JPH0451029A - Pulse-driven electronic flash device - Google Patents

Abstract

PURPOSE:To reduce glaringness that a person to be photographed has and to prevent a red-eye phenomenon from being generated by providing a reference pulse generating means, a start pulse generating means, a stop pulse generating means, a light emission trigger means, etc., and performing intermittent light emission plural times and giving the best lighting conditions for the purpose. CONSTITUTION:A pulse signal generation part 7 consists of the reference pulse generating means 8 which can vary the period of pulses, a frequency dividing and phase shifting circuit 9 which serves as the start pulse generating means and the stop pulse generating means by dividing the frequency of reference pulses, and a phase varying means circuit 10 which shifts the phase of a stop pulse about a start pulse. Then the light emission trigger means 3 for turning on a light emission part and a light emission stopping means 4 which stops the light emission of the light emission part are provided, light with constant brightness is emitted and stopped intermittently and continuously repeatedly, and the momentary brightness of the light is limited. Consequently, the glaringness is reduced and the red-eye phenomenon can be prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to pulse-driven electronic flash devices used in photography.

2. Description of the Related Art In recent years, with the spread of cameras, electronic flash devices (also called strobe devices) have come into widespread use. A conventional electronic flash device will be described below with reference to the drawings.

FIG. 5 is a block diagram of a conventional electronic flash device. A high voltage that can cause the xenon discharge tube of the light emitting section 2 to emit light is supplied from the power supply circuit 1 .

The trigger circuit 3 is a circuit that drives the light emitting section to cause it to emit light. The light emission stop circuit 4 is a circuit that forcibly stops the light emission of the xenon discharge tube of the light emitting unit 2, and is used in an auto electronic flash device having an auto circuit that automatically adjusts the exposure amount or an electronic flash device having a light emission amount adjustment function. (with a variable guide number), but not in electronic flysch devices with a manual function that maintains a constant amount of light. The camera synchronization switch 6 closes in response to shutter operation of the camera.

The operation of the conventional electronic flash device with the above configuration will be explained below. When the camera non-crossing switch 6 becomes mechanically or electronically conductive for a moment in response to the shutter operation of the camera, the trigger circuit 3 triggers the light emitting unit 2. By applying the pulse, the light emitting section 2
The xenon discharge tube starts discharging, emits flash light and emits a predetermined amount of light, and then stops emitting light when a stop signal from the light emission stop circuit 4 arrives. In other words, with conventional electronic flash devices, the flash fires only once while the shutter is open.

In addition, there are multi-electronic flash devices for professional and special photography, but they are expensive, large and heavy, and difficult to use, so they lack versatility.

Problems to be Solved by the Invention Conventional electronic flash devices instantaneously emit strong light and are extremely dazzling, making it difficult to photograph natural facial expressions, and may cause red-eye phenomenon. Red-eye phenomenon occurs when the pupil is dilated in a dark place that requires an electronic flash device, so when the strong light from the electronic flash device enters the pupil, the light reflects inside the eyeball and returns to the camera, resulting in a red image. This phenomenon is also known as pink eye. This problem is especially likely to occur when cameras have electronic flash devices built into them, and the distance between the light source and the lens is small.

Furthermore, as mentioned above, there has not been a device capable of realizing special photography in which the trajectory of a moving object is intermittently captured in a single photograph, so-called multi-electronic flash device photography, which is compact, lightweight, inexpensive, and easy to operate.

Furthermore, since conventional electronic flash devices emit light for only 7 seconds, it is not possible to predict the appearance of shadows before taking a picture, which is inconvenient.

Also, when shooting with a camera with a motor drive, for example 1
There were only a few electronic flash devices that could shoot 5 frames per second, which was impossible as the batteries got old, and the guide numbers were small.

SUMMARY OF THE INVENTION The present invention aims to provide an electronic flash device that solves the above-mentioned problems of the prior art.

Means for Solving the Problems In order to achieve the above object, the present invention includes a reference pulse generating means, a start pulse generating means for dividing the frequency of the reference pulse to generate a start pulse, and a start pulse generating means for dividing the frequency of the reference pulse to generate a start pulse. It has a stop pulse generation means for generating a stop pulse, a light emission trigger means, and a light emission stop means, and is configured to emit light intermittently a plurality of times, and the period of the reference pulse is variable, and We decided to vary the phase of the stop pulse with respect to the start pulse, and also to completely stop the light emission when the integrated value of the reflected light from multiple light emission reached a certain value. The first light emission trigger operation and the final light emission stop are configured to be related to the shutter operation of the camera, and are manually controlled.

In addition, these components are built into the same case as the camera.

Effect: With the above configuration, the present invention can repeatedly emit and stop light of a certain brightness intermittently and continuously, limit the brightness of the light at a certain moment, and reduce glare. Prevent the occurrence of red eye phenomenon. At this time, by varying the phase of the stop pulse with respect to the start pulse, the duty cycle of the pulse can be changed and the amount of light can be varied.

It also enables special photography, so-called multi-electronic flash devices, that intermittently captures the trajectory of a moving object in a single photo.

In addition, prior to photographing, an electronic flash device of a certain brightness is emitted intermittently and continuously, and by utilizing the afterimage phenomenon in the eyes, it is possible to confirm in advance the presence of shadows.

Furthermore, the pulse period can be varied to make it slightly longer than the photographing period of the motor drive, and forced synchronization can be achieved by closing the synchronization switch.

EMBODIMENT A pulse-driven electronic flash device according to an embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 is a block diagram of an electronic flash device according to an embodiment of the present invention. Components having the same functions as those of the conventional example shown in FIG.

The trigger circuit 3, which is a light emission trigger means, is a circuit that drives the light emitting section to emit light, and in this embodiment, it is also triggered by a start pulse, which will be described later.

The light emission stop circuit 4, which is a light emission stop means, is a circuit that forcibly stops the light emission of the xenon discharge tube of the light emitting unit 2.
In this embodiment, the light emission can also be forcibly stopped using a stop pulse, which will be described later. The switch 6 is a switch for switching between the conventional one-time light emission state and the pulse-driven electronic flash device of the present invention. The pulse signal generating section 7 further includes a reference pulse generating circuit 8 which is a reference pulse generating means that can vary the period of the pulse, a start pulse generating means which divides the reference pulse and generates a start pulse, and a stop pulse generator. It consists of a frequency divider phase shift circuit 9 which is also a stop pulse generating means for generating , and a phase variable circuit 1o which is a phase variable means which varies the phase of the stop pulse with respect to the start pulse.

The operation of the electronic flash device having the above configuration will be described below. A reference pulse is generated in the reference pulse generation circuit 8 of the pulse signal generation section 7. The period of this pulse can be varied by means described later. This reference pulse is frequency-divided by the frequency division and phase shift circuit 9, and a plurality of pulses with different phases are sequentially generated.The first pulse is generated when the camera synchronization switch 6 is closed or when the switch 6 is manually operated. This becomes the start pulse after being operated, triggers the trigger circuit 6, and drives the light emitting section 2 to emit light. A pulse selected by the phase variable circuit 1o and delayed from the start pulse is applied as a stop pulse to the light emission stop circuit 4, and the light emission of the xenon discharge tube of the light emitting section 2 is forcibly stopped.

FIG. 2 shows a specific circuit diagram of the pulse-driven electronic flash device of the present invention, and its structure and operation will be explained below.

In the figure, when the power switch SW1 is turned on, the DC voltage of the battery B is converted to AC by a converter circuit composed of the oscillation transistor Tr1, the bias resistance R1 of Trl, the oscillation transformer T1, and the bias resistance R2. The voltage is stepped up by the transmitting transformer T1, rectified by the high-voltage rectifying diode D1, and charges are stored in the main capacitor C1 with the polarity shown. When the voltage across the main capacitor C1 reaches the lighting voltage of the neon lamp Ne1, the neon lamp Ne1 lights up, indicating that charging is complete. R23 is a current limiting resistor for the neon lamp N e 1. At this time, charge is also stored in the trigger capacitor C3 via the trigger circuit stabilizing resistor R7. Thigh lifter 5C1
1 control transistor Tτ2 has resistors Ra and R at its base.
The voltage divided by s passes through the base resistor R4 and is biased in the forward direction, making it conductive, a collector current flows through the collector resistor R6, the collector of Tr2 is at ground potential, and the trigger inverter 5CR1 is not conductive. be.

On the other hand, when the potential of the main capacitor C1 increases, the current limiting resistor R12,) bias resistor R1 of the transistor Tr3
3, capacitor C5 is charged to the polarity shown. At the same time, the capacitor C9 is charged to the polarity shown in the figure by the potential caused by the current flowing through the resistor R2s.

The voltage across the capacitor C6 is kept constant by the Zener voltage of the photometric circuit power supply Zener diode Dz1.

When the open flash switch SW2 is closed, or when the camera synchro switch I is closed when the normal/pulse changeover switch SWa is at q'', the base potential of Tr2 becomes the same potential as the ground (emitter).
2 is non-conductive, and when the collector potential is higher υ, the thyristor 5CR1 is conductive.

R8 is a gate resistance. 03 due to conduction of 5CR1
The charge stored in the trigger transformer T is discharged, and the trigger transformer T
The voltage change on the primary side of 2 induces a high trigger voltage on the secondary side. This voltage is the xenon emission' [tube
The xenon discharge tube Xe1 starts discharging and emits a flash of light.

When the auto/manual changeover switch SW4 is connected to the C'' side, when the xenon discharge tube The base and emitter of the switching transistor Tr3 are forward biased and conductive, and the automatic level setting variable resistor VR
1. Current flows through the auto-level dividing resistor R14, lowering the emitter potential of the transistor Tr4 for controlling the thyristor 5CR3. Since the base and emitter of the transistor Br4 are reverse biased, the transistor Tr4 is non-conductive and becomes 116. The intersection of R17 is at ground potential and the thyristor j9
CR3 remains non-conductive, thyristor 5CR2 is not commutated, and xenon discharge tube Xe1 continues to discharge until the main capacitor C1 is no longer charged. In other words, it is a manual operation.

Next, when the switch SW4 is connected to the d'' side, when the xenon discharge tube Xe1 is discharged, the charge of the capacitor C9 is also discharged, and the discharge current causes the bias resistor R13 to be connected to the transistor Tr for photometry circuit neutralization.
The base and emitter of the transistor Ti4 are forward biased and conductive, current flows through the automatic level setting variable resistor VR1 and the automatic level dividing resistor R14, the emitter potential of the thyristor 5CR3 control function transistor Tr4 decreases, and the base and emitter of the transistor Ti4 decreases. Since the emitters are reverse biased, the transistor Tr4 is non-conductive and the intersection of R17 and R17 is at ground potential. Now, when the light emitted by the xenon discharge tube Xe1 enters the light-receiving phototransistor Trs as reflected light from the subject, the transistor Trs
A 6iC collector current flows and is integrated by the time constant of the integrating resistor R18 and the integrating capacitor C6, and the collector potential of the transistor Tr5 gradually decreases. Since this potential is applied to the base of the transistor Tr4 through the base resistor R15 of the transistor Tr4, eventually the transistor Tr4
conducts, current flows through the load resistor R16 and the gate resistor R17 of the thyristor 5CR3, a potential difference is generated across the resistor R17, and this voltage conducts the thyristor 5CR3 for controlling the xenon power transmission tube Xe1. At this time, capacitor C4
is charged with the polarity shown in the figure, so thyristor 5CR3
As the anode potential of thyristor 5CR3 becomes the ground potential due to the conduction of The light emission of the tube Xe1 is stopped.

The various operations of the conventional auto strobe have been described above, and next, the operations in the pulse drive state will be explained with reference to FIG.

The following description will be made with reference to FIG. 3, which shows the signal waveforms at each part of the pulse signal generator 7 and the light emitting state of the xenon discharge tube Xe1.

The operation will be described when the normal vane changeover switch SW8 is connected to the "h" side, the control signal changeover switch SW3 is connected to the "b" side, and the reset control switch SWe is connected to the "f" side. Note that it is more convenient to use interlocking switches for the normal pulse changeover switch SW8, the control signal changeover switch SW3, and the reset control switch SWe.

When manual/automatic changeover switch SW7 is connected to "k" (manual) side, set/reset changeover switch SW
5 to the “j” (reset) side, NANDl
, NAND2, R19.

R-S flip-flop (hereinafter referred to as R-
(abbreviated as 8FF) NANDl output is LO level/I/
(hereinafter abbreviated as rLJ), so NANDs,
NAND4, capacitor C7, C8゜resistor R21, R
22, the astable multiviprator (hereinafter referred to as AM (!)), which is the reference pulse generation circuit 8 which is composed of diodes D8 and D9, is inactive and does not emit pulses, so the series of circuits is It does not operate.If the set/reset changeover switch SW5 is connected to the i'' (set) side, the input of NANDl is the switch SWs.

rLJ through SW7 “k” (Figure 3B), R
-8FF's NAND1 output goes to HI level (hereinafter abbreviated as rHJ) (Figure 3A), AM starts oscillating the reference pulse signal as shown in Figure 3C, and switch SWs
It lasts until it is connected to the “j” side. The period of this reference pulse can be changed by varying the capacitance of capacitors C7 and C8. The four flip-flops FF1 to FF4 form a binary counter, and by inputting the output of AM NAND3 to the clock CK1 of FF1, the output Q1 of FF1 has the waveform shown in the third diagram. That is, the input pulse changes from rHJ to rLJ
The polarity is reversed at the moment it changes to , resulting in a signal with twice the pulse width. Similarly, the Q1 output of FF1 is the next stage FF.
2, the output Q2 oscillates at a repetition period twice as long as Ql, and the E output shown in FIG. 3 is obtained. F
The output Q3 of Fs is as shown in F in FIG. 3, and the output Q4 of FF4 is as shown in G in FIG. Binary counter FF1 to F
When each output Q1 to Q4 of F4 is added to the inputs R, S, T, and U of decoder DEC1, the output of decoder DEC1 becomes 0.
is the O position of D in Fig. 3, that is, only the waveform of Fig. 3 H is rHJ.Hereafter, the output 1 signal of DEC1 is outputted as an rHJ pulse at a position delayed by 1 pulse from output 0 (Fig. 3). In addition, the waveform of output 1 and the waveform of output 2 are delayed by one pulse to output rHJ, and one waveform shown in FIG. 3 can be obtained.

Here, when the output 0 of the decoder DEC1 is applied as a start pulse to the gate of the sirinuta 5CR1, the xenon discharge tube Xe1 starts discharging in the rHJ state, and the 3 outputs of the decoder DEC1 are selected as a stop pulse by the digital switch DSW1. When input to the "f" terminal of the reset control switch SWe via the inverter IN2, after the 3rd output becomes rHJ, the xenon discharge tube e1 stops emitting light. By switching the digital switch DSW1, the light emission stop time can be arbitrarily selected and the light emission time of the xenon discharge tube Xe1 can be changed. The ratio of the constant light emission period and the light emission stop period (duty cycle) can be arbitrarily selected. By combining it with the reference pulse period described above, the light emission conditions can be changed significantly.

In FIG. 3, K indicates the output 3 of the decoder DEC1, and L indicates the output cuff of the decoder DEC1. Similarly, M in FIG. 3 illustrates the light-emitting and extinguishing states of the xenon discharge tube Xe1 when the start pulse is selected as 0 output of the decoder DEC1 and the stop pulse is selected as 3 of the decoder DEC1. Set/reset switch SWs @t″(
When connected to the reset) side, NAND 1. NAND2
, R19°R20 R-S flip-flop (hereinafter abbreviated as R-8FF) NANDl output is "
Since AM is inactive and stops generating the reference pulse, the xenon discharge tube Xe1 will not emit light again.

In this state, set the set/reset switch SWs to 1.
When connected to the side, the electronic flash device emits light intermittently using a pulse drive method, so change the position of the electronic flash device and use the afterimage phenomenon of the eye to check the state of shadow occurrence, and then All you have to do is take a picture.

Note that it is convenient to use the set/reset changeover switch SWs if it is always biased toward the "i" side.

Next, when the manual/automatic changeover switch SW7 is connected to the "1" side, the normal/pulse changeover switch SWs
is a synchro switch that is linked to the camera shutter when connected on the "H" side! A pulse-driven light emitting operation can be performed in conjunction with the closing of the shutter.

Next, if you want to capture the trajectory of a moving object intermittently in a single photo, select the period of the reference pulse appropriately depending on the movement of the moving object, and use a bulb shutter to easily capture the trajectory of a moving object in a professional-like manner. You can take pictures.

FIG. 4 is a circuit diagram of an electronic flash device according to another embodiment. The difference from FIG. 2 is that the reset control switch SWe is connected to the gate of the thyristor 5CR3 and the dividing resistor R.
16* placed between the connection points of R17 and the resistor R16,
Inverter I is connected between the connection point of R17 and the input of NAND2.
The connection was made via N2. Due to the former, in the circuit of FIG. 2, the discharging of the xenon discharge tube Xe1 for each pulse is affected by the resistor R18 and capacitor C6 of the integrating circuit, but in the example of FIG. 4, it is not affected. In the latter operation, when the phototransinutor Tr5 receives the light emitted from the xenon discharge tube
When the base bias voltage decreases, Tr4 becomes conductive through transistor 5. Then, although the connection point of resistors R16 and R17 was at Arne potential, a flefter current Ic flows through the dividing resistors R16 and R17, the potential rises by the resistance value xIc of R17, and the input of inverter IN2 becomes rHJ. The output becomes rLJ. Therefore, R-3FF is reset, and at the same time, AM, which is the reference pulse generation circuit 8, stops oscillating the basic pulse, and the xenon discharge tube Xe1 does not emit light again. This provided a sufficient amount of exposure for photographing. In this case, although not shown, if the camera shutter closes before the light emission is completely finished, sufficient exposure will not be possible, so the inverter I
It is also possible to instruct the camera circuit to keep the shutter open until the output of N2 reaches rLJ. In this case, it is more convenient if the electronic flash device and camera are integrated, since there are no unnecessary connections.

When used with a motor-driven camera, force synchronization by varying the pulse cycle to make it slightly longer than the motor drive's shooting cycle, and generating a start pulse each time the synchronizer contact is closed. can be done.

In the above embodiments, the mechanical contacts displayed on each switch may be replaced with electronic contacts.

Further, each part of the pulse signal generation circuit including the reference pulse generation circuit is not limited to the exemplified method, and other circuit configurations may be used to obtain the same result. For example, a ring counter and a differentiation circuit may be used in combination with the frequency dividing and phase shifting circuit 9.

Furthermore, although this embodiment describes a pulse-driven electronic flash device alone, it will be even more convenient if the pulse-driven electronic flash device of the present invention is incorporated into the same cane as a camera.

DETAILED DESCRIPTION OF THE INVENTION As described above, the pulse-driven electronic flash device of the present invention includes a reference pulse generating means, a start pulse generating means for dividing the frequency of the reference pulse to generate a start pulse, and a start pulse generating means for dividing the frequency of the reference pulse to generate a start pulse. It has a stop pulse generation means for generating a stop pulse, a light emission trigger means, and a light emission stop means, and is configured to emit light intermittently a plurality of times, and the period of the reference pulse is varied, and the period of the reference pulse is varied. By having a phase variable means for varying the phase of the stop pulse, the emission interval and
By arbitrarily changing the duty cycle of lighting and turning off the light to provide the optimal lighting conditions for the purpose, you can reduce glare on the subject, prevent the occurrence of red-eye, and reduce the amount of light in a single photo. Special photography that intermittently records the trajectory of a moving object, so-called multi-electronic flash photography, can be realized in a compact, lightweight, inexpensive, and easy-to-operate manner.

Furthermore, by utilizing the afterimage phenomenon of multiple light emissions, it is possible to predict how shadows will appear before photographing, thereby increasing the photographic effect.

Furthermore, it can provide a photographing means with high practical effects, such as being able to follow the high-speed photography of a motor drive camera.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of a pulse-driven electronic flash device according to an embodiment of the present invention, FIG. 2 is a specific circuit diagram of the same device, and FIG. FIG. 4 is a graph showing the light emitting state of the discharge tube Xe1, FIG. 4 is a specific circuit diagram of a device according to another embodiment, and FIG. 6 is a block diagram of a conventional example. 1...Power supply circuit, 2...Light emitting section, 3.
...Trigger circuit which is a light emission trigger means, 4.
...Light emission stop circuit, which is a light emission stop means, 5...
...Switch, 6...Camera synchronization switch, 7...Pulse signal generator, 8...
A reference pulse generation circuit serving as a reference pulse generation means, 9...
. . . A frequency dividing phase shift circuit which is both a start pulse generation means and a stop pulse generation means for generating a stop pulse. 1o . . . A phase variable circuit which is a phase variable means. Name of agent: Patent attorney Shigetaka Awano and one other person

Claims (5)

[Claims] (1) a reference pulse generation means; a start pulse generation means for frequency-dividing the reference pulse to generate a start pulse; a stop pulse generation means for frequency-dividing the reference pulse and generating a stop pulse; and a light emitting section. A pulse-driven electronic flash device that has a light emission trigger means for causing light emission and a light emission stop means for stopping light emission of a light emitting part, and is configured to perform intermittent light emission a plurality of times. (2) The pulse-driven electronic flash device according to claim 1, wherein the period of the reference pulse is variable. (3) The pulse-driven electronic flash device according to claim 1 or 2, further comprising phase variable means for varying the phase of the stop pulse with respect to the start pulse. (4) The pulse-driven electronic flash device according to any one of claims 1 to 3, wherein the light emission is completely stopped based on the integrated value of the reflected light of a plurality of light emission. (5) The pulse drive according to any one of claims 1 to 4, wherein the first operation of the light emission triggering means and the last operation of the light emission stopping means are correlated with the operation of the shutter of the camera. Electronic flash device.