JPS6299734A - Stroboscope for camera - Google Patents

Abstract

PURPOSE:To indicate excellently a stroboscope is under charging even when the power source battery is used up or at low temperature by providing a stopping circuit that stops operation of a strobe circuit by output of a detecting circuit when voltage is dropped below a voltage level that can light up an indicating means, and making charging again after stopping. CONSTITUTION:When battery voltage is lowered than the first specified level during a stroboscope charging, charging operation of the strobe is prohibited to prevent further lowering of battery voltage, and charging operation is restarted after the charging operation. That is, when charging operation is started, voltage UBAT of the power source battery 11 drops quickly at the time of low temperature and when the battery is consumed. When voltage became below a specified value V2, output of a comparator 39 is reversed to H level, and an oscillating transistor 12 is made off, and charging operation to a main capacitor 25 stops. Accordingly, voltage of the power source battery 11 returns to V1. Thereby the oscillating transistor 12 is turned on and charging operation to the main capacitor 25 is resumed.

Description

DETAILED DESCRIPTION OF THE INVENTION (1) Object of the Invention [Field of Industrial Application] The present invention relates to an indication that a strobe is being charged in a camera combined with a strobe device.

[Conventional technology]

Camera automation has progressed in recent years, and cameras have recently appeared that can determine the brightness of a subject and automatically emit strobe light when the brightness is low. In other words, the main switch closes during the first stroke of the camera's shutter button, measures the subject brightness at that time, and if it is below a predetermined value, starts charging the strobe's main capacitor, and releases the flash when charging is complete. A system is already known that allows the photographer to perform appropriate strobe photography without being conscious of the operation.

Another idea is to pop up the strobe light emitting part by determining the brightness of the subject, and then turn on the power switch of the strobe circuit and start the charging operation.
Considering the mechanical complexity, it would be simpler to use a non-pop-up system without a power switch.

In this system, it is important to let the photographer know that the main capacitor has finished charging and is ready to take a picture, but in the case of a non-pop-up system, the neon tube is left on after it is fully charged as before. If you do so, the battery will be consumed by the current flowing to the neon tube, and since it is a non-pop-up camera, it will be difficult for the photographer to notice that the flash mode is on, further accelerating battery consumption.

In the first place, in non-pop-up batteries, the battery is consumed by idling current after charging is complete, so a strobe circuit is often used that has a function that starts charging operation with a start signal and automatically stops strobe oscillation when charging is complete. Therefore, the charging completion display using a neon tube itself is inappropriate for this system.

Considering the above-mentioned background and the psychology of the photographer who is waiting for the main capacitor to complete charging, it has been proposed that it would be more appropriate to display a charging in progress display while the strobe is being charged.

[Problem that the invention seeks to solve]

If this is attempted to be done using LEDs, for example, the following serious problems will arise. In other words, when the battery is exhausted or at low temperatures, the battery voltage drops extremely due to the rush current at the beginning of charging the strobe, and the voltage drops below the forward voltage (hereinafter referred to as VF) of the LED, causing the LED itself to turn on. It becomes impossible. Further, after the initial stage of charging, the battery voltage gradually recovers and the LED can be turned on, but at this time the LED starts to turn on vaguely, which poses a problem in terms of display quality.

The present invention is intended to solve the above problems.

1. Configuration of the Invention [Means for Solving Problems] The present invention provides a strobe circuit A, a display means 52 for displaying a display at least during charging operation of the strobe circuit, and a control circuit B for controlling the strobe circuit. In the camera flash device, the control circuit B includes a first detection circuit C that detects the voltage of the power battery 11, and the voltage level of the power battery is at least as high as the display level. The strobe circuit has a stop circuit that stops the operation of the strobe circuit by the output of the first detection circuit C when the voltage drops below the voltage level that allows lighting of the means 52, and after stopping, the strobe circuit is charged again. This is a camera strobe device that features:

[For production]

When the battery voltage falls below a first predetermined level during strobe charging, the charging operation of the strobe is slowed down to prevent further drop in the battery voltage, and after the charging operation, the charging operation is restarted.

〔Example〕

Hereinafter, the present invention will be described in detail based on embodiments illustrated in the drawings.

FIG. 1(a) is an electric circuit diagram showing a first embodiment of the present invention. In the figure, 11 is a power supply battery, 12 is a strobe circuit oscillation transistor, 13 and 14 are oscillation stop transistors, and 15 and 16 are the collector and base resistances of the transistor 14. 161 is an oscillation transformer, 17 is a rectifying diode, 18 is a resistor, 19 is a thyristor, 2
0 and 21 are resistors and capacitors connected to their gates, 22 is a trigger coil, 23 is a trigger capacitor,
24 is a xenon tube, 25 is a main capacitor, 26 is a Zener diode for detecting the voltage of the main capacitor 25, and 27 is a resistor connected in series with 26.

30 is a main switch that is closed in conjunction with the camera's release button, 31 is a power supply capacitor, and 32 is a known photometering circuit and shutter control circuit.The output from these circuits generates a low-brightness warning signal (LL doubles) when the subject brightness is low. 34 is a one-shot pulse generation circuit, 35 and 36 are resistors and Zener diodes connected in series, 37 and 38 are resistors connected in series, and 39 is a comparator. As shown in the figure, the (-) input is connected to the connection point of the resistors 35 and 36, and the (-) input is connected to the connection point of the resistors 37 and 38, respectively.

40 and 41 are two-operated OR gates, and the one-operated gate of 40 is connected to the output of the comparator 39. 42 is R
An S flip-flop circuit (hereinafter abbreviated as R5-FF) has a set input S connected to the output of the OR gate 41 and a reset input R connected to the OR gate 40. 4
3 is an inverter connected to the Q output (CGCON) of the R9-FF42, 45 and 46 are switching transistors, and 44 and 47 are base resistors 45 and 46, respectively.

A timer circuit 48 is input to the output trigger terminal of the comparator 39, and its output is input to the OR gate 41. The timer circuit 4B has a function of generating one pulse after a predetermined time has elapsed after inputting the trigger signal. 49 is an R9-FF circuit, and the one-shot pulse generation circuit 34 and OR are connected to the set and reset terminals, respectively.
The output of gate 55 is connected. Further, its Q output is connected to the base of a transistor 50 for driving an LED via a base resistor 51. Reference numeral 52 represents an LED connected to its collector for indicating that the strobe is being charged, and reference numeral 53 represents a current limiting resistor. 54 is the power-up clear signal (
This is a generation circuit (hereinafter abbreviated as puc signal) and has a function of generating one pulse when the main switch 30 is closed. Reference numeral 55 is a two-man operated OR gate to which the output of the Zener diode 26 and the PUG signal are input, and its output is connected to the reset terminal of R5-FF49 and the OR gate 40.
is being input.

Figure 1 shows the operation of the electric circuit of the present invention configured as described above.
This will be explained with reference to the voltage waveform in (b).

When the main switch 30 is closed by the first stroke of the camera's release button, one pulse is generated from the PUC signal generation circuit 54, and R5-FF 42 and 49 are initially reset via OR gates 55 and 40, and their Q output is reset to L level. When the subject brightness is low and a low brightness warning signal (LL? signal) is generated from the photometry circuit 32, one pulse is generated from the one-shot pulse generation circuit 34, and R5-FF42 and 49 are set.
Their Q outputs are inverted to H level. Therefore, the switching transistor 46 is turned on, and the oscillation transistor 1
2 is also turned on, the step-up operation of the strobe starts, and the main capacitor 25 is charged.

Also, the transistor 50 is turned on and the LED 52 lights up to indicate that charging is in progress.

When this charging operation starts, the voltage U of the power supply battery 11
BAT rapidly decreases as shown in the figure when the temperature is low or the battery is exhausted. When the voltage becomes lower than the predetermined value v2, the output of the comparator 39 is inverted to H level, and R9-FF
42 is reset and its Q output (CGCOM signal) is L.
The switching transistor 46 is turned off, and the output of the inverter 43 becomes H level, so the transistor 45 is turned on. Therefore, the PNP transistor 13 is also turned on, and the oscillation transistor 12 is turned off.

Therefore, since the charging operation to the main capacitor 25 is stopped, the voltage UBAT of the power supply battery 11 returns to vI as shown in the figure. When the comparator 39 is inverted to H level, the timer circuit 48 is also triggered and starts operating, and after a predetermined period 34, one pulse is generated, thereby setting R5-FF42, and its Q output goes to H level. Invert.

Therefore, the transistor 46 is turned on, the transistor 45 is turned off, the oscillation transistor 12 is turned on, and the charging operation to the main capacitor 25 is restarted. As a result, the battery voltage UBAT decreases again, and when it falls below the predetermined value v2, the output of the comparator 39 is inverted to H level as described above.2. Charging operation stops.

By repeating the above operation, the main capacitor 25
The charging voltage UMAN increases as shown in the figure. As this charging voltage increases, the charging current itself also decreases, so the battery voltage tlBAT does not drop as much during charging as it does at the beginning of charging, and at the end of charging. In this case, the battery will not fall to the charging prohibition level and will reach the completion of charging. When charging is completed, the Zener diode 26 turns on, and the transistor 14
- 13 is turned on, the oscillation transistor 12 is turned off, and the charging operation is stopped, and the output of the OR gate 55 becomes H level, and R5-FF49 is reset.

Therefore, the transistor 50 is turned off, and the LE for displaying charging is turned off.
The port 52 turns off, indicating that the charging operation has ended.

In this embodiment, it goes without saying that the Zener voltage of the Zener diode 36 is set at least higher than the voltage at which the LED 52 can be lit.

Next, the second embodiment is shown in FIG. 2(a). In the configuration of this figure, only the points different from FIG. 1(a) will be described. 65 is a comparator, and 60 and 61 are Zener diodes connected in series. , 64 are resistors, and 62 and 63 are resistors connected in series. The input of the comparator 65 is the resistor 6
The (-) input is connected to the connection point between resistor 64 and Zener diode 60, respectively. 66
and 67 are two-man operated OR gates;
The output of the comparator 39 and the OR gate 55 are also input to the input 67. 68 is ccc
The R3-FF circuit outputs the ox signal, and the outputs of the OR gates 66 and 67 are input to the set and reset terminals, respectively.

The operation of this circuit having the above configuration will now be explained with reference to FIG. 2(b).

When the main switch 30 of the camera is closed and the photometry circuit 32 is energized, when the subject brightness is low, the LL signal is generated, and the R5 signal is passed through the OR gate 66 as in the first embodiment.
-FFB8 is set, its Q output is inverted to H level, and the strobe charging operation starts. When the battery is exhausted and its voltage rapidly drops below the v2 level, the output of the comparator 39 is inverted to H level, R5-FF88 is reset via the OR gate 67, and the Q output (aceOM signal) is The output of the inverter 43 is inverted to the L level, and the output of the inverter 43 is inverted to the H level, the strobe charging operation is stopped, and the battery voltage UBAT is restored, as in the first embodiment.

When the return level reaches the V□ level, the comparator 6
5 is inverted to H level, R9-FF 68 is set via OR gate 66, and its Q output is inverted to H level again, and the strobe charging operation is restarted. As a result, the battery voltage decreases, and when it drops below level 2, the charging operation of the strobe is prohibited as described above.By repeating the operation above 0, the charging voltage of the main capacitor 25 increases as shown in the figure. It's something that will happen. In this second embodiment, the restart of strobe charging is triggered by detecting the return of the battery voltage.

In this second embodiment as well, when the main capacitor is fully charged, the Zener diode 26 is turned on, the transistors 14-13 are turned on, the oscillation transistor 12 is turned off, and the strobe charging operation is stopped. Also, OR gate 55
Since the output of is inverted to H level, R5-FF68 is reset and the CGCOH signal is inverted to L level.

In the above embodiments, an LED is used as the display element during charging, but the present invention is not limited to this in any way. If another display element is used, it should be adjusted according to the lowest voltage at which it can emit light. All you have to do is set the v2 level.

The timer time of the timer circuit 48 in the first embodiment and the v rubel in the second embodiment are determined by taking into consideration the voltage recovery characteristics of the battery used, the guide number (GNO) of the strobe, etc. It is necessary to set it so that it does not become too long.

C.1 As described in detail, according to the present invention, even when the power source battery is exhausted or at low temperatures, it is possible to provide an excellent strobe charging indication.

In addition, by setting the predetermined level of the power supply battery to a level higher than the level at which light emitting elements such as LEDs can emit light, it is possible to provide a good charging display at all times even during strobe charging, and also have a function to restart the charging operation. Therefore, it is possible to provide a strobe device that does not cause any problems in charging operation.

[Brief explanation of drawings]

FIG. 1(a) is an electric circuit diagram showing a first embodiment of the present invention,
Figure 1 (b) is a voltage waveform diagram of Figure 2 (a), and Figure 2 (a)
2(b) is the electric circuit diagram of the second embodiment, and FIG. 2(a) is the electrical circuit diagram of the second embodiment.
voltage waveform diagram. A... Strobe circuit, 52... Charging operation display means,
B... Strobe circuit control circuit, 11... Power supply battery,
C: first detection circuit, D: stop/dock circuit stop circuit, Tt (48): timer circuit, E: second detection circuit.

Claims (3)

[Claims] (1) In a camera strobe device comprising a strobe circuit, a display means for displaying at least during charging operation of the strobe circuit, a control circuit for controlling the strobe circuit, and a power source battery, the control circuit comprises: A first detection circuit detects the voltage of the power supply battery, and when the voltage level of the power supply battery decreases to at least a voltage level at which the display means can be lit, the output of the first detection circuit detects the voltage of the power supply battery. A strobe device for a camera, characterized in that it has a stop circuit that stops the operation of the strobe circuit, and is configured to perform charging again after stopping. (2) In the camera strobe device according to claim 1, the control circuit has a timer circuit, the timer circuit is triggered by the first detection circuit, and the timer output causes the stoppage. A camera strobe device characterized by a circuit that stops the stop operation. (3) In the camera strobe device according to claim 1, the control circuit has a second detection circuit that detects the voltage of the power supply battery, and the detection level of the detection circuit is at least the second detection circuit that detects the voltage of the power supply battery. A strobe device for a camera, characterized in that the voltage level is set higher than the voltage level at which the display means can be lit, and the stop circuit stops the stop operation in response to an output of the second detection circuit.