and step S111, the amount of waste toner is “full” when the number of formed images is within the region from the vertical line T2 to the vertical line T3. It will be judged.

  On the other hand, in the present embodiment, the second determination step (step S108 to step S110) and step S111 are performed, so that when the number of image formations is within the area from the vertical line T2 to the vertical line T3, it is discarded. It can be determined that the toner amount is “near full”. For this reason, in the present embodiment, “full” and “near full” can be distinguished more accurately.

  As described above, the laser printer 1 according to the embodiment includes the first determination step and the second determination step, so that the determination unit includes more than the conventional technique including only one determination step. The amount of waste toner can be accurately measured. In particular, even when the waste toner is shifted to one of the first and second sensors 111 and 112, the second determination step can make a more accurate determination.

  Therefore, the laser printer 1 according to the embodiment can measure the amount of waste toner stored in the storage unit 110 with higher accuracy.

  As a result, in this laser printer 1, it is difficult to cause a situation where the period of maintenance work performed when the waste toner becomes full in the storage unit 110 becomes unnecessarily short.

  In the laser printer 1, the threshold value Vg1 and the threshold value Vg2 are in a relationship of Vg1 = Vg2, (Vg1 × n> Vg2, n = 2). The second determination step is either “full” or “near full” almost halfway between the determination that the toner has accumulated to some extent and the actual accumulation of waste toner in the storage unit 110. It can be determined that there is. Therefore, the laser printer 1 can measure the amount of waste toner more effectively.

  Further, in the laser printer 1, in the first determination step, when the detection values C1 and C2 output for each of the first and second sensors 111 and 112 are both equal to or less than the threshold value Vg1, determination by the second determination step Therefore, when the execution of the second determination step is unnecessary, the second determination step can be prevented from being performed, and the processing efficiency can be improved.

  In addition, since the laser printer 1 includes the collecting unit 100 that sends waste toner from the inlet 110a of the storage unit 110 into the storage unit 110, the laser printer 1 can surely enjoy the effects of the present invention.

  Further, in the laser printer 1, the first and second sensors 111 and 112 are arranged at the same distance from the entrance 110 a of the storage unit 110, so that even when waste toner is easily shifted in the storage unit 110. The effect of the present invention can be surely enjoyed.

  Further, in this laser printer 1, since the accommodating portion 110 is a substantially box-shaped body that is flat when viewed from the side surface, waste toner tends to be displaced in the accommodating portion 110, so that the operational effects of the present invention can be ensured. You can enjoy it.

  Further, in the laser printer 1, the detection values C1 and C2 output by the first and second sensors 111 and 112 are input to the non-inverting input terminal of one operational amplifier 123a, and the inverting input terminal of the operational amplifier 123a is The threshold value Vg1 and the threshold value Vg2 obtained by voltage division by the resistors R2 and R3 are input from the power feeding unit. For this reason, compared with a configuration in which the threshold value Vg1 and the threshold value Vg2 are set or changed separately, the device configuration can be further simplified, and the product cost can be reduced.

  While the present invention has been described with reference to the embodiments, it is needless to say that the present invention is not limited to the above-described embodiments and can be appropriately modified and applied without departing from the spirit thereof.

  The present invention is applicable to an image forming apparatus.

It is a schematic sectional drawing of the image forming apparatus of an Example. FIG. 4 is a partial enlarged cross-sectional view illustrating a storage unit and a collection unit according to the image forming apparatus of the embodiment. FIG. 3 is a cross-sectional view showing the III-III cross section of FIG. 2 according to the image forming apparatus of the embodiment. FIG. 4 is an electric circuit diagram illustrating first and second sensors and a determination unit according to the image forming apparatus of the embodiment. 6 is a flowchart illustrating a waste toner measurement routine according to the image forming apparatus of the embodiment. 6 is a graph illustrating a relationship between a detection window shielding ratio of first and second sensors and a voltage at a connection point P1 in the image forming apparatus according to the example. 6 is a graph illustrating a relationship between detection window shielding rates of first and second sensors, detection values C1 and C2, and a combined value C3 in the image forming apparatus according to the example. 6 is a graph showing the relationship between the number of images formed in a test example and the detection window shielding ratio of first and second sensors in an image forming apparatus of an example. 6 is a graph illustrating a relationship between detection window shielding rates of first and second sensors, detection values C1 and C2, and a combined value C3 in an image forming apparatus according to an example.

1. Image forming apparatus (laser printer)
DESCRIPTION OF SYMBOLS 100 ... Collecting means 110 ... Accommodating part 110a ... Entrance of accommodating part 111, 112 ... Sensor (111 ... 1st sensor, 112 ... 2nd sensor)
111a, 112a ... light receiving unit 123 ... comparator circuit 123a ... operational amplifier A, B ... light projecting unit C1, C2 ... detection value C3 ... composite value of detection value Vg1, Vg2 ... threshold S101-S106 ... first determination step S108-S110 ... Second determination step

Claims (7)

A storage section for storing the objects to be increased or decreased;
As a result of the detection operation of receiving light emitted from the light projecting unit toward the inside of the housing unit by the light receiving unit, the light receiving unit receives a change in the amount of light received by the light receiving unit. A plurality of sensors that are detection values and output an absolute value of a current value or a voltage difference that flows according to a change in the amount of received light;
A first determination step for determining for each sensor whether or not each of the detected values output by the detection operation performed independently for each sensor is equal to or less than a predetermined threshold value Vg1, and for the plurality of sensors A combined value of the detected values output by the detection operation performed at the same time, and an absolute value of a combined current value or voltage difference that flows in accordance with a change in the amount of light received by each light receiving unit is equal to or less than a predetermined threshold value Vg2. Determination means having a second determination step for determining whether or not
Measuring means for measuring a relative amount of the object with respect to the threshold value Vg1 and the threshold value Vg2 based on the determination of the first determination step and the second determination step of the determination unit;
In the first determination step, the measurement means has a case where each detected value is equal to or less than a predetermined threshold value Vg1, and in the second determination step, a combined value of the detected values is equal to or less than a predetermined threshold value Vg2. An image forming apparatus that distinguishes the relative amount of the object to be stored when the combined value of the detection values is not equal to or less than a predetermined threshold value Vg2.   The image forming apparatus according to claim 1, wherein the plurality of sensors are arranged at the same distance from an entrance of the housing portion. The threshold value Vg1 and the threshold value Vg2 are:
Vg1 × n> Vg2, (n is the number of sensors, n ≧ 2)
The image forming apparatus according to claim 1, wherein the image forming apparatus has a relationship of The threshold value Vg1 and the threshold value Vg2 are:
Vg1 = Vg2
The image forming apparatus according to claim 3, wherein:   5. The determination according to claim 1, wherein in the first determination step, the determination by the second determination step is performed when all of the detection values output for each of the sensors are equal to or less than a predetermined threshold value Vg <b> 1. Image forming apparatus. Each of the plurality of the detected values output by the sensor, the input to one port in the determination means according to claim 1 to an image forming apparatus according to any one of the 5. 7. The image forming apparatus according to claim 6, wherein the one port is one input terminal of a comparator, and the threshold value Vg1 and the threshold value Vg2 are input as comparison values to the other input terminal of the comparator.

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