JP2003280069A - Strobe light control method, strobe light control circuit, and stroboscope device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To make constant the brightness of strobe light when the light is controlled by a microcomputer. <P>SOLUTION: When a microcomputer switches on-off light emission of a discharge tube to control the emitted light quantity, it outputs to an emission control circuit an light emitting signal which instructs the discharge tube to start emitting light at a high level and instructs the discharge tube to stop emitting light at a low level, and the high level period and the low level period of this light emitting signal are varied to make the brightness of the discharge tube constant. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a strobe device that emits light in conjunction with a shutter of a camera, and more particularly to a strobe light control circuit and a strobe light control method for controlling the amount of light emitted when strobe light is emitted.

[0002]

2. Description of the Related Art Conventionally, a strobe device mounted on a camera is equipped with a dimming circuit, and this dimming circuit controls the strobe light emission amount so that proper exposure can be taken. It is being appreciated.

Some conventional strobe light control circuits feedback control the amount of strobe light emission to the brightness at which proper exposure can be obtained by the intensity of light reflected from the subject when strobe light is emitted. Therefore, there is a method in which the amount of stroboscopic light emission is controlled in a feedforward manner based on a preset program to irradiate the subject with strobe light to a brightness at which proper exposure is obtained.

In this conventional example of the latter method, FIG. 3 (a) shows a program preset by a microcomputer to a light emission control circuit of a strobe light control circuit on the basis of a preset program. The emission amount of the discharge tube is dimming-controlled by outputting the light emission signals having the same pulse shape at equal intervals to cause the discharge tube to emit light in a pulsed manner as shown in FIG. 3B.

[0005]

However, the above-mentioned FIG.
When a light emission signal having the same pulse shape as shown in (a) is applied to the light emission control circuit, the light emission waveform of the discharge tube 2 is shown in FIG.
As shown in (1), since the swell is generated and is not constant, the brightness at the time of light emission is not constant, which causes a problem that stable exposure cannot be performed.

The present invention has been made to solve the above-mentioned conventional problems, and an object thereof is strobe dimming capable of making constant the brightness of strobe light emission during dimming control by a microcomputer. A circuit, a strobe light control method, and a strobe device equipped with this strobe light control circuit.

[0007]

The means of solving the problems of the present invention is a light emitting amount of the discharge tube of a strobe device having a light emission control means for controlling light emission start and light emission stop of the discharge tube. In the strobe light control method for controlling the light emission control means, the light emission control means is instructed to start light emission of the discharge tube at a high level, and the light emission signal is instructed to stop light emission of the discharge tube at a low level during the high level period. By changing the low-level period, a light emission signal for making the brightness of the discharge tube constant is output from the microcomputer to the light emission control means.

According to a second aspect of the present invention, in the strobe light control circuit for controlling the amount of light emission of the discharge tube of the apparatus, the strobe light control circuit has a light emission control means for controlling light emission start and light emission stop of the discharge tube. A high-level instruction to start light emission of the discharge tube, and a low-level instruction signal to stop light emission of the discharge tube by changing the high-level period and the low-level period by changing the high-level period and the low-level period. Is provided with a microcomputer for outputting a light emission signal for making the brightness of the light emission control unit constant to the light emission control means.

According to a third aspect of the present invention, a discharge tube, a booster circuit for boosting the voltage of a battery, a main capacitor charged with a voltage obtained by rectifying the boosted voltage of the booster circuit, and a charge for the main capacitor are discharged. A light emission control means for performing a light emission start control for discharging through the tube and a light emission stop control for stopping the discharge of the main capacitor into the discharge tube; and a high level instruction for starting the light emission of the discharge tube to the light emission control means. A light emission signal for giving an instruction to stop light emission of the discharge tube at a level and varying the high level period and the low level period to a light emission signal for making the brightness of the discharge tube constant to the light emission control means. And a microcomputer for outputting.

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram showing a configuration example of a flash device according to an embodiment of the present invention.
However, the same parts as those of the conventional example will be described using the same reference numerals. The strobe device includes a light emission control circuit 1 that controls the light emission of the discharge tube 2, a discharge tube (Xe tube) 2 that emits light when a discharge current flows, a trigger electrode 3 for activating the discharge of the discharge tube 2, and a discharge tube 2. IGBT that turns on and off the current flowing through it
4, a main capacitor 5 for accumulating electric charges flowing in the discharge tube 2, a battery 6 for supplying power to the booster circuit 8, a booster circuit (high voltage charging circuit) 8 for boosting the voltage of the battery 6, and a rectified booster voltage of the booster circuit 8. Rectifying diode 9, a microcomputer 10 for performing individual control such as dimming control and overall device control, an operation unit 11 for inputting various set values such as dimming level to the microcomputer 10, exposure level and device mode It has a display unit (LCD) 12 for displaying, for example.

Next, the operation of this embodiment will be described. When the strobe device of this example is attached to, for example, a digital camera (not shown) to perform stroboscopic photography, the photographer considers the F-number, aperture, shutter speed, etc. of the digital camera and uses the operation unit 11 to set the exposure level. The microcomputer 1
Enter 0. The microcomputer 10 displays the input exposure level and the like on the display unit 12 and selects a dimming program in the memory 101 corresponding to the exposure level.

On the other hand, the booster circuit 8 boosts the voltage of the battery 6, and the boosted voltage is rectified by the rectifier diode 9 to charge the main capacitor 5. After that, when the release button of the digital camera is pressed, the microcomputer 10 detects this and executes the program described above, and outputs a high level light emission signal 200 as shown in FIG. 2A to the light emission control circuit 1. .

As a result, the light emission control circuit 1 applies the trigger voltage to the trigger electrode 3 of the discharge tube 2 and the IGBT 4
In order to turn on, the electric charge of the main capacitor 5 flows through the discharge tube 2 and the IGBT 4, and the discharge tube 2 becomes
Light is emitted with a light emission waveform as shown in.

After that, when the light emission signal 200 becomes low level, the light emission control circuit 1 turns off the IGBT 4, so that the discharge of the main capacitor 5 to the discharge tube 2 is stopped, and FIG.
The light emission is stopped as shown in (b). After that, when the light emission signal 200 becomes high level again, the light emission control circuit 1 turns on the IGBT 4, so that the electric charge of the main capacitor 5 is discharged to the discharge tube 2 and the discharge tube 2 emits light. Or later,
By repeating the above-described operation, the discharge tube 2 is corresponding to the high level period of the light emission signal 200 as shown in FIG.
Light is emitted, and the light emission of the discharge tube 2 is stopped corresponding to the low level period.

Here, as shown in FIG. 2A, the light emission signal 200 output from the microcomputer 10 is set by appropriately setting its high level period (pulse width) and low level period (pulse interval). The light emission waveform of the discharge tube 2 is controlled so that the brightness during light emission is constant. That is, when a conventional light emission signal having a constant waveform is generated at equal intervals, the dark part is made longer in the high level period or the low level period of the light emission signal 200 is shortened.
On the contrary, when it becomes bright, shorten the high level period,
Alternatively, the brightness of the discharge tube 2 during light emission is made constant by lengthening the low level period. Since the undulation of the brightness of the discharge tube 2 at the time of light emission has a predetermined tendency, the microcomputer 10 cancels the undulation by the light emission signal 20.
A program that outputs 0 is stored in the memory 101 for each exposure level.

According to the present embodiment, when the light quantity of the discharge tube 2 is controlled by the microcomputer 10, the pulse width and the pulse interval of the light emission signal 200 output from the microcomputer 10 are set to the brightness at the time of light emission of the discharge tube 2. By varying so that the value is constant, the brightness during dimming control of the discharge tube 2 by the microcomputer 10 can be made constant, and photographing with proper exposure can be stably performed. Further, since the light quantity of the discharge tube 2 is controlled by software without using hardware, the number of parts of the apparatus can be reduced, the circuit scale of the strobe light control circuit can be reduced, and the strobe apparatus can be inexpensive. be able to. In particular, since the microcomputer 10 has been conventionally used for controlling the strobe device, it is not necessary to mount a new microcomputer for dimming control, and the strobe dimming circuit can be manufactured at an extremely low cost.

The present invention is not limited to the above-described embodiments, and can be carried out in various other modes in specific configurations, functions, actions and effects without departing from the scope of the invention. it can.

[0018]

As described above in detail, according to the present invention, by varying the pulse width and pulse interval of the light emission signal output from the microcomputer, the brightness of the strobe light emission during the dimming control by the microcomputer. Can be constant.

[Brief description of drawings]

FIG. 1 is a block diagram showing a configuration example of a flash device according to an embodiment of the present invention.

FIG. 2 is a diagram showing a light emission signal output from a microcomputer shown in FIG. 1 and a light emission waveform of a discharge tube.

FIG. 3 is a diagram showing a light emission signal output from a conventional microcomputer and a light emission waveform of a discharge tube.

[Explanation of symbols]

1 Light emission control circuit 2 discharge tube 3 trigger poles 4 IGBT 5 Main capacitor 6 batteries 8 Booster circuit 9 Rectifier diode 10 Microcomputer 11 Operation part 12 Display

Claims (3)

[Claims] 1. A strobe dimming method for controlling the amount of light emission of the discharge tube of a device to a strobe having a light emission control means for controlling light emission start and light emission stop of the discharge tube, wherein the light emission control means is discharged at a high level. The brightness of the discharge tube is kept constant by changing the high level period and the low level period, which is a light emission signal that gives an instruction to start light emission of the tube and gives an instruction to stop light emission of the discharge tube at a low level. The strobe light control method is characterized in that the microcomputer outputs a light emission signal to the light emission control means. 2. A strobe dimming circuit for controlling the amount of light emission of the discharge tube of an apparatus, comprising a light emission control means for controlling light emission start and light emission stop of the discharge tube, wherein the light emission control means is discharged at a high level. The brightness of the discharge tube is kept constant by changing the high level period and the low level period, which is a light emission signal that gives an instruction to start light emission of the tube and gives an instruction to stop light emission of the discharge tube at a low level. A strobe dimming circuit comprising a microcomputer for outputting a light emission signal to the light emission control means. 3. A discharge tube, a booster circuit for boosting the voltage of a battery, a main capacitor charged with a voltage obtained by rectifying the boosted voltage of the booster circuit, and light emission for discharging the electric charge of the main capacitor through the discharge tube. A light emission control means for performing a start control and a light emission stop control for stopping the discharge of the main capacitor into the discharge tube; and an instruction to start light emission of the discharge tube at a high level to the light emission control means, and the discharge tube at a low level. A microcomputer for outputting a light emission signal for giving a light emission stop instruction to the light emission control means by varying the high level period and the low level period to make the brightness of the discharge tube constant. A strobe device comprising: