JP6601346B2 - Electronics - Google Patents

Description

  The present invention relates to an electronic apparatus including a device control unit that executes a predetermined control end process.

  An electronic device such as a printer may be provided with a device such as a display panel and a device control unit such as a display control unit that controls the operation of the display panel. In this type of electronic device, the device control unit operates with power supplied from a power source connected to an external power source. Further, in the electronic device, a control end process that is predetermined in the device control unit may be executed before the power supply to the device control unit is stopped. For example, in the control end process executed by the display control unit, power supply to the display panel provided in the display control unit is stopped after power supply to the display panel is stopped.

  By the way, in an electronic device, a power supply path between an external power source and a power source may be interrupted due to an operation of a main power switch by a user or a power failure. In this case, power supply to the device control unit may be stopped before the end of the control end process, resulting in a malfunction such as an abnormality in device operation. On the other hand, there is known an electronic device that can execute the control termination process when a decrease in the output voltage of the power supply is detected (see, for example, Patent Document 1).

JP 2000-305524 A

  By the way, when another load is connected to the power supply, the output voltage of the power supply may drop rapidly, and the end of the control end process may not be in time for stopping the power supply to the device control unit. On the other hand, based on the detection result of the output voltage of the other power supply whose output voltage is lowered before the power supply due to the interruption of the power supply path between the external power supply and the power supply, the device control unit performs the control end processing. Can be executed. However, when the other power source is provided on another substrate different from the substrate on which the device control unit is mounted, a detection circuit for detecting the output voltage of the other power source is also provided on the other substrate. Therefore, when the board on which the device control unit is mounted is removed from the electronic device, the control end process cannot be completed before the power supply to the device control unit is stopped.

  An object of the present invention is to provide an electronic device capable of ending the control end process before stopping the power supply to the device control unit even when the board on which the device control unit is mounted is removed. It is in.

  The electronic apparatus according to the present invention includes a device control unit, a first power supply, a second power supply, a diode, a capacitor, a detection unit, and a signal output unit. The device control unit controls the operation of the device, and executes a predetermined control end process when a predetermined control end signal is input. The first power source is provided on a first substrate on which the device control unit is mounted, and supplies power to the device control unit. The second power source is provided on a second substrate different from the first substrate, and supplies power to the first power source. The diode has an anode terminal connected to the first power source and a cathode terminal connected to the device controller. The capacitor is connected between the cathode terminal and the ground. The detection unit detects a reverse bias in the diode. The signal output unit outputs the control end signal to the device control unit when the reverse bias is detected by the detection unit.

  According to the present invention, it is possible to realize an electronic apparatus capable of ending the control end process before stopping the power supply to the device control unit even when the board on which the device control unit is mounted is removed. .

FIG. 1 is a diagram showing a configuration of an image processing apparatus according to an embodiment of the present invention. FIG. 2 is a block diagram showing a system configuration of the image processing apparatus according to the embodiment of the present invention. FIG. 3 is a block diagram showing the configuration of the power supply unit of the image processing apparatus according to the embodiment of the present invention. FIG. 4 is a circuit diagram showing a configuration of a signal output circuit of the image processing apparatus according to the embodiment of the present invention.

  Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings for understanding of the present invention. The following embodiment is an example embodying the present invention, and does not limit the technical scope of the present invention.

[Schematic Configuration of Image Processing Apparatus 10]
First, a schematic configuration of the image processing apparatus 10 according to the embodiment of the present invention will be described with reference to FIGS. Here, FIG. 1 is a schematic cross-sectional view showing the configuration of the image processing apparatus 10.

  The image processing apparatus 10 is a multifunction machine having a plurality of functions such as a facsimile function or a copy function, in addition to a scan function for reading image data from a document and a print function for forming an image based on the image data. Here, the image processing apparatus 10 is an example of an electronic apparatus according to the present invention. Further, the present invention is applicable to electronic devices such as a scanner device, a printer device, a facsimile device, a copier, a personal computer, a television, an air conditioner, and a refrigerator.

  As shown in FIGS. 1 and 2, the image processing apparatus 10 includes an ADF 1, an image reading unit 2, an image forming unit 3, a paper feeding unit 4, a main control unit 5, an operation unit 6, a display unit 7, and a power supply unit. 8 is provided.

  The ADF 1 is an automatic document conveyance device that includes a document setting unit, a plurality of conveyance rollers, a document pressing unit, and a paper discharge unit, and conveys a document read by the image reading unit 2. The image reading unit 2 includes a document table, a light source, a plurality of mirrors, an optical lens, and a CCD (Charge Coupled Device), and can read image data from the document.

  The image forming unit 3 can form an image by electrophotography based on the image data read by the image reading unit 2 or image data input from an information processing apparatus such as an external personal computer. Specifically, the image forming unit 3 includes a photosensitive drum, a charging device, an optical scanning device (LSU), a developing device, a transfer roller, a cleaning device, a fixing roller, a pressure roller, and a paper discharge tray. Then, in the image forming unit 3, an image is formed on the sheet supplied from the paper feeding unit 4, and the sheet after the image formation is discharged to the paper discharge tray.

  The main control unit 5 includes control devices such as a CPU, ROM, RAM, and EEPROM (registered trademark) (not shown). The CPU is a processor that executes various arithmetic processes. The ROM is a non-volatile storage unit in which information such as a control program for causing the CPU to execute various processes is stored in advance. The RAM is a volatile storage unit used as a temporary storage memory (working area) for various processes executed by the CPU. The EEPROM is a nonvolatile storage unit. In the main controller 5, various control programs stored in advance in the ROM are executed by the CPU. As a result, the image processing apparatus 10 is comprehensively controlled by the main control unit 5. The main control unit 5 may be an electronic circuit such as an integrated circuit (ASIC), and is a control unit provided separately from the control unit that controls the image processing apparatus 10 in an integrated manner. May be.

  The operation unit 6 is an operation key or a touch panel for inputting various types of information to the main control unit 5 in accordance with a user operation.

  The display unit 7 displays various information such as the operation state of the image processing apparatus 10 in accordance with a control instruction from the main control unit 5. As shown in FIG. 2, the display unit 7 includes a display panel 71 and a display control unit 72. For example, the display panel 71 is a liquid crystal panel.

  The display control unit 72 can control the display on the display panel 71. For example, the display control unit 72 has a control circuit that operates with a voltage of 3.3V supplied from a first power supply 82 of the power supply unit 8 described later, and a voltage of 3.3V supplied from the first power supply 82 of 24V. A boosting circuit that boosts the driving voltage and supplies the driving voltage to the display panel 71 is provided. The control circuit controls driving of the display panel 71 based on screen data input from the main control unit 5.

  In addition, the display control unit 72 executes a predetermined control end process before the display control of the display panel 71 is ended. In the control end process, power supply to the booster circuit and the control circuit is stopped in the order of the booster circuit and the control circuit. Here, the display panel 71 is an example of a device in the present invention. The display control unit 72 is an example of a device control unit in the present invention. Note that the device in the present invention may be another device capable of executing the control end process. For example, the device in the present invention may be a hard disk drive or a motor.

  The display control unit 72 executes the control end process when a predetermined control end signal is input. For example, the display control unit 72 executes the control end process when the input level of the electrical signal input to the input terminal 72A (see FIG. 4) is switched from the high level to the low level. That is, the low-level electric signal input to the input terminal 72A is an example of a predetermined control end signal in the present invention. The display control unit 72 may execute the control end process when the input level of the electric signal input to the input terminal 72A is switched from the low level to the high level.

  The power supply unit 8 supplies power to each unit of the image processing apparatus 10. As shown in FIGS. 2 and 3, the power supply unit 8 includes a second power supply 81, a first power supply 82, and a signal output circuit 83.

  As shown in FIG. 3, the second power supply 81 supplies power supplied from the external power supply 20 to the first power supply 82. Further, as shown in FIG. 3, the second power supply 81 supplies power supplied from the external power supply 20 to another load 10 </ b> C. For example, the other loads 10 </ b> C are the ADF 1, the image reading unit 2, and the image forming unit 3.

  For example, the second power supply 81 is an AC-DC converter that converts an AC voltage of 100 volts supplied from the external power supply 20 into a DC voltage of 24 volts. As shown in FIG. 3, the second power supply 81 is provided on the second substrate 10A.

  As shown in FIG. 3, the first power supply 82 supplies power supplied from the second power supply 81 to the display control unit 72. Moreover, the 1st power supply 82 supplies the electric power supplied from the 2nd power supply 81 to other load 10D, as FIG. 3 shows. For example, the other load 10 </ b> D is a communication interface that communicates with the main control unit 5 and an external information processing apparatus.

  For example, the first power supply 82 is a DC-DC converter that converts a DC voltage of 24 volts supplied from the second power supply 81 into a DC voltage of 3.3 volts. As shown in FIG. 3, the first power supply 82 is provided on a first substrate 10B different from the second substrate 10A. Further, the signal output circuit 83, the display control unit 72, and the other load 10D are also provided on the first substrate 10B.

  Incidentally, in the image processing apparatus 10, the power supply path between the external power supply 20 and the second power supply 81 may be interrupted due to the operation of the main power switch by the user or a power failure. In this case, if the power supply to the display control unit 72 is stopped before the end of the control end process executed in the display control unit 72, problems such as an abnormality in the operation of the display panel 71 may occur. There is. On the other hand, there is known an electronic device that can execute the control end process when a decrease in the output voltage of the first power supply 82 is detected.

  Here, when another load 10 </ b> D is connected to the first power supply 82 as in the image processing apparatus 10, the output voltage of the first power supply 82 rapidly decreases before the power supply to the display control unit 72 is stopped. The control end process may not end. On the other hand, based on the detection result of the output voltage of the second power supply 81 on the upstream side of the power supply path by the external power supply 20 with respect to the first power supply 82, the display control unit 72 may execute the control end process. It is done. However, since the second power supply 81 is provided on the second substrate 10A, a detection circuit for detecting the output voltage of the second power supply 81 is also provided on the second substrate 10A. Therefore, when the first substrate 10B on which the display control unit 72 is mounted is removed from the image processing apparatus 10, the control end process cannot be completed before power supply to the display control unit 72 is stopped.

  On the other hand, in the image processing apparatus 10 according to the embodiment of the present invention, as will be described below, even when the first substrate 10B on which the display control unit 72 is mounted is removed, the display control unit 72. It is possible to end the control end processing before stopping the power supply to.

  Hereinafter, the signal output circuit 83 will be described with reference to FIG.

  The signal output circuit 83 generates the control end signal and outputs it to the display control unit 72 when the output voltage of the first power supply 82 decreases. As illustrated in FIG. 4, the signal output circuit 83 includes a diode 831, a smoothing capacitor 832, a detection unit 833, and a signal output unit 834.

  The diode 831 is connected between the first power supply 82 and the display control unit 72. Specifically, as illustrated in FIG. 4, the diode 831 has an anode terminal connected to the first power supply 82 and a cathode terminal connected to the display control unit 72.

  The smoothing capacitor 832 is connected between the cathode terminal of the diode 831 and the ground, as shown in FIG. Smoothing capacitor 832 absorbs and smoothes fluctuations in the DC voltage output from first power supply 82. The smoothing capacitor 832 supplies the charged power to the display control unit 72 when the connection between the external power supply 20 and the second power supply 81 is interrupted. The capacitance of the smoothing capacitor 832 is set to an appropriate value based on the power consumption during the execution of the control end process in the display control unit 72 and the execution time of the control end process. Here, the smoothing capacitor 832 is an example of a capacitor in the present invention.

  The detection unit 833 detects a reverse bias in the diode 831. Specifically, the detection unit 833 includes a first resistor 833A and a PNP transistor 833B as shown in FIG. As shown in FIG. 4, the first resistor 833A is connected between the anode terminal of the diode 831 and the base terminal of the PNP transistor 833B. As shown in FIG. 4, the PNP transistor 833B has a base terminal connected to the anode terminal of the diode 831 via the first resistor 833A, an emitter terminal connected to the cathode terminal of the diode 831, and a collector terminal connected to the signal. Connected to the output unit 834.

  The signal output unit 834 outputs the control end signal to the display control unit 72 when the reverse bias in the diode 831 is detected by the detection unit 833. Specifically, the signal output unit 834 includes a second resistor 834A, a third resistor 834B, and an NPN transistor 834C, as shown in FIG. The second resistor 834A is connected between the cathode terminal of the diode 831 and the input terminal 72A of the display control unit 72, as shown in FIG. As shown in FIG. 4, the third resistor 834B is connected between the collector terminal of the PNP transistor 833B of the detection unit 833 and the base terminal of the NPN transistor 834C. As shown in FIG. 4, the NPN transistor 834C has a base terminal connected to the collector terminal of the PNP transistor 833B of the detection unit 833 via the third resistor 834B, and a collector terminal connected to the input terminal of the display control unit 72. The emitter terminal is connected to the ground.

  Next, the operation of the signal output circuit 83 will be described.

  First, while power is being supplied from the external power supply 20 to the second power supply 81, a voltage of 3.3 volts is output from the first power supply 82. In this case, the diode 831 is forward biased, and power is supplied from the first power supply 82 to the display control unit 72. Further, the smoothing capacitor 832 is charged by the power supplied from the first power supply 82. Further, both the PNP transistor 833B of the detection unit 833 and the NPN transistor 834C of the signal output unit 834 are turned off. Therefore, a high-level electric signal is input to the input terminal 72A of the display control unit 72.

  Next, when the connection between the external power supply 20 and the second power supply 81 is interrupted, the output voltage at the second power supply 81 decreases and the output voltage of the first power supply 82 also decreases. When the potential at the anode terminal of the diode 831 becomes lower than the potential at the cathode terminal due to a decrease in the output voltage of the first power supply 82, the diode 831 becomes reverse biased. Thereby, the energization path which connects the 1st power supply 82 and the display control part 72 is interrupted | blocked. In addition, discharge is started from the smoothing capacitor 832. The display control unit 72 is operated by the electric power charged in the smoothing capacitor 832 after the diode 831 is reverse-biased. When the potential at the anode terminal of the diode 831 is lower than the potential at the cathode terminal, a current flows between the emitter terminal and the base terminal of the PNP transistor 833B of the detection unit 833, and the PNP transistor 833B is turned on. . As a result, a current flows between the base terminal and the emitter terminal of the NPN transistor 834C of the signal output unit 834, and the NPN transistor 834C is turned on. Therefore, the output level of the electric signal input to the input terminal 72A of the display control unit 72 is switched from the high level to the low level. That is, the control end signal is output from the signal output unit 834 to the display control unit 72. Thereby, the display control unit 72 executes the display end process.

  Here, while the display end process is executed in the display control unit 72, the energization path connecting the first power supply 82 and the display control unit 72 is blocked by the diode 831. Thereby, it is avoided that the electric power charged in the smoothing capacitor 832 is supplied to another load 10 </ b> D connected to the first power supply 82. Therefore, the operation time by the power supply from the smoothing capacitor 832 in the display control unit 72 is not affected by the load state of the other load 10D connected to the first power supply 82.

  As described above, in the image processing apparatus 10, when the output voltage of the first power supply 82 is lowered, the energization path connecting the first power supply 82 and the display control unit 72 is cut off and the display by the smoothing capacitor 832 is performed. Power supply to the control unit 72 is started, and the control end signal is generated and output to the display control unit 72. In the image processing apparatus 10, the first power supply 82 and the signal output circuit 83 are provided on the first substrate 10 </ b> B on which the display control unit 72 is mounted. Thus, even when the first substrate 10B on which the display control unit 72 is mounted is removed, the control end process can be ended before the power supply to the display control unit 72 is stopped.

1 ADF
2 image reading unit 3 image forming unit 4 paper feeding unit 5 main control unit 6 operation unit 7 display unit 8 power supply unit 10 image processing apparatus 10A second substrate 10B first substrate 71 display panel 72 display control unit 81 second power source 82 first 1 power supply 83 signal output circuit 831 diode 832 smoothing capacitor 833 detection unit 834 signal output unit

Claims (3)

A device control unit that controls the operation of the device and executes a predetermined control end process when a predetermined control end signal is input;
A first power source provided on a first substrate on which the device control unit is mounted, and supplying power to the device control unit;
A second power source provided on a second substrate different from the first substrate and supplying power to the first power source;
A diode having an anode terminal connected to the first power source and a cathode terminal connected to the device controller;
A capacitor connected between the cathode terminal and the ground;
A detector for detecting a reverse bias in the diode;
A signal output unit that outputs the control end signal to the device control unit when the reverse bias is detected by the detection unit;
Equipped with a,
The detection unit includes a PNP transistor having a base terminal connected to the anode terminal via a first resistor, an emitter terminal connected to the cathode terminal, and a collector terminal connected to the signal output unit. ,
The signal output unit includes a second resistor connected between the cathode terminal and an input terminal to which the control end signal is input in the device control unit, and a PNP transistor via a third resistor. An electronic device comprising: a base terminal connected to the collector terminal; a collector terminal connected to the input terminal; and an NPN transistor having an emitter terminal connected to ground . The device is a display panel;
The electronic device according to claim 1 . An image reading unit capable of reading image data from a document, and an image forming unit capable of forming an image based on the image data, or both.
The electronic device according to claim 1 or 2 .

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