JP7547841B2 - Power Control Unit - Google Patents

Description

The present invention relates to a power supply control device.

Patent document 1 describes a power supply device in which a voltage from a commercial AC power supply is supplied to a load of a drive system via a first DC/DC converter, and a voltage from the commercial AC power supply is supplied to the load of the drive system via a first DC/DC converter and a second DC/DC converter. In patent document 1, in a normal mode, the voltage from the commercial AC power supply is converted to a first DC voltage by the first DC/DC converter and supplied to the load of the drive system, and the second DC/DC converter converts the output voltage from the first DC/DC converter to a second DC voltage lower than the first DC voltage and supplies it to the load of the control system. In a standby mode, the first DC/DC converter converts to a third DC voltage lower than the second DC voltage, and does not supply the output voltage required to drive the load of the drive system to the load of the drive system. The second DC/DC converter supplies the output voltage from the first DC/DC converter as it is to the load of the control system.

In short, in normal mode, a first DC voltage is supplied to the drive system loads, and a third DC voltage is supplied to the control system loads. In standby mode, no voltage is supplied to the drive system loads, and voltage continues to be supplied only to the control system loads.

JP 2019-111741 A JP 2010-142071 A

However, when the power supply and the load (corresponding to the "control system load" in the above example) are physically separated, as in conventional technology, it is said that the load responsiveness deteriorates. This creates the possibility that the load may malfunction.

The present invention aims to prevent improper operation of the load that may occur when transitioning from a power saving mode, in which a specified voltage generated by the power supply unit is output to the load via a DC/DC converter, to a normal mode, in which the output voltage of the power supply unit is converted to a specified voltage by the DC/DC converter and then output to the load.

The power supply control device of the present invention comprises a processor, a power supply unit that outputs a first voltage in normal mode and a second voltage lower than the first voltage in power saving mode, and a DC/DC converter that converts the first voltage from the power supply unit to a second voltage and then outputs it to a connected load in normal mode, and supplies the second voltage output from the power supply unit as is in power saving mode, wherein the processor controls the load to prohibit execution of a process from being performed during a predetermined period of time required for the output voltage from the DC/DC converter to stabilize from the instruction to transition from power saving mode to normal mode, but allows the execution of the process if the fluctuation in current generated by the execution of the process in the load is less than a predetermined threshold value even before the predetermined period of time has elapsed .

The end of the predetermined period is the point in time when the output voltage from the power supply unit becomes the first voltage.

According to the invention of claim 1, it is possible to prevent an unauthorized operation of a load that may occur when switching from a power saving mode in which a predetermined voltage generated by a power supply unit is output to a load via a DC/DC converter to a normal mode in which the output voltage of the power supply unit is converted to a predetermined voltage by the DC/DC converter and then output to the load. Furthermore, even if the output voltage from the DC/DC converter is unstable, it is possible to execute a process that is assumed not to cause an unauthorized operation of the load.

According to the invention described in claim 2 , a process in which a current fluctuation occurs in the load can be performed after the output voltage from the DC/DC converter stabilizes as the output voltage from the power supply unit becomes the first voltage.

1 is a schematic configuration diagram showing an embodiment of a power supply control device according to the present invention; 4 is a diagram showing the relationship between a power supply mode and control of a control system load in the present embodiment. FIG. 5 is a flowchart showing a mode transition process in the present embodiment.

The following describes a preferred embodiment of the present invention with reference to the drawings. In this embodiment, the power supply control device is applied to an image forming device equipped with a printer, scanner, etc., as an example.

Figure 1 is a schematic diagram showing one embodiment of a power supply control device 10 according to the present invention.

Figure 1 shows an input section 11, a power supply generating section 12, a switch 13, a DC/DC converter 14, a control system load 15, and a drive system load 16.

The input unit 11 includes a commercial AC power supply and a rectifying and smoothing circuit that rectifies and smoothes the AC voltage from the commercial AC power supply, and outputs an AC voltage. The power supply generating unit 12 has an AC-DC converter that converts the AC voltage from the input unit into a DC voltage, and a DC/DC converter that converts the AC voltage into a DC voltage required by a load, and supplies the DC voltage to the drive system load and the DC/DC converter. In this embodiment, the input unit and the power supply generating unit form a power supply unit. The power supply unit outputs a first voltage in normal mode, and outputs a second voltage smaller than the first voltage in power saving mode.

Switch 13 is a switch that opens and closes according to instructions from the processor. When switch 13 is controlled to be closed, it supplies voltage to drive system load 16, and when it is controlled to be open, it cuts off the supply of voltage to drive system load 16.

The DC/DC converter 14 converts the first voltage from the power supply unit to a second voltage and outputs it to the connected control system load 15 in normal mode, and supplies the second voltage output from the power supply unit as is in power saving mode.

The loads 15 and 16 operate by receiving a voltage supply, but the drive system load 16 operates by requiring a relatively high voltage equivalent to the first voltage. In this embodiment, a description is given assuming 24V. In the case of the power supply control device of this embodiment mounted on an image forming device, the drive system load 16 corresponds to a motor that operates a printer or a paper tray. On the other hand, the control system load 15 operates by requiring a relatively low voltage equivalent to the second voltage. In this embodiment, a description is given assuming 5V. In the case of the power supply control device of this embodiment mounted on an image forming device, the control system load 15 is a processor, memory, HDD (hard disk drive), etc. The processor that controls the opening and closing of the switch 13 is included in the control system load 15. Therefore, the processor included in the control system load 15 is at least included in the components of the power supply control device 10.

Here, the power supply control device 10 in this embodiment operates in two power supply modes: a normal mode and a power saving mode. The "normal mode" is a mode in which the image forming device equipped with the power supply control device 10 operates in a state in which a predetermined voltage (5V for the control load 15, 24V for the drive load 16) is supplied to each load 15, 16 so that the functions equipped in the image forming device, such as the print function and the facsimile function, can be performed normally. On the other hand, the "power saving mode", also called the energy saving mode or standby mode, is a mode in which the image forming device equipped with the power supply control device 10 is placed in a state in which power consumption is suppressed by preventing the drive load 16 from operating, and the control load 15 is operated in a state in which a predetermined operation can be performed. Note that the "predetermined operation" here means that the control load 15 is operated according to the specifications of the power saving mode. For example, the CPU clock number is reduced and the RAM is partially made available.

As described above, in the power supply control device 10 in this embodiment, in the power saving mode, the DC/DC converter included in the power supply generating unit 12 converts the first voltage to the second voltage. Then, the DC/DC converter 14 supplies the second voltage from the DC/DC converter of the power supply generating unit 12 to the control system load 15 as it is. In this way, the state in which the DC/DC converter 14 operates to output without voltage conversion is also called "through mode", but in order to realize the through mode, it is necessary to include a DC/DC converter for voltage conversion of the voltage from the commercial power supply in the power supply generating unit 12. In other words, the power supply (corresponding to the above-mentioned "commercial AC power supply") and the control system load 15 are electrically connected via the DC/DC converter of the power supply generating unit 12, and are therefore connected physically apart. In this case, it is said that the load responsiveness of the control system load 15 to load fluctuations deteriorates. Therefore, when switching between power saving mode and normal mode, the current supplied to the DC/DC converter 14 increases rapidly to increase the voltage from 5 V to 24 V, but this causes the voltage output from the DC/DC converter 14 to the control load 15 to become unstable. For example, the operation of the control load 15 cannot be guaranteed due to the occurrence of an overshoot.

The processor in this embodiment is characterized by controlling the control system load 15 to prohibit the execution of processing from the instruction to transition from the power saving mode to the normal mode until a predetermined period of time required for the output voltage from the DC/DC converter 14 to stabilize has elapsed. In other words, this embodiment makes it possible to prevent improper operation of the control system load 15, a so-called specification out, that may occur when transitioning from the power saving mode to the normal mode due to instability in the voltage supplied to the control system load 15.

Figure 2 is a diagram showing the relationship between the power supply mode and the control of the control system load 15 in this embodiment. In Figure 2, the horizontal direction indicates time, and the vertical direction indicates the power supply mode and the control of the control system load 15. Also, Figure 3 is a flowchart showing the mode transition process in this embodiment. Below, using these figures, the process performed in conjunction with the transition of the power supply mode in this embodiment will be explained.

The image forming device in this embodiment operates in normal mode while being used by a user (N in step 101). At this time, the control system load 15 is steadily supplied with a voltage of 5 V, which is necessary for normal operation. Therefore, as shown in FIG. 2, there is no need to impose any restrictions on the execution of the processing performed by the control system load 15.

When the processor instructs the image forming device to transition to the power saving mode (Y in step 101) because the image forming device has not been operated by the user for a predetermined period of time or more, the power supply control device 10 transitions to the power saving mode (step 102). When transitioning from the normal mode to the power saving mode is performed, the power supply generating unit 12 changes the current to reduce the output voltage from 24 V to 5 V. Note that the voltage output control by the power supply generating unit 12 may be the same as before.

As shown in FIG. 2, when the processor issues an instruction to switch to the power saving mode, it prohibits the control load 15 from carrying out processing. Of course, processing that continues to be carried out even in the power saving mode is not included. In this embodiment, the period during which the control load 15 is prohibited from carrying out processing that generates a current fluctuation is referred to as the "load fluctuation prohibition period." During the load fluctuation prohibition period, as shown in FIG. 2, during the period T1 from when the transition to the power saving mode is instructed to when the transition to the normal mode is instructed and during a predetermined period T2 described later, execution of processing other than processing that can be carried out in the power saving mode is prohibited. Then, the power supply control device 10 enters the power saving mode when the output voltage from the power generation unit 12 is switched from 24V to 5V and the output voltage is stabilized. As shown in FIG. 2, a time lag occurs between the instruction to switch to the power saving mode and the actual transition of the power supply mode to the power saving mode.

Then, while the image forming device is operating in the power saving mode, and as long as no return event occurs (N in step 103), the image forming device continues to operate in the power saving mode. Then, when a return event to the normal mode occurs, for example, due to the image forming device being operated by a user (Y in step 103), the processor instructs the power control device 10 to transition from the power saving mode to the normal mode. In response to this instruction, the power control device 10 starts the transition to the normal mode (step 104). Even after the transition to the normal mode has started, the processor maintains the load change prohibition period until a predetermined period (period T2 shown in FIG. 2) has elapsed (N in step 105). The processing shown in steps 107 to 109 that is performed until the predetermined period T2 has elapsed will be described later.

The specified period T2 is the period required for the output voltage from the DC/DC converter 14 to stabilize after an instruction to transition from the power saving mode to the normal mode (i.e., the occurrence of an event to return to the normal mode). For the output voltage from the DC/DC converter 14 to stabilize, the output voltage from the DC/DC converter included in the power generation unit 12 must stabilize at 24V. Therefore, the end of the specified period T2 is the point at which the output voltage from the power generation unit 12 stabilizes at 24V and the DC/DC converter included in the power generation unit 12 returns to normal operation in the normal mode. Accordingly, operation in the DC/DC converter 14 also stabilizes.

The end of this predetermined period T2 can be set in advance, for example, based on the specifications of the power supply control device 10, test operation, etc. Alternatively, the power supply generating unit 12 can be configured to detect when the power supply has stabilized to 24 V, and when the power supply generating unit 12 detects that the power supply has stabilized, it can notify the processor of this, making it possible to dynamically set the predetermined period T2.

Then, when a predetermined period T2 has elapsed since the occurrence of the event to return to normal mode (Y in step 105), the processor lifts the prohibition on the execution of the process that was prohibited in step 102 (step 106).

The image forming device then operates in normal mode. Here, we will explain the processing shown in steps 107 to 109.

As described above, when a return event to the normal mode occurs (Y in step 103), even if the power supply mode is switched to the normal mode, the prohibition on the execution of the prohibited process is lifted after a predetermined period T2 has elapsed, the operation of the DC/DC converter included in the power supply generating unit 12 has stabilized, and the operation of the DC/DC converter 14 has stabilized.

However, processes that generate relatively large current fluctuations may malfunction if the voltage supplied is insufficient, but processes that do not generate large current fluctuations are unlikely to malfunction even if the output voltage from the DC/DC converter 14 is insufficient or unstable, because a voltage of 5V or more is supplied to the control system load 15. Therefore, in this embodiment, even before the specified period T2 has elapsed, if the current fluctuation that may occur due to the execution of a process in the control system load 15 is less than a specified threshold, the execution of that process is permitted. The reference value shown in FIG. 3 corresponds to the specified threshold value here. The reference value is set in advance.

For example, although it depends on the specifications of the image forming device, if the process of turning on the scanner LED, which corresponds to the control system load 15, requires a current of more than 1A, and the reference value is set to 1A, the scanner LED will not be turned on until a specified period T2 has elapsed after the occurrence of an event to return to normal mode. On the other hand, processes such as operating the network interface and referring to the time require less than 1A of current, and can therefore be performed within the specified period T2.

That is, if the fluctuation in current caused by the execution of the process is less than the reference value (N in step 107), the processor allows the execution of the process (step 108). On the other hand, if the fluctuation in current caused by the execution of the process is equal to or greater than the reference value (Y in step 107), the processor continues to prohibit the execution of the process that was set when the power saving mode was entered (step 109).

In this embodiment, the power supply control device 10 has been described as being applied to an image forming device, but it is not necessary to be limited to an image forming device, and the power supply control device 10 can be applied to any device that requires a configuration for controlling voltage. In addition, 24V and 5V have been described as specific examples of the first and second voltages, respectively, but the first and second voltages may be set appropriately depending on the specifications of the device in which the power supply control device 10 is installed.

In the above embodiment, the term "processor" refers to a processor in a broad sense, including general-purpose processors (e.g., CPU: Central Processing Unit, etc.) and dedicated processors (e.g., GPU: Graphics Processing Unit, ASIC: Application Specific Integrated Circuit, FPGA: Field Programmable Gate Array, programmable logic device, etc.).

The processor operations in the above embodiments may not only be performed by a single processor, but may also be performed by multiple processors located at physically separate locations working together. The order of the processor operations is not limited to the order described in the above embodiments, and may be changed as appropriate.

10 Power supply control device, 11 Input unit, 12 Power supply generation unit, 13 Switch, 14 DC/DC converter, 15 Control system load, 16 Drive system load.

Claims (2)

A processor;
a power supply unit that outputs a first voltage in a normal mode and outputs a second voltage lower than the first voltage in a power saving mode;
a DC/DC converter that converts a first voltage from the power supply unit into a second voltage and outputs the second voltage to a connected load in a normal mode, and that supplies the second voltage output from the power supply unit as is in a power saving mode;
Equipped with
The processor controls the load to prohibit execution of processing during a predetermined period of time required for the output voltage from the DC/DC converter to stabilize after an instruction to transition from a power saving mode to a normal mode has elapsed, but allows execution of the processing if the fluctuation in current generated by the execution of the processing in the load is less than a predetermined threshold value even before the predetermined period of time has elapsed . The power supply control device according to claim 1, characterized in that the end of the predetermined period is the point in time when the output voltage from the power supply unit becomes the first voltage.

Images