JP3523653B2 - Strobe light emission control device - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a strobe light emission control device, and more particularly to a strobe light emission control device for adjusting the amount of light emitted from a strobe by controlling the light emission duration.

[0002]

2. Description of the Related Art Heretofore, a stroboscopic light emission control device applied to a compact camera or the like has generally been compatible with stroboscopic photographing in a range of about 4 m to 1 m as a subject distance. And for distances closer than 1 m,
As will be described later, since it is impossible to adjust the minute light amount with the conventional control device, it is necessary to change the aperture value of the photographing system, change the mode such as mounting the diffuser, and perform stroboscopic photographing.

A conventional strobe light emission control device will now be described. FIG. 3 shows a block diagram of an automatic strobe light emission control device. This device mainly comprises a strobe control portion 1 for controlling a flash light emission portion. It is composed of a strobe device 2 having a built-in flash light emitting section. Then, the strobe control unit 1 includes a flip-flop circuit (hereinafter referred to as an FF circuit) 8 for giving a light emission control signal to the strobe device 2, a light receiving element 3 for receiving the strobe reflected light from the subject, and the light receiving element 3 of the light receiving element 3. The integrator 4 that integrates the output as the corresponding value of the accumulated light emission amount, the reference voltage source 5 whose voltage is set from the camera body side (not shown) corresponding to the target emitted light amount, and the integration of the integrator 4 It is composed of a comparator 6 that outputs an ON signal when the output voltage exceeds the reference voltage, and a gate circuit 7 that outputs a stop signal based on the output.

In the strobe control device configured as described above, when performing stroboscopic photography, the FF circuit 8 sends a light emission start signal, which is a light emission start command from the camera body side.
When the control signal C to the strobe device 2 which is the output of the FF circuit 8 is turned on, strobe light emission is started. The start signal is also input to the integrator 4 to reset the integrator 4. Further, it is output to the camera side as a shutter open signal. Here, the control signal C is a signal that starts light emission when turned on and stops light emission when turned off. There are two input lines to the strobe device 2, one for starting light emission, and the other for stopping light emission. May be The strobe light is reflected by the subject, and a part thereof enters the light receiving element 3. The output is integrated in the integrator 4 as a strobe light amount corresponding value. When the voltage value reaches the target value given by the reference voltage source 5, the comparator 6 outputs an ON signal. FF through the gate circuit 7
It is output to the circuit 8 as a stop signal, to the integrator 4 as an integration stop signal, and further to the camera side as a shutter close signal. Therefore, the FF circuit 8
Turns off the control signal C to the strobe device 2 to stop the light emission, and stops the light emission. The gate circuit 7 is connected to a forced stop signal line for forcibly stopping the flash light emitting operation from the camera side, and when the subject is at a long distance or when it is difficult to reflect light. For example, when the amount of reflected light is small and the ON signal is not output from the comparator 6 even after a lapse of a predetermined time, the forced stop signal is input. Then, the stop signal is F from the gate circuit 7.
It is output to the F circuit 8 to stop strobe emission.

FIG. 4 is a diagram showing a change in the light quantity q per unit time, which is the light emission intensity in the case of full flash emission by the strobe light emission control device. The light emission pulse corresponds to the light emission control signal, Ts is the light emission start time, and tp is the time until the peak of the light emission amount is reached. At the time of full light emission, light emission is performed by the total amount of charged electric charge regardless of the output of the integrator 4. The time tp is usually several 100 μsec to several m.
sec. FIG. 5 is a diagram showing a change in the light quantity q per unit time in stroboscopic light emission with a small light quantity in flash photography at a close range. The light emission pulse serving as the light emission control signal is turned on from Ts at the light emission start time to Te at the light emission stop time. When it is determined at time Te that the output of the integrator 4 has reached the target light amount Qa set by the camera side, the light emission control signal C causes the strobe device 2 to stop the light emission operation. However, the flash operation of the strobe device 2 does not immediately stop the flash,
After the surplus light amount Qb is emitted for a few μsec, it is completely stopped. Hereinafter, the surplus light amount Qb is referred to as a surplus light emission amount. FIG. 6 is a diagram showing the above-mentioned light emission state by a light amount obtained by integrating the light amount q per unit time, that is, a change in the integrated light amount output from the integrator 4, and the target light amount Qa and the surplus light emission amount Qb. Is shown as in this figure. The total light emission amount is given by Qa + Qb. The light emission time t is shown between the times Ts and Te. The surplus emitted light amount Qb is an error amount, and when the target light amount Qa is large,
The ratio becomes smaller and does not affect the actual exposure. However, when the subject distance is close and the target light amount Qa is small, the ratio of the surplus light emission amount Qb to the target light amount Qa becomes large, and the influence on the exposure cannot be ignored.

For that reason, in the past, as a subject distance at which stroboscopic photography is possible without changing the mode such as the aperture value, for example, GNo. (Guide number) 12
With the strobe of the class, it remained in the range of about 4 m to 1 m. Therefore, in stroboscopic photography at a closer range than that, it is necessary to change the aperture value or the mode such as mounting the diffuser as described above. Since the subject distance affects the exposure at the time of stroboscopic photography by its square, the range of 4 m to 1 m is 24 db as the dynamic range required to control the strobe light amount. If the closest distance is approached from 1 m to 0.25 m, the dynamic range required for the above control is 48 db.

[0007]

However, in the case of stroboscopic photography, the fact that the long-distance side is limited is unavoidable, but the short-distance side is limited, and it is necessary to switch modes such as changing the aperture and installing a diffuser. Very bad. In other words, in recent years, due to the development of distance measurement technology, it has become possible to measure the subject distance to the closest distance, and even considering from the fact that cameras with lens systems capable of macro photography have become common, Only the slight flash control of the strobe limits the flash photography at close range, and continuous flash photography is not possible without changing the mode from medium range to the closest range, resulting in poor usability. Also, even if the mode switching itself
It is necessary to detect when to switch,
When obtaining the distance information for that purpose, for example, it is difficult to obtain the distance information itself from the autofocus device in a wide-lens camera or a still video camera, and the usability in that respect is very poor.

Therefore, the present inventor has made the above-mentioned target light quantity Qa.
As a result of investigating the relationship between the ratio of the excess light emission amount Qb and the dimming time, which is the light emission pulse width, with a conventional strobe device, as a result, the relative excess light emission rate ε with respect to the dimming time t shown in FIG.
A diagram of (%) was obtained. The relative surplus light emission rate ε is a value indicating the ratio of the surplus light emission amount Qb to the target light amount Qa, and is represented by ε = (Qb / Qa) × 100. As shown in FIG. 7, the dimming time t is 45 μs.
When the ec is less than or equal to ec, the surplus light emission rate ε is 23% (0.3E
V) or more. Further, when the dimming time t is 10 μsec, the surplus light emission rate ε becomes 400%, which is far from the target amount of emitted light. Normal,
Light emission up to 20 to 30 μsec of the dimming time t is an allowable limit in light emission control. Due to this limit, the limit distance for stroboscopic photography with a fixed setting mode is 4 m to 1 as described above.
Since it becomes impossible to control the flash light at a distance of 1 m or less than 1 m, it is necessary to change the mode setting state so as to increase the amount of emitted light each time and execute flash photography, which is very complicated. It was supposed to.

The electronic still camera and electronic flash for electronic still camera disclosed in Japanese Patent Laid-Open No. 125573/1990 allow multiple flashes to be emitted during flash photography. In order to obtain a knee characteristic corresponding to the exposure characteristic of the image sensor for the purpose of preventing the blackout of the screen, stroboscopic light emission with different light amounts is performed multiple times. Rather, this conventional strobe light emitting device also has the same problem as that of the conventional strobe device in terms of control of a minute amount of light.

The present invention has been made in order to solve the above-mentioned problems. In a strobe light emission control device, the light emission amount is controlled by controlling the light emission continuation time each time, and a minute light amount is controlled. In flash photography, for example, it is an object of the present invention to provide a stroboscopic light emission control device that enables photography up to a close range without changing modes such as aperture value change and diffuser mounting. To do.

[0011]

The stroboscopic light emission control device of the present invention applies a pulsed light emission command a plurality of times.
It allowed electronic flash by, the calling when the accumulated value of the light emission amount of the flash reaches the total light emission amount to the target
A strobe light emission control device for controlling light emission of the strobe by stopping application of a light command ,
Issuing up to the first specified number of times among the above multiple emission commands
For light command , duration of each light command (tc)
Is emitted when a continuous light emission command is applied.
When the application of the light emission command is stopped by the
The remainder of the strobe, which is the duration of the remaining
Under the condition that it is limited to twice the surplus light emission time (ts) or less,
It is characterized in that the flash emission control is executed .

[0012]

[0013]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below based on the illustrated embodiments. FIG. 1 is a block diagram of a strobe light emission control device showing an embodiment of the present invention. The configuration of the present device is an emission limiting means AN between the strobe device 2 and the flip-flop circuit (FF circuit) 8 as the strobe control section 11 as compared with the conventional strobe emission control device shown in FIG.
A D gate circuit 10 is additionally provided and a pulse generator 9 which is also a light emission limiting means is provided. Then, the output of the FF circuit 8 is input to the AND gate circuit 10 as a light emission start / stop control signal A, and the output which becomes the light emission interruption signal of the pulse generator 9 is also output to the gate circuit 10.
To enter. The output of the AND gate circuit 10 is input to the strobe device 2 as a control signal B which is a light emission control signal.
Other configurations are the same as those shown in FIG. 3 and are denoted by the same reference numerals.

The control operation of the strobe light emission control device of the present invention configured as described above will be described with reference to the time chart of FIG.
Will be explained. First, when a start signal which is a light emission start command is input from the camera body side, the pulse generator 9 outputs a light emission interruption signal at the same time. The light emission interruption signal is the on-time tc of the pulse width of a predetermined time,
It is formed with the off-time ti. While the control signal A is on, the control signal B is on for the on time tc, and light emission is continued during that time. The on-time tc is a time sufficiently shorter than the time tp until the strobe light emission intensity shown in FIG. 4 is maximized, and the result of the research conducted by the present inventor shows that the excess light-emission time ts shown in FIG. By comparison, t
It has been found that if c ≦ 2 · ts is adopted, a clear effect can be obtained in controlling the minute emission light amount.
For example, the value is 1 to 2 μsec. On the other hand, during the off time ti, the control signal B is turned off and the light emitting operation is stopped. The off-time ti is determined in combination with the value of the on-time tc, and is, for example, 10 to 20 μse.
Let be c. These values are not determined only by the ratio, but proper effects can be obtained by proper combination of specific values. As an integrated light quantity Q which is a strobe light quantity, a curve E in FIG. 2 shows the initial light-emission portion in the conventional light-emission state shown in FIGS. The curve is rising.
The change in the integrated light quantity Q, which is the quantity of light emitted by the strobe, by the control device of the present embodiment, increases slightly in a pulse form during the on-time tc as shown by the curves F and F ', and the off-time t.
It changes with a gentle rising curve during the period i. The curves F and F'are stepwise as compared with the curve E, but rise more gently. Note that the integrated light amount value Qc shown in FIG. 2 is a target light amount of a small amount, and indicates a small amount of strobe light for an object at an extremely close distance within 1 m, for example.

After the start signal is output, the stop signal is output when the integrated light quantity Q reaches the value Qc set on the camera side. Then, the control signal A is turned off, the control signal B is not output thereafter, and the light emission is stopped when the integrated light amount slightly exceeds the value Qc by about 20% at the maximum. The light amount slightly exceeding the above value Qc is not a value that affects the exposure. In the conventional case, the integrated light amount rises along the curve E, so that the surplus light emission amount after the value reaches Qc also becomes large as compared with the value Qc, and the error value therefor reaches 400%. was there. As described above, in the control device of the present embodiment, highly accurate control of the minute light amount is performed.

As described above, the strobe light emission control device of this embodiment controls the minute light emission amount by using the light emission interruption signal with the integrated light amount characteristic of the gently changing curves F and F'in FIG. be able to. And subject distance 4m ~
4 of the dynamic range that enables stroboscopic photography without changing the mode such as aperture value in the range of 0.25 m
8db can be obtained.

Next, a strobe light emission control device showing a second embodiment of the present invention will be described. The control device of the present embodiment is configured by the on-time tc and the off-time ti shown in the device of the first embodiment during the initial fixed period of the light emission operation or during the constant pulse number of the light emission interruption signal. The strobe light amount control by the light emission interruption signal is executed, and thereafter, the conventional light emission processing is executed. Obey here
The conventional light emission processing is explained with reference to FIG. 3, FIG. 4, and FIG.
Conventional technology, that is, the total amount of emitted light is the target
The light emission pulse is turned on continuously until the value is reached.
(Therefore, if the target value is never reached
It goes without saying that it is control. Therefore, in the present embodiment, in the range where the target emitted light amount is very small, the highly accurate minute light amount control is performed, and when the target emitted light amount is larger than the predetermined value, until the first fixed period. Minute
Light emission control suitable for light intensity control is performed, but continues after that
The conventional light emission control that shortens the light emission time is performed
Therefore, the total light emission time can be lengthened unnecessarily.
It is excellent in that it does not exist. The configuration of the control device of this embodiment
Is the same as that of the first embodiment. Moreover, FIG.
The time chart of the second embodiment corresponding to the time chart of No. 2
The conventional light emission control is executed from the middle.
Therefore, the integrated light amount characteristic curve becomes F ″, and the first embodiment
The light emission is completed faster than in the case of. In addition, it is easy
Therefore, the number of pulses corresponding to a small amount of light is only 3 pulses at the beginning.
Although it shows, it emits light from the viewpoint of the resolution of minute light control.
Increase this number of pulses as long as time allows
Therefore, it goes without saying that it is advantageous to set, for example, several tens or more.
Is.

Next, a strobe light emission control device showing a third embodiment of the present invention will be described. The control device according to the present embodiment is configured such that the number of pulse outputs of the light emission interruption signal at the initial stage of the light emission operation is 6
The light emission control is performed with the on-time tc of 1 μsec and the off-time ti of 20 μsec for four pulses, and the on-time tc of 2 μsec and off-time for the next 64 pulses of the light emission interruption signal. The light emission is controlled by setting ti to 10 μsec. Furthermore, after that,
Similar to the second embodiment, the conventional light emitting process is performed. Supplementally here, the pulse width (on-time t
The ratio of c) to the pulse interval (off time ti) is small.
The better the controllability of the amount of light, the better
Of course, the amount of light emitted from
Because it approaches the conventional control (continuous ON state) relatively
Light controllability is poor, but the amount of light emitted per unit time is large.
I hear On the other hand, the subject is very close
If the total amount of light required is very small, high absolute controllability is required.
However, the subject distance is relatively large and the total amount of light required is large.
However, even if the absolute light quantity controllability is low,
There is a situation that the impact will be small, so some power
The total amount of light reaches the target value even after the number of light emission has been performed.
If not, increase the ratio of the above pulse width and interval
It is more advantageous to shorten the time until the light emission is completed.
Therefore, in the case of the present embodiment, light emission is performed in a shorter time than in the first and second embodiments even if the target light emission amount is in a relatively small amount range, and the phase relative to the total light amount is
As for the accuracy, the minute light amount control with the same accuracy is performed.
When the amount of light is large, light emission control with a short light emission time is performed as in the second embodiment. As is apparent from the third embodiment, the optimum combination of tc and ti is not uniform depending on the situation. For example, the value may be changed with the passage of time, and if it is not a problem to make it complicated, the value may be changed little by little for each on / off time.

The stroboscopic light emission control device of the present invention is not limited to the automatic dimming device as in the above-described embodiments, but can be applied to a non-dimming device for stroboscopic light emission of a predetermined amount of light. Further, the present apparatus can be applied not only to a silver halide film camera having a lens shutter but also to a strobe light emission control device of an electronic camera using an image pickup device using a device shutter. The stroboscopic light emission control device of the present invention controls the stroboscopic light emission a plurality of times for photographing one screen as described above. The purpose of this is to control a very small amount of light emission with high precision. Since the pulse width of the light emission is extremely narrow, the actual light emission does not necessarily become a plurality of discontinuous light emission, although it is somewhat pulsed as described above, but rather continuous light emission. Get closer to. On the other hand, the strobe disclosed in the above-mentioned Japanese Patent Application Laid-Open No. 2-125573 causes the strobe emission control to be performed a plurality of times in stroboscopic photography, but this device obtains a desired knee characteristic. For the purpose, stroboscopic light emission with different light intensity is performed a plurality of times. Therefore, even in this conventional strobe device, if the strobe light emission control device of the present invention is applied to control a minute amount of light, the dynamic range of the light amount control becomes wider, and stroboscopic photography up to a closer distance is possible. It will be easier.

[0020]

As described above, the strobe light emission control device of the present invention is configured to continuously emit light within a plurality of predetermined transient time intervals within a predetermined time immediately after the light emission start command is issued. Therefore, it is possible to perform highly accurate control of a minute amount of emitted light, and there are many remarkable effects such as stroboscopic photography without changing the mode up to the closest distance.

[Brief description of drawings]

FIG. 1 is a block configuration diagram of a flash emission control device showing a first embodiment of the present invention.

2 is a time chart of a light emission operation of the strobe light emission control device of FIG.

FIG. 3 is a block configuration diagram of a conventional strobe emission control device.

FIG. 4 is a diagram showing a change in the amount of light per unit time when the flash emission control device of FIG.

5 is a diagram showing a change in light amount per unit time when the flash light emission control device of FIG. 3 controls the light emission amount.

FIG. 6 is a diagram showing a change in integrated light amount when the light emission amount of the strobe light emission control device of FIG. 3 is controlled.

FIG. 7 is a diagram showing a change in relative surplus light emission rate at the time of minute light amount control of the strobe light emission control device of FIG. 3;

FIG. 8 is a strobe emission control device showing a second embodiment of the present invention .
Chart of the light emitting operation of the display.

[Explanation of symbols]

9 ……………… Pulse generator (light emission limiting means) 10 ……………… AND gate circuit (light emission limiting means) q ……………… Emission light intensity (light emission intensity) Q per unit time. ……… Integrated light intensity (cumulative amount of light emission) tc …………… On-time (duration of each light emission, within transient time interval)

Claims (3)

(57) [Claims] 1. A pulsed light emission command is applied a plurality of times.
It allowed electronic flash by, before when the accumulated value of the light emission amount of the flash reaches the total light emission amount to the target
Serial A flash emission controller for controlling light emission of the strobe by stopping the application of light emission command, the first predetermined times of at least the plurality of times of light emission command
The emission command up to a few, each of light emission command duration of (tc), light is emitted by applying a continuous emission command
In the case that the application of the light emission command is stopped, its application
This is the duration of the remaining light emission that still occurs after the stop.
Articles limited to less than twice the flash emission time (ts)
A stroboscopic light emission control device, characterized in that the stroboscopic light emission control is executed according to the circumstances. 2. A predetermined command among the plurality of light emission commands.
The flash command applied after several times is
Except when the cumulative light emission amount reaches the target total light emission amount.
A predetermined amount sufficient to output the total amount of light emitted by the strobe.
Seems to be applied continuously over time
The strobe according to claim 1, characterized in that
Light emission control device. 3. The duration time (tc) of each light emission command
And the time interval (ti) between each of the above flash commands
Control tc / ti to increase over time.
The strike according to claim 1 or 2, wherein the strike is controlled.
Robo light emission control device.