JP2002287218A - Camera - Google Patents

Abstract

PROBLEM TO BE SOLVED: To efficiently consume the power of a main power source. SOLUTION: A charge necessary to emit light from a stroboscope 48 is accumulated by a capacitor included in a strobe light emission control circuit 46. When the main power source 34 is turned off without discharging the charge of the capacitor, the terminal voltage of the capacitor C1 is applied on a step- down DC/DC converter 42. A backup power source 38 is charged by a charging circuit 40 with a voltage supplied from the step-down DC/DC converter.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a camera,
In particular, for example, the present invention relates to a camera that emits a flash when shooting an object.

[0002]

2. Description of the Related Art A strobe provided in a camera emits light based on electric charges stored in a capacitor by a battery. The capacitor is charged prior to the operation of the shutter button, whereby the strobe can be quickly emitted when the shutter button is operated.

[0003]

However, if the main power supply is turned off without performing flash photography in spite of charging the capacitor, the capacitor is naturally discharged. As a result, there has been a problem that the batteries are wasted.

[0004] Therefore, a main object of the present invention is to provide a camera capable of improving power consumption efficiency.

[0005]

SUMMARY OF THE INVENTION The present invention relates to a camera having a backup power supply, a strobe that emits light when an object is photographed, an accumulating means for accumulating electric charges required for light emission of the strobe prior to photographing, and a main power supply. A charging unit that charges a backup power supply based on the electric charge stored in the storage unit when the camera is turned off.

[0006]

The electric charge required for strobe light emission is accumulated by the electric storage means prior to photographing. When the main power supply is turned off, the charging means charges the backup power supply based on the electric charge stored in the storage means. As a result, power consumption of the main power supply is made more efficient.

[0007] The voltage value generated by the storage means is preferably dropped to the charging voltage value of the backup power supply by the voltage drop means. That is, since the voltage value required for strobe light emission and the voltage value required for charging the backup power supply are significantly different, the voltage value is adjusted by the voltage drop unit.

When the on operation of the main power supply in the off state is detected by the detecting means, the detecting means is driven by the backup power supply.

Further, when the image sensor generates an image signal corresponding to the optical image of the subject by photoelectric conversion and the monitor displays an image based on the image signal, the supply means supplies the image sensor and the monitor based on the main power supply. Supply power.

[0010]

According to the present invention, since the backup power supply is charged by the electric charge stored in the storage means, the power consumption of the main power supply can be made more efficient.

The above and other objects, features and advantages of the present invention will become more apparent from the following detailed description of embodiments with reference to the drawings.

[0012]

Referring to FIG. 1, a digital camera 10 of this embodiment includes a subsystem controller 26 which is backed up by a backup power supply (battery) 38 when a main power supply (battery) 34 is off. When the power switch 30 a provided on the operation panel 30 is switched from the off state to the on state, the subsystem controller 26 turns on the main power supply 34. by this,
DC / DC converter 28 for main system, DC / DC converter 36 for subsystem, and DC for strobe
The power supply voltage is supplied to the / DC converter 44.

DC / DC converter 2 for main system
8 generates a drive voltage for the main system based on the supplied power supply voltage. The main system is formed by circuits necessary for an image processing system such as the image sensor 12, the signal processing circuit 14, the main system controller 16, the LCD controller 22, and the LCD 24, and the generated driving voltage is supplied to these circuits. At this time, the main system controller 16 starts processing the program stored in the program memory 20.

DC / DC converter 36 for subsystem
Generates a drive voltage for the subsystem based on the supplied power supply voltage. The subsystem controller 26 responds to the ON operation of the power switch 30a,
Selects the DC / DC converter 36 for the subsystem. The drive voltage from the subsystem DC / DC converter 36 is supplied to the subsystem controller 26 via the selector 32. Subsystem controller 26
When the power switch 30a is on, the memory 50 is driven by the drive voltage from the DC / DC converter 36 for the subsystem.

DC / DC converter 36 for subsystem
The driving voltage generated by the above is also supplied to the charging circuit 40. The charging circuit 40 charges the backup power supply 38 based on the applied drive voltage. When the power switch 30a is off, the subsystem controller 26 causes the selector 32 to select the backup power supply 38. Subsystem controller 26 and memory 32
Are driven by a backup power supply 38. In addition,
The memory 50 is a volatile memory that stores setting information such as shutter speed and date information.

The strobe DC / DC converter 44 includes:
A drive voltage for the strobe light 48 is generated. The strobe light emission control circuit 46 accumulates electric charges in a strobe light emission capacitor C1 described later by the generated drive voltage.

When the monitor start button 30b is operated while the power switch 30a is on, the subsystem controller 26 gives a corresponding control signal to the main system controller 16. The main system controller 16 instructs the image sensor 12 to perform thinning-out reading,
From the image sensor 12, a low-resolution raw image signal is output at a predetermined frame rate. The output raw image signal of each frame is converted into a YUV signal by the signal processing circuit 14, and the main system controller 16 controls the LCD driver 22 based on the converted YUV signal. As a result, a real-time moving image (through image) of the subject is displayed on the LCD 24.

When the shutter button 30c is operated, the main system controller 16 provides a trigger signal to the strobe light emission control circuit 46 and instructs the image sensor 12 to read all pixels. When the trigger signal is given, the slot light emission control circuit 46 sets the capacitor C1.
The strobe 48 is caused to emit light by the electric charges stored in the strobe 48, and the image sensor 12 reads out a one-frame raw image signal generated by the exposure at the time when the strobe light is emitted, in an all-pixel system. The read high-resolution raw image signal is converted into a YUV signal by the signal processing circuit 14 in the same manner as described above. The main system controller 16 writes the applied YUV signal to the image memory 18 in a compressed state, and drives the LCD controller 22 based on the same YUV signal. As a result, the shutter button 30
A still image at the time when c is operated is obtained in the image memory 18 and the same still image (frozen image) is displayed on the LCD.
24.

After the still image has been displayed for a predetermined time, the above-described through image display processing is restarted.
Further, the capacitor C1 for strobe light emission is charged by the drive voltage from the DC / DC converter 44 for strobe light.

When the power switch 30a is switched from the on state to the off state, the subsystem controller 26
Turns off the main power supply 34 and causes the selector 32 to select the backup power supply 38. Therefore, while the power switch 30a is off, the subsystem controller 26 is driven by the backup power supply 38. The subsystem controller 26 further connects the capacitor C1 for strobe light emission to the step-down DC / DC converter 42. The step-down DC / DC converter 42 drops the terminal voltage of the capacitor C1 to the charging voltage of the backup power supply, and supplies the dropped voltage to the charging circuit 40. The charging circuit 40 charges the backup power supply 38 with the supply voltage from the step-down DC / DC converter 42.

That is, although the capacitor C1 is charged prior to the operation of the shutter button 30c, the power switch 30a may be turned off without operating the shutter button 30c, that is, without causing the flash 48 to emit light. In such a case, if the electric charge charged in the capacitor C1 is discharged spontaneously, the power of the main power supply 34 is wasted. For this reason, in this embodiment, when the power switch 30a is turned off, the capacitor C1 is connected to the step-down DC / DC converter 42, and the backup power supply 38 is charged by the electric charge accumulated in the capacitor C1. Thereby, the efficiency of power consumption of the main power supply 34 is improved.

The flash emission control circuit 46 is configured as shown in FIG. The anode of the diode D1 is connected to the output terminal of the DC / DC converter for strobe 44, and the cathode is connected to one end of the capacitor C1 whose other end is grounded. The cathode and the plate of the strobe light 48 are connected to one end and the other end of the capacitor C1, respectively. One end of the capacitor C1 is also connected to the step-down DC / DC converter 42 via the switch SW1.

The cathode of the diode D1 is also connected to one end of the resistor R1. The other end of the resistor R1 is connected to the anode of the thyristor S whose cathode is grounded, and the gate of the thyristor S is grounded via the resistor 2. The thyristor S is a GOT (Gate Turn Off) type thyristor.

One end of the resistor R1 is connected to one end of a primary coil forming a transformer T via a capacitor C2. One end of the secondary coil forming the transformer T is connected to the grid of the strobe light 48. Both the primary coil and the secondary coil are grounded.

The capacitor C1 is a DC / DC for strobe.
It is charged by the drive voltage supplied from converter 44. The terminal voltage of the capacitor C1 is applied to the cathode of the strobe 48. Main system controller 1
The trigger signal output from 6 is applied to the gate of thyristor S. The thyristor S conducts in response to the trigger signal, and at this time, the terminal voltage of the capacitor C1 fluctuates.
A voltage is excited in the secondary coil of the transformer T, that is, the grid of the strobe 48 based on the voltage fluctuation, and the strobe 48 emits light based on the terminal voltage of the capacitor C1.

The switch SW1 is turned on in response to the SW signal output from the subsystem controller 26. Switch S without flash 48
When W1 is turned on, the terminal voltage of the capacitor C1 is applied to the step-down DC / DC converter 42. The charging circuit 40 shown in FIG. 1 charges the backup power supply 38 based on the terminal voltage of the capacitor C1.

The subsystem controller 26 specifically processes the flowchart shown in FIG. First, step S1
To determine whether or not the power switch 30a has been turned on.
If so, the process of step S1 is repeated. At this time, the main power supply 34 is off, and the subsystem controller 2
6 and the memory 50 are driven by the backup power supply 38. When the power switch 30a is turned on, the main power supply 34 is turned on in step S3, and step S5 is performed.
Causes the selector 32 to select the subsystem DC / DC converter 36, and turns off the switch SW1 shown in FIG. 2 in step S7.

When the main power supply 34 is turned on, the main power supply 3
4 is supplied to the DC / DC converter 28 for the main system, the DC / DC converter 36 for the subsystem, and the DC / DC converter 44 for the strobe. The main system is activated by the drive voltage generated by the main system DC / DC converter 28. In addition, the subsystem controller 26 and the memory 50 are driven and the backup power supply 38 is charged by the drive voltage generated by the subsystem DC / DC converter 36. Further, electric charges are accumulated in the capacitor C1 shown in FIG. 2 by the drive voltage generated by the strobe DC / DC converter 44. Since the switch SW1 is turned off, the charging voltage of the capacitor C1 becomes DC / DC for step-down.
There is no leakage to the converter 42.

In step S9, it is determined whether or not the power switch 30a has been turned off. In step S17, it is determined whether or not the camera has been operated. If the monitor activation button 30b or the shutter button 30c has been operated, the process proceeds from step S17 to step S19, where a state signal corresponding to the operation button is given to the main system controller 16. Therefore, when the monitor activation button 30b is pressed, a through image is displayed on the LCD 24, and when the shutter button 30c is pressed while the through image is displayed, a still image is stored in the image memory 18, and The freeze image is displayed on the LCD 24.

On the other hand, when the power switch 30a is turned off, YES is determined in the step S9, and the process proceeds to the steps after the step S11. First, the switch SW1 is turned on in step S11, the backup power supply 38 is selected by the selector 32 in step S13, and
At 5, the main power supply 34 is turned off.

When the switch SW1 is turned on, the terminal voltage of the capacitor C1 is reduced.
2 is applied. The charging circuit 40 charges the backup power supply 38 with the voltage supplied from the step-down DC / DC converter 42. When the selector 32 selects the backup power supply 38, the subsystem controller 26 and the memory 50 are driven by the backup power supply 26. Further, when the main power supply 34 is turned off, the DC / DC converter 28 for the main system, the DC / DC converter 36 for the subsystem, and the DC / DC converter 44 for the strobe are disabled.

As can be seen from the above description, the strobe 4
The charge required for the light emission of No. 8 is stored by the capacitor C1. When the main power supply 34 is turned off without discharging the charge of the capacitor C1, the charging circuit 40
The backup power supply 38 is charged based on the electric charge charged to 1. Thus, the power consumption of the main power supply 34 can be made more efficient.

[Brief description of the drawings]

FIG. 1 is a block diagram showing one embodiment of the present invention.

FIG. 2 is a circuit diagram illustrating an example of a configuration of a strobe light emission control circuit.

FIG. 3 is a flowchart showing a part of the operation of the subsystem controller.

[Explanation of symbols]

 Reference Signs List 10 digital camera 26 subsystem controller 28 DC / DC converter for main system 36 DC / DC converter for subsystem 38 backup power supply 40 charging circuit 42 DC / DC converter for step-down 44 DC / DC for strobe Converter 46 ... Strobe light emission control circuit 48 ... Strobe

Claims (4)

[Claims] 1. A camera provided with a backup power supply, a strobe that emits light when photographing a subject, an accumulating means for accumulating electric charges required for light emission of the strobe before photographing, and the accumulator when the main power is turned off. A camera comprising: charging means for charging the backup power supply based on the electric charge stored in the means. 2. The camera according to claim 1, wherein said charging means includes voltage drop means for dropping a voltage generated by said storage means to a charging voltage of said backup power supply. 3. The camera according to claim 1, further comprising detection means driven by said backup power supply when said main power supply is turned off, and detecting an on operation of said main power supply. 4. An image sensor for generating an image signal corresponding to an optical image of a subject by photoelectric conversion, a monitor for displaying an image based on the image signal, and a power supply for the image sensor and the monitor based on the main power supply. The supply device according to claim 1, further comprising a supply unit.
4. The camera according to any one of claims 3 to 3.