JP4561102B2 - POWER CONTROL DEVICE, POWER CONTROL METHOD, AND ELECTRONIC DEVICE - Google Patents

Description

  The present invention relates to a power supply control apparatus, a power supply control method, and an electronic apparatus that supply a predetermined set voltage to each of a display section and a driver that sends a video signal to the display section.

  In an electronic device having a display unit such as a liquid crystal panel, such as a digital still camera or a digital video camera, power is supplied by applying a set voltage to the display unit and a driver for sending a video signal or the like to the display unit. It is carried out.

FIG. 7 is a block diagram illustrating a conventional power supply control device. The voltage given from the battery (BATT) is sent to the DC / DC converter 21, where (1) the first set voltage (driver power supply) corresponding to the driver 22 and the display unit 23 which is a liquid crystal panel (2 ) It is converted into a second set voltage (panel power supply). (1) The first set voltage is sent directly from the DC / DC converter 21 to the driver 22. (2) The second set voltage is sent to the display unit 23 via the FET 24. (2) The second set voltage is also sent to the driver 22 before the FET 24.

FIG. 8 is a timing chart of power supply control. That is, when the power of the electronic device is turned ON (POWER.ON) by the user, (1) 2.8V, which is the first set voltage, rises and is sent from the DC / DC converter 21 to the driver 22. On the other hand, the (2) second set voltage, which is a panel power supply, controls the FET 24 by the rising edge of the SAVE signal output from the driver 22, and the 13.5V panel power supply generated by the DC / DC converter 21 is the SAVE signal. Is sent to the display unit 23 along with the rising edge.

  When the power of the electronic device is turned off (POWER.OFF) by the user, the SAVE signal output from the driver 22 falls and the FET 24 is controlled, and (2) the second set voltage is turned off. Thereafter, (1) the first set voltage is turned OFF and the power supply to the driver 22 is stopped.

In such power control, POWER. When it is ON, the driver power supply is turned on before the panel power supply, and POWER. At the time of the OFF, it is to lower cut off the driver power in later than the panel power.

  That is, POWER. In the case of ON, the signal to the display unit 23 is unstable for a while after the driver power is supplied, and if the panel power is supplied during this time, the unstable signal becomes noise and the display unit 23 Will be displayed. Therefore, POWER. In the case of ON, the panel power is supplied after a certain time elapses from when the driver power is supplied until the signal is stabilized.

  Also, POWER. Similarly, when the driver power is turned off, an unstable signal is output until the power is not completely supplied. Therefore, the driver power is controlled to stop after the panel power is turned off first. ing.

  In the conventional power supply control device, when performing such delay control between the driver power supply and the panel power supply, the FET 24 is controlled using the SAVE signal to control ON / OFF of the panel power supply. This SAVE signal is a signal indicating the transition to the power saving mode, and POWER. It starts up after a certain period from ON or OFF.

Japanese Patent Laid-Open No. 7-294882

  However, such a conventional power supply control device and power supply control method have the following problems. That is, the SAVE signal that is a reference for performing the delay control of the power supply is sent from the CPU to the driver 22, but the POWER. Delay time from ON / OFF to generation of SAVE signal, POWER. Since the delay time from turning OFF to the driver power supply is stored as data in ROM (Read Only Memory), it is necessary to recreate the ROM when the set of the liquid crystal panel etc. is changed. There is a problem that can not be.

  Also, since the panel power supply is switched on / off using the FET controlled by the SAVE signal, this FET is required separately, which increases the number of parts. In the FET, the power supply to the display unit is turned on. Even though the power supply to the display unit is stopped by this FET, the panel power is supplied to the driver for a while because the panel power is supplied to the driver. This has hindered the reduction of power consumption.

  The present invention has been made to solve such problems. That is, the present invention relates to a converter that receives a power supply voltage, converts it to a set voltage corresponding to each of the display unit and a driver that supplies a video signal to the display unit, and supplies a set voltage to the driver for the converter. A first control signal for transmitting a second control signal for supplying a set voltage to the display unit, and a timing at which each of the first control signal and the second control signal is generated in the control unit And a storage unit that stores rewritable data in a rewritable manner. Moreover, it is also an electronic device using this power supply control apparatus.

  Further, according to the present invention, when the power supply control device is instructed to turn on the power supply voltage, the first control signal instructs the start of the supply of the set voltage to the driver, and then the data read from the storage unit This is a power supply control method that starts counting based on and instructs the start of setting voltage supply to the display unit by a second control signal after counting for a predetermined period.

  Further, according to the present invention, in the power supply control device, when there is an instruction to turn off the power supply voltage, the second control signal instructs the stop of the set voltage supply to the display unit, and then the data read from the storage unit Is a power supply control method for instructing to stop the supply of the set voltage to the driver by a first control signal after starting counting based on the above and counting for a predetermined period.

  In the present invention, when the power supply voltage is turned on or turned off, the control section is based on the data stored in the rewritable storage section with the power supply to the driver and the display section, and the timing of stoppage. This makes it possible to easily change this timing. Further, since the converter directly controls the power supply to the driver and the display unit by a control signal from the control unit, it is not necessary to separately provide a control component between the converter and the driver or the display unit.

  Therefore, according to the present invention, when the set of the display unit or the like is changed, or even when there is a variation in each electronic device, the timing of power control can be easily changed, so that a flexible response can be performed. Become. In addition, the number of parts related to power supply control can be reduced, and the cost can be reduced. In addition, since the output of the converter is directly controlled, unnecessary power is not supplied and the power consumption can be reduced.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a block diagram illustrating a power supply control device according to the present embodiment. The power supply control device converts a power supply voltage supplied from a battery (BATT) into a set voltage corresponding to each of the driver 12 and the display unit 13 and supplies the converted voltage to the driver 12 and the converter 11 to the driver 12. A CPU (control unit) 14 for sending a first control signal for supplying a set voltage and a second control signal for supplying a set voltage to the display unit 13, and a first control signal and a second control signal And a storage unit (flash memory) 15 that rewriteably stores data related to the generation timing of each. Further, a power supply control unit 16 is provided between the CPU 14 and the DC / DC converter 11, and various signals output from the CPU 14 are appropriately selected / processed and passed to the DC / DC converter 11.

  The driver 12 is an integrated circuit (IC), and generates and gives a video signal and a timing pulse for driving to the display unit 13 formed of a liquid crystal panel or the like. The DC / DC converter 11 receives the power supply voltage of the battery (BATT) and generates (1) a first set voltage (driver power supply) necessary for driving the driver 12. The driver power supply is, for example, 2.8V. Further, the DC / DC converter 11 generates (2) a second set voltage (panel power supply) corresponding to the display unit 13. The panel power supply is, for example, 13.5V.

  In this embodiment, by directly controlling the driver power supply and panel power supply output from the DC / DC converter 11, unnecessary parts can be eliminated and flexible power supply control is realized. Various power supplies output from the DC / DC converter 11 are turned on / off by a control signal output from the CPU 14.

  Various signal lines such as SCK (system clock), CS (chip select), SI (serial input), and SO (serial output) are connected between the CPU 14 and the power supply control unit 16. Among these, SCK, CS, and SO are passed from the power supply control unit 16 to the DC / DC converter 11. Therefore, the CPU 14 sends a control signal by serial communication to the DC / DC converter 11 via the power supply control unit 16 to perform ON / OFF control of the driver power supply and the panel power supply.

  When the control signal is output at a predetermined timing, the CPU 14 reads data stored in advance in the storage unit 15, performs a counting operation based on this data, and outputs various control signals after a predetermined time has elapsed. The storage unit 15 is a rewritable memory such as a flash memory, and stores data (delay time) for this counting operation. Since the storage unit 15 is rewritable, an external personal computer or the like can be connected to the CPU 14 and data can be easily changed from the personal computer or the like. Although FIG. 1 shows a configuration in which the storage unit 15 is connected separately from the CPU 14, a configuration in which the storage 15 is incorporated in the CPU 14 may be used.

  FIG. 2 is a block diagram illustrating the internal configuration of the DC / DC converter. The DC / DC converter 11 applied in the power supply control device of the present embodiment includes a serial / parallel converter 160 and two opening / closing means 161 and 162 in addition to a normal voltage conversion circuit.

  The serial / parallel converter 160 receives SCK, CS, and SO output from the power supply controller 16 (CPU 14), appropriately switches the SO signal as serial output, and outputs it to the two opening / closing means 161 and 162. Yes. Of the signals output from the serial / parallel converter 160, the signal output to the first opening / closing means 161 is the first control signal, and the first control signal is determined by the H (High) and L (Low) of this signal. An opening / closing operation of the opening / closing means 161 is performed. On the other hand, the signal output from the serial / parallel converter 160 to the second opening / closing means 162 is the second control signal, and the opening / closing of the second opening / closing means 162 is determined by H (High) and L (Low) of this signal. Operation is performed.

  (1) A first set voltage (for example, 2.8 V) is input to the first opening / closing means 161 that opens / closes in response to the first control signal. When the first opening / closing means 161 is closed, the first opening / closing means 161 is closed. (1) When the first set voltage is supplied and the first opening / closing means 161 is opened, (1) the supply of the first set voltage to the driver 12 is stopped.

  On the other hand, (2) a second set voltage (for example, 13.5 V) is input to the second opening / closing means 162 that opens and closes in response to the second control signal, and is displayed when the second opening / closing means 162 is closed. When (2) the second set voltage is supplied to the unit 13 and the second opening / closing means 162 is opened, the supply of (2) the second set voltage to the display unit 13 is stopped.

  Since the serial / parallel converter 160 and the first and second opening / closing means 161 and 162 are built in the DC / DC converter 11, it is not necessary to separately provide parts for controlling the power supply, thereby reducing the cost. Can be achieved. In addition, since various power sources output from the DC / DC converter 11 are directly controlled by a control signal output from the CPU 14, even if a panel power source is branched from the middle to the driver 12 or the like, the power source is controlled. Since these input power sources can also be controlled, unnecessary power source input can be prevented and low power consumption can be achieved.

  Next, a power control method using this power control device will be described. FIG. 3 is a timing chart of power control. First, when the user turns on the power of the electronic device (POWER.ON), the first control signal becomes H (High), the first opening / closing means 161 is closed, and (1) the first power source. A set voltage is supplied to the driver 12. As a result, the driver 12 and the CPU 14 are initialized. After completion of initialization (point A in the figure), the CPU 14 performs counting based on the data read from the storage unit 15, and sets the second control signal to H (High) after the count time (C1) has elapsed. As a result, the second opening / closing means 162 is closed, and (2) the second set voltage, which is a panel power supply, is supplied to the display unit 13.

  On the other hand, when the user turns off the power of the electronic device (POWER.OFF), after performing necessary control on each device before turning off the panel power (point B in the figure), the second control signal Becomes L (Low), the second opening / closing means 162 is opened, and (2) the supply of the second set voltage as the panel power supply is stopped. As a result, the display on the display unit 13 ends. The CPU 14 performs a predetermined count operation from the point B based on the data read from the storage unit 15, and sets the first control signal to L (Low) after the count time (C2) has elapsed. As a result, the first opening / closing means 161 is opened, and the supply of (1) the first set voltage as the driver power supply is stopped.

  Here, POWER. Count time C1 and POWER. The count time C2 at the time of OFF can be determined by data stored in the storage unit 15 in advance. This data has a value set in units of, for example, a vertical scanning period (Vs: 1/60 seconds), and is read from the storage unit 15 to the CPU 14 at a predetermined timing. Therefore, by rewriting this data, POWER. Count time C1 and POWER. The count time C2 at the time of OFF can be set easily.

  Serial communication of signals sent from the CPU 14 to the power supply control unit 16 is performed in synchronization with the CS timing. FIG. 4 is a diagram showing CS generation timing from power ON to OFF, and FIG. 5 is a diagram showing data communication timing performed in synchronization with CS. As shown in FIG. 4, CS repeats the transition from the High level to the Low level in synchronization with the vertical scanning period Vs while 2.8V as the driver power supply is ON.

  When the power is turned on and the driver power is turned on, the driver 12 and the CPU 14 are initialized. When the initialization ends (point A in FIG. 3), the CPU 14 performs a counting operation based on the data read from the storage unit 15. Start. For example, if the count time C1 shown in FIG. 3 is set to 3 Vs, the second control signal is switched from Low during the CS Low period after 3 Vs (about 50 milliseconds) has elapsed since the end of initialization. It switches to High and is output from CPU14.

  Here, the second control signal corresponds to any bit of SO (SOn-1 to S48n-1) shown in FIG. The data of each bit of SO is sent from the CPU 14 to the power supply control unit 16 at the rising edge of SCK while CS is Low.

  For example, if SO bit S1n-1 corresponds to the first control signal for controlling the driver power supply and bit S2n-1 corresponds to the second control signal for controlling the panel power supply, Of the SO sent during the period when the first CS is Low, the data of the bit S1n-1 sent at the rising edge of the second SCK, that is, the first control signal is sent High, and the rising edge of the third SCK. The data of the bit S2n-1, that is, the second control signal is Low. The data of each bit of SO is sent from the CPU 14 to the serial / parallel converter 160 of the DC / DC converter 11 via the power controller 16.

  Since the serial / parallel converter 160 repeatedly switches (distributes) the output in accordance with the number of rising edges of SCK every time CS becomes low, in this example, the second control signal is used as the first control signal. The first opening / closing means 161 is assigned, and the third is assigned as the second control signal to the second opening / closing means 162.

  Therefore, after the power is turned on, the first control signal (High) is supplied to the first opening / closing means 161 and the second control signal (Low) is supplied to the second opening / closing means 162 in the period when CS becomes Low first. ) Is supplied, and only 2.8 V of driver power is supplied to the driver 12.

  Further, the count of the CPU 14 is started from the point A in FIG. 3 where the initialization of the driver 12 and the CPU 14 is completed. For example, in the period in which CS becomes low after 3 Vs elapses, the data of the SO bit S2n-1 shown in FIG. That is, the second control signal is switched to High. As a result, the second control signal sent from the serial / parallel converter 160 of the DC / DC converter 11 to the second opening / closing means 162 becomes High, and the panel power supply of 13.5 V is supplied to the display unit 13 after 3 Vs has elapsed from the point A. Will be supplied.

  When the power is turned off (POWER.OFF), for example, if the count time C2 shown in FIG. 3 is set to 5 Vs, 5 Vs (approximately 83 V from the point B where the necessary control is performed on each device is performed. The first control signal switches from Hihg to Low during the CS low period after elapse of .3 milliseconds).

  That is, at point B, the SO bit S1n-1, that is, the first control signal shown in FIG. 5, remains high, and the SO bit S2n-1, that is, the second control signal, becomes low, and the DC / DC converter 11 The second control signal sent from the serial / parallel conversion section 160 to the second opening / closing means 162 becomes Low, the second opening / closing means 162 is opened, and the panel power supply to the display section 13 is stopped.

  Then, the CPU 14 counts 5Vs from the point B in FIG. 3, and then switches the SO bit S1n-1, which is output during the period when CS is low, that is, the first control signal to low. As a result, the first control signal sent from the serial / parallel converter 160 of the DC / DC converter 11 to the first opening / closing means 161 becomes Low, and the first opening / closing means 161 is opened, and the driver power supply to the driver 12 is opened. Supply stops. As a result, the driver power supply stops after 5 Vs has elapsed since the panel power supply stopped at point B.

  Next, another example of the power supply control device according to the present embodiment will be described. FIG. 6 is a block diagram for explaining another embodiment, and shows an internal configuration of a DC / DC converter. In this example, two opening / closing means 161 and 162 are incorporated in the subsequent stage of the serial / parallel converter 160, and an OR circuit 180 is provided between the first opening / closing means 161 and the serial / parallel converter 160. ing.

  The serial / parallel converter 160 receives SCK, CS, and SO output from the power supply controller 16 (CPU 140) shown in FIG. 1, and switches between the two open / close means 161 by appropriately switching the SO signal as the serial output. 162 is output.

  Among these, the signal output to the first opening / closing means 161 side is the first control signal, the signal output to the second opening / closing means 162 side is the second control signal, and the first control signal Is the first input of the OR circuit 180. An ON / OFF signal from the power switch 170 is connected to the second input of the OR circuit 180. Therefore, the first opening / closing means 161 uses the output signal from the OR circuit 180 for opening / closing control.

  With this configuration, when the user presses the power switch to turn on the power, the second input of the OR circuit 180 becomes H (High), so that the first opening / closing means 161 does not depend on the first control signal. The first opening / closing means 161 is closed and (1) the first set voltage is supplied to the driver 12. As a result, the driver 12 and the CPU 14 are initialized. At this stage, the second opening / closing means 162 is given L (Low) as the second control signal, and the second opening / closing means 162 is opened. As a result, (2) the second set voltage is not applied to the display unit. After the power switch 170 is turned ON, the first control signal becomes H (High) at a predetermined timing.

  Further, after initialization is completed (point A in FIG. 3), the CPU 14 shown in FIG. 1 performs counting based on the data read from the storage unit 15, and after the count time (C1) has elapsed, the second control signal is set to H (High). To. As a result, the second opening / closing means 162 is closed, and (2) the second set voltage, which is a panel power supply, is supplied to the display unit.

  On the other hand, when the user turns off the power switch 170, the second input of the OR circuit 180 becomes L (Low), but since the first control signal is H (High), The output remains H (High). Accordingly, (1) the supply of the first set voltage to the driver 12 continues with the first opening / closing means 161 closed.

  Further, after necessary control is performed on each device before turning off the panel power supply after turning off the power switch 170 (point B in FIG. 3), the second control signal becomes L (Low). Then, the second opening / closing means 162 is opened, and the supply of the second set voltage, which is the panel power supply, is stopped. As a result, the display on the display unit 13 ends.

  Then, the CPU 14 performs a predetermined count operation from the point B based on the data read from the storage unit 15, and sets the first control signal to L (Low) after the count time (C2) has elapsed. As a result, both inputs of the OR circuit 180 become L (Low), the output becomes L (Low), the first opening / closing means 161 opens, and (1) the supply of the first set voltage as the driver power supply stops. .

  In this way, the first control signal output from the serial / parallel converter 160 and the output signal of the power switch 170 are input to the OR circuit 180, and the first opening / closing means 161 is controlled by the output signal. As soon as the power switch is turned on, the first set voltage can be supplied to the driver 12 (1) without waiting for H (High) of the first control signal output from the serial / parallel converter 160. The power supply of can be started.

  The power supply control device according to the present embodiment described above can be applied to an electronic device that drives the display unit 13 by the driver 12. For example, the display device 13 can be used in various electronic devices such as a digital still camera, a digital video camera, a mobile phone, a PDA (Personal Digital Assistant), a telephone, a facsimile machine, a copier, and a printer using a liquid crystal panel. is there.

  In the present embodiment, the power control in the case where the liquid crystal panel is used as the display unit has been mainly described. However, the present invention can also be applied to a display unit (for example, an organic EL display device) other than the liquid crystal panel.

It is a block diagram explaining the power supply control device which concerns on this embodiment. It is a block diagram explaining the internal structure of a DC / DC converter. It is a timing chart of power control concerning this embodiment. It is a figure which shows the generation | occurrence | production timing of CS from power supply ON to OFF. It is a figure which shows the timing of the data communication performed synchronizing with CS. It is a block diagram explaining other embodiment. It is a block diagram explaining the conventional power supply control apparatus. It is a timing chart of power supply control.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 11 ... DC / DC converter, 12 ... Driver, 13 ... Display part, 14 ... CPU, 15 ... Memory | storage part, 16 ... Power supply control part, 160 serial / parallel conversion part, 161 ... 1st opening / closing means, 162 ... 2nd Open / close means, 170 ... power switch, 180 ... OR circuit

Claims (6)

A converter that receives a power supply voltage and converts it to a set voltage corresponding to each of the display unit and a driver that supplies a video signal to the display unit;
A control unit for sending a first control signal for supplying a set voltage to the driver and a second control signal for supplying a set voltage to the display to the converter;
A storage unit that rewriteably stores data related to the generation timing of each of the first control signal and the second control signal in the control unit;
The data stored in the storage unit has a delay time of the second control signal from the time when the initialization of the driver and the control unit when an instruction to turn on the power supply voltage is given,
When there is an instruction to turn on the power supply voltage, the control unit is configured to display the display unit when a delay time of the second control signal from the time point when the initialization of the driver and the control unit ends. A power supply control device for sending a second control signal for supplying a set voltage to the power supply. The data stored in the storage unit has a delay time of the first control signal from the time when the stop of the set voltage supply to the display unit is instructed when the power supply voltage is instructed to be turned off. The power supply control device according to claim 1. The converter includes a first opening / closing means for opening / closing a voltage supply circuit to the driver in response to the first control signal, and a voltage supply circuit to the display unit in response to the second control signal. The power supply control device according to claim 1, further comprising second opening / closing means that performs an opening / closing operation. A converter that receives a power supply voltage and converts it to a set voltage corresponding to each of the display unit and a driver that supplies a video signal to the display unit;
A control unit for sending a first control signal for supplying a set voltage to the driver and a second control signal for supplying a set voltage to the display to the converter;
In the power control method by the power control device, comprising: a storage unit that rewriteably stores data related to the generation timing of each of the first control signal and the second control signal in the control unit,
The data stored in the storage unit has a delay time of the second control signal from the time when the initialization of the driver and the control unit when an instruction to turn on the power supply voltage is given,
When there is an instruction to turn on the power supply voltage, the first control signal instructs the start of setting voltage supply to the driver, and the memory is stored with reference to the time when initialization of the driver and the control unit is completed. starts counting based on the data read from the parts, when the delay time of the second control signal from the time when the initialization of the driver and the control unit counts a predetermined time period has ended has elapsed, the second A power supply control method characterized by instructing start of supply of a set voltage to the display unit by a control signal of No. 2. A converter that receives a power supply voltage and converts it to a set voltage corresponding to each of the display unit and a driver that supplies a video signal to the display unit;
A control unit for sending a first control signal for supplying a set voltage to the driver and a second control signal for supplying a set voltage to the display to the converter;
In the power control method by the power control device, comprising: a storage unit that rewriteably stores data related to the generation timing of each of the first control signal and the second control signal in the control unit,
The data stored in the storage unit has a delay time of the first control signal from the time when the stop of the set voltage supply to the display unit is instructed when the power supply voltage is instructed to be turned off. ,
When instructed off of the power supply voltage, the point in time the by second control signal instructs to stop setting voltage supply to the display unit, which instructs to stop setting voltage supply to the front Symbol Table radical 113 Counting based on the data read from the storage unit is started as a reference, and the delay time of the first control signal has elapsed since a predetermined period was counted and the stop of setting voltage supply to the display unit was instructed Sometimes, the first control signal instructs to stop the supply of the set voltage to the driver. A driver for supplying a video signal to the display unit;
A converter that receives a power supply voltage and converts the supply voltage into a set voltage corresponding to each of the display unit and the driver;
A control unit for sending a first control signal for supplying a set voltage to the driver and a second control signal for supplying a set voltage to the display to the converter;
A storage unit that rewriteably stores data related to the generation timing of each of the first control signal and the second control signal in the control unit;
The data stored in the storage unit has a delay time of the second control signal from the time when the initialization of the driver and the control unit when an instruction to turn on the power supply voltage is given,
When there is an instruction to turn on the power supply voltage, the control unit is configured to display the display unit when a delay time of the second control signal from the time point when the initialization of the driver and the control unit ends. A second control signal for supplying a set voltage to the electronic device is sent.

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