JP2009142133A - Power supply control circuit, imaging apparatus, and control method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a power supply control circuit that reduces time required for starting an apparatus (a digital camera, for example). <P>SOLUTION: The power supply control circuit of a power supply section, which has a voltage generation means that generates a predetermined output voltage and supplies it to an apparatus, includes a storing means, which stores data necessary for the voltage generation means to generate an output voltage of the predetermined value; a control means, which controls the voltage generation means using the data stored in the storing means; a clock generation means, which generates a clock for driving the control means; and a changeover means, which changes over the clock supplied to the control means to the clock generated by the clock generation means or to a clock input from outside. The changeover means supplies the clock generated by the clock generation means to the control means when starting the power supply control circuit, and supplies the clock input from outside to the control means when the clock is supplied from outside. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a power supply control circuit, an imaging apparatus, and a control method.

  2. Description of the Related Art In recent years, digital cameras that capture and record an image of a subject by forming light from a subject on an image sensor via an optical lens have become widespread as an imaging device. In such a digital camera, a switching regulator controller is generally used.

  FIG. 9 is a schematic block diagram mainly showing a configuration of a power supply control circuit of a conventional digital camera. In FIG. 9, 1100 is a battery for driving the digital camera, 1200 is a fuse, 1300 is a regulator (REG) for supplying power to the system controller 1400, and 1500 is a power switch (SW) for starting the digital camera. is there.

  In the power supply unit 2000, 2100 is a switching regulator controller, and 2200 is a switching regulator unit. The switching regulator controller 2100 includes a control unit 2110 having a PWM generation unit, A / D conversion units 2120 and 2130, a comparison unit 2140, a communication interface (IF) unit 2150, and a reference voltage data unit 2160. Reference voltage data unit 2160 stores reference voltage data used in comparison unit 2140. The switching regulator unit 2200 generates the output voltage VCC1 based on the voltage supplied from the battery 1100 and the control of the switching regulator controller 2100.

  Hereinafter, with reference to FIG. 9, FIG. 10, and FIG. 11, an operation at the time of starting the digital camera after the power source SW 1500 is pressed in the conventional digital camera will be described. FIG. 10 is a timing chart showing the output of each part in the operation at the time of starting the conventional digital camera. FIG. 11 is a flowchart for explaining the operation at the time of starting the conventional digital camera.

  When power SW1500 is pressed at time t1 (power SW1500 → ON) (step S4002), system control unit 1400 to which power is always supplied via regulator 1300 detects that power SW1500 has been pressed. Then, the system control unit 1400 drives the system clock, which has been slowed down to save power or periodically driven to detect that the power switch 1500 has been pressed, at a normal clock speed. (Step S4004).

  Next, the system control unit 1400 transmits voltage setting data to the switching regulator controller 2100 in order to output a predetermined voltage (that is, the output voltage VCC1) from the switching regulator unit 2200 (step S4006).

  Next, the switching regulator controller 2100 starts control of the switching regulator unit 2200 using the voltage setting data from the system control unit 1400. Accordingly, the switching regulator unit 2200 starts outputting the output voltage VCC1 at time t2, for example (step S4008). The output voltage VCC1 output from the switching regulator unit 2200 gradually increases from time t2, and reaches a predetermined voltage at time t3 (step S4010). In other words, the switching regulator unit 2200 outputs the output voltage VCC1 having a predetermined voltage from time t3.

Such a technique has been conventionally proposed (see Patent Document 1).
Japanese Patent Laid-Open No. 2005-20886

  However, in the conventional power supply control circuit, even if the power supply SW is pressed, the switching regulator controller cannot start the control of the switching regulator unit by itself. It was. This is because the switching regulator controller had to receive voltage setting data related to the output voltage of the switching regulator unit from the system control unit in order to control the switching regulator unit.

  In view of the above-described problems of the related art, an object of the present invention is to provide a power supply control circuit that can reduce the time required to start up a device (for example, a digital camera).

  In order to achieve the above object, a power supply control circuit according to one aspect of the present invention is a power supply control circuit for a power supply unit that includes voltage generation means for generating an output voltage having a predetermined value and supplying the output voltage to a device. Storage means for storing data necessary for the generation means to generate the output voltage of the predetermined value, control means for controlling the voltage generation means using the data stored in the storage means, and the control means A clock generating means for generating a clock for driving; and a switching means for switching a clock supplied to the control means to a clock generated by the clock generating means or a clock input from the outside. When the power supply control circuit is activated, the means supplies the clock generated by the clock generation means to the control means, and the clock is input from the outside It is characterized by supplying the clock input from the outside to the control unit.

  An image pickup apparatus according to another aspect of the present invention includes an image pickup unit that picks up an image of a subject, and a power supply control circuit of a power supply unit including a voltage generation unit that generates an output voltage of a predetermined value and supplies the output voltage to the image pickup unit. The power supply control circuit controls the voltage generation means using storage means for storing data necessary for the voltage generation means to generate the output voltage of the predetermined value, and the data stored in the storage means. And a clock generation unit that generates a clock for driving the control unit, and a clock supplied to the control unit is switched to a clock generated by the clock generation unit or a clock input from the outside. Switching means, and when the power supply control circuit is activated, the switching means supplies the clock generated by the clock generation means to the control means, and If the Luo clock is input, and supplying a clock input from the outside to the control unit.

  According to still another aspect of the present invention, there is provided a control method that generates a predetermined value of output voltage and supplies it to a device, and data necessary for the voltage generator to generate the predetermined value of output voltage. And a control means for controlling the voltage generation means using data stored in the storage means for driving the control means. A clock generation step for generating the clock, and a switching step for switching the clock supplied to the control means to a clock generated in the clock generation step or a clock input from the outside. In the switching step, When starting up the power supply control circuit, the clock generated in the clock generation step is supplied to the control means, and the clock is input from the outside. If it is, and supplying a clock input from the outside to the control unit.

  According to still another aspect of the present invention, there is provided a control method comprising: an imaging unit that images a subject; a voltage generation unit that generates an output voltage having a predetermined value and supplies the output voltage to the imaging unit; Imaging having a storage means for storing data necessary for generating an output voltage, and a power supply control circuit of a power supply unit comprising control means for controlling the voltage generation means using the data stored in the storage means A method of controlling an apparatus, wherein a clock generation step for generating a clock for driving the control means and a clock supplied to the control means are inputted from the clock generated in the clock generation step or from the outside. A switching step for switching to a clock. In the switching step, the clock generated in the clock generation step is activated when the power supply control circuit is activated. Supplying click to the control means, when said external clock is input, and supplying a clock input from the outside to the control unit.

  Further objects and other features of the present invention will become apparent from the preferred embodiments described below with reference to the accompanying drawings.

  ADVANTAGE OF THE INVENTION According to this invention, the power supply control circuit which can reduce the time concerning starting of an apparatus (for example, digital camera) can be provided, for example.

  DESCRIPTION OF EXEMPLARY EMBODIMENTS Hereinafter, preferred embodiments of the invention will be described with reference to the accompanying drawings. In addition, in each figure, the same reference number is attached | subjected about the same member and the overlapping description is abbreviate | omitted.

  FIG. 1 is a schematic block diagram showing a configuration of an imaging apparatus 1 as one aspect of the present invention. In this embodiment, the imaging device 1 is embodied as a digital camera and images a subject.

  As shown in FIG. 1, the imaging apparatus 1 includes a lens 10, an aperture / shutter unit 12, a solid-state imaging device 14, a CDS unit 16, a clamp circuit unit 18, an A / D conversion unit 20, and signal processing. Part 22. Further, the imaging apparatus 1 includes a timing pulse generation unit 24, an optical system driving unit 26, a display unit 28, a recording medium 30, a system control unit 40, a power supply unit 50, and a power switch (SW) 60. Have.

  The lens 10 forms an optical image of the subject on the solid-state imaging device 14.

  The lens / shutter unit 12 has a shutter function and a diaphragm function for controlling the amount of light that has passed through the lens 10.

  The solid-state imaging device 14 takes in an optical image of a subject formed through the lens 10 as an electrical signal.

  The CDS unit 16 performs correlated double sampling on the electrical signal output from the solid-state imaging device 14 to reduce clock and reduce noise.

  The clamp circuit unit 18 clamps the signal output from the CDS unit 16 to a predetermined reference voltage at the timing of a clamp pulse supplied from a timing pulse generation unit 24 described later.

  The A / D converter 20 converts the signal output from the clamp circuit unit 18 from an analog signal to a digital signal.

  The signal processing unit 22 performs various signal processing and conversion processing on the signal output from the A / D conversion unit 20 to display or record the optical image of the subject, and converts the signal into a predetermined format.

  The timing pulse generator 24 generates necessary pulses for the solid-state imaging device 14, the CDS unit 16, the clamp circuit unit 18, and the A / D converter 20.

  The optical system driving unit 26 drives the lens 10 and the aperture / shutter unit 12.

  The display unit 28 displays, for example, an image of the subject on an LCD or the like based on the signal output from the signal processing unit 22.

  The recording medium 30 is composed of a semiconductor memory or the like for recording or reading image data.

  The system control unit 40 controls the entire imaging apparatus 1 and executes various calculations.

  The power supply unit 50 supplies power to all the components of the imaging device 1 (device). The configuration of the power supply unit 50 will be described in detail later.

  The power supply SW60 is a main switch for turning on (ON) or turning off (OFF) the power supply (that is, the power supply unit 50) of the imaging apparatus 1.

  Next, the basic operation of the imaging apparatus 1 will be described with reference to FIG. First, when the power supply SW60 is pressed (power supply SW60 → ON) (step S102), the power supply unit 50 starts operating and supplies power to the imaging apparatus 1. The operation of the power supply unit 50 will be described in detail later.

  When power is supplied from the power supply unit 50, the system control unit 40 determines whether the operation mode of the imaging apparatus 1 is the playback mode or the imaging mode (step S104).

  If the operation mode of the imaging device 1 is the playback mode, the system control unit 40 reads the image data stored in the recording medium 30 into the signal processing unit 22 (step S106), and performs signal processing for displaying the image data. Is displayed on the display unit 28 (step S108). Then, the system control unit 40 monitors whether the power SW 60 is turned off (step S110), displays an image on the display unit 28 until the power SW 60 is turned off, and displays the image when the power SW 60 is turned off. Stop and turn off the power supply 50.

  On the other hand, if the operation mode of the imaging apparatus 1 is the imaging mode, the system control unit 40 starts driving the imaging system such as the optical lens 10, the solid-state imaging device 14, and the timing pulse generation unit 24. In the present embodiment, the system control unit 40 drives the lens position of the autofocus (AF) lens to the initial position (reset position) via the optical system driving unit 26 (step S112). Further, the system control unit 40 opens the aperture / shutter unit 12 via the optical system driving unit 26 (step S114), and executes a photometric sequence (step S116). In the photometric sequence, the signal captured by the solid-state imaging device 14 is subjected to correlated double sampling by the CDS unit 16, clamped by the clamp circuit unit 18, and A / D converted by the A / D conversion unit 20. Then, the signal A / D converted by the A / D converter 20 is processed by the signal processor 22 and input to the system controller 40, and the exposure control value is calculated from the photometric value.

  The system control unit 40 determines the aperture diameter, shutter speed, and the like of the aperture of the aperture / shutter unit 12 from the program diagram according to the calculation result (that is, the exposure control value) in the photometry sequence (step S116). Set to the shutter unit 12 (step S118).

  Next, the system control unit 40 determines whether or not the display mode is set to ON (that is, whether or not a subject preview is displayed) (step S120). If the display mode is set to ON, the system control unit 40 displays a subject preview on the display unit 28 (step S122). If the display mode is not set to ON, the system control unit 40 waits until the first switch of the release button (for example, half-pressing the release button) that instructs to image the subject is pressed.

  When the first switch of the release button is pressed (first switch → ON) (step S124), the system control unit 40 executes a photometric sequence (step S126). The photometric sequence is the same as that in step S116, and a detailed description thereof is omitted here.

  The system control unit 40 re-determines the aperture diameter, shutter speed, etc. of the aperture / shutter unit 12 from the program diagram according to the calculation result (exposure control value) in the photometry sequence (step S126). The shutter unit 12 is reset (step S128).

  Next, the system control unit 40 extracts a high frequency component from a signal obtained via the solid-state imaging device 14, the CDS unit 16, the clamp circuit unit 18, and the A / D conversion unit 20, and the distance to the subject. Is calculated (step S130). Then, the system control unit 40 drives the AF lens based on the distance to the subject calculated in step S130, and determines whether or not it is in focus (step S132). If it is not in focus, the process returns to step S130 to calculate the distance to the subject. If it is in focus, the second switch of the release button (for example, the release button of the release button) that instructs imaging of the subject. Wait until it is pressed.

  When the second switch of the release button is pressed (second switch → ON) (step S134), the system control unit 40 images the subject (that is, exposes a still image of the subject) (step S136). When the imaging of the subject is completed, the system control unit 40 uses the signal processing unit 22 to generate a signal (image data) obtained via the solid-state imaging device 14, the CDS unit 16, the clamp circuit unit 18, and the A / D conversion unit 20. Is recorded on the recording medium 30.

  Next, the system control unit 40 checks whether or not the second switch of the release button is being pressed (maintains an ON state) (step S138). If the second switch is kept pressed, the system control unit 40 displays the image of the subject captured in step S136 on the display unit 28 (step S140). The image of the subject is displayed until the second switch of the release button is turned off. If the second switch is not kept pressed (if it is in the OFF state), the system control unit 40 confirms whether or not the power SW 60 is turned off.

  If the power switch 60 is not turned off, the process returns to step S112, and the system control unit 40 executes the processes of steps S112 to S120 (the process until the first switch of the release button is pressed). Wait until the switch is pressed. When the power SW 60 is turned off, the system control unit 40 returns the AF lens or the like to a predetermined position via the optical system driving unit 26 and stops the operation of the power supply unit 50.

  Hereinafter, the operation of the power supply unit 50, particularly the operation at the time of starting up the power supply unit 50 will be described. First, a detailed configuration of the power supply unit 50 will be described with reference to FIG. FIG. 3 is a schematic block diagram illustrating the configuration of the power supply unit 50 of the imaging apparatus 1. However, FIG. 3 illustrates a part of the power supply unit 50 for generating a voltage to be supplied to the imaging device 1. In FIG. 3, BT is a battery for supplying power, and FS is a fuse.

  The power supply unit 50 includes a switching regulator controller 520, a switching regulator unit 540, and a logic circuit 560. The switching regulator controller 520 functions as a power supply control circuit for the power supply unit 50. The switching regulator unit 540 functions as a voltage generating unit that generates the output voltage VCC1 based on the voltage supplied from the battery BT and the control of the switching regulator controller 520. The logic circuit 560 outputs a HI signal to the switching regulator controller 520 when the signal input from the power supply SW 60 or the system control unit 40 is HI.

  The switching regulator controller 520 includes a control unit 521, an A / D conversion unit 522, an A / D conversion unit 523, a comparison unit 524, and a communication interface (I / F) unit 525. The switching regulator controller 520 includes a reference voltage data unit 526, a storage unit 527, a clock generation unit 528, and a switching unit 529.

  The control unit 521 controls the switching regulator unit 540. The control unit 521 also has a function of monitoring whether the system clock is supplied from the system control unit 40.

  The A / D conversion unit 522 converts the voltage supplied from the battery BT from an analog value to a digital value.

  The A / D conversion unit 523 converts the output voltage VCC1 output from the switching regulator unit 540 from an analog value to a digital value.

The comparison unit 524 compares the digital output voltage VCC 1 output from the A / D conversion unit 523 with the reference voltage data stored in the reference voltage data unit 526.
The communication I / F unit 525 is an interface that enables communication with the system control unit 40.

  The reference voltage data unit 526 stores reference voltage data used in the comparison unit 524.

  The storage unit 527 is configured by a ROM or the like, and stores voltage setting data necessary for setting the output voltage VCC1 and phase characteristics output from the switching regulator unit 540.

  The clock generation unit 528 generates a clock for driving each component (particularly, the control unit 521) of the switching regulator controller 520.

  The switching unit 529 switches the clock supplied to the control unit 521 to the clock generated by the clock generation unit 528 or the system clock input from the system control unit 40 (that is, outside the power supply control circuit). Specifically, the switching unit 529 selects the clock generation unit 528 side (that is, connects the control unit 521 and the clock generation unit 528) or the system control unit 40 side as the input of the control unit 521 (that is, the system control unit 40 side). The control unit 521 and the system control unit 40 are connected). As a result, the clock generated by the clock generation unit 528 or the system clock input from the system control unit 40 is supplied to the control unit 521.

  The switching regulator unit 540 includes a switching element 541, a diode 542, an inductor 543, and a capacitor 544 for generating a predetermined value of the output voltage VCC1. The switching regulator unit 540 has a step-down configuration in the present embodiment, but is not limited to this configuration. For example, the switching regulator unit 540 may have a synchronous rectification configuration in which the diode 542 is replaced with a switching element, or may have another configuration such as a boosting configuration or a buck-boost configuration.

  Next, with reference to FIGS. 3, 4, and 5, the operation at the time of starting the power supply unit 50 after the power supply SW 60 is pressed in the imaging apparatus 1 will be described. FIG. 4 is a timing diagram showing the output of each unit in the operation at the time of starting up the power supply unit 50. FIG. 5 is a flowchart for explaining the operation at the time of starting the power supply unit 50.

  When the power supply SW60 is pressed at time t11 (power supply SW60 → ON) (step S402), the output from the logic circuit 560 becomes HI, and the HI signal is input to the Cont terminal of the switching regulator controller 520. Thereby, the switching regulator controller 520 starts operation.

  A voltage is supplied from the battery BT to each component of the switching regulator controller 520, and the clock generation unit 528 generates a clock for driving the control unit 521 (step S304). Since the switching unit 529 selects the clock generation unit 528 side as an input to the control unit 521 in the initial state (before the power switch 60 is pressed), the clock generated by the clock generation unit 528 is used as the control unit. 521 is supplied.

  The control unit 521 to which the clock is supplied from the clock generation unit 528 starts driving. Specifically, the control unit 521 starts control of the switching regulator unit 540 using voltage setting data necessary for the switching regulator unit 540 stored in the storage unit 527 to generate the output voltage VCC1 having a predetermined value. To do. Accordingly, the switching regulator unit 540 starts outputting the output voltage VCC1 (step S306).

  The output voltage VCC1 from the switching regulator unit 540 is output to the load side (for example, the imaging system of the imaging device 1), is input to the A / D conversion unit 523, and is stored in the reference voltage data unit 526 by the comparison unit 524. Compared to the reference voltage data. At this time, the control unit 521 controls the switching regulator unit 540 so that the output voltage VCC1 from the switching regulator unit 540 becomes a predetermined value. Accordingly, the output voltage VCC1 from the switching regulator unit 540 gradually increases from time t11, and reaches the predetermined output voltage VCC1 at time t12 (step S308).

  The output voltage VCC1 from the switching regulator unit 540 that has reached a predetermined value is also supplied to the system control unit 40, and the system control unit 40 is activated by the output voltage VCC1 from the switching regulator unit 540 (that is, starts a driving operation). ). Then, the system control unit 40 generates a system clock for driving the control unit 521, and inputs the system clock to the switching regulator controller 520 (step S310).

  Further, the system control unit 40 sets the latch pulse input to the logic circuit 560 to HI. Accordingly, since the HI signal is always input to the Cont terminal of the switching regulator controller 520, the operation of the power supply unit 50 is continued even if the power supply SW60 is not kept pressed. In other words, the power source SW 60 may be either a type that maintains continuity or a type that does not maintain continuity.

  For example, when the power supply SW60 is a type that does not maintain continuity, the power supply SW60 is released after the power supply unit 50 is activated, and a LOW signal is input to the Cont terminal of the switching regulator controller 520. Then, when the operation of the imaging apparatus 1 is stopped, the power SW 60 is pressed again, and a HI signal is input to the Cont terminal of the switching regulator controller 520. Therefore, in the program, after the imaging apparatus 1 is started, when the signal input to the Cont terminal of the switching regulator controller 520 once becomes LOW and becomes HI again, it is defined that the operation to stop the imaging apparatus 1 is started. You just have to. Accordingly, the system control unit 40 can stop the operation of the power supply unit 50 by setting the latch pulse to LOW after performing various processes of the imaging device 1 by setting the latch pulse to the logic circuit 560 to HI. it can.

  Further, when the power supply SW 60 is of a type that maintains continuity, the power supply SW 60 is pressed when the imaging apparatus 1 is stopped so that the continuity is lost, and a LOW signal is input to the Cont terminal of the switching regulator controller 520. Therefore, in this case, it may be defined that the operation of stopping the imaging apparatus 1 is entered, as described above. As a result, the system control unit 40 can stop the operation of the power supply unit 50 by setting the latch pulse to the logic circuit 560 to LOW after performing various processes of the imaging device 1.

  When the system control unit 40 starts generating the system clock, the control unit 521 monitors whether the system clock is reliably supplied from the system control unit 40 to the switching regulator controller 520. When the system clock is reliably supplied, the switching unit 529 changes the clock supplied to the control unit 521 from the clock generated by the clock generation unit 528 to the system clock generated by the system control unit 40 at time t13. Switching (step S312). As a result, the control unit 521 (switching regulator controller 520) switches from the operation based on the clock from the clock generation unit 528 to the operation based on the system clock from the system control unit 40, and can operate in synchronization with the system control unit 40. It becomes possible.

  Here, the system clock supplied from the system control unit 40 to the control unit 521 is generated from a crystal resonator, a ceramic resonator, or the like, and the clock speed is faster than the clock generated by the clock generation unit 528, and the frequency deviation is also large. Few. Therefore, the switching regulator controller 520 can perform control with good responsiveness synchronized with the system control unit 40.

  Next, the system control unit 40 transmits data necessary for the operation of the imaging device 1 to the switching regulator controller 520 (step S314). In order to operate the image pickup apparatus 1, a plurality of data (voltage data) is necessary, but the storage unit 527 stores only necessary minimum data (that is, voltage setting data), and the system control unit 40. Send other data at the required timing after the. Other data includes, for example, voltage data of an imaging system including the solid-state imaging device 14 and voltage data of a display system such as the display unit 28. In this way, by storing only the minimum necessary data in the storage unit 527, the capacity of the storage unit 527 can be saved.

  As described above, the clock supplied to the control unit 521 (switching regulator controller 520) is switched to the system clock supplied from the system control unit 40 by the switching unit 529 in step S314. Accordingly, the clock generation unit 528 stops generating the clock at time t14 (step S316).

  As described above, in the imaging apparatus 1 of the present embodiment, when the power supply SW 60 is pressed, the switching regulator controller 520 starts up independently without communicating with the system control unit 40 and controls the switching regulator unit 540. Can start. Therefore, the imaging apparatus 1 can reduce (improve) the time from when the power SW 60 is pressed until the imaging apparatus 1 is activated.

  In the power control circuit of the conventional digital camera, in order to detect that the power SW 60 is pressed, the power is always supplied to the system control unit so as to always start at a slow clock speed, or periodically. Had to be started. Furthermore, it is necessary to always supply power to the switching regulator controller so that a signal (for example, voltage setting data) from the system control unit can be received at any time. Therefore, even if the system control unit is started by slowing down the clock speed or the system control unit is started periodically to reduce power consumption, power is always supplied to the system control unit and the switching regulator controller. As a result, battery consumption was accelerated.

  On the other hand, the imaging apparatus 1 of the present embodiment is configured to supply power only to the switching regulator controller 520 and not supply power to the system control unit 40 when the imaging apparatus 1 is on standby. Consumption of the battery BT can be suppressed.

  In the imaging device 1, when the system clock is supplied from the system control unit 40 to the control unit 521, the clock generation unit 528 stops generating the clock. However, as described below with reference to FIGS. 6 to 8, the clock generation unit 528 may supply the clock to the control unit 521 without stopping the generation of the clock.

  FIG. 6 is a schematic block diagram illustrating another configuration of the power supply unit 50 of the imaging apparatus 1. However, FIG. 6 illustrates a part of the power supply unit 50 for generating a voltage to be supplied to the imaging apparatus 1.

  The power supply unit 50 shown in FIG. 6 is the same as the power supply unit 50 shown in FIG. 3, but the configurations of the control unit 521A and the switching unit 529A are different. A power supply unit 50 illustrated in FIG. 6 includes a switching regulator controller 520, a switching regulator unit 540, and a logic circuit 560.

  The switching regulator controller 520 includes a control unit 521A, an A / D conversion unit 522, an A / D conversion unit 523, a comparison unit 524, and a communication interface (I / F) unit 525. The switching regulator controller 520 includes a reference voltage data unit 526, a storage unit 527, a clock generation unit 528, and a switching unit 529A.

  The control unit 521A has a function of controlling the switching regulator unit 540. In particular, the control unit 521A includes a PWM control unit 521Aa that controls driving of the switching element 541, specifically, PWM (Pulse Width Modulation) control. The PWM control unit 521Aa functions as a drive control unit for the switching element 541. Here, the PMW control is called a pulse width modulation method, and is a method of controlling by the ratio (duty ratio) between the time when the power switch is turned on and the time when it is turned off. The control unit 521 also has a function of monitoring whether the system clock is supplied from the system control unit 40. The PWM control unit 521Aa is connected to the clock generation unit 528, and is configured to be supplied with the clock generated by the clock generation unit 528 regardless of the switching of the switching unit 529A.

  The switching unit 529A switches the clock supplied to the control unit 521A to the clock generated by the clock generation unit 528 or the system clock input from the system control unit 40 (that is, outside the power supply control circuit). Specifically, the switching unit 529A selects the clock generation unit 528 side (ie, connects the control unit 521A and the clock generation unit 528) or the system control unit 40 side as an input of the control unit 521A (ie, the system control unit 40 side). The control unit 521A and the system control unit 40 are connected). As a result, the clock generated by the clock generation unit 528 or the system clock input from the system control unit 40 is supplied to the control unit 521A excluding the PWM control unit 521Aa. However, even when the switching unit 529A selects the system control unit 40 side, the PWM control unit 521Aa and the clock generation unit 528 are connected, and the system control unit 40 is connected to the control unit 521A except the PWM control unit 521Aa. Is supplied with the system clock. In other words, the clock generated by the clock generator 528 is always supplied to the PWM controller 521Aa.

  Next, with reference to FIGS. 6, 7, and 8, an operation at the time of starting the power supply unit 50 after the power supply SW 60 is pressed in the imaging apparatus 1 will be described. FIG. 7 is a timing chart showing the output of each unit in the operation at the time of starting the power supply unit 50. FIG. 8 is a flowchart for explaining the operation when the power supply unit 50 is activated.

  When the power supply SW60 is pressed at time t21 (power supply SW60 → ON) (step S402), the output from the logic circuit 560 becomes HI, and the HI signal is input to the Cont terminal of the switching regulator controller 520. Thereby, the switching regulator controller 520 starts operation.

  A voltage is supplied from the battery BT to each component of the switching regulator controller 520, and the clock generation unit 528 generates a clock for driving the control unit 521A (step S404). Since the switching unit 529 selects the clock generation unit 528 side as an input to the control unit 521 in the initial state (before the power switch 60 is pressed), the clock generated by the clock generation unit 528 is used as the control unit. 521A.

  The control unit 521A to which the clock is supplied from the clock generation unit 528 starts driving. Specifically, the control unit 521A starts control of the switching regulator unit 540 using voltage setting data necessary for the switching regulator unit 540 stored in the storage unit 527 to generate the output voltage VCC1 having a predetermined value. To do. Thereby, the switching regulator unit 540 starts outputting the output voltage VCC1 (step S406).

  The output voltage VCC1 from the switching regulator unit 540 is output to the load side (for example, the imaging system of the imaging device 1), is input to the A / D conversion unit 523, and is stored in the reference voltage data unit 526 by the comparison unit 524. Compared to the reference voltage data. At this time, the control unit 521A controls the switching regulator unit 540 so that the output voltage VCC1 from the switching regulator unit 540 becomes a predetermined value. Accordingly, the output voltage VCC1 from the switching regulator unit 540 gradually increases from time t21, and reaches the predetermined output voltage VCC1 at time t22 (step S408).

  The output voltage VCC1 from the switching regulator unit 540 that has reached a predetermined value is also supplied to the system control unit 40, and the system control unit 40 is activated by the output voltage VCC1 from the switching regulator unit 540 (that is, starts a driving operation). ). Then, the system control unit 40 generates a system clock for driving the control unit 521A, and inputs the system clock to the switching regulator controller 520 (step S410).

  Further, the system control unit 40 sets the latch pulse input to the logic circuit 560 to HI. Accordingly, since the HI signal is always input to the Cont terminal of the switching regulator controller 520, the operation of the power supply unit 50 is continued even if the power supply SW60 is not kept pressed.

  When the system control unit 40 starts generating the system clock, the control unit 521A monitors whether the system clock is reliably supplied from the system control unit 40 to the switching regulator controller 520. When the system clock is reliably supplied, the switching unit 529A changes the clock supplied to the control unit 521A from the clock generated by the clock generation unit 528 to the system clock generated by the system control unit 40 at time t23. Switching (step S412). However, the switching unit 529A supplies the clock generated by the clock generation unit 528 for the clock supplied to the PWM control unit 521Aa of the control unit 521A, and does not switch to the system clock generated by the system control unit 40. In other words, in step S412, the switching unit 529A supplies the clock generated by the clock generation unit 528 to the PWM control unit 521Aa, and sends the system clock from the system control unit 40 to the control unit 521A excluding the PWM control unit 521Aa. Supply.

  This is effective when the optimal clock for the PWM control unit 521Aa and the optimal clock for the components of the control unit 521A (switching regulator controller 520) excluding the PWM control unit 521Aa are different. For example, the control unit 521A is effective when it is desired to operate at the fastest clock speed, but the clock speed of the PWM control unit 521Aa cannot be increased considering the loss of the switching element 541 and the efficiency of the switching regulator unit 540.

  Therefore, the control unit 521A except the PWM control unit 521Aa can switch from the operation based on the clock from the clock generation unit 528 to the operation based on the system clock from the system control unit 40, and can operate in synchronization with the system control unit 40. Become. The PWM control unit 521Aa maintains the operation based on the clock from the clock generation unit 528.

  As described above, the system clock supplied from the system control unit 40 to the control unit 521A has a faster clock speed and less frequency deviation than the clock generated by the clock generation unit 528. Therefore, the switching regulator controller 520 can perform control with good responsiveness synchronized with the system control unit 40.

  Next, the system control unit 40 transmits data necessary for the operation of the imaging device 1 to the switching regulator controller 520 (step S414).

  As described above, the clock for driving the control unit 521A (switching regulator controller 520) excluding the PWM control unit 521Aa is switched to the system clock supplied from the system control unit 40. However, since the clock generated by the clock generation unit 528 is used by the PWM control unit 521Aa of the control unit 521A, the clock generation unit 528 maintains the operation (ie, clock generation) as it is.

  As described above, it is possible to optimize the efficiency of the power supply unit 50 by always supplying the optimal clock from the clock generation unit 528 without switching the clock supplied to the PWM control unit 521Aa.

  The preferred embodiments of the present invention have been described above, but the present invention is not limited to these embodiments, and various modifications and changes can be made within the scope of the gist.

It is a schematic block diagram which shows the structure of the imaging device as 1 side surface of this invention. 3 is a flowchart for explaining a basic operation of the imaging apparatus shown in FIG. 1. It is a schematic block diagram which shows the structure of the power supply part of the imaging device shown in FIG. FIG. 4 is a timing diagram illustrating outputs of respective units in an operation at the time of starting the power supply unit illustrated in FIG. 3. 4 is a flowchart for explaining an operation at the time of starting the power supply unit shown in FIG. 3. It is a schematic block diagram which shows another structure of the power supply part of the imaging device shown in FIG. FIG. 7 is a timing chart showing outputs of respective units in an operation at the time of starting the power supply unit shown in FIG. 6. It is a flowchart for demonstrating the operation | movement at the time of starting of the power supply part shown in FIG. It is a schematic block diagram which mainly shows the structure of the power supply control circuit of the conventional digital camera. It is a timing diagram which shows the output of each part in the operation | movement at the time of starting of the conventional digital camera. It is a flowchart for demonstrating the operation | movement at the time of starting of the conventional digital camera.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Imaging device 10 Lens 12 Aperture / shutter unit 14 Solid-state imaging device 16 CDS unit 18 Clamp circuit unit 20 A / D conversion unit 22 Signal processing unit 24 Timing pulse generation unit 26 Optical system driving unit 28 Display unit 30 Recording medium 40 System control Unit 50 power supply unit 520 switching regulator controller 521 control unit 521A control unit 521Aa PWM control unit 522 A / D conversion unit 523 A / D conversion unit 524 comparison unit 525 communication interface unit 526 reference voltage data unit 527 storage unit 528 clock generation unit 529 Switching unit 540 Switching regulator unit 541 Switching element 542 Diode 543 Inductor 544 Capacitor 560 Logic circuit 60 Power switch

Claims (8)

A power supply control circuit of a power supply unit including a voltage generation unit that generates an output voltage of a predetermined value and supplies it to a device,
Storage means for storing data necessary for the voltage generating means to generate the output voltage of the predetermined value;
Control means for controlling the voltage generation means using data stored in the storage means;
Clock generating means for generating a clock for driving the control means;
Switching means for switching a clock supplied to the control means to a clock generated by the clock generation means or a clock input from the outside,
The switching means is
When starting up the power supply control circuit, supply the clock generated by the clock generation means to the control means,
When a clock is input from the outside, the power control circuit supplies the clock input from the outside to the control means. The externally input clock is generated by system control means for controlling the power supply control circuit,
The power supply control circuit according to claim 1, wherein the system control unit starts activation by the output voltage output from the voltage generation unit. The voltage generation means includes a switching element for generating the output voltage of the predetermined value,
The control means includes drive control means for controlling driving of the switching element,
The switching means is
When a clock is input from the outside, the clock generated by the clock generation unit is supplied to the drive control unit, and the clock input from the outside is supplied to the control unit excluding the drive control unit. The power supply control circuit according to claim 1.   The power supply control circuit according to claim 1, wherein the clock input from the outside has a clock speed faster than the clock generated by the clock generation unit.   The power supply control circuit according to claim 1, wherein the clock input from the outside has a smaller frequency deviation than the clock generated by the clock generation unit. Imaging means for imaging a subject;
A power supply control circuit of a power supply unit including a voltage generation unit that generates an output voltage of a predetermined value and supplies the output voltage to the imaging unit,
The power supply control circuit
Storage means for storing data necessary for the voltage generating means to generate the output voltage of the predetermined value;
Control means for controlling the voltage generation means using data stored in the storage means;
Clock generating means for generating a clock for driving the control means;
Switching means for switching a clock supplied to the control means to a clock generated by the clock generation means or a clock input from the outside,
The switching means is
When starting up the power supply control circuit, supply the clock generated by the clock generation means to the control means,
An imaging apparatus, wherein when an external clock is input, an externally input clock is supplied to the control means. Voltage generating means for generating an output voltage of a predetermined value and supplying it to the device, storage means for storing data necessary for the voltage generating means to generate the output voltage of the predetermined value, and stored in the storage means And a control means for controlling the voltage generating means using the obtained data.
A clock generation step of generating a clock for driving the control means;
A switching step of switching a clock supplied to the control means to a clock generated in the clock generation step or a clock input from the outside,
In the switching step,
When starting up the power supply control circuit, supply the clock generated in the clock generation step to the control means,
When a clock is inputted from the outside, the control method is characterized in that the clock inputted from the outside is supplied to the control means. Imaging means for imaging a subject;
A voltage generation unit that generates an output voltage of a predetermined value and supplies the output unit with the imaging unit, a storage unit that stores data necessary for the voltage generation unit to generate the output voltage of the predetermined value, and a storage unit A control method for an imaging apparatus, comprising: a power supply control circuit of a power supply unit comprising control means for controlling the voltage generation means using stored data,
A clock generation step of generating a clock for driving the control means;
A switching step of switching a clock supplied to the control means to a clock generated in the clock generation step or a clock input from the outside,
In the switching step,
When starting up the power supply control circuit, supply the clock generated in the clock generation step to the control means,
When a clock is inputted from the outside, the control method is characterized in that the clock inputted from the outside is supplied to the control means.

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