JP5683415B2 - Image forming apparatus - Google Patents

Description

  The present invention relates to an image forming apparatus including a fixing unit that fixes a toner image formed on a transfer material such as paper.

  An image forming apparatus such as a printer or a copier has a paper feed cassette that stores a plurality of sheets, an image forming unit that forms a toner image on a photosensitive drum or an intermediate transfer belt, and a sheet from the paper feed cassette. Some of them include a transfer unit that transfers a toner image formed by an image forming unit to a formed sheet, and a fixing unit that fixes the toner image on the sheet. Further, the image forming apparatus includes a temperature detection element (thermistor) that detects the temperature of the fixing unit and a detection circuit that detects whether a thermistor unit including the thermistor is mounted on the fixing unit. There is one that determines whether or not a thermistor unit is attached to the fixing unit (see Patent Document 1).

JP-A-6-250563

  In the apparatus described in Patent Document 1, the value detected by the detection circuit when the thermistor unit is not attached to the fixing unit is the reference potential (GND) level. However, in the apparatus described in Patent Document 1, when the thermistor fails and is short-circuited, the value detected by the detection circuit is also at the GND level. For this reason, in the invention described in Patent Document 1, it is not possible to distinguish between the case where the thermistor unit is not attached to the fixing unit and the case where the thermistor fails and is short-circuited.

  SUMMARY OF THE INVENTION An object of the present invention is to provide an image forming apparatus that determines whether a fixing unit is not mounted and whether a temperature detection element is malfunctioning.

  The present invention relates to an image forming apparatus main body that forms a toner image on a transfer material, and a fixing that is detachable from the image forming apparatus main body and fixes the toner image formed on the transfer material to the transfer material. An image forming apparatus comprising: a temperature detecting element for detecting a temperature of a heating rotating body that heats a toner image formed on a transfer material; and the temperature detecting element. A first resistor electrically connected in parallel, and a first connector connected to both ends of a parallel circuit composed of the temperature detection element and the first resistor, the image forming apparatus main body comprising: When the fixing unit is attached to the main body of the image forming apparatus, the second connector connected to the first connector, the first connector, and the second connector are electrically connected to one end of the parallel circuit. Connected The second resistor, the power supply unit electrically connected to the end of the second resistor opposite to the end connected to the parallel circuit, the first connector and the second connector , Measuring a voltage value between a reference potential portion electrically connected to the other end of the parallel circuit and the parallel circuit and the second resistor, and based on the measured voltage value, The present invention relates to an image forming apparatus comprising: a control unit that determines that a connector and the second connector are not connected and that the temperature detection element is abnormal.

  The temperature detecting element is preferably a thermistor.

  According to the present invention, it is possible to provide an image forming apparatus that determines whether the fixing unit is not mounted on the image forming apparatus main body and that the temperature detecting element is in failure.

1 is a diagram illustrating an overall configuration of a copier according to an embodiment of an image forming apparatus. 2 is a block diagram illustrating a functional configuration of a copier. FIG. It is a circuit diagram for describing one embodiment of the present invention. 6 is a flowchart for explaining an example of the operation of the copier.

  A copier according to an embodiment of an image forming apparatus of the present invention will be described below with reference to the drawings. First, the overall configuration of the copy machine 1 will be described. FIG. 1 is a diagram for explaining an overall configuration of a copier 1 according to an embodiment of an image forming apparatus.

The copier 1 includes a copier main body (image forming apparatus main body) 2 that forms a toner image on a paper T as a transfer material. Specifically, the copier 1 includes a document transport unit 10, a document reading unit 20, a paper transport unit 30, an image forming unit 40, a transfer unit 50, and a fixing unit 60 in the copier body 2. .
The document transport unit 10 is an ADF (Automatic Document Feeder), and includes a document placement unit 11, a first feed roller 12, a guide 13, a timing roller pair 14, and a document discharge unit 15. The first feed roller 12 supplies the document G placed on the document placement unit 11 to the timing roller pair 14 one by one in order. The timing roller pair 14 is a timing at which the document reading unit 20 reads an image of the document G and a timing at which the document G is supplied to a position where the image of the document G is read by the document reading unit 20 (a position where the guide 13 is disposed). In order to match, the conveyance of the original G or the conveyance stop of the original G is performed. The guide 13 guides the conveyed document G to a first reading surface 21a described later. The document discharge unit 15 discharges the document G whose image has been read by the document reading unit 20 (passed through the guide 13) to the outside of the copier body 2.
A document stacking unit 16 is formed outside the copying machine main body 2 in the document discharge unit 15. In the document stacking unit 16, the documents G discharged from the document discharge unit 15 are stacked and stacked.

  The document reading unit 20 includes a first reading surface 21a and a second reading surface 22a. The first reading surface 21 a is formed along the upper surface of the first contact glass 21 disposed to face the guide 13 and serves as a surface for reading an image of the document G. The second reading surface 22a is disposed adjacent to the first reading surface 21a (in the case shown in FIG. 1, over the most right side of the first reading surface 21a). The second reading surface 22 a is used when reading an image of the document G without using the document transport unit 10. The second reading surface 22a is formed along the upper surface of the second contact glass 22 on which the document G is placed, and serves as a surface for reading an image of the document G.

  The document reading unit 20 includes an illumination unit 23, a first mirror 24, a second mirror 25, a third mirror 26, an imaging lens 27, and an imaging unit 28 inside the copier body 2. . The illumination unit 23 and the first mirror 24 move in the sub-scanning direction X, respectively. The second mirror 25 and the third mirror 26 are disposed on the left side of the illumination unit 23 and the first mirror 24 in FIG. Further, the second mirror 25 and the third mirror 26 are the first reading surface 21 a or the second reading surface 22 a through the first mirror 24, the second mirror 25, the third mirror 26, and the imaging lens 27. To the imaging unit 28 while moving in the sub-scanning direction X while keeping the distance (optical path length) constant.

  The illumination unit 23 is a light source that irradiates the original G with light. The first mirror 24, the second mirror 25, and the third mirror 26 are mirrors for guiding the light reflected by the document G to the imaging lens 27 while keeping the optical path length constant. The imaging lens 27 focuses the light incident from the third mirror 26 on the imaging unit 28. The imaging unit 28 is an imaging device for obtaining image data based on an imaged optical image by converting incident light into an electrical signal. For example, the imaging unit 28 is a CCD (Charge Coupled Device) or a CMOS (Complementary). It is an image sensor such as Metal Oxide Semiconductor).

The paper transport unit 30 includes a second feed roller 31, a third feed roller 32, a registration roller pair 33, and a paper discharge unit 34. The second feed roller 31 supplies the transfer unit 50 with the paper T (transfer material) stored in the paper feed cassette 36. The third feed roller 32 supplies the paper T (transfer material) placed on the manual feed tray 37 to the transfer unit 50. The registration roller pair 33 performs the conveyance of the paper T or the conveyance stop of the paper T in order to match the timing when the toner image reaches the transfer unit 50 and the timing when the paper T is supplied to the transfer unit 50. Further, the registration roller pair 33 performs skew (oblique feeding) correction of the paper T. The paper discharge unit 34 discharges the paper T on which the toner image is fixed to the outside of the copier body 2.
A paper discharge stacking unit 35 is formed outside the copier body 2 in the paper discharge unit 34. In the paper discharge stacking unit 35, the paper T discharged from the paper discharge unit 34 is stacked and stacked.

The image forming unit 40 is for forming a toner image. The image forming unit 40 includes a photosensitive drum 41, a charging unit 42, a laser scanner unit 43, a developing device 44, a cleaning unit 45, a toner cartridge 46, 1 A next transfer roller 47, an intermediate transfer belt 48, and a counter roller 49 are provided.
The photoconductor drum 41 (41a, 41b, 41c, 41d) functions as a photoconductor or an image carrier in order to form toner images of black, cyan, magenta, and yellow, respectively. Around each photosensitive drum 41a, 41b, 41c, 41d, in order from the upstream side to the downstream side along the rotation direction of the photosensitive drum 41, a charging unit 42, a laser scanner unit 43, a developing device 44, A cleaning unit 45 is disposed. The charging unit 42 charges the surface of the photosensitive drum 41. The laser scanner unit 43 is arranged apart from the surface of the photosensitive drum 41 and scans and exposes the surface of the photosensitive drum 41 based on image data relating to the original G read by the original reading unit 20. As a result, the exposed portion of the charge is removed from the surface of the photosensitive drum 41 to form an electrostatic latent image. The developing device 44 forms a toner image by attaching toner to the electrostatic latent image formed on the surface of the photosensitive drum 41. The cleaning unit 45 removes toner and the like remaining on the surface of the photosensitive drum 41 after the surface of the photosensitive drum 41 is neutralized by a static eliminator (not shown).
The toner cartridge 46 stores toner of each color supplied to the developing device 44. The toner cartridge 46 and the developing device 44 are connected by a toner supply path (not shown).

  The primary transfer rollers 47 (47a, 47b, 47c, 47d) are arranged on the opposite sides of the intermediate transfer belt 48 from the photosensitive drums 41a, 41b, 41c, 41d, respectively. The intermediate transfer belt 48 is a belt that passes through the image forming unit 40 and the transfer unit 50. A part of the intermediate transfer belt 48 is sandwiched between the photosensitive drums 41a, 41b, 41c, and 41d and the primary transfer rollers 47a, 47b, 47c, and 47d, and the photosensitive drums 41a, 41b, 41c, and 41d. The toner image formed on the surface is primarily transferred. The opposing roller 49 is a driving roller that is disposed inside the intermediate transfer belt 48 having an annular shape, and advances the intermediate transfer belt 48 in the direction of arrow A shown in FIG.

  The transfer unit 50 includes a secondary transfer roller 51. The secondary transfer roller 51 is disposed on the opposite side of the intermediate transfer belt 48 from the opposing roller 49, and a part of the intermediate transfer belt 48 is sandwiched between the opposing roller 49. Further, the secondary transfer roller 51 secondarily transfers the toner image primarily transferred to the intermediate transfer belt 48 onto the paper T.

  The fixing unit 60 fixes the toner image formed on the paper T to the paper T. Specifically, the fixing unit 60 includes a heating rotator 61 and a pressure rotator 62. The heating rotator 61 and the pressure rotator 62 sandwich the paper T on which the toner image is secondarily transferred, melt and pressurize the toner, and fix the toner to the paper T. The fixing unit 60 is configured to be detachable from the copier body 2.

Next, the functional configuration of the copy machine 1 will be described. FIG. 2 is a block diagram showing a functional configuration of the copy machine 1.
The copier 1 includes the above-described components (the document transport unit 10, the document reading unit 20, the paper transport unit 30, the image forming unit 40, the transfer unit 50, and the fixing unit 60). The engine unit 3 is configured by the paper transport unit 30, the image forming unit 40, the transfer unit 50, and the fixing unit 60. Note that the description of the components described with reference to FIG. 1 is omitted.
Further, the copier 1 includes an operation unit 70, a storage unit 80, and a control unit 90 in addition to the functional configuration described above.

  The operation unit 70 includes a numeric keypad (not shown), a touch panel (not shown), a start key (not shown), and the like. The numeric keypad is operated to input numbers such as the number of copies to be printed. The touch panel displays a plurality of keys to which various functions (for example, a function for setting a print magnification and a function for allocating a plurality of pages to one sheet of paper T (such as 2 in 1)) are assigned. A key displayed on the touch panel is operated to cause the copier 1 to execute any of various functions. The start key is operated to execute printing. When any key is operated, the operation unit 70 supplies a signal indicating that this key has been operated to the control unit 90.

  The storage unit 80 includes a hard disk, a semiconductor memory, and the like. The storage unit 80 stores image data based on the document G read by the document reading unit 20. Further, the storage unit 80 stores a control program used in the copier 1, data used by the control program, and the like.

  The control unit 90 controls the document conveying unit 10, the document reading unit 20, the engine unit 3, the operation unit 70, and the like.

  Next, features of the present invention will be described. FIG. 3 is a circuit diagram for explaining an embodiment of the present invention.

  As described above, the fixing unit 60 is configured to be detachable from the copier body 2. In order to enable attachment / detachment, the fixing unit 60 includes a first connector 103, and the copier body 2 includes a second connector 104. The second connector 104 is connected to the first connector 103 when the fixing unit 60 is attached to the copier body 2. Thus, the circuit on the fixing unit 60 side and the circuit on the copier body 2 side are electrically connected via the first connector 103 and the second connector 104. In addition, when the fixing unit 60 is detached from the copier body 2, the first connector 103 and the second connector 104 are disconnected.

The fixing unit 60 includes a thermistor 101 as a temperature detection element and a first resistor 102.
The thermistor 101 is for detecting the temperature of the heating rotator 61 (see FIG. 1) for heating the toner image formed on the paper T. Specifically, the thermistor 101 is disposed in the vicinity of the heating rotator 61, and the resistance value changes according to the temperature of the heating rotator 61. The control unit 90 described above detects the temperature of the heating rotator 61 based on the voltage value that varies depending on the resistance value of the thermistor 101.

The first resistor 102 is electrically connected to the thermistor 101 in parallel. The resistance value of the first resistor 102 is obtained by conducting an experiment or the like in advance so that it can be detected that the fixing unit 60 is not attached to the copier body 2 and that the thermistor 101 is out of order. Set as appropriate.
The first connector 103 is connected to both ends of the parallel circuit 100 including the thermistor 101 and the first resistor 102.

  The copier body 2 includes a second resistor 105, a power supply unit 106, a reference potential unit 107, and the control unit 90 described above.

  The second resistor 105 is electrically connected to one end of the parallel circuit 100 including the thermistor 101 and the first resistor 102. That is, the second resistor 105 is electrically connected to one end of the parallel circuit 100 via the second connector 104 and the first connector 103. The resistance value of the second resistor 105 is determined by conducting an experiment or the like in advance so that it can be detected that the fixing unit 60 is not attached to the copier body 2 and that the thermistor 101 is out of order. Set as appropriate.

The power supply unit 106 is electrically connected to the end of the second resistor 105 opposite to the end connected to the parallel circuit 100. For example, the power supply unit 106 applies a voltage of 3.3 V to the second resistor 105.
The reference potential portion (GND) 107 is electrically connected to the other end of the parallel circuit 100 via the first connector 103 and the second connector 104.

The control unit 90 measures the voltage value between the parallel circuit 100 and the second resistor 105, and based on the measured voltage value, the first connector 103 and the second connector 104 are disconnected (the fixing unit). 60 is detached from the copying machine main body 2), and it is determined that the thermistor 101 is abnormal.
When the fixing unit 60 is not attached to the copier body 2, the control unit 90 detects the voltage value at the second resistor 105. For example, the control unit 90 detects a voltage value of 3.3V.

具体的な一例としては、電源部１０６が３．３Ｖである場合には、制御部９０は、約３．０Ｖ以上３．３Ｖ未満の電圧値を検出する。 Further, since the fixing unit 60 is mounted on the copying machine main body 2 (the first connector 103 and the second connector 104 are connected) and the thermistor 101 is out of order, the fixing unit 60 is electrically opened. If the thermistor 101 is disconnected from the parallel circuit 100, the control unit 90 detects the output voltage Vout of the voltage dividing circuit of the first resistor 102 and the second resistor 105. Here, the output voltage Vout is expressed by Equation 1, where Vin is the input voltage, R1 is the resistance value of the first resistor 102, and R2 is the resistance value of the second resistor 105.

As a specific example, when the power supply unit 106 is 3.3 V, the control unit 90 detects a voltage value of about 3.0 V or more and less than 3.3 V.

  Further, since the fixing unit 60 is mounted on the copying machine main body 2 (the first connector 103 and the second connector 104 are connected), and the thermistor 101 is out of order, it is electrically short-circuited. If it is, the control unit 90 detects 0V.

具体的な一例としては、電源部１０６が３．３Ｖである場合には、制御部９０は、約０．５Ｖ以上約３．０Ｖ未満の電圧値を検出する。 Further, when the fixing unit 60 is attached to the copying machine main body 2 (the first connector 103 and the second connector 104 are connected) and the thermistor 101 is not broken, the control unit 90 The output voltage Vout of the voltage dividing circuit of the one resistor 102, the thermistor 101, and the second resistor 105 is detected. Here, the output voltage Vout is expressed by Equation 2 when the resistance of the thermistor 101 is R3.

As a specific example, when the power supply unit 106 is 3.3 V, the control unit 90 detects a voltage value of about 0.5 V or more and less than about 3.0 V.

  As described above, when the fixing unit 60 is attached to the copier body 2 (when the first connector 103 and the second connector 104 are connected), the fixing unit 60 is not attached to the copier body 2. In the case (when the first connector 103 and the second connector 104 are not connected), and when the thermistor 101 is out of order, the voltage value measured by the control unit 90 is different. Based on the measured voltage value, it is determined in any of the above cases.

  As an example, the control unit 90 determines that the fixing unit 60 is detached from the copier body 2 when the detected voltage value is 3.3V. Further, when the detected voltage value is about 3.0 V or more and less than 3.3 V, the control unit 90 indicates that the fixing unit 60 is attached to the copier body 2 and the thermistor 101 has failed. Therefore, it is determined that the circuit is electrically open or the thermistor 101 is disconnected from the parallel circuit 100 (thermistor 101 is abnormal). In addition, the control unit 90 determines that the detected voltage value is normal when the detected voltage value is about 0.5 V or more and less than about 3.0 V. When the detected voltage value is 0V, the control unit 90 is electrically short-circuited because the fixing unit 60 is mounted on the copier body 2 and the thermistor 101 is out of order. (Thermistor 101 is abnormal).

Next, an example of the operation of the copy machine 1 will be described. FIG. 4 is a flowchart for explaining an example of the operation of the copy machine 1.
In step ST1, the control unit 90 measures the voltage value between the parallel circuit 100 and the second resistor 105.

  In step ST2, the control unit 90 determines whether or not the voltage value measured in step ST1 is a predetermined value. Here, the predetermined value is the same value as the voltage value of the power supply unit 106, and is 3.3V as an example. The predetermined value may be a voltage value range including the same value as the voltage value of the power supply unit 106. If the voltage value is a predetermined value (Yes), the process proceeds to step ST3. If the voltage value is not a predetermined value (No), the process proceeds to step ST4.

  In step ST3, the control unit 90 is not mounted on the fixing unit 60 copying machine body 2 (the fixing unit 60 is detached from the copying machine body 2 (the first connector 103 and the second connector 104 are not connected). Yes)).

  If “No” is determined in step ST2, in step ST4, the controller 90 determines whether or not the voltage value measured in step ST1 is within the first range. In the first range, the fixing unit 60 is mounted on the copier body 2 (the first connector 103 and the second connector 104 are connected), and the thermistor 101 is broken down, so that it is electrically opened. This is a voltage value range indicating that the state or the thermistor 101 is out of the parallel circuit 100. As an example, the first range is a range of about 3.0V or more and less than 3.3V. When the predetermined value in step ST2 defines the voltage value range, the first range does not overlap with the voltage value range. If the voltage value is within the first range (Yes), the process proceeds to step ST5. If the voltage value is not within the first range (No), the process proceeds to step ST6.

  In step ST5, the control unit 90 determines that the thermistor 101 is abnormal. Specifically, the control unit 90 includes the fixing unit 60 mounted on the copier body 2 (the first connector 103 and the second connector 104 are connected), and the thermistor 101 is out of order. It is determined that the circuit is electrically open or the thermistor 101 is disconnected from the parallel circuit 100.

  If “No” is determined in step ST4, in step ST6, the controller 90 determines whether or not the voltage value measured in step ST1 is within the second range. In the second range, the fixing unit 60 is mounted on the copying machine main body 2 (the first connector 103 and the second connector 104 are connected), and the thermistor 101 is not broken (when normal). Is a range of voltage values. As an example, the second range is a range of about 0.5 V or more and less than about 3.0 V. If the voltage value is within the second range (Yes), the process proceeds to step ST7. If the voltage value is not within the second range (No), the process proceeds to step ST8.

  In step ST7, the control unit 90 determines that the fixing unit 60 is normal. In this case, the control unit 90 measures the temperature of the heating rotator 61 based on the voltage value that changes according to the resistance value of the thermistor 101.

  On the other hand, in step ST8, the controller 90 determines that the thermistor 101 is abnormal. Specifically, the control unit 90 includes the fixing unit 60 mounted on the copier body 2 (the first connector 103 and the second connector 104 are connected), and the thermistor 101 is out of order. It is determined that the circuit is electrically short-circuited.

In addition, after the process of step ST3, step ST5, and step ST8, the control part 90 may display the determination result on the touch panel mentioned above.
In addition, after the processes of step ST3, step ST5, step ST7, and step ST8, the process ends.

As described above, according to the copying machine 1 of the present embodiment, the following effects are produced.
That is, the copier 1 of the present embodiment is connected in parallel to the thermistor 101 and the thermistor 101 for detecting the temperature of the heating rotator 61 that heats the toner image formed on the paper T. The first resistor 102, the second resistor 105 electrically connected to the parallel circuit 100 including the thermistor 101 and the first resistor 102, and the power supply unit 106 electrically connected to the second resistor 105. And the reference potential unit 107 electrically connected to the parallel circuit 100, and the voltage value between the parallel circuit 100 and the second resistor 105 are measured. Based on the measured voltage value, the first connector 103 and the second And a control unit 90 that determines that the two connector 104 is not connected and that the thermistor 101 is abnormal. Thereby, in the copying machine 1, the first connector 103 and the second connector 104 are not connected (the fixing unit 60 is detached from the copying machine body 2), and the thermistor 101 is abnormal. Each of these can be determined.

In addition, this invention is not limited to embodiment mentioned above, It can implement with a various form.
The copier 1 of the present embodiment is a color copier, but is not limited to this form and may be a monochrome copier.
In the copying machine 1 of the present embodiment, the toner image is transferred to the paper T via the intermediate transfer belt 48 (indirect transfer method). However, the present invention is not limited to this form, and is formed on the photosensitive drum. The transferred toner image may be directly transferred to the paper T (direct transfer method).
The copier 1 of the present embodiment is configured to print one side of the paper T, but is not limited to this, and may be configured to print both sides of the paper.

Further, the image forming apparatus of the present invention is not limited to the copying machine 1 described above. In other words, the image forming apparatus of the present invention may be a multi-function machine having a copy function, a facsimile function, a printer function, and a scanner function, or may be a printer.
The transfer material on which the toner image is fixed by the image forming apparatus of the present invention is not limited to the paper T, and may be a film sheet such as an OHP (overhead projector) sheet.

DESCRIPTION OF SYMBOLS 1 ... Copy machine (image forming apparatus) 60 ... Fixing part 90 ... Control part 100 ... Parallel circuit 101 ... Thermistor (temperature detection element) 102 ... 1st resistance 103 ... 1st connector 104 ... 1st 2 connectors 105 ... second resistor 106 ... power supply unit 107 ... reference potential unit

Claims (2)

An image forming apparatus main body that forms a toner image on a transfer material, and a fixing unit that is detachable from the image forming apparatus main body and fixes the toner image formed on the transfer material to the transfer material. An image forming apparatus comprising:
The fixing unit is
A temperature detection element for detecting the temperature of the heating rotator for heating the toner image formed on the transfer material;
A first resistor electrically connected in parallel to the temperature sensing element;
A first connector connected to both ends of a parallel circuit composed of the temperature detection element and the first resistor,
The image forming apparatus main body includes:
A second connector connected to the first connector when the fixing unit is attached to the main body of the image forming apparatus;
A second resistor electrically connected to one end of the parallel circuit via the first connector and the second connector;
A power supply unit electrically connected to an end of the second resistor opposite to the end connected to the parallel circuit;
A reference potential portion serving as a ground potential , electrically connected to the other end of the parallel circuit via the first connector and the second connector;
The voltage value between the parallel circuit and the second resistor is measured, and based on the measured voltage value, the first connector and the second connector are not connected, and the temperature detection element is abnormal And a control unit for determining that
The controller is
When the measured voltage value is the same voltage value as the power supply unit, it is determined that the first connector and the second connector are not connected,
When the measured voltage value is a voltage value within a first range lower than the voltage value of the power supply unit, the first connector and the second connector are connected, and the temperature detection Determining that the device is electrically open due to an element failure or that the temperature sensing element is out of the parallel circuit;
When the measured voltage value is a voltage value in a second range lower than the voltage value in the first range, the first connector and the second connector are connected, and It is determined that the temperature detection element has not failed,
When the measured voltage value is different from the voltage value of the power supply unit and is not a voltage value within the first range and is not a voltage value within the second range, It is determined that the second connector is connected, and that the temperature detection element has failed and is electrically short-circuited.
Image forming apparatus. The image forming apparatus according to claim 1, wherein the temperature detection element is a thermistor.

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