JP5976727B2 - Electronics - Google Patents

Description

  The present invention relates to an electronic device including a heater and a sensor such as a photosensor.

  In an image forming apparatus which is an electronic device, it is known that when a recording paper containing moisture is used, paper feeding does not operate normally and the occurrence frequency of jam increases. Therefore, a cassette heater is provided in the paper feed cassette to dehumidify the recording paper stored in the paper feed cassette.

JP 2005-252945 A

However, although power is supplied to the cassette heater from a commercial AC power supply via a power supply circuit, noise may occur in the power supply line due to the circumstances of the commercial AC power supply. This noise affects the sensor output line of the transport switch (a sensor such as a photosensor that detects feeding of recording paper from the paper feed cassette) as AC line noise, and the sensor output may be erroneously detected.
Although measures can be taken so that the power supply line and the sensor output line do not run in parallel, it is difficult to ensure a sufficient distance between the power supply line and the sensor output line when space saving is to be performed.
Further, the power supply circuit or power supply line may be provided with a noise filter composed of a capacitor or the like, or a noise filter using differential amplification processing of a differential amplifier (see, for example, Patent Document 1) to remove AC line noise. Though conceivable, it is difficult to completely remove high-frequency noise such as AC line noise with a low-cost noise filter.

  In view of the above problems, an object of the present invention is to provide an electronic device that can solve the problems of the prior art and prevent erroneous detection of sensor output due to AC line noise generated in a power supply line that supplies power to a heater. There is to do.

An electronic device of the present invention is an electronic device including a sensor and a control unit that performs control based on a detection signal output from the sensor, and a heater, a power supply circuit that supplies power to the heater, A noise detection line that runs parallel to the power supply line from the power supply circuit to the heater; and a noise determination unit that detects AC line noise propagated from the power supply line to the noise detection line. The detection signal output from the sensor is invalidated for a preset invalid period from the timing at which the AC line noise is detected by the noise determination unit.
Furthermore, in the electronic apparatus of the present invention, the noise detection line may be set to have a higher impedance than the sensor output line of the sensor.
Furthermore, in the electronic apparatus of the present invention, the noise determination unit is turned on during the invalid period from a noise detection circuit that detects the AC line noise and a timing at which the AC line noise is detected by the noise detection circuit. An invalid signal generation circuit that generates a sensor output invalid signal may be provided.

  According to the present invention, the AC line noise generated in the power supply line that supplies power to the heater is detected, and the sensor output is invalidated for a preset invalid period from the timing at which the AC line noise is detected. There is an effect that it is possible to prevent erroneous detection of sensor output due to noise.

It is a schematic sectional drawing which shows the structural example of embodiment of the electronic device which concerns on this invention. It is a block diagram which shows schematic structure of the electronic device shown in FIG. It is a block diagram which shows the structure of the power supply circuit and noise determination part which are shown in FIG.

Next, embodiments of the present invention will be specifically described with reference to the drawings.
The electronic apparatus according to the present embodiment is an image forming apparatus 100 such as a copying machine, and includes a document reading unit 120, a document feeding unit 130, and a recording unit 140 as illustrated in FIG. The document reading unit 120 is disposed above the recording unit 140, and the document feeding unit 130 is disposed above the document reading unit 120. Further, on the front side of the image forming apparatus 100, a touch panel device 10 for setting the image forming apparatus 100 and instructing operation is disposed. Although the image forming apparatus 100 of the present embodiment has been described with reference to a copying machine, it is needless to say that a scanner, a multifunction peripheral, and the like are included.

  The document reading unit 120 includes a scanner 121, a platen glass 122, and a document reading slit 123. The scanner 121 includes light emitting means such as an exposure lamp and LED, and reading means such as a CCD (Charge Coupled Device) sensor, and is configured to be movable in the transport direction of the document MS by the document feeding unit 130. The platen glass 122 is an original table made of a transparent member such as glass. The document reading slit 123 has a slit formed in a direction orthogonal to the direction in which the document MS is conveyed by the document feeding unit 130.

  When reading the document MS placed on the platen glass 122, the scanner 121 is moved to a position facing the platen glass 122 and reads the document MS while scanning the document MS placed on the platen glass 122. Image data is acquired, and the acquired image data is output to the recording unit 140. When reading the document MS conveyed by the document feeding unit 130, the scanner 121 is moved to a position facing the document reading slit 123, and the document MS by the document feeding unit 130 is moved through the document reading slit 123. The document MS is read in synchronism with the transport operation to acquire image data, and the acquired image data is output to the recording unit 140.

  The document feeding unit 130 includes a document placing unit 131, a document discharge unit 132, and a document transport mechanism 133. The documents MS placed on the document placement unit 131 are sequentially fed out one by one by the document conveyance mechanism 133 and conveyed to a position facing the document reading slit 123 of the document reading unit 120, and then the document discharge unit. It is discharged to 132. The document feeding unit 130 is configured to be retractable, and the upper surface of the platen glass 122 can be opened by lifting the document feeding unit 130 upward.

  The recording unit 140 includes an image forming unit 150, and includes a paper feeding unit 160, a conveyance path 170, a conveyance roller 181, a discharge roller 182, and a discharge tray 190.

  The paper feeding unit 160 includes a plurality of paper feeding cassettes 161a to 161d that store the recording paper P, a paper feeding roller 162 that feeds the recording paper P from the paper feeding cassettes 161a to 161d one by one to the conveyance path 170, and a paper feeding cassette. A cassette heater 163 that dehumidifies the recording paper P stored in 161 a to 161 d and a transport switch 4 that detects the recording paper P fed from the paper feeding cassettes 161 a to 161 by the paper supply roller 162 are provided. The paper feed roller 162, the transport roller 181 and the discharge roller 182 function as a transport unit, and the recording paper P is transported. The recording paper P fed from the paper feed cassettes 161 a to 161 d by the paper feed roller 162 is detected by the transport switch 4 and transported to the image forming unit 150 by the transport roller 181 at a predetermined timing. Note that a photo sensor is used as the transport switch 4. The recording paper P on which recording has been performed by the image forming unit 150 is output to the outside by the discharge roller 182. The recording sheet P on which recording has been performed is guided to the discharge roller 182 and output to the discharge tray 190.

  The image forming unit 150 includes a photosensitive drum 151, a charging unit 152, an exposure unit 153, a developing unit 154, a transfer unit 155, a cleaning unit 156, and a fixing unit 157. The exposure unit 153 is an optical unit including a laser device, a mirror, and the like. The exposure unit 153 outputs laser light based on image data, exposes the photosensitive drum 151 charged by the charging unit 152, and An electrostatic latent image is formed on the surface. The developing unit 154 is a developing unit that develops the electrostatic latent image formed on the photosensitive drum 151 using toner, and forms a toner image based on the electrostatic latent image on the photosensitive drum 151. The transfer unit 155 transfers the toner image formed on the photosensitive drum 151 by the developing unit 154 to the recording paper P. The fixing unit 157 heats the recording paper P on which the toner image is transferred by the transfer unit 155 to fix the toner image on the recording paper P.

Next, a hardware configuration example of the image forming apparatus 100 will be described with reference to FIG.
The touch panel device 10, the document reading unit 120, the document feeding unit 130, the image forming unit 150, and the transport unit (paper feed roller 162, transport roller 181, discharge roller 182) are connected to the control unit 1 and operated by the control unit 1. Be controlled. In addition, a storage unit 2, an image processing unit 3, and a noise determination unit 6 are connected to the control unit 1.

  The control unit 1 is an information processing unit such as a microcomputer including a ROM (Read Only Memory), a RAM (Random Access Memory), and the like. The ROM stores a control program for performing operation control of the image forming apparatus 100. The control unit 1 reads out a control program stored in the ROM and develops the control program in the RAM, so that it corresponds to predetermined instruction information input from the touch panel device 10 and a detection signal output from the transport switch 4. The conveyance control of the recording paper P and the image formation control are performed.

  The storage unit 2 is a storage unit such as a semiconductor memory or a HDD (Hard Disk Drive), and stores image data acquired by reading a document by the document reading unit 120.

  The image processing unit 3 is a unit that performs predetermined image processing on image data, and performs, for example, image improvement processing such as enlargement / reduction processing, density adjustment, and gradation adjustment.

  The noise determination unit 6 detects AC line noise generated in the power supply line 50 that supplies power from the power supply circuit 5 for the cassette heater 163 to the cassette heater 163.

  Referring to FIG. 3, the power supply circuit 5 includes a noise filter 51, an inrush current prevention circuit 52, an input rectification smoothing circuit 53, a converter circuit 54, and an output smoothing circuit 55. The noise filter 51 is a circuit configured by a capacitor or the like that removes noise superimposed on an input AC voltage input from a commercial AC power supply. The inrush current prevention circuit 52 is a circuit that is provided at a subsequent stage of the noise filter 51 and is configured by electronic components such as a resistor and a thermistor that suppress an inrush current when the power is turned on. The input rectifying / smoothing circuit 53 is a circuit that is provided in the subsequent stage of the inrush current preventing circuit 52 and is configured by a diode bridge, a smoothing capacitor, or the like that rectifies the input AC voltage into a pulsating current and then smoothes it. The converter circuit 54 is a circuit that is provided at the subsequent stage of the input rectifying / smoothing circuit 53 and converts the DC voltage rectified and smoothed by the input rectifying / smoothing circuit 53 into a desired output voltage. The output smoothing circuit 55 is a circuit that is provided in the subsequent stage of the converter circuit 54 and is configured by a smoothing capacitor that smoothes the output voltage converted by the converter circuit 54.

  As shown in FIG. 3, a noise detection line 60 that runs in parallel to a power supply line 50 that supplies power from the power supply circuit 5 to the cassette heater 163 is connected to the noise determination unit 6. The noise detection line 60 is set to have a higher impedance than the sensor output line 40 that transmits the sensor output of the transport switch 4 to the control unit 1 by a resistor 63 interposed between the noise detection line 60 and the ground terminal. Further, the noise detection line 60 is provided so as to run in parallel with the power supply line 50 at a position closer to the sensor output line 40. As a result, when AC line noise affecting the sensor output line 40 is generated in the power supply line 50, the AC line noise is reliably transmitted from the power supply line 50 to the noise detection line 60.

  The noise determination unit 6 includes a high pass filter 61 and an integration circuit 62. It is difficult to completely remove AC line noise, which is high-frequency noise, with a low-cost filter. Therefore, AC line noise propagated from the power supply line 50 to the noise detection line 60 is detected using the high pass filter 61. That is, AC line noise that is high-frequency noise passes through the high-pass filter 61. The integrating circuit 62 integrates the AC line noise that has passed through the high pass filter 61 to generate a pulse signal that is at a high level for a predetermined time from the detection of the AC line noise, and uses the generated pulse signal as a sensor output invalid signal. Input to the control unit 1.

  The control unit 1 invalidates the detection signal output from the transport switch 4 while the sensor output invalid signal is at a high level, that is, during an invalid period set in advance from the timing at which AC line noise is detected. In general, AC line noise often occurs continuously in a short period of time, and this continuously generated AC line noise affects the sensor output and the control unit 1, and the sensor output is erroneously detected. . Therefore, in the present embodiment, the invalid period preset from the timing when the AC line noise is detected invalidates the detection signal output from the transport switch 4, and thus the AC line noise generated continuously. The sensor output and the controller 1 are not affected, and erroneous detection of the sensor output due to AC line noise is prevented.

As described above, the present embodiment is an image forming apparatus 100 that is an electronic apparatus including the transport switch 4 that is a sensor and the control unit 1 that performs control based on the detection signal output from the transport switch 4. The cassette heater 163, the power supply circuit 5 that supplies power to the cassette heater 163, the noise detection line 60 that runs parallel to the power supply line 50 from the power supply circuit 5 to the cassette heater 163, and the noise detection line from the power supply line 50. And a noise determination unit 6 that detects AC line noise propagated to 60, and the control unit 1 starts from the transport switch 4 during an invalid period preset from the timing when the AC line noise is detected by the noise determination unit 6. Disable the output detection signal.
With this configuration, AC line noise generated in the power supply line 50 that supplies power to the transport switch 4 is detected, and the sensor output is invalidated for a preset invalid period from the timing at which the AC line noise is detected. Since the sensor output is not affected by the AC line noise generated in this way, it is possible to prevent erroneous detection of the sensor output due to the AC line noise.

Further, in the present embodiment, the noise detection line 60 is set to have a higher impedance than the sensor output line 40 of the transport switch 4.
With this configuration, AC line noise affecting the sensor output line 40 of the transport switch 4 can be reliably propagated to the noise detection line 60, and AC line noise can be detected more reliably.

Furthermore, in the present embodiment, the noise determination unit 6 includes a high-pass filter 61 that functions as a noise detection circuit that detects AC line noise, and an invalid period and an on state from the timing when the AC line noise is detected by the high-pass filter 61. And an integration circuit 62 functioning as an invalid signal generation circuit for generating a sensor output invalid signal.
With this configuration, AC line noise can be detected with an inexpensive configuration.
In the above embodiment, the noise determination unit 6 includes the high-pass filter 61 and the integration circuit 62. However, a diode may be provided between the high-pass filter 61 and the integration circuit 62. With this configuration, when AC line noise appears on both polar sides of the output from the high-pass filter 61, the AC line noise on one of the polar sides can be removed by the diode and input to the integrating circuit 62. . Therefore, it is possible to prevent the integration signal from being subtracted (cancelled) by the AC line noise on the opposite polarity side in the integration circuit 62, and a preferable pulse signal can be output.

  Note that the present invention is not limited to the above-described embodiments, and it is obvious that the embodiments can be appropriately changed within the scope of the technical idea of the present invention. In addition, the number, position, shape, and the like of the constituent members are not limited to the above-described embodiment, and can be set to a suitable number, position, shape, and the like in practicing the present invention. In each figure, the same numerals are given to the same component.

DESCRIPTION OF SYMBOLS 1 Control part 2 Memory | storage part 3 Image processing part 4 Conveyance switch 5 Power supply circuit 6 Noise determination part 10 Touch panel apparatus 40 Sensor output line 50 Power supply line 51 Noise filter 52 Inrush current prevention circuit 53 Input rectification smoothing circuit 54 Converter circuit 55 Output smoothing circuit Reference Signs List 60 Noise Detection Line 61 High Pass Filter 62 Integration Circuit 63 Resistance 100 Image Forming Apparatus 120 Document Reading Unit 121 Scanner 122 Platen Glass 123 Document Reading Slit 130 Document Feeding Unit 131 Document Placement Unit 132 Document Ejecting Unit 133 Document Feeding Mechanism 140 Recording Unit 150 Image forming unit 151 Photosensitive drum 152 Charging unit 153 Exposure unit 154 Development unit 155 Transfer unit 156 Cleaning unit 157 Fixing unit 160 Paper feed unit 161a to d Paper feed cassette 162 Paper feed low Over 163 cassette heater 170 transport path 181 transport rollers 182 discharge roller 190 discharge tray

Claims (3)

An electronic device including a sensor and a control unit that performs control based on a detection signal output from the sensor,
A heater,
A power supply circuit for supplying power to the heater;
A noise detection line running in parallel with the power supply line from the power supply circuit to the heater;
A noise determination unit that detects AC line noise propagated from the power supply line to the noise detection line;
The electronic device is characterized in that the control unit invalidates a detection signal output from the sensor for a preset invalid period from the timing when the AC line noise is detected by the noise determination unit.   The electronic device according to claim 1, wherein the noise detection line is set to have a higher impedance than a sensor output line of the sensor. The noise determination unit includes a noise detection circuit that detects the AC line noise;
3. The invalid signal generating circuit for generating a sensor output invalid signal that is turned on during the invalid period from a timing at which the AC line noise is detected by the noise detection circuit. Electronics.

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