JP3847155B2 - Camera with built-in flash - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a built-in strobe cameras and, more particularly, to a camera equipped with a charging circuit for charging the main capacitor at a low current or a high current.
[0002]
[Prior art]
Many modern photo cameras and digital (still) cameras have built-in strobes. When the power switch is turned on, the camera generally starts up in the standard mode, and the strobe is set in the low brightness automatic light emission mode. Then, the charging circuit is activated immediately after the power switch is turned on to charge the main capacitor so that the flash light preparation is completed quickly, and for the same reason, charging to the main capacitor is started immediately after shooting. I am doing so.
[0003]
On the other hand, immediately after the charging of the main capacitor is started, a large current is consumed, and the voltage drop of the built-in battery also increases. Accordingly, sufficient power cannot be supplied to other circuit loads built in the camera, which may cause malfunction. In order to avoid such a situation, for example, a method of temporarily stopping charging of the strobe during film feeding may be used in a photo camera.
[0004]
[Problems to be solved by the invention]
However, if the charging of the strobe is completely interrupted, there is a disadvantage that the standby time until the next strobe shooting, that is, the cycle time becomes long. In addition, some cameras so far automatically stop charging when charging to the main capacitor is completed, and automatically when the charging voltage drops below the specified level or after a certain time has elapsed after charging is complete. However, the charging is restarted in the same manner even when the strobe is switched to the light emission inhibition mode. For this reason, even when attempting to take a picture without using a strobe, there is a disadvantage that continuous photography cannot be performed due to a voltage drop immediately after resuming charging.
[0005]
Furthermore, immediately after turning on the power switch of the camera, the motor is driven to open the lens barrier and feed the lens barrel in the retracted state. Shooting preparation operation is performed. Therefore, if the main capacitor that consumes a large current is charged immediately after the power switch is turned on, there is a disadvantage that it takes time for the shooting preparation operation due to the voltage drop of the built-in battery.
[0006]
The present invention has been made to solve the above-described problems. Even if the main capacitor starts to be charged immediately after the power switch is turned on or in a state where the strobe is set to the light emission inhibition mode, a large burden is not applied to the built-in battery. Furthermore, it is an object of the present invention to provide a camera that can shorten the strobe cycle time as much as possible.
[0007]
[Means for Solving the Problems]
To achieve the above object, the camera with a built-in strobe of the present invention includes a charging circuit that receives power from a built-in battery when a power switch is turned on and charges a main capacitor for flash emission, and the charging circuit supplies a charging current. Current switching means for switching to a high current or a low current is provided, and the main capacitor is charged with a low current when the power switch is turned on and when the light emission prohibit mode for prohibiting strobe light emission is set. When charging of the main capacitor of the power switch was put was started, the camera by suppressing the occurrence of under to voltage drop low charging current, to allow also sufficient supply power to other circuit load To prevent malfunction.
[0008]
The current switching means switches the charging current from a low current to a high current after a lapse of a fixed time after the power switch is turned on when the light emission inhibition mode is not set. After the power switch is turned on, each device in the camera in a certain time period is after the start of stably driven, switching the charging current to the high current from a low current, as much as possible reduce the charging wait time.
[0009]
The current switching means includes a current limiter, and the charging current is switched between a high current and a low current from a power supply circuit of the camera through the current limiter .
[0010]
DETAILED DESCRIPTION OF THE INVENTION
A digital camera 1 shown in FIGS. 1 and 2 is provided with a retractable lens barrel 4 holding a photographing lens 3 on the front surface of a camera body 2. A CCD image sensor is disposed behind the photographic lens 3. Further, a red-eye prevention lamp 5, an optical finder 6, and an auto strobe sensor 7 are provided.
[0011]
On the upper surface of the camera body 2, a pop-up strobe light emitting unit 8 and a function dial 9 are provided. The strobe light emitting unit 8 pops up when a pop-up button 10 provided on the side surface of the camera body 2 is pressed, and is stored in the original position manually when the strobe shooting is completed. The function dial 9 is operated when switching various settings according to a prescribed shooting pattern such as long-distance shooting, short-distance shooting, and indoor shooting. The function dial 9 is provided with a release button 11 at the center thereof.
[0012]
A memory card slot 12 is provided on the side of the camera body 2, and a memory card for storing image data of the photographed subject is inserted. Further, a connector 13 is provided and can be connected to a peripheral device such as a personal computer or a printer. The grip portion 14 has a battery chamber inside, and is loaded with a power source battery for the digital camera 1.
[0013]
An operation input panel 15 and a liquid crystal display 16 capable of full color display are provided below the operation input panel 15 on the back of the camera body 2. The power switch 17 is provided at the center of the mode switching lever 18. The mode switching lever 18 is used when switching between the imaging mode and the reproduction mode. The liquid crystal display 16 continuously displays the subject image formed on the CCD sensor in the imaging mode, and reproduces and displays the image stored in the memory card in the reproduction mode.
[0014]
The cross keys 20 arranged in a circle are used for manually adjusting the exposure and setting the resolution, and various setting states can be confirmed on the liquid crystal panel 22 for monochrome display.
[0015]
In FIG. 3, when the CPU 26 detects that the power switch 17 is turned on, the built-in battery 25 stored in the battery chamber inside the grip portion 14 supplies power to the power circuit 27. Each load circuit unit 28 is supplied with electric power from the power supply circuit 27 under the control of the CPU 26 and its drive is controlled.
[0016]
The strobe device of the digital camera 1 includes a strobe light emitting unit 8 having a xenon tube 29, a strobe charging circuit 30, and a timer circuit 31. The strobe charging circuit 30 includes a main capacitor 32 that is charged at a high voltage, a booster circuit 33 that boosts the voltage of the built-in battery 25, a current limiter 34 that limits a current value flowing through the booster circuit 33, a trigger circuit 35 that induces strobe light emission, The charging voltage detection circuit 36 detects that the capacitor 32 has reached a predetermined charging voltage.
[0017]
The current limiter 34 is switched on and off by a control signal from the CPU 26, and switches the value of the current flowing through the strobe charging circuit 30 in two steps: high current and low current. When the current limiter 34 is off, a high current flows through the strobe charging circuit 30, and when the current limiter 34 is on, a low current of less than half of the high current, for example, about 30%, flows.
[0018]
The trigger circuit 35 generates a trigger discharge in response to the pressing operation of the release button 11 when the strobe light emitting unit 8 is popped up, and induces the strobe discharge. The trigger discharge is generated by a trigger signal output from the CPU 26. Charge charge of the main capacitor 32 flows into the xenon tube 29 by the trigger discharge, and strobe light emission is performed. On the other hand, when the strobe light emitting unit 8 is housed, the strobe light emission prohibition mode is activated, and even if the release button 11 is operated, no trigger signal is sent from the CPU 28 and the strobe light is not emitted.
[0019]
The timer circuit 31 includes a switching timer 37 and a charging timer 38. The switching timer 37 counts the time for which the current limiter 34 is turned on when the power switch 17 is turned on. The charging timer 38 starts counting immediately after the completion of charging is detected by the charging voltage detection circuit 36, and sends a signal to the CPU 26 when a fixed time of about 5 minutes elapses without strobe light emission. Start again.
[0020]
The circuit load unit 28 represents main components that consume power, such as the CCD image sensor 39 and the liquid crystal display 16. The CCD image sensor 39 is provided on the back surface of the taking lens 3, and minute color filters that disperse an optical image of a subject into red, green, and blue in units of pixels are arranged in a matrix. A photodiode is provided corresponding to each color filter, and an optical image detected for each pixel is output to the image data processing circuit 40 as an imaging signal.
[0021]
In the image data processing circuit 40, the output image pickup signal is amplified to an appropriate level, and after digital conversion, image processing is performed by performing signal processing such as white balance adjustment and gamma correction. When this image data is sent to the liquid crystal display 16, it is displayed as a subject image.
[0022]
The memory control circuit 41 temporarily stores the image data of the subject photographed by operating the release button 3, and transfers the image data to the loaded memory card. Further, it is driven when image data is read from the memory card.
[0023]
The barrier motor 42 is a motor for opening and closing a lens barrier (not shown) that protects the photographing lens 3 when the power switch 17 is OFF. The barrel motor 43 is used when the lens barrel 4 is extended or retracted. It is a motor driven by.
[0024]
The pop-up detection switch 44 detects the pop-up state of the strobe light emitting unit 8. When the strobe light emitting unit 8 is housed, a light emission prohibition signal is sent to the CPU 26, and the digital camera 1 is set to the strobe light emission prohibition mode.
[0025]
Next, the operation of the present invention will be described with reference to FIGS. When the power switch 17 is turned on, the CPU 26 turns on the power circuit 27. At the same time, the CPU 26 outputs an operation signal to the switching timer 35 to start counting of the switching timer 35 and turns on the current limiter 34.
[0026]
When the power supply circuit 27 is turned on, the CCD image sensor 39, the barrier motor 40, and the like start to be activated, and a charge start signal is output from the CPU 26 to the power supply circuit 27. The power supply circuit 27 supplies power to the strobe charging circuit 30 and the charging process of the main capacitor 32 is started. At this time, the current limiter 34 is activated and the charging process is performed at a low current, and the voltage drop of the built-in battery 25 is suppressed. Thereby, the photographing preparation operation such as driving of the barrier motor 42 and the lens barrel motor 43 and starting of the CCD image sensor 39 is stably performed. After the time of about 2 seconds spent for the shooting preparation operation has elapsed, the count of the switching timer 37 ends. Thus, the operation time T1 of the switching timer 37 is set slightly longer than the time required for the shooting preparation operation.
[0027]
When the strobe light emitting unit 8 is popped up after the count of the switching timer 37 is finished, the current limiter 34 is turned off, and a high current flows through the strobe charging circuit 30 to perform high-speed charging. On the other hand, if the strobe light emitting unit 8 is housed and the light emission prohibition mode is set, the current limiter 34 is kept on even after the operation of the switching timer 37 is finished, and the charging process at a low current is performed. Is done. The transition to activation and cancellation of the light emission inhibition mode is constantly monitored by the pop-up detection switch 44. When the power is turned on, the current limiter is kept on until the count of the switching timer 37 is completed, and high-speed charging is not performed even if the light emission inhibition mode is canceled during the counting of the switching timer 37.
[0028]
When the charging process with a high current or a low current is performed and the charging voltage of the main capacitor 32 reaches a specified level, a charging completion detection signal is output from the charging voltage detection circuit 36. The power circuit 27 cuts off the power supply to the strobe charging circuit 30, and the CPU 26 outputs an operation signal for operating the charging timer 38. The charging timer 38 is reset every time the power switch 17 is disconnected or photographing is performed. When the charging timer 38 counts for 5 minutes without shooting or disconnecting the power switch 17, a charging start signal is sent from the CPU 26 to the power circuit 27, and the charging process is resumed.
[0029]
As described above, by providing the timer circuit 31 and the current limiter 34, the startup operation of the power switch 17 at the beginning is normally performed, and thereafter, the operation state and the release state of the light emission inhibition mode are detected to detect the low current. Alternatively, a charging process with a high current is performed.
[0030]
Next, the flow of electrical operation after shooting will be described. The subject is imaged by operating the release button 11, and image data is written to the memory card through the memory control circuit 41.
[0031]
Here, when the flash photography is performed, since the flash light emitting unit 8 is popped up, the current limiter 34 is turned off and high-speed charging is performed. When the strobe light emitting unit 8 is housed during the high-speed charging process, the current limiter 34 is activated, and the charging process is continued by shifting to low-speed charging at a low current.
[0032]
On the other hand, when the flash photography is not being performed, the charging process at a high current is started when the flash light emitting unit 8 is popped up if the count of the charging timer 38 is not finished. Since the main capacitor 32 has been charged in advance since the power was turned on, only the voltage reduced by the natural discharge is compensated, so the charging process is immediately terminated.
[0033]
As described above, the digital camera 1 has a different charging process depending on the state of the flash unit 8 after photographing. That is, the magnitude of the charging current is appropriately switched between two steps of high and low depending on the operation or release state of the light emission inhibition mode. As a result, depending on the necessity of flash photography, high-speed charging is performed to shorten the strobe charging standby time as much as possible, or low-speed charging is performed to reduce the burden on the built-in battery 25 and extend the battery life. Is possible.
[0034]
When the charging process is completed, a charging completion detection signal is output from the charging voltage detection circuit 36, power supply to the strobe charging circuit 30 is cut off, and a charging timer 38 is activated.
[0035]
In the present invention, the charging current switching control by the timer circuit 31 and the current limiter 34 is performed by the CPU 26 as in the above embodiment. However, the present invention is not limited to this. For example, the state of the light emission inhibition mode is detected. The charging current may be directly switched from the signal to be performed. Further, the present invention can be used not only for a camera equipped with a pop-up type strobe, but also for a camera in which whether or not strobe photography can be set by a button operation. Moreover, it is effective to apply not only to a digital camera but also to a photographic camera using a silver salt film.
[0036]
【The invention's effect】
As described above, according to the camera with a built-in strobe of the present invention, when set to Flash Off mode is turned on and when the flash of the power switch, since to start charging the main capacitor in depressive example low current low charging current , the rise time of the camera is Rukoto and a long, it is not that bad with the rising action occurs. When the strobe is not used, high-speed charging is not performed and the number of times is reduced, thereby reducing the burden on the built-in battery and extending the life .
[0037]
This current switching means is controlled by a timer circuit to switch the charging current from a low current to a high current after a certain time has elapsed since the power switch was turned on. Can perform high-speed charging to shorten the strobe charging standby time as much as possible.
[Brief description of the drawings]
FIG. 1 is a diagram illustrating a state of a front side of a digital camera embodying the present invention.
FIG. 2 is a diagram illustrating a state on the back side of a digital camera embodying the present invention.
FIG. 3 is a block diagram illustrating an electrical configuration of the digital camera according to the embodiment.
FIG. 4 is a time chart showing the flow of electrical processing in the digital camera.
FIG. 5 is a flowchart showing the flow of electrical processing when power is turned on.
FIG. 6 is a flowchart showing a flow of electrical processing after a photographing operation.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Digital camera 8 Strobe light emission window 11 Release button 16 Liquid crystal display 17 Power switch 25 Built-in battery 26 CPU
28 Load circuit unit 30 Strobe charging circuit 31 Timer circuit 32 Main capacitor 34 Current limiter 44 Pop-up detection switch

Claims (3)

In the camera with built-in flash equipped with a charging circuit that receives power from the built-in battery by turning on the power switch and charges the main capacitor for flash emission,
The charging circuit includes a current switching means for switching a charging current to a high current or a low current ,
The camera with a built-in strobe is characterized in that the charging circuit charges the main capacitor with a low current when a power switch is turned on and when a light emission prohibiting mode for prohibiting light emission of the strobe is set . The current switching means switches the charging current from a low current to a high current after a lapse of a fixed time after the power switch is turned on when the light emission inhibition mode is not set . Strobe built-in camera. 3. The camera with a built- in strobe according to claim 1, wherein the current switching unit includes a current limiter, and switches the charging current to a high current or a low current from the power supply circuit of the camera through the current limiter .

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