JP2017079561A - Power supply device and image forming apparatus including the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To adjust a potential difference between outputs from a plurality of power supply circuits provided for a single device so as to easily satisfy a condition for the potential difference.SOLUTION: A power supply device comprises: a first power supply circuit that supplies a power to a processing circuit provided in a device; a second power supply circuit that supplies a power to another processing circuit in the device in which the processing circuit is provided; and a control circuit that performs output adjustment processing on the second power supply circuit. The control circuit recognizes a potential difference between a first output voltage from the first power supply circuit and a second output voltage from the second power supply circuit, starts the output adjustment processing when the potential difference is outside an allowable range, and adjusts the second output voltage in the output adjustment processing so that the potential difference falls within the allowable range.SELECTED DRAWING: Figure 6

Description

  The present invention relates to a power supply device including a plurality of power supply circuits. The present invention also relates to an image forming apparatus including the power supply device.

  Various devices such as circuits, ICs, and electronic parts are mounted on image forming apparatuses such as printers, multifunction machines, copiers, and facsimile machines. Further, since power saving is achieved by reducing the number of devices to be operated in the power saving mode, the devices to be supplied (driven) in the normal operation mode and the power saving mode are different. In order to input an appropriate voltage to each device and supply power according to the prepared mode, the image forming apparatus is equipped with a plurality of types of power supplies.

  Specifically, Patent Document 1 includes a main power supply unit for a normal operation mode and a sub power supply unit for an energy saving mode. The main power supply unit includes a main power supply power generation unit and a main power source that controls the main power supply unit. A power supply control unit, and the sub power supply unit includes a sub power supply power generation unit and a sub power supply control unit for controlling the sub power supply unit. The sub power supply power generation unit operates the main power control unit and the sub power supply control unit. The sub power supply unit is in an operating state in both the normal operation mode and the energy saving mode, and the power supply from the sub power supply power generation unit to the main power supply control unit is stopped in the energy saving mode. A power supply is described. With this configuration, the power supply to the load is stopped and there is no delay in the rise of the power supply, and an efficient power supply apparatus is to be provided (see Patent Document 1: Claim 1, paragraph [0011], etc.).

JP 2012-114973 A

  Some devices include a plurality of types of circuits having different functions (processing contents) in one device. One type of such circuit is an ASIC. The ASIC is an integrated circuit that is designed specifically for the application.

  In a device including a plurality of circuits having different functions, a power source may be required for each circuit. In such a device, if the difference in power supply voltage input to each circuit is large, the potential difference between the internal circuits increases, and the device may not operate normally. In such a device, it is ideal to input a power supply voltage having the same magnitude to each circuit. In some cases, it is difficult to input a voltage having the same potential to each circuit. In practice, the potential difference between the power supply voltages input to each circuit is within an allowable range. In other words, a condition may be imposed on the potential difference of the power supply voltage.

  If the output of the same power supply circuit is supplied to a plurality of circuits, the potential difference condition can be cleared. However, some circuits included in one device include circuits that are not used in the power saving mode. If power supply to circuits that are not used in the power saving mode can be stopped independently, power consumption in the power saving mode can be reduced. Therefore, one power supply circuit such as a DCDC converter may be provided for each circuit in one device that requires input of a voltage having the same magnitude or potential difference within an allowable range.

  A power supply circuit is provided for each circuit in one device, and it is necessary to satisfy the potential difference condition that each power supply circuit must generate and output a voltage having the same magnitude or potential difference within an allowable range. The voltage (set voltage) that is set as the output of each power supply circuit is the same value. However, a different type of power supply circuit may be connected to each power supply terminal. Each power supply circuit has a difference in temperature characteristics and output characteristics. Therefore, it is difficult to always match the output voltages of the power supply circuits. As a result, there arises a problem that the potential difference between the output voltages of the plurality of power supply circuits may exceed an allowable range.

  Japanese Patent Application Laid-Open No. 2004-151561 describes how to use the main power supply unit and the sub power supply unit in the normal operation mode and the power saving mode. However, there is no description about the potential difference between the output voltages of the plurality of power supply circuits. Therefore, the above problem cannot be solved.

  The present invention has been made in view of the above-described problems of the prior art, and adjusts the potential difference of output voltages from a plurality of power supply circuits provided for one device so that the potential difference condition can be easily satisfied. To.

  In order to solve the above problem, a power supply device according to a first aspect includes a first power supply circuit, a second power supply circuit, and a control circuit. The first power supply circuit supplies power to a processing circuit provided in the device. The second power supply circuit supplies power to another processing circuit in the device provided with the processing circuit. The control circuit controls the output voltage of the second power supply circuit and performs output adjustment processing. Further, the control circuit recognizes a potential difference between a first output voltage that is an output voltage of the first power supply circuit and a second output voltage that is an output voltage of the second power supply circuit, and the potential difference is determined in advance. When it is out of range, the output adjustment process is started. In the output adjustment process, the second output voltage is adjusted so that the potential difference is within the allowable range.

  According to the present invention, a power supply circuit is provided for each circuit in one device, and when each power supply circuit must generate and output a voltage having the same magnitude or potential difference within an allowable range, The potential difference of the output of the power supply circuit can be adjusted. And the potential difference of the output voltage of each power supply circuit can be kept in an allowable range, and the potential difference condition can be easily satisfied.

1 is a diagram illustrating an example of a printer according to an embodiment. It is a figure which shows an example of the electric power supply system of the printer which concerns on embodiment. It is a figure for demonstrating the electric power supply to ASIC which concerns on embodiment. It is a figure which shows an example of the power supply device which concerns on embodiment. It is a figure showing an example of the 2nd power supply circuit concerning an embodiment. It is a flowchart which shows an example of the flow of the output adjustment process which concerns on embodiment. It is a figure which shows an example of the temperature corresponding | compatible data which concern on embodiment. It is a flowchart which shows an example of the flow of the setting of the initial adjustment value of the reference voltage at the time of the operation | movement start of the 2nd power supply circuit which concerns on embodiment.

  Hereinafter, an image forming apparatus including the power supply device 1 according to the present invention will be described with reference to FIGS. The printer 100 will be described as an example of the image forming apparatus. However, each element such as the configuration and arrangement described in this embodiment does not limit the scope of the invention and is merely an illustrative example.

(Outline of image forming apparatus)
First, the printer 100 according to the embodiment will be described with reference to FIG. FIG. 1 is a diagram illustrating an example of a printer 100 according to the embodiment.

  The printer 100 includes a main control unit 2 (main control board). The main control unit 2 controls the overall operation of the apparatus and controls each unit of the printer 100. The main control unit 2 is provided with a main CPU 21 as a central processing unit. The main control unit 2 is mounted with circuits such as an ASIC 10 (corresponding to a device), a ROM 22 and a RAM 23 for storing a control program and data. The ASIC 10 performs image processing and communication processing necessary for printing. Details of the ASIC 10 will be described later.

  The printer 100 also includes a mass storage device such as the HDD 24. An SSD may be used instead of the HDD 24. The main control unit 2 is communicably connected to the HDD 24. The main control unit 2 reads out necessary image data, programs, and various control data stored in the HDD 24 and stores them in the RAM 23.

  The main control unit 2 is connected to the operation panel 3 so as to be communicable. The operation panel 3 displays a setting screen, the status of the printer 100, and a message. The operation panel 3 also accepts a user's operation on a touch panel and hard keys provided on the operation panel 3. Then, the main control unit 2 recognizes the setting operation content performed on the operation panel 3. Then, the main control unit 2 controls the printer 100 so as to operate as set by the user.

  The printer 100 includes a printing unit 4. The printing unit 4 includes an engine control unit 40, a paper feeding unit 4a, a conveyance unit 4b, an image forming unit 4c, an intermediate transfer unit 4d, and a fixing unit 4e. The engine control unit 40 actually controls printing-related processes such as paper feeding, paper conveyance, toner image formation, transfer, and fixing. The engine control unit 40 and the main control unit 2 are connected to be communicable. The main control unit 2 gives the engine control unit 40 a print instruction, the contents of the print job, and image data used for printing. Based on the received content, the engine control unit 40 controls the paper feed unit 4a, the conveyance unit 4b, the image forming unit 4c, the intermediate transfer unit 4d, and the fixing unit 4e. Specifically, various types of rotating bodies related to paper feeding, conveyance, image formation, transfer, and fixing are rotated to control printing.

  The engine control unit 40 supplies the sheets one by one to the sheet feeding unit 4a. The engine control unit 40 transports the supplied paper to the transport unit 4b through the image forming unit 4c, the intermediate transfer unit 4d, and the fixing unit 4e to a discharge tray (not shown). The engine control unit 40 causes the image forming unit 4c to form a toner image to be placed on the sheet conveyed from the conveyance unit 4b. The printer 100 is capable of color printing, and includes an exposure device 42 and a plurality of image forming units 41 (in FIG. 1, only one image forming unit is shown for convenience). Each image forming unit 41 includes members and devices such as a photosensitive drum, a charging device, and a developing device. Each image forming unit 41 has a different toner image color. The exposure device 42 scans and exposes each photosensitive drum based on the image data. The engine control unit 40 controls the operations of the image forming units 41 and the exposure device 42.

  The intermediate transfer unit 4d includes an intermediate transfer belt that receives primary transfer of the toner images of the respective colors formed on the photosensitive drums of the image forming units 41. The engine control unit 40 rotates the intermediate transfer belt to the intermediate transfer unit 4d, and secondarily transfers the toner image primarily transferred to the intermediate transfer belt onto the conveyed paper. Further, the engine control unit 40 fixes the toner image transferred to the paper on the fixing unit 4e. The transport unit 4b discharges the sheet on which the toner image is fixed to the discharge tray.

  The printer 100 includes a communication I / F 25. The communication I / F 25 is an interface for connecting to a network. The main control unit 2 is connected to the communication I / F 25. Thereby, the main control part 2 can communicate via a network. The communication I / F 25 receives print data including data indicating print contents such as image data and data indicating settings related to printing from the computer 200. The main control unit 2 causes the printing unit 4 to perform printing based on the printing data.

(Power supply system)
Next, an example of the power supply system in the printer 100 according to the embodiment will be described with reference to FIG. FIG. 2 is a diagram illustrating an example of a power supply system of the printer 100 according to the embodiment.

  The printer 100 includes a primary power supply unit 5 and a secondary power supply unit 6. The primary power supply unit 5 is connected to a commercial power supply by a power cable (not shown). The primary power supply unit 5 is a switching power supply having a rectifier circuit, a transformer, a switching element, and a smoothing circuit. The primary power supply unit 5 outputs a DC voltage when a commercial power supply is connected. The primary power supply unit 5 generates, for example, DC 24V for driving the motor. For the sake of convenience, illustration of the motor driving voltage wiring is omitted.

  The secondary power supply unit 6 includes a plurality of power conversion circuits such as a regulator and a DCDC converter. In addition, the power supply device 1 which concerns on embodiment is a part of power converter circuit contained in the secondary power supply part 6 (refer FIG. 3). In addition, you may provide the secondary power supply part 6 in the form disperse | distributed to each board | substrate. The secondary power supply unit 6 generates a plurality of types of DC voltages based on the voltage generated by the primary power supply unit 5. In each device such as the main CPU 21 ASIC 10, ROM 22, RAM 23, and other elements, a range of voltage values to be input (supplied) is determined. The secondary power supply unit 6 generates a voltage within the range of the voltage value to be input (supplied) and supplies it to each device.

  The secondary power supply unit 6 is a main CPU 21 of the main control unit 2, ROM 22, RAM 23, ASIC 10, CPU in the engine control unit 40, memory, display panel (not shown) provided in the operation panel 3, and display in the operation panel 3 A voltage necessary for driving is supplied to various devices such as a memory (not shown) for storing image data.

  Here, in order to prevent an abnormal operation from occurring, the order of voltage application (power supply) and voltage cutoff (power supply stop) to each device is predetermined. In addition, when a plurality of types of voltages are applied to one device, the order of voltages to be applied may be determined. For example, in a circuit such as a CPU, when applying a voltage, there is a rule that a voltage for a core is applied and then a voltage for I / O is applied. That is, the start order and stop order of the operations of the various power conversion circuits included in the secondary power supply unit 6 are determined in advance.

  Therefore, a power supply sequence circuit 60 (power supply sequence circuit) is provided in the printer 100. The power supply sequence circuit 60 starts voltage application to each substrate and each device in the printer 100 in a predetermined order. The power supply sequence circuit 60 stops voltage application to each substrate and each device in the printer 100 in a predetermined order. For this reason, the power supply sequence circuit 60 controls ON / OFF of the power conversion circuit (including the power supply device 1) included in the secondary power supply unit 6.

(Normal mode and power saving mode)
Next, a normal mode and a power saving mode in the printer 100 (power supply device 1) according to the embodiment will be described with reference to FIGS.

  The printer 100 (power supply device 1) has a normal mode and a power saving mode. In the power saving mode, power supply to a predetermined supply stop portion is stopped. Specifically, during the power saving mode, the power supply sequence circuit 60 stops the power conversion circuit that supplies power to the supply stop portion of the secondary power supply unit 6. In the printer 100, the operation panel 3 and the printing unit 4 are included in the supply stop portion. In FIG. 2, in the power saving mode, power supply to the devices in the engine control unit 40 (engine board) and the operation panel 3 (panel board) is stopped. On the other hand, in the normal mode, power is supplied to the supply stop portion. In other words, the normal mode is a mode that keeps the printer 100 in a printable state. When the main power is turned on, the printer 100 (power supply device 1) starts in the normal mode.

  In the main control unit 2, power is supplied to the main CPU 21, ROM 22, RAM 23, and communication I / F 25 even in the power saving mode. Of the ASIC 10 of the main control unit 2, when the power supply is stopped in the power saving mode, the power supply is stopped at a predetermined portion, and when the power supply is continued in the power saving mode, the power supply is supplied to the predetermined portion. Continued (details will be described later).

  The main control unit 2 (main CPU 21) recognizes that the condition for shifting to the power saving mode predetermined in the normal mode is satisfied. At this time, the main control unit 2 shifts the printer 100 (power supply device 1) to the power saving mode. When shifting to the power saving mode, upon receiving an instruction for shifting to the power saving mode from the main control unit 2, the power supply sequence circuit 60 stops power supply to the supply stop portion (power conversion for supplying power to the supply stop portion) Stop the circuit).

  During the power saving mode, the main control unit 2 (main CPU 21) recognizes that a predetermined return condition is satisfied. At this time, the main control unit 2 returns the printer 100 (power supply device 1) to the normal mode. When returning to the normal mode, upon receiving an instruction to return to the normal mode from the main control unit 2, the power supply sequence circuit 60 resumes power supply to the supply stop portion (power conversion for supplying power to the supply stop portion) Operate the circuit).

  Here, the transition condition is appropriately determined. The main control unit 2 (main CPU 21) is set in advance for several minutes without entering the next print job in the communication I / F 25 after the normal mode or the print job is completed. When the specified time has elapsed, it is determined that the transition condition is satisfied. The main control unit 2 determines that the transition condition is satisfied when an instruction to shift to the power saving mode is input to the operation panel 3. The transition condition is not limited to the above.

  Return conditions are also determined as appropriate. The main control unit 2 (main CPU 21) determines that the return condition is satisfied when a print job (print data) is input to the communication I / F 25 (ASIC 10) during the power saving mode. The main control unit 2 determines that the return condition is satisfied when the operation panel 3 is operated. Therefore, power is supplied to the part that receives the operation of the operation panel 3 even in the power saving mode. The return condition is not limited to the above.

(Power supply to power supply 1 and ASIC 10)
Next, power supply to the ASIC 10 by the power supply device 1 and the power supply device 1 according to the embodiment will be described with reference to FIG. FIG. 3 is a diagram for explaining power supply to the ASIC 10 according to the embodiment.

  First, the ASIC 10 is provided in the main control unit 2 (see FIG. 1). As shown in FIG. 3, the ASIC 10 includes a first processing circuit 11 (corresponding to a processing circuit) and a second processing circuit 12 (corresponding to another processing circuit). The first processing circuit 11 is a circuit in which a plurality of types of circuits (functions) used only in the normal mode are collected. The second processing circuit 12 is a circuit in which a plurality of types of circuits (functions) used in both the normal mode and the power saving mode are collected.

  The first processing circuit 11 includes a first calculation unit 11a and an image memory 11b. The first arithmetic unit 11a includes a circuit that reads image data from the RAM 23 and HDD 24 to the image memory 11b and writes image data stored in the image memory 11b to the RAM 23 and HDD 24. The first calculation unit 11a also includes a circuit for performing image processing on the image data. The first arithmetic unit 11a is necessary for executing image processing performed by the printer 100, such as a circuit that compresses and decompresses image data, a circuit that expands and reduces image data, and a format conversion circuit for image data. Includes circuitry. The image memory 11b temporarily stores image data before, during, and after the processing of the first calculation unit 11a.

  Since the processing of the image data is performed when the job is executed, it is performed only in the normal mode. As described above, the first processing circuit 11 is a circuit in which a plurality of types of circuits that are operated in the normal mode and are not operated in the power saving mode are collected.

  On the other hand, the second processing circuit 12 includes a second calculation unit 12a. The second arithmetic unit 12 a includes a communication processing circuit and a control circuit for the ROM 22 and RAM 23. Of the second arithmetic unit 12a, the communication processing circuit recognizes the content of the signal received by the communication I / F 25. Further, the communication processing circuit performs a response process to the received request from the network.

  Access control and communication processing to the ROM 22 and RAM 23 must be performed even in the power saving mode. In particular, when printing data is received from the computer 200 during the power saving mode, it is determined that the return condition is satisfied (the power saving mode is canceled). Therefore, the second calculation unit 12a is operated in the normal mode and the power saving mode.

  A power supply device 1 for supplying power to the ASIC 10 is provided in the printer 100. The power supply device 1 includes a control circuit 7, a first power supply circuit 8, and a second power supply circuit 9. In the printer 100 of the present embodiment, both the first power supply circuit 8 and the second power supply circuit 9 are DCDC converters. The first power supply circuit 8 supplies power to the first processing circuit 11 provided in the ASIC 10 (device). The second power supply circuit 9 supplies power to the second processing circuit 12 in the same device (ASIC 10) in which the first processing circuit 11 is provided.

  The magnitude of the first output voltage V1, which is the output voltage of the first power supply circuit 8, is set based on the specifications of the ASIC 10. In other words, the first power supply circuit 8 outputs, as the first output voltage V1, a set voltage that is predetermined within the range of the voltage to be supplied in accordance with the specifications of the ASIC 10. In the second power supply circuit 9, a voltage having the same magnitude as the first output voltage V1 or a difference between the first output voltage V1 within an allowable range is set as a set voltage (second output voltage V2) (details will be described later). ).

  Similarly to the printer 100, the power supply device 1 also has a normal mode and a power saving mode. Similar to the printer 100, the power supply device 1 shifts to the power saving mode when a predetermined transition condition is satisfied in the normal mode, and returns to the normal mode when a predetermined return condition is satisfied in the power saving mode.

  The first processing circuit 11 is used only in the normal mode and is not used in the power saving mode. Therefore, the first power supply circuit 8 supplies power to the first processing circuit 11 in the normal mode and does not supply power to the first processing circuit 11 in the power saving mode. Specifically, the power supply sequence circuit 60 operates the first power supply circuit 8 in the normal mode from the main power supply ON to OFF. On the other hand, the power supply sequence circuit 60 stops the first power supply circuit 8 in the power saving mode and when the main power supply is OFF.

  On the other hand, the second processing circuit 12 is used in both the normal mode and the power saving mode. Therefore, the second power supply circuit 9 supplies power to the second processing circuit 12 in the normal mode and the power saving mode. Specifically, the power supply sequence circuit 60 operates the second power supply circuit 9 from the main power supply ON to the main power supply OFF. The power supply sequence circuit 60 stops the second power supply circuit 9 by turning off the main power supply.

  The printer 100 is provided with a main power switch 61 (see FIG. 2). When an operation to turn on the main power switch 61 is performed, a signal from the main power switch 61 is input to the power sequence circuit 60. The power supply sequence circuit 60 operates the secondary power supply unit 6 including the power supply device 1 and activates the printer 100 in the normal mode. When an operation to turn off the main power switch 61 is performed, a signal from the main power switch 61 is input to the power sequence circuit 60. The power supply sequence circuit 60 stops the operation of the secondary power supply unit 6 including the power supply device 1 and puts the printer 100 in a power OFF state.

(Power supply 1)
Next, the power supply device 1 according to the embodiment will be described with reference to FIGS. 3 and 4. FIG. 4 is a diagram illustrating an example of the power supply device 1 according to the embodiment.

  As illustrated in FIGS. 3 and 4, the power supply device 1 includes a control circuit 7, a first power supply circuit 8, a second power supply circuit 9, a potential difference detection unit 74, and a feedback voltage generation unit 75.

  The control circuit 7 is an element such as a CPU or a microcomputer. The control circuit 7 includes a processing unit 71, a DA converter 72, and a control memory 73. The processing unit 71 is a circuit for performing control and calculation of the power supply device 1.

  The control circuit 7 receives power supply from a power conversion circuit other than the power supply device 1 included in the secondary power supply unit 6, and is activated before the second power supply circuit 9 is activated and starts its operation. That is, the power supply sequence circuit 60 is a power conversion circuit other than the power supply device 1 included in the secondary power supply unit 6 and operates the power conversion circuit that operates the control circuit 7 earlier than the second power supply circuit 9.

Thus, when the operation of the second power supply circuit 9 is started, the control circuit 7 has already been activated. The processing unit 71 outputs a digital value (initial value and initial adjustment value, details of which will be described later) indicating the magnitude of the voltage to be output to the DA converter 72 when the operation of the second power supply circuit 9 is started. When adjusting the two output voltages V2, a digital value corresponding to the output of the potential difference detection unit 74 is input to the DA converter 72 (instruction of the magnitude of the reference voltage Vref). The DA converter 72 converts power from a power supply (not shown) prepared separately, outputs a voltage corresponding to the input digital value as a reference voltage Vref, and inputs the voltage to the second power supply circuit 9. The second power supply circuit 9 generates and outputs a voltage according to the magnitude of the reference voltage Vref. In other words, the second output voltage V2 is set by the reference voltage Vref. Since the second power supply circuit 9 also operates in the power saving mode, it is necessary to input the reference voltage Vref to the second power supply circuit 9 (an output monitoring unit 93 described later) even in the power saving mode. Therefore, power is supplied to the control circuit 7 even in the power saving mode. For example, the control circuit 7 is supplied with power from a power conversion circuit other than the power supply device 1 in the secondary power supply unit 6. The control circuit 7 can be realized by the main CPU 21.

  The control circuit 7 is communicably connected to the ASIC 10 (the first processing circuit 11 and the second processing circuit 12). The control circuit 7 can give an instruction to the ASIC 10. The ASIC 10 operates according to instructions.

  The potential difference detection unit 74 is a circuit for detecting a potential difference between the first output voltage V1 output from the first power supply circuit 8 and the second output voltage V2 output from the second power supply circuit 9. For example, the potential difference detection unit 74 notifies the control circuit 7 of the magnitude relationship between the first output voltage V1 and the second output voltage V2 and the absolute value of the potential difference between the first output voltage V1 and the second output voltage V2. The potential difference detector 74 may not be provided, and the first output voltage V1 and the second output voltage V2 may be input to the AD conversion port of the control circuit 7 so that the control circuit 7 recognizes the magnitude relationship and the absolute value of the potential difference. .

  The feedback voltage generation unit 75 includes a series circuit including a first resistor R1 and a second resistor R2. Specifically, one end of the first resistor R1 and one end of the second resistor R2 are connected. The other end of the first resistor R1 is connected to the output of the second power supply circuit 9. The other end of the second resistor R2 is connected to the ground. Therefore, the second output voltage V2 is applied to the series circuit. A voltage at a connection point provided between the first resistor R1 and the second resistor R2 (a voltage obtained by dividing the second output voltage V2 by the first resistor R1 and the second resistor R2) is used as the feedback voltage FB in the second power supply circuit. 9 is input.

(Second power supply circuit 9)
Next, the second power supply circuit 9 according to the embodiment will be described with reference to FIG. FIG. 5 is a diagram illustrating an example of the second power supply circuit 9 according to the embodiment.

  The second power supply circuit 9 is a DCDC converter. The second power supply circuit 9 includes an output smoothing unit 91, a switching unit 92, an output monitoring unit 93, and a controller 94.

  The output smoothing unit 91 includes an output coil L1 and an output capacitor C1 connected to one end of the output coil L1. The other end of the output capacitor C1 is connected to the ground. A voltage between the output coil L1 and the output capacitor C1 is output as the second output voltage V2. The switching unit 92 includes a switching element that performs ON / OFF of voltage application to the output smoothing unit 91. The switching unit 92 is connected to the output smoothing unit 91.

  Specifically, the switching unit 92 includes two transistors, a first transistor FET1 and a second transistor FET2. FIG. 5 shows an example using MOS transistors. The source of the first transistor FET1 is connected to the power supply Vcc (for example, the output voltage of the primary power supply unit 5). The gate of the first transistor FET1 is connected to the controller 94. The drain of the first transistor FET1 is connected to the drain of the second transistor FET2. The other end of the output coil L1 is connected to a connection point provided between the first transistor FET1 and the second transistor FET2. The source of the second transistor FET2 is connected to the ground. The gate of the second transistor FET2 is connected to the controller 94. The controller 94 does not simultaneously turn on both the first transistor FET1 and the second transistor FET2.

  When the controller 94 turns on the first transistor FET1 and turns off the second transistor FET2, a voltage is applied to the output smoothing unit 91 and the second output voltage V2 rises. On the other hand, when the controller 94 turns off the first transistor FET1 and turns on the second transistor FET2, the output smoothing unit 91 is connected to the ground, and the second output voltage V2 drops. The output smoothing unit 91 is alternately connected to the power source Vcc and the ground, and the voltage smoothed by the output coil L1 and the output capacitor C1 becomes the second output voltage V2. The controller 94 controls the switching of the first transistor FET1 and the second transistor FET2, and controls the magnitude of the second output voltage V2.

  The output monitoring unit 93 receives the reference voltage Vref and the feedback voltage FB. In the example of FIG. 5, an example is shown in which the comparator COM <b> 1 is used as the output monitoring unit 93. The output monitoring unit 93 generates an output state signal S1 corresponding to the time during which the feedback voltage FB exceeds the reference voltage Vref. In the example of FIG. 5, the comparator COM1 outputs High when the reference voltage Vref is equal to or higher than the feedback voltage FB, and outputs a signal that becomes Low when the reference voltage Vref is lower than the feedback voltage FB.

  For example, when the feedback voltage FB is less than the reference voltage Vref, the controller 94 controls the switching unit 92 to apply a voltage to the output smoothing unit 91 (first transistor FET1ON, second transistor FET2OFF). On the other hand, when the feedback voltage FB is equal to or higher than the reference voltage Vref, the controller 94 stops the voltage application to the output smoothing unit 91. Thus, the magnitude of the output (second output voltage V2) of the second power supply circuit 9 can be set based on the magnitude of the reference voltage Vref. For example, the second output voltage V2 (set voltage) can be determined by the resistors R1 and R2 with respect to the default value of the reference voltage Vref. Note that an error amplifier (error amplifier circuit) and a PWM comparator may be used for the output monitoring unit 93 of the second power supply circuit 9.

(Output adjustment processing)
Next, the flow of the output adjustment process of the power supply device 1 according to the embodiment will be described with reference to FIGS. FIG. 6 is a flowchart illustrating an example of the flow of output adjustment processing of the power supply device 1 according to the embodiment. FIG. 7 is a diagram illustrating an example of the temperature correspondence data D2 according to the embodiment.

  The start of FIG. 6 is the time when the first power supply circuit 8 and the second power supply circuit 9 start to operate when the main power supply of the printer 100 is turned on. Further, the start of FIG. 6 may be a time point when the operation of the first power supply circuit 8 is started by returning from the power saving mode to the normal mode.

  The processing unit 71 of the control circuit 7 inputs a digital value indicating an initial value (predetermined set value, default value) of the reference voltage Vref that is automatically selected when the second power supply circuit 9 is activated to the DA converter 72. First, the reference voltage Vref having a magnitude corresponding to the initial value is output to the DA converter 72 (step # 11). Thereby, first power supply circuit 8 starts voltage generation, and second power supply circuit 9 starts voltage generation based on the initial value of reference voltage Vref (step # 12).

  After the second output voltage V2 rises, the processing unit 71 recognizes the current temperature from the output of the temperature sensor 26 (see FIG. 5, details will be described later), and sets the initial value of the reference voltage Vref as an initial adjustment value according to the temperature. Adjust to. Therefore, the processing unit 71 determines an initial adjustment value of the reference voltage Vref based on the temperature correspondence data D2 (see FIG. 7), inputs a digital value indicating the initial adjustment value of the reference voltage Vref to the DA converter 72, and sets the initial adjustment value. A reference voltage Vref having a magnitude corresponding to is output to the DA converter 72 (step # 13). Note that when returning from the power saving mode to the normal mode, the second power supply circuit 9 has already been activated and generates a voltage, so steps # 11 to 13 can be skipped.

  A waiting time set in advance as a time from when the operation of at least one of the first power supply circuit 8 and the second power supply circuit 9 starts until the output voltage of each power supply circuit including the initial adjustment of the second power supply circuit 9 rises and stabilizes. When has elapsed, the control circuit 7 recognizes the potential difference between the first output voltage V1 and the second output voltage V2 based on the output of the potential difference detector 74 (step # 14). Then, the control circuit 7 checks whether or not the potential difference is within a predetermined allowable range (step # 15). The control circuit 7 may confirm whether or not the absolute value of the potential difference is within the allowable range based on whether or not the absolute value of the potential difference exceeds the allowable value based on the allowable range. For example, the smaller value of the absolute values of the upper limit value and the lower limit value of the allowable range can be determined as the allowable value.

  The power supply destination of the first power supply circuit 8 and the second power supply circuit 9 is the ASIC 10. That is, the power supply destinations of the first power supply circuit 8 and the second power supply circuit 9 are the same device. When power is supplied to a circuit in the same device, in order to prevent an abnormal operation (to prevent a difference in voltage value between internal circuits of the ASIC 10 from becoming too large), the ASIC 10 of this embodiment also uses the first processing circuit. Ideally, the voltage input to 11 (first output voltage V1) and the voltage input to the second processing circuit 12 (second output voltage V2) are the same voltage. However, it is difficult to cause the first power supply circuit 8 and the second power supply circuit 9 to generate completely the same voltage. An allowable range of a potential difference between the first output voltage V1 and the second output voltage V2 that does not cause a problem in the operations of the first processing circuit 11 and the second processing circuit 12 is determined in advance. For example, it is defined as −α ≦ ΔV (potential difference) ≦ β. In this case, β is the upper limit value of the allowable range, and −α is the lower limit value of the allowable range.

  The first power supply circuit 8 and the second power supply circuit 9 are designed and set so that the potential difference falls within an allowable range. However, the characteristics of each power supply circuit are not ideal and vary somewhat. In addition, the characteristics may change with the influence of temperature and use. Therefore, the difference between the first output voltage V1 and the second output voltage V2 may exceed the allowable range. Therefore, the power supply device 1 can adjust the second output voltage V2.

  When it is within the allowable range (Yes in step # 15), there is no need to adjust the second output voltage V2, so this flow ends (END). When it is outside the allowable range (No in step # 15), the control circuit 7 starts output adjustment processing (step # 16).

  At the start of the output adjustment process, as a preparation for accurate adjustment, the control circuit 7 inputs an instruction to keep the stationary state until the end of the adjustment to the first processing circuit 11 and the second processing circuit 12 (steps). # 17). Thereby, the current consumption of the first processing circuit 11 and the second processing circuit 12 having different circuit scales can be made closer. In other words, the control circuit 7 sets the current consumption level to the same level for the first processing circuit 11 and the second processing circuit 12.

  Then, the control circuit 7 adjusts the second output voltage V2 so that the potential difference is within the allowable range (step # 18). Specifically, during the output adjustment process, the processing unit 71 of the control circuit 7 recognizes the potential difference between the first output voltage V1 and the second output voltage V2 based on the output of the potential difference detection unit 74 in step # 14. Yes. Then, the processing unit 71 inputs a digital value indicating a reference voltage Vref such that the potential difference is within an allowable range or becomes zero to the DA converter 72. The DA converter 72 generates a reference voltage Vref having the magnitude of the received digital value. The magnitude of the output voltage (reference voltage Vref) of the DA converter 72 is adjusted to match the second output voltage V2 with the first output voltage V1.

  The control memory 73 in the control circuit 7 stores adjustment data D1 that defines an amount (adjustment amount) for changing the reference voltage Vref in accordance with the potential difference (see FIG. 4). The adjustment amount is determined so that the reference voltage Vref increases as the second output voltage V2 is smaller than the first output voltage V1. Further, the adjustment amount is determined so that the reference voltage Vref becomes smaller as the second output voltage V2 is larger than the first output voltage V1.

  After the adjustment, the control circuit 7 re-recognizes the potential difference between the first output voltage V1 and the second output voltage V2 based on the output of the potential difference detector 74 (step # 19). Then, the control circuit 7 reconfirms whether or not the potential difference is within a predetermined allowable range (step # 110).

  When it is outside the allowable range (No in step # 110), it is still necessary to adjust the second output voltage V2. Therefore, in this case, the flow returns to step # 18. On the other hand, when it is within the allowable range (Yes in step # 110), it is not necessary to adjust the output of the second power supply circuit 9 any more. Therefore, the control circuit 7 inputs a stationary state release notification to the first processing circuit 11 and the second processing circuit 12 (step # 111). As a result, the stationary state of the first processing circuit 11 and the second processing circuit 12 is released, and the first processing circuit 11 and the second processing circuit 12 perform the requested calculation and processing.

  Here, the printer 100 is provided with a temperature sensor 26 (see FIGS. 1 and 5). The temperature sensor 26 is provided in the vicinity of the second power supply circuit 9. Further, as the temperature sensor 26, a temperature sensor provided in the vicinity of the exterior cover for detecting the outside temperature may be used. The output of the temperature sensor 26 is input to the main control unit 2. The main control unit 2 recognizes the temperature based on the output of the temperature sensor 26. The main control unit 2 notifies the detected temperature to the control circuit 7. Alternatively, as shown in FIG. 5, the output of the temperature sensor 26 may be input to the control circuit 7 so that the control circuit 7 recognizes the temperature without going through the main control unit 2.

  Then, the control circuit 7 measures the temperature based on the output of the temperature sensor 26 and updates the temperature correspondence data D2 (step # 112 → end, end of the output adjustment process). The temperature correspondence data D2 is data used to determine an initial adjustment value of the reference voltage Vref of the second power supply circuit 9. The temperature correspondence data D2 is stored in the control memory 73 in a nonvolatile manner. The temperature correspondence data D2 is data including one or a plurality of combinations of the adjusted reference voltage Vref when the output adjustment process is performed and the temperature at the time of adjustment detected based on the temperature sensor 26 (see FIG. 7).

  When the output adjustment process is performed, the control circuit 7 stores the combination of the detected temperature and the adjusted reference voltage Vref in the control memory 73 as the temperature correspondence data D2. When the temperature detected in the current output adjustment process is not in the temperature correspondence data D2, the control circuit 7 adds the combination of the detected temperature in the current output adjustment process and the adjusted reference voltage Vref to the temperature correspondence data D2. To do. Note that when the combination of the temperature and the reference voltage Vref that is the same as the temperature detected in the current output adjustment process is already included in the temperature correspondence data D2, the control circuit 7 uses the reference voltage Vref after this adjustment as the previous value. Overwrite the adjusted reference voltage Vref. In this way, the temperature correspondence data D2 is updated.

(Setting of the initial adjustment value of the reference voltage Vref at the start of the operation of the second power supply circuit 9)
Next, the flow of setting the initial adjustment value of the reference voltage Vref when the operation of the second power supply circuit 9 according to the embodiment starts will be described with reference to FIG. FIG. 8 is a flowchart illustrating an example of a flow of setting an initial adjustment value of the reference voltage Vref at the start of operation of the second power supply circuit 9 according to the embodiment.

  When the operation of the second power supply circuit 9 is started, the processing unit 71 of the control circuit 7 automatically inputs a digital value indicating the initial value of the reference voltage Vref to the DA converter 72 when the second power supply circuit 9 is started. A reference voltage Vref having a magnitude corresponding to the value is output to the DA converter 72. Thereafter, the control circuit 7 measures the temperature and is defined in the temperature correspondence data D2, and determines an initial adjustment value of the reference voltage Vref corresponding to the measured temperature. Therefore, in the start of FIG. 8, after the operation of the second power supply circuit 9 is started, voltage generation is started based on the initial value of the reference voltage Vref and the second output voltage V2 rises, and then the control circuit 7 sets the initial adjustment value. This is the time when the corresponding reference voltage Vref is to be input to the second power supply circuit 9.

  First, the control circuit 7 recognizes the current temperature based on the output of the temperature sensor 26 or the notification from the main control unit 2 (step # 21). Then, the control circuit 7 refers to the temperature correspondence data D2, and selects data having a temperature closest to the current temperature among the temperatures included in the temperature correspondence data D2 (step # 22).

  Subsequently, the control circuit 7 reads the reference voltage Vref combined with the selected temperature (corresponding to the selected temperature) (step # 23). Then, the control circuit 7 determines the voltage having the magnitude of the read reference voltage Vref as an initial adjustment value of the reference voltage Vref, inputs a digital value indicating the initial adjustment value to the DA converter 72, and sets the voltage corresponding to the initial adjustment value. The reference voltage Vref is output to the DA converter 72 (step # 24 → end). That is, when the control circuit 7 starts the operation of the second power supply circuit 9, the reference voltage Vref corresponding to the current temperature detected based on the temperature sensor 26 in the temperature correspondence data D <b> 2 is output from the second power supply circuit 9. Input to the output monitoring unit 93.

  Thus, the initial adjustment value of the reference voltage Vref is determined. That is, the reference voltage Vref determined in the previous output adjustment process and determined at the same or close temperature as the current temperature is used as the initial adjustment value at the start of the operation. As a result, the difference between the first output voltage V1 of the first power supply circuit 8 and the second output voltage V2 of the second power supply circuit 9 tends to be within an allowable range from the beginning of the operation. Therefore, the second power supply circuit 9 can be quickly started up (the startup process is completed) without executing the output adjustment process.

  As described above, the power supply device 1 according to the embodiment includes the first power supply circuit 8 that supplies power to the processing circuit (first processing circuit 11) provided in the device, and the processing circuit (first processing circuit 11). The second power supply circuit 9 that supplies power to another processing circuit (second processing circuit 12) in the device provided with the control circuit 7 that controls the output voltage of the second power supply circuit 9 and performs output adjustment processing And including. The control circuit 7 recognizes the potential difference between the first output voltage V1 that is the output voltage of the first power supply circuit 8 and the second output voltage V2 that is the output voltage of the second power supply circuit 9, and the potential difference is in a predetermined allowable range. When it is outside, the output adjustment process is started. In the output adjustment process, the output voltage value of the second power supply circuit 9 is adjusted so that the potential difference is within the allowable range.

  Accordingly, it is necessary that the first output voltage V1 of the first power supply circuit 8 and the second output voltage V2 of the second power supply circuit 9 are input to one device, and that each output voltage has the same or almost the same potential. In such a case, when the difference between the output voltages does not satisfy the condition (specification), the second output voltage V2 can be adjusted (corrected) so as to satisfy the condition of the potential difference. Therefore, even if the characteristics of each power supply circuit have variations and errors, the potential difference condition can be easily satisfied.

  In addition, the power supply device 1 according to the embodiment includes a feedback voltage generation unit 75 that receives the second output voltage V2 and generates a feedback voltage FB for confirming the magnitude of the second output voltage V2. The second power supply circuit 9 includes an output smoothing unit 91 that includes an output coil L1 and an output capacitor C1 connected to the output coil L1, and outputs a voltage to another processing circuit (second processing circuit 12). 91 is connected to the switching unit 92 to turn ON / OFF the voltage application to the output smoothing unit 91, and the output state according to the time when the reference voltage Vref and the feedback voltage FB are input and the feedback voltage FB exceeds the reference voltage Vref It is a DCDC converter including an output monitoring unit 93 that generates a signal S1 and a controller 94 that controls the switching unit 92 to control ON / OFF of voltage application to the output smoothing unit 91 based on the output state signal S1. The control circuit 7 includes a DA converter 72 and inputs the output of the DA converter 72 to the output monitoring unit 93 as a reference voltage Vref, and the DA converter so that the potential difference becomes a value within an allowable range or zero during the output adjustment process. The magnitude of the output voltage 72 is adjusted.

  Thereby, the magnitude | size of the reference voltage Vref input into a DCDC converter can be adjusted. Therefore, the condition of the potential difference can be satisfied easily and quickly only by adjusting the second output voltage V2.

  In addition, the power supply device 1 according to the embodiment stores the temperature correspondence data D2 in which the adjusted reference voltage Vref when the output adjustment process is performed and the temperature at the time of adjustment detected based on the temperature sensor 26 are associated with each other. (Control memory 73). When starting the operation of the second power supply circuit 9, the control circuit 7 inputs the reference voltage Vref corresponding to the current temperature detected based on the temperature sensor 26 in the temperature corresponding data D <b> 2 to the output monitoring unit 93.

  As a result, a voltage value that is highly likely to satisfy the potential difference condition at the current temperature based on the past adjustment result can be output to the second power supply circuit 9 from the beginning of the operation of the second power supply circuit 9. In addition, the absolute value of the potential difference recognized at the recognition timing tends to be less than or equal to the allowable value, and output adjustment processing can be omitted. Therefore, the second output voltage V2 can be promptly brought into a state where there is no abnormality.

  In addition, when the potential difference is outside the predetermined allowable range, the control circuit 7 issues a command to the effect that it should be kept stationary during the output adjustment process (second processing circuit 11) and another processing circuit (second processing circuit). Input to the processing circuit 12). As a result, the output currents (voltages) of the first power supply circuit 8 and the second power supply circuit 9 can be stabilized. Therefore, the potential difference between the outputs of the first power supply circuit 8 and the second power supply circuit 9 can be accurately grasped.

  The power supply device 1 has a normal mode and a power saving mode. When a predetermined transition condition is satisfied in the normal mode, the mode is shifted to the power saving mode. When a predetermined return condition is satisfied in the power saving mode, the mode is returned to the normal mode. The first power supply circuit 8 supplies power to the processing circuit (first processing circuit 11) in the normal mode, and does not supply power to the processing circuit in the power saving mode. The second power supply circuit 9 supplies power to another processing circuit (second processing circuit 12) in the normal mode and the power saving mode. Thereby, since the voltage is generated even in the power saving mode, it is possible to adjust the output voltage of the power supply circuit (second power supply circuit 9) that is likely to change in characteristics due to use.

  The image forming apparatus (printer 100) according to the embodiment includes the power supply device 1 described above. Since the image forming apparatus includes the power supply apparatus 1 that can easily satisfy the condition of the potential difference even if the characteristics of each power supply circuit have variations and errors, the image forming apparatus is stable in operation and does not cause an abnormality. be able to.

  In the above-described embodiment, the example in which the first power supply circuit 8 supplies power to the first processing circuit 11 and the second power supply circuit 9 supplies power to the second processing circuit 12 has been described. However, the combination of the power supply circuit and the processing circuit may be interchanged. That is, the second power supply circuit 9 may supply power to the first processing circuit 11, and the first power supply circuit 8 may supply power to the second processing circuit 12.

  Moreover, although the embodiment of the present invention has been described, the scope of the present invention is not limited to this, and various modifications can be made without departing from the spirit of the invention.

  The present invention is applicable to a power supply device including a DCDC converter and an image forming apparatus including the power supply device.

DESCRIPTION OF SYMBOLS 100 Printer (image forming apparatus) 1 Power supply device 11 1st processing circuit (processing circuit) 12 2nd processing circuit (another processing circuit)
7 Control Circuit 72 DA Converter 73 Control Memory (Memory) 75 Feedback Voltage Generation Unit 8 First Power Supply Circuit 9 Second Power Supply Circuit 91 Output Smoothing Unit 92 Switching Unit 93 Output Monitoring Unit 94 Controller D2 Temperature Corresponding Data S1 Output Status Signal C1 Output Capacitor L1 Output coil FB Feedback voltage V1 First output voltage V2 Second output voltage Vref Reference voltage

Claims (6)

A first power supply circuit for supplying power to a processing circuit provided in the device;
A second power supply circuit for supplying power to another processing circuit in the device provided with the processing circuit;
A control circuit that controls the output voltage of the second power supply circuit and performs output adjustment processing,
The control circuit recognizes a potential difference between a first output voltage that is an output voltage of the first power supply circuit and a second output voltage that is an output voltage of the second power supply circuit, and the potential difference is outside a predetermined allowable range. The output adjustment process is started at the time, and the second output voltage is adjusted in the output adjustment process so that the potential difference is within the allowable range. A feedback voltage generating unit that receives the second output voltage and generates a feedback voltage for confirming the magnitude of the second output voltage;
The second power supply circuit includes an output coil and an output capacitor connected to the output coil, and outputs an output smoothing unit that outputs a voltage to the other processing circuit, and a voltage to the output smoothing unit that is connected to the output smoothing unit. A switching unit that performs ON / OFF of application, an output monitoring unit that receives a reference voltage and the feedback voltage and generates an output state signal according to a time when the feedback voltage exceeds the reference voltage, and the switching unit A DCDC converter including a controller that controls and controls ON / OFF of voltage application to the output smoothing unit based on the output state signal;
The control circuit includes a DA converter, and inputs the output of the DA converter as the reference voltage to the output monitoring unit, and the potential difference becomes a value within the allowable range or zero during the output adjustment processing. The power supply apparatus according to claim 1, wherein the output voltage of the DA converter is adjusted as described above. A memory for storing temperature correspondence data in which the reference voltage after adjustment when the output adjustment processing is performed and the temperature at the time of adjustment detected based on a temperature sensor are associated;
The control circuit, when starting the operation of the second power supply circuit, inputs the reference voltage corresponding to the current temperature detected based on the temperature sensor in the temperature correspondence data to the output monitoring unit. The power supply device according to claim 2.   4. The control circuit according to claim 1, wherein when the potential difference is outside a predetermined allowable range, the control circuit inputs a command to the effect that the control circuit should be kept stationary to the processing circuit and the another processing circuit. The power supply device according to any one of the above. Has normal mode and power saving mode,
When the predetermined transition condition is satisfied in the normal mode, the mode is shifted to the power saving mode, and when the predetermined return condition is satisfied in the power saving mode, the mode is returned to the normal mode.
The first power supply circuit supplies power to the processing circuit in the normal mode, does not supply power to the processing circuit in the power saving mode,
5. The power supply device according to claim 1, wherein the second power supply circuit supplies power to the another processing circuit in the normal mode and the power saving mode. 6.   An image forming apparatus comprising the power supply device according to claim 1.

Images