JP2014057382A - Power control device and image forming apparatus - Google Patents

Abstract

In a power supply control device, measures are taken against both discharge of an electrolytic capacitor and an instantaneous withstand capability.
A power supply control device comprising an AC / DC conversion section 30 having a smoothing electrolytic capacitor C2, an AC power interruption detecting means S1, and a discharging means R1 of the smoothing electrolytic capacitor C2. Furthermore, a human detection means S2 for detecting a person and a controller CC1 for controlling the discharge of the smoothing electrolytic capacitor C2 are provided. When the controller CC1 detects that the AC power supply Vac is cut off by the AC power supply cut-off detecting means S1, the controller CC1 does not discharge the electric charge of the smoothing electrolytic capacitor C2 if no person is detected by the human detection means S1. When a person is detected, the electric charge of the smoothing electrolytic capacitor C2 is discharged.
[Selection] Figure 2

Description

  The present invention relates to a power supply control device, and more particularly to a power supply control device including an AC / DC converter and an image forming apparatus including the power supply control device.

  In general, an electrophotographic image forming apparatus such as a printer or a copying machine is equipped with a power source including an AC / DC conversion unit. In such a power source, when the input power source is turned off, the electrolytic capacitor for smoothing is discharged to prevent an electric shock accident. In a power supply with a large capacity rating, when a user wants to reset the device when a runaway occurs during light load operation such as in energy saving mode, the voltage remains in the electrolytic capacitor in the power supply when the power switch is turned off and on. Therefore, there is a problem that the power cannot be turned off and the CPU cannot be reset.

  Also, when a service person opens the device and accesses the power supply when a trouble occurs in the power supply, there is a risk of electric shock due to the residual voltage of the electrolytic capacitor. For this reason, if the electrolytic condenser in the power supply is discharged uniformly after a lapse of a predetermined time when the power is shut off, the power supply interruption resistance may be reduced in an area where the power supply situation is bad, and the operation of the device may suddenly stop. is there.

  Patent Document 1 describes control for discharging an electrolytic capacitor when an AC input power source is cut off. However, this control has a problem that it can not handle instantaneous interruption because it discharges regardless of the presence or absence of a person around the device.

  Patent Document 2 describes control for discharging an electrolytic capacitor when it is detected by a detection circuit that the connection of the capacitor unit connected to the apparatus body from the apparatus body is disconnected from the apparatus body. However, this control has the problem that the power switch cannot be turned off or reset because it detects the person pulling out the capacitor unit and discharges the electrolytic capacitor regardless of the interruption of the AC input power supply. doing.

  That is, in any of the techniques described in Patent Documents 1 and 2, countermeasures for both the discharge of the electrolytic capacitor and the momentary interruption tolerance are not sufficient.

JP 2004-282922 A Japanese Patent Laid-Open No. 08-205401

  SUMMARY OF THE INVENTION An object of the present invention is to provide a power supply control device and an image forming apparatus that take measures against both discharge of an electrolytic capacitor and instantaneous withstand capability.

The power supply control device according to the first aspect of the present invention is:
In a power supply control device comprising an AC / DC converter having a smoothing electrolytic capacitor, an AC power interruption detection means, and a discharging means for the smoothing electrolytic capacitor,
Human detection means for detecting a person;
A control unit for controlling discharge of the smoothing electrolytic capacitor;
With
When the control unit detects that the AC power supply is cut off by the AC power supply cut-off detecting unit, if the person is not detected by the human detection unit, the controller does not discharge the electric charge of the smoothing electrolytic capacitor. And if a person is detected, discharging the electric charge of the smoothing electrolytic capacitor,
It is characterized by.

  An image forming apparatus according to a second aspect of the present invention includes the power supply control device.

  In the power supply control device, when the AC power is cut off, the smoothing electrolytic capacitor mounted on the AC / DC converter is discharged only when a person is detected. That is, when a person is near the device when the input power is shut off, the electrolytic capacitor is discharged to protect a nearby person (in many cases, a service person) from an electric shock accident. On the other hand, if there is no person nearby, the electrolytic capacitor will not be discharged even if the input power is cut off, preventing a power reset and a decrease in the instantaneous interruption tolerance of the apparatus.

  According to the present invention, it is possible to protect a person against the discharge of the electrolytic capacitor, and to prevent the instantaneous interruption resistance from being lowered when the safety of the person can be ensured.

1 is a schematic configuration diagram illustrating an image forming apparatus according to an embodiment. It is a block diagram which shows the power supply control apparatus which is 1st Example. It is a flowchart figure which shows the control procedure in 1st Example. It is a block diagram which shows the power supply control apparatus which is a 2nd control example. It is a flowchart figure which shows the control procedure in 2nd Example. It is a flowchart figure which shows the other example of a control procedure.

  Hereinafter, embodiments of a power supply control device and an image forming apparatus according to the present invention will be described with reference to the accompanying drawings. In addition, the same code | symbol is attached | subjected to the same member and part in each figure, and the overlapping description is abbreviate | omitted.

(Schematic configuration of image forming apparatus, see FIG. 1)
First, a schematic configuration of an image forming apparatus according to an embodiment will be described with reference to FIG. This image forming apparatus is configured as a full-color printer 1 based on electrophotography.

  In this printer 1, Y (yellow), M (magenta), and C (cyan) color image forming photoconductors 2y, 2m, and 2c and a B (black) black image forming photoconductor 2k are juxtaposed. It is configured as a tandem system, and image forming elements such as developing units 3y, 3m, 3c, 3k and a laser scanning unit 4 for image exposure are arranged around the respective photoreceptors 2y, 2m, 2c, 2k. . An intermediate transfer belt 5 is disposed immediately above the photoreceptors 2y, 2m, 2c, and 2k, and toner supply units 6y and 6m that supply new toner to the developing units 3y, 3m, 3c, and 3k are disposed immediately above the belts. , 6c, 6k are arranged. The process of forming latent images and toner images on the respective photoreceptors 2y, 2m, 2c, and 2k is well known and will not be described.

  A paper feed cassette 10 is disposed immediately below the laser scanning unit 4. The sheets fed one by one from the sheet feeding cassette 10 are conveyed to the nip portion between the intermediate transfer belt 5 and the transfer roller 7 by rollers 11 and 12, and the toner image from the intermediate transfer belt 5 is 2 on the sheet. Next transferred. Thereafter, the sheet is sent to the fixing unit 8 where the toner is thermally fixed and discharged from the discharge roller 13 onto the discharge tray 9 on the upper surface of the main body.

  The above photoreceptors and rollers are driven by the following motors. That is, the main motor M1 drives the paper conveyance system from the paper feed cassette 10 to the secondary transfer portion (transfer roller 7), the intermediate transfer belt 5, and the black photosensitive member 3k. The fixing motor M2 drives the fixing unit 8. The black developing motor M3 drives the black developing unit 3k. The color developing motor M4 drives the color developing units 3y, 3m, 3c. The color photoconductor motor M5 drives the color photoconductors 2y, 2m, and 2c.

(Refer to the first embodiment of the power control device, FIG. 2 and FIG. 3)
As shown in FIG. 2, the power supply control device 20A according to the first embodiment is obtained by connecting an AC / DC conversion unit 30 to the line L and the line N of the AC power supply Vac. A heater lamp H1 of the fixing unit 8 is connected via a triac TR1.

  The AC / DC conversion unit 30 includes diodes D1, D2, D3, D4, a smoothing electrolytic capacitor C2, a discharge resistor R1, and a transformer T1, and further includes a discharge control circuit CC1, an AC power interruption detector S1, and a human sense. Sensor S2. The electrolytic capacitor C2 and the discharge resistor R1 are connected in parallel between the power supply lines DC1 and DC2. One end of the discharge resistor R1 is connected to the output portion of the discharge control circuit CC1 via the MOS field effect transistor Q2. The AC voltage input from the AC power supply Vac is rectified by the diodes D1 to D4 and smoothed by the electrolytic capacitor C2.

  An AC power interruption detector S1 and a human sensor S2 are connected to the input of the discharge control circuit CC1. The AC power interruption detector S1 is connected to the lines L and N via the lines LS1 and NS1. The human sensor S2 is a sensor that directly detects that a person has approached by infrared rays, temperature, or the like.

  A MOS field effect transistor Q1 is connected in series to the primary winding of the transformer T1, and energy on the primary side is transmitted to and cut off from the secondary side by turning on and off the transistor Q1. The secondary winding has a 24V output terminal t1 and a 5V output terminal t2, and is rectified and smoothed by diodes D5 and D6 and electrolytic capacitors D3 and C4, respectively. The output terminal t1 of 24V is used as a power supply terminal for driving systems such as the motors M1 to M5. The 5V output terminal t2 is used as a power supply terminal for a control system such as a CPU that controls the printer 1 as a whole.

  When the AC power supply Vac is cut off, the voltage between the lines LS1 and NS1 changes, and in response to this change, the detector S1 outputs an AC interruption signal ACS1 to the discharge control circuit CC1. When the human sensor S2 senses that there is a person nearby, the human sensor signal MS1 is output to the discharge control circuit CC1. The discharge control circuit CC1 does not discharge the electric charge of the smoothing electrolytic capacitor C when it is detected that the AC power supply is cut off by the AC power supply interruption detector S1 and the human sensor S2 is not detecting a person. When a person is detected, the emission signal DC01 is output to turn on the transistor Q2, and the electric charge of the smoothing electrolytic capacitor C2 is discharged. At this time, the electric charge is released as heat at the discharge resistor R1.

  In consideration of an instantaneous voltage drop when the AC power supply Vac is shut off, the smoothing electrolytic capacitor C2 has a capacity sufficient to operate the printer 1 during an AC 1 cycle time (20 milliseconds), which is an instantaneous interruption resistance. When the human sensor S2 senses a person and the detector S1 detects the interruption of the AC power supply Vac, the transistor Q2 is turned on after an alternating current cycle time (20 milliseconds) which is an instantaneous interruption resistance, and the electrolytic capacitor C2 The electric charge charged to is discharged by the discharge resistor R1. When the sensor S2 is not sensing a person, the transistor Q2 is not turned on and the electrolytic capacitor C2 is not discharged even if the detector S1 detects the interruption of the AC power supply Vac.

  By the above control, when a person can be protected against the discharge of the smoothing electrolytic capacitor C2 and the safety of the person can be ensured, it is possible to prevent the instantaneous interruption resistance from being lowered.

  Next, a control procedure in the power supply control device 20A will be described with reference to FIG. When the power is turned on, the presence of a person is detected by the human sensor S2 (YES in step S1), and when the AC power supply interruption detector S1 detects the interruption of the AC power supply Vac (step). When 20 milliseconds have elapsed (YES in S2) (YES in Step S3), the electrolytic capacitor C2 is discharged (Step S4).

(Refer to the second embodiment of the power supply control device, FIG. 4 and FIG. 5)
As shown in FIG. 4, the power supply control device 20B according to the second embodiment has various parameters provided on the operation panel of the printer 1 in place of the human sensor S2 included in the power supply control device 20A. Is a touch sensor S3 or a switch for the user to input. That is, the touch sensor S3 is operated to indirectly detect that a person is approaching the printer 1 (more specifically, the power supply control device 20B). Note that the touch sensor and the switch are not necessarily limited to those provided on the operation panel.

  The power control device 20B according to the second embodiment is the same as the power control device 20A according to the first embodiment in other configurations and operations, and can protect people against the discharge of the smoothing electrolytic capacitor C2, In addition, when the safety of a person can be ensured, the same can be said that a reduction in the momentary interruption tolerance can be prevented.

  Next, a control procedure in the power supply control device 20B will be described with reference to FIG. When the power is turned on, if the presence of a person is detected by the touch sensor S3 (YES in step S11), the AC power interruption detector S1 while the timer counts 10 seconds (NO in step S12). When the interruption of the AC power supply Vac is detected by (step S13: YES), when 20 milliseconds have elapsed (YES in step S14), the electrolytic capacitor C2 is discharged (step S15). When the timer counts 10 seconds (YES in step S12), the control for discharging the electrolytic capacitor S2 is not executed because the person is separated from the printer 1 after 10 seconds from the human detection timing. Because it is.

(Control of discharge time by operation mode, see FIG. 6)
When the printer 1 has the first mode and the second mode that consumes less power than the first mode as the operation mode, in the first and second embodiments, the AC power cut-off detector S1 causes an alternating current. The time from when the power supply Vac is cut off until the smoothing electrolytic capacitor C2 is discharged is the same when the first mode is executed and when the second mode is executed. It was.

  On the other hand, the time from when the AC power supply interruption detector S1 detects that the AC power supply Vac is cut off until the smoothing electrolytic capacitor C2 is discharged is relatively long when the first mode is executed. When the second mode is being executed, it may be set relatively short. That is, when the printer 1 has operation modes with different loads, the capacity of the electrolytic capacitor C2 with respect to the momentary interruption tolerance is selected with the maximum load. For this reason, if the operation is in the second mode with a light load such as a standby mode or a sleep mode, the instantaneous interruption tolerance can be increased by slightly delaying the start of discharge.

  FIG. 6 shows a control procedure in which the discharge start time of the electrolytic capacitor C2 is varied according to the operation mode of the printer 1. In FIG. 6, steps S11 to S13 are the same as the control procedure shown in FIG. If it is detected in step S13 that the AC power supply Vac is shut off, the electrolytic capacitor C2 is turned off when 20 milliseconds have elapsed (YES in step S22) during operation in the print mode with a large load (YES in step S21). Discharging is started (step S28). It is considered that the energy of the electrolytic capacitor C2 disappears after 20 msec, which is the instantaneous interruption tolerance of the printer 1.

  During operation in the standby mode (YES in step S23), discharging of the electrolytic capacitor C2 is started when 100 milliseconds have elapsed (YES in step S24) (step S28). In the standby mode, since the energy of the electrolytic capacitor C2 remains as much as less power consumption than in the print mode, the discharge is started after 100 milliseconds. Next, during operation in the sleep mode (YES in step S25), discharging of the electrolytic capacitor C2 is started when 500 milliseconds have elapsed (YES in step S26) (step S28). The sleep mode takes into consideration that the load is lighter than the standby mode.

  When operating in a mode other than the above mode, discharging of the electrolytic capacitor C2 is started when one second has elapsed (YES in step 27) (step S28). As other operation modes, a further low power consumption mode is assumed as an energy saving standard. When operating in such a low power consumption mode, there is a momentary withstand capability for a considerably long time. However, if the time until the start of discharge is set too long, there is a problem in resetting the power off and on. Therefore, in this control example, the upper limit is set to 1 second. Further, the delay time in this control example may be a time for satisfying the maximum instantaneous interruption tolerance depending on the operation mode.

(Other examples)
The power supply control device and the image forming apparatus according to the present invention are not limited to the above-described embodiments, and can be variously modified within the scope of the gist.

  In particular, details of the configuration of the AC / DC converter 30 are arbitrary. Needless to say, the image forming apparatus is not limited to the printer 1.

  As described above, the present invention is useful for a power supply control device and an image forming apparatus, and is particularly excellent in that it can protect a person against the discharge of an electrolytic capacitor and can prevent a reduction in instantaneous interruption resistance. .

DESCRIPTION OF SYMBOLS 1 ... Printer 20A, 20B ... Power supply control apparatus 30 ... AC / DC conversion part C2 ... Smoothing electrolytic capacitor Vac ... AC power supply S1 ... AC power-off detection sensor S2 ... Human sensor S3 ... Touch sensor R1 ... Discharge resistance CC1 ... Discharge Control circuit

Claims (6)

In a power supply control device comprising an AC / DC converter having a smoothing electrolytic capacitor, an AC power interruption detection means, and a discharging means for the smoothing electrolytic capacitor,
Human detection means for detecting a person;
A control unit for controlling discharge of the smoothing electrolytic capacitor;
With
When the control unit detects that the AC power supply is cut off by the AC power supply cut-off detecting unit, if the person is not detected by the human detection unit, the controller does not discharge the electric charge of the smoothing electrolytic capacitor. And if a person is detected, discharging the electric charge of the smoothing electrolytic capacitor,
A power supply control device. The human detection means is a human sensor,
The control unit controls the discharge of the electrolytic capacitor for smoothing when a person is detected by the human sensor from a predetermined time before the AC power supply is shut off until the shutoff;
The power supply control device according to claim 1. The human detection means is a touch sensor or a switch operated by a user,
The control unit controls the discharge of the smoothing electrolytic capacitor when a person is detected by operating the touch sensor or the switch from a predetermined time before the AC power is shut off until the power is shut off;
The power supply control device according to claim 1. A first mode and a second mode that consumes less power than the first mode;
The time from when the AC power supply interruption detecting means detects that the AC power supply has been cut off until the smoothing electrolytic capacitor is discharged is the time when the first mode is executed and the time when the second mode is executed. Being the same as when
The power supply control device according to any one of claims 1 to 3, wherein A first mode and a second mode that consumes less power than the first mode;
The time from when it is detected that the AC power supply has been cut off by the AC power supply cut-off detecting means until the smoothing electrolytic capacitor is discharged is relatively long when the first mode is executed, Be relatively short when performing the second mode,
The power supply control device according to any one of claims 1 to 3, wherein   An image forming apparatus comprising the power supply control device according to claim 1.

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