JPH1048715A - Flash device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To always obtain stable flat light emission and also to prevent the occurrence of exposure irregularity and photometric error by varying the responsiveness of a light emission intensity detecting means in the middle of the flat light emission. SOLUTION: The CNTL terminal of a microcomputer 111 is set to be a high level for a specified time after light emission start. Thus, the responsiveness of the light emission intensity detecting means 110 becomes slow in an area where the light emission easily gets unstable from the start of the flat light emission. Since the output of the means 110 is delayed with respect to the light emission waveform of a discharge tube 105 in a condition that the responsiveness of the means 110 is slow, the flat light emission whose amplitude is large is performed. Then, when the CNTL terminal of the microcomputer 111 is set to be a low level, the responsiveness of the means 110 becomes fast, so that the flat light emission whose amplitude is small is performed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improvement in a flash device capable of emitting flat light.

[0002]

2. Description of the Related Art Heretofore, there has been known a flash device capable of flat light emission that maintains light emission with substantially uniform light emission intensity even when a focal plane shutter performs slit exposure (during high-speed shutter). In this type of flash device, the response of the means for detecting the emission intensity of the flat light emission is unique to the flash device, and is constant until the end of the flat light emission. Furthermore, in order to eliminate unevenness during exposure with flat light emission, or to reduce the error in photometry of pre-emission due to flat light emission, it is necessary to reduce the amplitude of flat light emission, and therefore, there has been a tendency to increase responsiveness. .

[0003]

However, when the response of the means for detecting the light emission intensity is constant and fast as in the prior art, the coil connected between the main capacitor and the discharge tube is reduced in size. Then, as shown by the light emission waveform b in FIG. 8, there is a problem that unstable light emission occurs such as an abnormally fast ON / OFF cycle of the light emission control means immediately after the start of flat light emission (in addition, there is a problem). a is a waveform at the time of normal flat light emission). That is, there is a problem that the coil connected between the main capacitor and the discharge tube must be increased to some extent in order to stabilize the flat light emission.

(Object of the Invention) A first object of the present invention is to provide a flash device capable of always performing stable flat light emission and preventing occurrence of uneven exposure and photometric error. It is in.

A second object of the present invention is to provide a relatively long time,
An object of the present invention is to provide a flash device that can make exposure unevenness less noticeable even in a state where the response of the light emission intensity setting means must be slowed down.

A third object of the present invention is to provide a flash device capable of appropriately changing the response of the light emission intensity detecting means.

[0007]

In order to achieve the first object, the present invention according to claims 1 to 4, according to the present invention, comprises: a light emission intensity detecting means for detecting the light emission intensity of a discharge tube; A light emission control means for controlling the light emission control means, and outputs a light emission stop signal to the light emission control means when the output of the light emission intensity detection means becomes larger than a predetermined value, and outputs a light emission start signal to the light emission control means when the output becomes smaller than the predetermined value. In a flash device capable of flat light emission having a light emission control signal output means, the response of the light emission intensity detection means is changed during flat light emission, and in a region where light emission is likely to be unstable from the start of flat light emission, The response of the light emission intensity detecting means is slowed down, the light emission of the actual discharge tube is made flat light emission having a large amplitude, and the on / off cycle of the light emission control means is not shortened. Prone area becomes unstable so that may be referred to as experimental short period of time has been confirmed, as to or cause unevenness in the exposure, in the region that affect the photometric now, to speed up the response.

In order to achieve the second object,
According to the third aspect of the present invention, the response of the light emission intensity detecting means is gradually delayed from the start of the flat light emission.

Further, in order to achieve the third object,
According to a fourth aspect of the present invention, the response of the light emission intensity detecting means is determined only in accordance with the set light emission intensity of the flat light emission, specifically, only when the light emission intensity is set to cause unstable light emission. The gender is changed (slowed).

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described in detail based on illustrated embodiments.

FIG. 1 is a block diagram showing a main part of a flash device according to a first embodiment of the present invention. In FIG. 1, reference numeral 101 denotes a battery serving as a power supply;
The existing boosting means for boosting the voltage of 01, 103 is a main capacitor for storing the electric energy boosted by the boosting means 102, and 104 is for exciting the discharge tube 105 by a signal from an output terminal TRIG of a microcomputer 111 to be described later. Existing trigger means to bring the state, 105
Is a discharge tube for converting the electric energy of the main capacitor 103 into light, and 106 is a coil connected between the main capacitor 103 and the anode of the discharge tube 105. 107 is a diode, the anode is on the cathode of the discharge tube 105, the cathode is on the high potential side of the main capacitor 103,
Each is connected.

Reference numeral 108 denotes an existing light emission control means which is connected between the cathode side of the discharge tube 105 and the ground and controls light emission of the discharge tube 105; 111 controls the operation of various circuits such as the trigger circuit 104 described above. Microcomputer, 1
09 is an output terminal D / A of the microcomputer 111
This is a D / A converter that receives a signal from _OUT as an input. Reference numeral 110 denotes light emission intensity detection means for converting the light emission intensity of the discharge tube 105 into a voltage output. The light emission intensity detection means 110 can reduce the response by inputting a high-level signal from the CNTL output terminal of the microcomputer 111. It has a possible configuration. Reference numeral 112 denotes a comparator whose non-inverting input terminal receives a signal from the D / A converter 109 and whose inverting input terminal receives the light emission intensity detecting means 1.
Signals from 10 are input respectively. The output is input to the light emission control unit 108.

Here, the microcomputer 11
1. The D / A converter 109 and the comparator 112 constitute a light emission control signal output unit.

FIG. 2 shows the light emission intensity detecting means 1 shown in FIG.
FIG. 10 is a circuit diagram showing details of the circuit 10;

1, reference numeral 201 denotes an input terminal connected to the CNTL output terminal of the microcomputer 111 shown in FIG. 1, 202 denotes a resistor connected to the base of a transistor 204 described later, and 203 denotes a transistor 204 described later.
Is a resistor connected between the base and the emitter. 204
Is a transistor and the collector is a capacitor 205
The emitter is connected to the ground. 20
Reference numeral 5 denotes a capacitor, and terminals other than those connected to the collector of the transistor 204 are photodiodes 20 described later.
6 and the resistor 208. Reference numeral 206 denotes a photodiode (which may be a photoelectric element such as a phototransistor). The cathode is a power supply, and the anode is a resistor 2.
08 to the ground. 207
Is an output terminal of the light emission intensity detecting means 110, and FIG.
Of the comparator 112 is connected to the inverting input terminal.

In the above configuration, the photodiode 20
6 receives light from the discharge tube 105 of FIG. 1, a photocurrent is generated in the photodiode 206 in accordance with the intensity of the light emission, and the photocurrent is converted from the photodiode 206 to the resistor 208.
→ The current flows to the ground, and a voltage is generated in the resistor 208 according to the photocurrent, and this voltage is input to the inverting input terminal of the comparator 112.

The microcomputer 111 shown in FIG.
When a high-level signal is input from the CNTL output terminal of (1), the transistor 204 is turned on, and the capacitor 205 is connected in parallel with the resistor 208. Becomes possible.

Hereinafter, the control during flat light emission will be described.
A description will be given using the waveforms of FIG.

The main capacitor 103 by the boosting means 102
Is charged. Microcomputer 111
The D / A converter 10 outputs a value corresponding to the peak intensity of the flat light emission set by a camera (not shown) or setting means (not shown) from the D / A_OUT output terminal.
9 is output. The D / A converter 109 outputs the designated D / A output to the comparator 112.

At this time, since the light has not yet been emitted, “the output of the set D / A converter 109> the emission intensity detecting means 11
0 output ”, the comparator 112
Is in a high level state. Accordingly, the light emission control means 108 is connected to the high potential side of the main capacitor 103 → the coil 10
6 → discharge tube 105 → light emission control means 108 → discharge path on the low potential side of main capacitor 103 is formed, and light emission is possible.

In this state, when the microcomputer 111 sets the TRIG terminal to a high level, the trigger means 104 applies a high voltage to the discharge tube 105. As a result, the discharge tube 105 starts to emit light. After the start of the light emission, the light emission intensity detecting means 110 receives the light from the discharge tube 105 and outputs a voltage to the comparator 112 according to the light emission intensity. Then, when the relationship of “the output of the set D / A converter 109 <the output of the light emission intensity detection unit 110” is satisfied,
At that time (T1 in FIG. 3), the output of the comparator 112 is inverted from the high level to the low level, and the light emission control unit 108 stops emitting light (see output b in FIG. 3).

When the light emission is stopped as described above, the energy accumulated in the coil 106 is discharged in the path from the discharge tube 105 to the diode 107. Therefore, the light emission intensity of the discharge tube 105 is determined by the light emission control means 110. It starts to fall a little after the stop state. Then, when the intensity of the light emission decreases and the relation of “the output of the set D / A converter 109> the output of the light emission intensity detecting means 110” is reached (T2 in FIG. 3), the output of the comparator 112 again changes from the low level to the high level , The light emission control means 108 is again enabled to emit light, and the emission intensity starts to increase as shown in FIG.

By repeating the above, flat light emission is maintained.

Next, the control of the light emission intensity detecting means 110 will be described with reference to the waveforms of FIG.

By setting the CNTL terminal of the microcomputer 111 to a high level from T3 to T4 as shown by an output e in FIG. 4 until a predetermined time from the start of light emission, the transistor 204 in FIG. During this time, since the capacitor 205 is connected in parallel with the resistor 208, the response of the light emission intensity detection unit 110 is slower than the state where the transistor 204 is off.

When the response of the light emission intensity detecting means 110 is delayed, the output b of the light emission intensity detecting means 110 is delayed with respect to the light emission waveform a of the discharge tube 105 shown in FIG. .

Thereafter, the C of the microcomputer 111
When the NTL terminal is set to a low level (after T4 in FIG. 4),
Since the transistor 204 shown in FIG. 2 is turned off and the capacitor 205 connected in parallel with the resistor 208 disappears, the response of the light emission intensity detecting means 110 is increased. Therefore, after T4 in FIG. 4, flat light emission with a small amplitude is performed (see light emission waveform a in FIG. 4).

(Second Embodiment) FIG. 5 is a block diagram showing a main part of a flash device according to a second embodiment of the present invention. Here, FIG. The difference from the flash device will be described.

In the figure, a reference power supply Vref is input to a non-inverting input terminal of a comparator 412, and a signal from a light emission intensity detecting means 410 is input to an inverting input terminal. Reference numeral 411 denotes a microcomputer, and a signal from the CNTL output terminal is used as an input for controlling the responsiveness of the light emission intensity detection means 410. Other configurations are the same as those in FIG. In the second embodiment, the comparator 412 constitutes a light emission control signal output unit.

FIG. 6 shows the light emission intensity detecting means 4 shown in FIG.
FIG. 10 is a circuit diagram showing details of the circuit 10;

Reference numeral 506 denotes a photodiode which receives light from the discharge tube 405 shown in FIG. 5, the cathode is a power supply, and the anodes are resistors 508a to 508d and a transistor 512a.
５512d to the ground. 507 is
The anode of the photodiode 506 and a resistor 508a
The output terminal is connected to the connection point of .about.508d, from which the output of the emission intensity detection means 410 is sent to the inverting input terminal of the comparator 412 in FIG. 509a-50
Reference numeral 9d denotes input terminals connected to the output terminals OUT_A to OUT_D of the microcomputer 411 in FIG. 5, respectively.
Transistor 512 via 10d, 511a to 11d
a to 512d are respectively turned on.

Reference numeral 501 denotes a microcomputer of the microcomputer 411.
This is an input terminal to which a signal from the NTL terminal is input.
3, the transistor 504 is turned on, and the response of the light emission intensity detecting means 410 is delayed.

Next, control during flat light emission will be described.

The difference from the first embodiment is that the microcomputer 411 outputs a value corresponding to the intensity of the flat light emission set by a camera (not shown) or setting means (not shown) to OUT_A to OUT_D. The light is output from the output terminal to the light emission intensity detecting means 410. This allows
OUT_A to OUT_D of the microcomputer 411
Depending on the output from the output terminal, the transistors 512a to 512a
12d is turned on, and the anode of the photodiode 506 is connected to the combined resistance of the resistors 508a to 508d corresponding to the turned on transistors 512a to 512d. When the photodiode 506 receives light emitted from the discharge tube 405, it generates a photocurrent. The photocurrent flows through the combined resistors 508a to 508d, becomes a voltage output, and is output to the inverting input of the comparator 412.

At this point, since the light has not yet emitted, the output of the comparator 412 is at a high level because the relation of “reference voltage of the non-inverting input terminal of the comparator 412> output of the light emission intensity detecting means 410” is established. Therefore, the light emission control means 408 is connected to the high potential side of the main capacitor 403 → the coil 40
6 → discharge tube 405 → light emission control means 408 → discharge path on the low potential side of main capacitor 403 is formed, and light emission is enabled.

In this state, the microcomputer 411
When the TRIG terminal goes high, the trigger means 40
4 applies a high voltage to the discharge tube 405. As a result, the discharge tube 405 starts emitting light, and after the start of the emission, the discharge tube 4
The light-emission intensity detection means 410 receives the light of No. 05 and outputs the light according to the light-emission intensity. When the relation “reference voltage of the non-inverting input terminal of the comparator 412 <output of the light-emission intensity detection means” is satisfied, Is changed from the high level to the low level, and the light emission control unit 408 enters the light emission stop state.

When the light emission is stopped as described above, the energy accumulated in the coil 406 is discharged along the path from the discharge tube 405 to the diode 407, and the light emission control means 408 determines the light emission intensity of the discharge tube 405. It begins to fall a little after the condition. Then, when the intensity of the light emission decreases and the relation of “reference voltage of the non-inverting input terminal of the comparator 412> output of the light emission intensity detection means” is satisfied, the output of the comparator 412 changes from the low level to the high level again, and the light emission control means 408 Becomes ready to emit light, and the intensity of light emission starts to increase.

By repeating the above, flat light emission is maintained.

The control of the response of the light emission intensity detecting means 410 is the same as in the first embodiment.

(Third Embodiment) FIG. 7 is a circuit diagram showing a detailed configuration of a light emission intensity detecting means 610 according to a third embodiment of the present invention. The configuration of the flash device according to the third embodiment is the same as that of the microcomputer 1 shown in FIG.
11 is the same as FIG. 1 except that the number of CNTL terminals is four (however, it may be four or more), and the details are omitted.

Reference numeral 306 denotes a photodiode for receiving light from the discharge tube 105. The cathode is connected to a power supply, and the anode is connected to a resistor 308. An output terminal 307 outputs a voltage corresponding to the light emission intensity to the inverting input terminal of the comparator 112. 301a to 301d are input terminals connected to the CNTL terminal of the microcomputer 111, and when a high-level signal is input thereto,
Resistors 302a to 302d and 303a to 303d respectively
, The transistors 304 a to 304 d are turned on, and the capacitors 305 a to 305 d are connected in parallel with the resistor 308. With such a configuration, it is possible to control the responsiveness of the light emission intensity detecting means 610 in 16 steps in FIG.

Note that the microcomputer 111 sets the CNTL terminals a to d (input terminal 301a) from the start of the flat light emission.
By switching between the high level and the low level of the terminals connected to .about.301d, it is possible to change the responsiveness of the light emission intensity detecting means 610 stepwise.

(Fourth Embodiment) The configuration of a flash device according to a fourth embodiment is the same as that of the third embodiment described above, and is not shown here.

In the fourth embodiment, the microcomputer 111 sends to the D / A converter 109 a value corresponding to the flat light emission intensity set by a camera (not shown) or setting means (not shown). Output. By switching between the high level and the low level of the CNTL terminals a to d corresponding to the flat light emission intensity set by the setting means or the like, it becomes possible to change the response of the light emission intensity detection means. Other operations are the same as in the third embodiment.

According to each of the above embodiments, by setting the CNTL terminal of the microcomputer to the high level for a predetermined time from the start of light emission, the response of the light emission intensity detecting means can be delayed. As a result, even if the coil connected between the main capacitor and the discharge tube is made small, unstable light emission occurs such as an abnormally fast ON / OFF cycle of the light emission control means at the beginning of flat light emission. It is possible to avoid the problem.

By setting the CNTL terminal of the microcomputer to a low level after a predetermined time, the output of the light emission intensity detecting means can be made quicker.
This makes it possible to reduce the amplitude of flat light emission, eliminate unevenness during exposure with flat light emission, and reduce errors in photometry of pre-emission by flat light emission.

Further, as in the third embodiment, by gradually increasing the control of the response of the light emission intensity detecting means, the response of the light emission intensity detecting means is reduced for a relatively long time. Even when it is necessary to do so, unevenness during exposure can be made inconspicuous.

Further, as in the fourth embodiment, by changing the response of the light emission intensity detecting means in accordance with the set light emission intensity of the flat light emission, the light emission control means can be turned on and off.
Only when the light emission intensity is set so as to cause unstable light emission such as an abnormally fast OFF cycle, the response of the light emission intensity detection means can be reduced.

(Modification) The present invention may have a configuration in which the above embodiments or their techniques are appropriately combined.

The present invention is not limited to the configuration of each of the above embodiments, but may be any configuration that can achieve the functions described in the claims or the functions of the embodiments. Needless to say, it may be.

[0051]

As described above, according to the present invention,
In a region where the light emission tends to be unstable from the start of the flat light emission, the response of the light emission intensity detecting means is delayed so that the actual light emission of the discharge tube is flat light emission having a large amplitude, and the light emission control means is turned on and off. It has been experimentally confirmed that the period is not shortened, while the region that is likely to be unstable is experimentally confirmed to have a short period, and the responsiveness remains unchanged in the region that causes unevenness during exposure or affects photometry. Since the speed is increased, stable flat light emission can always be performed, and uneven exposure and a photometric error can be prevented.

According to the present invention, since the response of the light emission intensity detecting means is gradually delayed from the start of flat light emission, the response of the light emission intensity setting means must be delayed for a relatively long time. Even in such a state, uneven exposure can be made inconspicuous.

Further, according to the present invention, the response of the light emission intensity detecting means is delayed according to the set light emission intensity of the flat light emission, so that light emission that causes unstable light emission is generated. Only when the intensity is set, the responsiveness of the emission intensity detecting means can be changed.

[Brief description of the drawings]

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

FIG. 2 is a circuit diagram showing a detailed configuration of a light emission intensity detecting unit of FIG.

FIG. 3 is a diagram showing waveforms of respective parts when the flash device according to the first embodiment of the present invention emits flat light.

FIG. 4 is a diagram showing waveforms of respective sections when the light emission intensity detecting means of FIG. 1 is controlled.

FIG. 5 is a block diagram showing a main configuration of a flash device according to a second embodiment of the present invention.

FIG. 6 is a circuit diagram showing a detailed configuration of a light emission intensity detecting unit of FIG.

FIG. 7 is a circuit diagram showing a detailed configuration of a light emission intensity detection means of a flash device according to the third and fourth embodiments of the present invention.

FIG. 8 is a diagram showing a light emission waveform of a discharge tube of a conventional flash device and an output waveform of a light emission intensity detecting means.

[Explanation of symbols]

 103,403 Main capacitor 104,404 Trigger means 105,405 Discharge tube 106,406 Coil 107,407 Diode 108,408 Light emission control means 109,409 D / A converter 110,410 Light emission intensity detection means 111,411 Microcomputer 610 Light emission Intensity detection means

Claims (4)

[Claims] 1. A light emission intensity detecting means for detecting light emission intensity of a discharge tube, a light emission control means for controlling light emission of a discharge tube,
When the output of the light emission intensity detection means becomes larger than a predetermined value,
A flash control device that outputs a light emission stop signal to the light emission control means and outputs a light emission start signal to the light emission control means when the light emission control signal becomes smaller than a predetermined value. A flash device capable of flat light emission, wherein the response of the means is changed during flat light emission. 2. The flash device according to claim 1, wherein the responsiveness of the light emission intensity detecting means is delayed for a predetermined time from the start of flat light emission. 3. The flash device according to claim 1, wherein the response of the light emission intensity detecting means is gradually increased from the start of the flat light emission. 4. The flash device according to claim 1, wherein the responsiveness of said light emission intensity detecting means is varied according to the set light emission intensity of the flat light emission.