JPH0455288B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an improvement in a charging start-up device for a camera strobe, and more particularly to effective control of charging start-up for a strobe.

In recent years, cameras have been proposed that have automatic strobes that fire automatically when it gets dark, making it possible to always take pictures with appropriate exposure without the need for complicated operations. The DC/DC converter for charging the main capacitor of this auto-firing strobe is connected to the first button of the release button.
A method is known in which the device is restarted every time a photograph is taken by generating a starting pulse when the stroke changes from ON to OFF or when winding is completed (Japanese Unexamined Patent Publication No. 159625/1983). According to this method, the strobe is charged every time the photographing is completed, and as a result, the performance of rapid shooting in continuous strobe photography is improved.

However, when using this method, the strobe must be restarted after each shot, and even if the subject is bright and the strobe does not fire, the battery is consumed quickly because the DC/DC converter is constantly operating. This had the inconvenience of reducing the number of shots that could be taken using the flash with each battery change.
Furthermore, parts related to the strobe charging operation wear out more quickly, leading to more breakdowns. Furthermore, in order to restart the flash regardless of its charging status, the flash had to wait for a certain period of time even if the flash was at an unnecessary brightness level, resulting in a problem that the time between shots became longer. .

The present invention has been made in view of the above circumstances, and
A charge start signal output means for outputting a charge start signal to the strobe after photography, a photometer for measuring subject brightness, and whether the strobe is required to emit light according to the photometry result of the photometer when the shutter release button is pressed. a determining means for determining whether or not strobe light emission is required; a storage means for storing a determination result of the determining means; is equipped with a disabling means for disabling the action of the charging start signal output means, and starts charging the strobe after shooting, stores the photometry result when the shutter release button is pressed, and uses the photometry result based on the photometry result. When strobe light emission is not required, charging is not started after the above-mentioned photograph is taken, and as a result, unnecessary strobe charging operation is not performed when strobe light is not required, and the life of the battery and components is extended. , a camera that can take flash photography without having to wait for the strobe to charge when releasing the shutter when a strobe is required, and without requiring any extra operations, improving instant shooting and operability. The purpose of this invention is to provide a charging start device for a strobe.

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a circuit diagram of a camera showing an embodiment of the present invention.

In FIG. 1, a battery 1 serves as a power source, and serves as a power source for a shutter circuit 30, a winding circuit 32, and a strobe circuit A. Switch 2 is the main switch and is always turned on when shooting. Switches 3 and 4 are switches that are linked to the first stroke of the release button, and switch 4 is
When turned on, current flows through resistors 5 and 6, transistor 7 is turned on, and a potential of Vcc is output to the collector. This potential Vcc serves as a power source for the exposure control circuit B. Reference numeral 8 denotes a battery for backing up the control circuit C, which is constructed separately from the battery 1 described above.

First, we will explain the operation of determining whether the strobe's main capacitor is fully charged. In strobe circuit A, if transistor 100 is OFF and starting transistor 110 is ON, in this state, oscillation transistor 1
20 is ON, and transistor 124 is OFF. In the figure, transistors 120 and 12
4, resistors 122 and 126, and transformer 130 constitute a step-up DC/DC converter. Note that the resistors 102, 104, 112, and 114 are current limiting resistors. The transistor 120
When it is ON, current flows from the battery 1 and a high voltage is generated on the anode side of the diodes 132 and 134 on the secondary side of the transformer 130. As a result, a voltage stepped down by 1 Vf is output to the cathode sides of diodes 132 and 134, which is smoothed by capacitor 136 and divided by resistors 140 and 142. This divided voltage and the set constant voltage V ₂
is input to the comparator 150, and when the main capacitor 180 reaches the charging completion level, the comparator 150 outputs an L signal, and when the main capacitor 180 reaches the charging completion level, it outputs an H signal. This configuration makes it possible to determine whether the strobe is fully loaded or not. In the figure, thyristor 16
0, capacitors 162 and 164, a trigger transformer 166, and resistors 168, 170, and 172 constitute a trigger circuit. When the TRIG terminal becomes H, the thyristor 160 turns on and the capacitor 162
The transformer 1 is excited by draining the charge of
A high voltage is momentarily generated on the secondary side of the main capacitor 180, and the kinocene tube 190 lights up due to the charge of the main capacitor 180, thereby emitting strobe light.

Next, a circuit for determining the brightness of a subject will be described.

In exposure control circuit B, photodiode 20
The photocurrent generated at 0 is converted into a logarithmically compressed voltage by an amplifier 202 and a diode 204. And a level shift diode 206
and the voltage level provided by resistor 208;
The comparator 220 compares the voltage obtained by dividing Vcc by the resistors 210 and 212, and if the brightness of the subject is low, so-called low brightness, the comparator 22
It is configured to generate an output signal from 0 to H. Reference numeral 230 denotes a well-known time setting circuit, which is configured to set the time for energizing the shutter circuit 30 and to output a TRIG signal at the same time as the energization to the shutter circuit 30 ends. switch 1
0 is ON with the second stroke of the release button
The shutter starts operating in response to the ON signal, and the output 230a becomes H for only the energization time created by the time setting circuit 230.

The winding circuit 32 winds the exposed film after photographing, and is connected to the time setting circuit 2 of the exposure control circuit B.
30 finishes its operation and the output 230a becomes L,
The output of an inverter 380 of a control circuit C, which will be described later, is H.
When the switch 3 is turned OFF, the output of the AND gate 382 becomes H, and the winding operation begins. When the winding is completed, the switch 34 is turned ON.

The backlight detection circuit 40 uses a known method, for example,
No. 57-4028, a spot photometric element at the center of the angle of view and an average photometric element for the entire angle of view are provided, and during normal shooting, the spot photometric value and the average photometric value are compared, and the spot photometric value is calculated as the average photometric value. This system determines a backlight condition when the value is particularly smaller than the value, and performs daytime synchronized photography. The backlight detection circuit 40 in this embodiment is set to generate an H output when backlight is detected.

Next, the control circuit C that controls the charging start of the strobe
I will explain about it. In this explanation of the control circuit C, the operation will be explained according to each state of the output signals from the strobe circuit A, the exposure control circuit B, and the backlight detection circuit 40.

First, as case 1, a state will be described in which the strobe circuit A is not fully charged and the exposure control circuit B is detecting low brightness of the subject or the backlight detection circuit 40 is detecting backlight.

In this state, comparator 1 of strobe circuit A
50 is H, and the output of the comparator 220 of the exposure control circuit B or the output of the backlight detection circuit 40 is H. As a result, the output of the OR gate 50 becomes H, and if the switch 3 is ON during the first stroke of the release button, the output of the AND gate 52 becomes H. NAND gate 304 becomes L in this state, and the output of the latch circuit constituted by NAND gates 310 and 312 becomes H. In addition, the output of the NAND gate 306 also becomes L,
The output of the latch circuit composed of NAND gates 314 and 316 also becomes H. The H outputs of NAND gates 310 and 314 in both latch circuits are supplied to AND gate 322 via OR gate 320. The AND gate 322 also has a winding circuit 3.
Since the output of the switch 34 at 2 is supplied via the inverter 384, and the output of the switch 3 is also supplied, when the switch 3 is OFF and the winding is completed and the switch 34 is ON, the output of the AND gate 322 is The output becomes H. and gate 32
When the output of the D-type flip-flop 324 and the AND gate 326 becomes H, the output of the one-shot circuit composed of the D-type flip-flop 324 and the AND gate 326 momentarily becomes H at the timing of the clock signal of the oscillator 360. Since the outputs of both the latch circuits mentioned above are H, the output of the AND gate 330 is H, so the AND gate 332
The output becomes H, turning on the transistor 110 for starting the strobe circuit A. In this state, the output of the OR gate 350 is L, so the transistor 10
0 is set to OFF, so the DC/DC converter starts up.

The one-shot circuit constituted by the D-type flip-flop 340 and the NAND gate 342 outputs the NAND gate 3 with a delay from the activation signal.
An H output for resetting both latch circuits constituted by latches 10, 312, 314 and 316 is output at the timing of the clock signal of oscillator 360. By resetting both latch circuits, transistor 110 is turned off.

Next, as case 2, we will explain the case where the strobe circuit A is in a fully charged state. Since the output of the comparator 150 is L, the output of the latch circuit composed of NAND gates 314 and 316 becomes L. Therefore, the outputs of AND gates 330 and 332 are L,
Transistor 110 remains OFF and DC/
DC converter does not start.

Next, as case 3, when the subject is not of low brightness and there is no backflow, the output of the comparator 220 is L and the output of the backlight detection circuit 40 is L, so a latch circuit is constructed of NAND gates 310 and 312. The output of is L. Therefore, the outputs of AND gates 330 and 332 are L, transistor 110 remains OFF, and the DC/DC converter does not start.

Furthermore, to explain a case 4 in which the states of both cases 2 and 3 are overlapped, that is, the output of the comparator 150 is L,
The output of the OR gate 50 is in the L state, and the outputs of the two latch circuits constituted by the NAND gates 310, 312, 314 and 316 are in the L state. Naturally, even in this case, the transistor 110 is turned off and the DC/DC converter is turned off. It is understood that it will not start.

On the other hand, the transistor 100 that stops the oscillation of the DC/DC converter of the strobe circuit A is turned on by the H output of the OR gate 350. Specifically, when the switch 3 is ON, that is, when the release button is operated on the first stroke, and when the switch 34 of the winding circuit 32 is OFF, the inverter 3
When the output of the strobe 52 becomes H, that is, during the winding operation, when charging of the main capacitor 180 of the strobe is completed, the output of the comparator 150 becomes L, and the output of the inverter 354 becomes H;
There are three states. The reason why the DC/DC converter of the strobe circuit A is not driven during the first stroke of the release button and during the winding operation described above is to avoid the load and heavy load of other AF operations (not shown) such as motor winding. In addition, the purpose of disabling the strobe from being driven when charging is completed is to extend the life of the battery by not performing more charging than necessary.

On the other hand, the output of the switch 10 that is turned on at the second stroke of the release button is Noah Gate 70.
Validity and invalidity are controlled by . This Noah Gate 7
A switch 10 and an AND gate 7 are connected to the input terminal of 0.
The input terminal of this AND gate 72 is supplied with the output of a comparator 150 that detects whether the strobe is uncharged, and the output of an OR gate 50 that outputs the detection results of low brightness and backlight of the subject. Supplied. Therefore, if strobe light emission is required and the strobe is not yet fully charged, photography can be prohibited.

The feature of this embodiment configured as described above is that charging of the strobe is started only when necessary, and two things are used as conditions for starting the charging: the brightness level information of the subject and the charging state information of the strobe. ing. In other words, by starting the charging of the strobe only when the subject requires strobe light emission and the strobe is not fully charged, it is possible to restart the strobe without waste. . Specifically, the conditions for restarting the strobe are that strobe circuit A
Detection occurs when the main capacitor 180 has not reached the charging voltage level and at least one of the following occurs: when the exposure control circuit B detects a low brightness level of the subject, or when the backlight detection circuit 40 detects a backlight condition. This state is stored in two latch circuits constituted by NAND gates 310 to 316 of control circuit C, and the above-mentioned strobe restart is performed. Therefore, it is possible to eliminate the waste of starting charging even though the main capacitor 180 of strobe circuit A is at the charging voltage level, or starting charging the strobe even though the subject is of high brightness and no strobe light is required. can. Therefore, the life of the power supply battery can be extended, and the number of images that can be taken using the strobe can be increased with one battery replacement.

In addition, in this embodiment, if the main capacitor 180 of the strobe circuit A has reached the charging voltage level and the strobe light is not used during shooting, no strobe charging operation is required, so the next possible shooting time will be shortened. is shorter than that of the conventional method, which improves quick-shooting ability.

In the embodiment, information on the charging state of the flash and the brightness level of the subject is stored in the first stroke operation state of the release button (switch 3).
ON), and the brightness information of the subject that the photographer is trying to photograph is used as one of the conditions for charging the strobe, making the judgment more accurate and the operation for making that judgment easier. Since there is no need to provide a separate special setting, it is possible to improve operability and instant photographing.

Furthermore, since charging of the strobe is started after photographing based on the information stored at the time of the release operation, there is no need to wait for the strobe to be charged at the time of the release operation, and it is possible to improve instant shooting performance.

Next, another embodiment of the present invention will be described based on FIG. In the embodiment shown in FIG. 2, the same components as those in the embodiment shown in FIG.

Another embodiment shown in FIG.
The backlight condition of 0 was detected after the release button was released, that is, at the timing when the switch 3 was turned from ON to OFF. That is, when the switch 3 linked to the first stroke of the release button is switched from ON to OFF, the one-shot circuit composed of the D-type flip-flop 380 and the AND gate 382 momentarily goes high at the timing of the clock signal of the oscillator 360. becomes. At this time, if the comparator 150 of the strobe circuit A is not fully charged and outputs H, and the output of the comparator 220 of the exposure control circuit B or the backlight detection circuit 40 is H at a low brightness level, the NAND gate 304 and 306
outputs L and connects NAND gates 310, 312, 3
Both latch circuits constituted by 14 and 316 are
After that, similarly to the embodiment shown in FIG. 1, the starting transistor 110 is turned on to start charging the strobe.

The features of other embodiments configured as above are as follows:
In the embodiment shown in FIG. 1 above, the timing of detecting the strobe charge state information, subject brightness information, and backlight information is performed when the release button is released, and other operations are the same as in the above embodiment. It is.

Next, another embodiment of the present invention will be described with reference to FIG. In the embodiment shown in FIG. 3, the same components as those in the embodiment shown in FIG.

In yet another embodiment shown in FIG. 3, low brightness or backlight of the subject is detected when the release button is operated, that is, when the switch 3 is turned ON, while the main capacitor 180 of the strobe circuit A is charged. The status is detected after the release button is released, that is, from switch 3 ON to OFF.
This was done at the same time as the switch was made. In other words, when the switch 3 linked to the first stroke of the release button is ON and the subject is low brightness or backlit, the NAND gate 304 is activated.
outputs L and connects NAND gates 310 and 312
Let the output of the latch circuit constructed by . Furthermore, when the release button is released, that is, when the switch 3 is switched from ON to OFF, the one-shot circuit composed of the D-type flip-flop 390 and the AND gate 392 momentarily becomes H at the timing of the clock signal of the oscillator 360. At this time, if the comparator 150 of the strobe circuit A outputs H because the strobe is not fully charged, the NAND gate 306 outputs L, and the latch circuit constituted by NAND gates 314 and 316 outputs H. Thereafter, as in the embodiment shown in FIG. 1 described above, the starting transistor 110 is turned on to start charging the strobe.

A feature of yet another embodiment configured as described above is that the timing for detecting the charging state information of the strobe in the embodiment shown in FIG. The operation is similar to the embodiment shown in FIG. 1 described above.

In the embodiments shown in FIGS. 2 and 3 above, the charging state of the strobe after photography is detected, so the waiting time for continuous strobe emission when the strobe light is emitted during photography is the same as that shown in Figure 1. The difference is that it is faster than the example.

Note that the detection timing of the charging state of the strobe, the brightness level of the subject, and the backlighting state of the subject may be other than those shown in the above-described embodiments.

In the above embodiment, the storage means for storing the output signals from the brightness level detection means and the uncharged detection means has a temporal difference between the detection timing of the two detection means and the subsequent output timing of the charging start signal. Since the deviation is set, various configurations other than the combination of latch circuits and AND gates shown in the embodiments are possible, although this is necessary.

In the above embodiment, the AND gate 322,
The D-type flip-flop 324 and the AND gate 326 correspond to the charging start signal output means of the present invention, the photodiode 200, the amplifier 202, the diode 204, and the backlight detection circuit 40 correspond to the photometry means of the present invention, and the AND gate 52 corresponds to the determination means of the present invention, and NAND gates 310 and 3
The latch circuit constituted by 12 corresponds to the storage means of the present invention, and the AND gate 332 corresponds to the invalidation means of the present invention.

As explained above, according to the present invention, the flash is charged after shooting, and the photometry result at the time of pressing the shutter release button is stored, and based on the photometry result, when flash emission is not required, Since charging is not activated after taking the above picture, unnecessary strobe charging is not performed when the strobe is not needed, extending the life of the battery and components, and the shutter release is not activated when the strobe is needed. This allows flash photography to be carried out without having to wait for the strobe to be charged, and without any special extra operations, thereby improving immediate shooting performance and operability.

[Brief explanation of drawings]

FIG. 1 is a circuit diagram of a camera showing an embodiment of the present invention. FIG. 2 is a circuit configuration diagram of a camera showing another embodiment of the present invention. FIG. 3 is a circuit configuration diagram of a camera showing still another embodiment of the present invention. A...Strobe circuit, B...Exposure control circuit, C
... Control circuit, 3, 4 ... Switch, 32 ... Winding circuit, 40 ... Backlight detection circuit, 110 ... Starting transistor, 150 ... Comparator,
180...Main capacitor, 200...Photodiode, 202...Amplifier, 204...Diode, 220...Comparator, 310, 31
2, 314, 316... NAND gate forming a latch circuit, 322... AND gate, 324...
...D type flip-flop, 326...and gate, 332...and gate.

Claims (1)

[Claims] 1. Requires charging start signal output means for outputting a charge start signal to the strobe after photography, photometry means for measuring subject brightness, and strobe light emission according to the photometry result of the photometry means when the shutter release button is pressed. determining means for determining whether or not strobe light emission is required; a storage means for storing the determination result of the determining means; A charging activation device for a camera strobe, comprising: a disabling means for disabling the operation of the charging activation signal output means.