JPH1187082A - Stroboscope device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a stroboscope device avoiding a common power source for the concerned stroboscope device from being placed in an overload condition, in the case of oscillating a main capacitor charging transformer by a separate excitation fly back system. SOLUTION: When a large current load such as driving of a zoom motor is applied to a power source 1, in a CPU 101, a pulse width of an on-period of a stroboscopic pulse signal for driving an oscillation transformer 13 output from a stroboscope pulse signal generating circuit 35 is controlled so as to be relatively narrowed, or a pulse period is controlled so as to be relatively extended, or a charge signal generating circuit 34 is controlled, a charge is temporarily stopped.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a strobe device applied to a camera, and more particularly to an improvement of a strobe device having a circuit for exciting a main capacitor charging transformer in a separately excited flyback system.

[0002]

2. Description of the Related Art In recent years, in electronic still cameras with a built-in strobe, models using a separately-excited flyback type charging circuit as a strobe charging circuit have been put on the market due to ease of current control.

In a camera system equipped with such a strobe charging circuit, a power supply for charging a main capacitor is used in addition to a power supply for driving various actuators and the like in the camera system in accordance with recent miniaturization of the camera. It is often used also as a power supply supplied to each control circuit.

[0004]

However, in recent years, various types of actuators mounted on a camera are diversified, and while a power supply having a high current supply capability is desired, downsizing of the power supply itself is also demanded. It is difficult to mount a power supply that can withstand overload.

By the way, when the actuator or the like is driven, a large load is applied to the common power supply, causing a temporary drop in the power supply voltage.

On the other hand, since it is desirable that the charging operation of the strobe main capacitor can be performed quickly and accurately, the charging operation has been performed in parallel even when driving another actuator or the like in the camera. .

At this time, if the actuator is driven alone, the degree of drop of the power supply voltage does not cause any trouble. However, if the charging operation of the main capacitor is performed in parallel with the driving of the actuator. , The load exceeds the rating of the power supply, and the system cannot operate.
There is a possibility that various troubles may occur.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-described problems, and it is possible to prevent an overload state of a common power supply of a strobe device when oscillating a transformer for charging a main capacitor in a separately excited flyback system. An object of the present invention is to provide a strobe device.

[0009]

In order to achieve the above object, a first strobe device of the present invention comprises a main capacitor for storing electric charge for causing a flash tube to emit light, and a device for charging the main capacitor. A transformer whose secondary side is connected to the main capacitor, an excitation pulse generation circuit for supplying a pulse voltage to the primary side of the transformer to excite the transformer, an excitation pulse generation circuit and other loads. A power supply circuit for supplying power to the strobe device, comprising: a power supply state detection unit that detects that power is supplied from the power supply circuit to a specific one of the other loads; When the power supply state detecting means detects that power is supplied to the specific load, the circuit relatively narrows the pulse width of its own output pulse or sets a pulse width. Characterized in that it is one that is configured to control the generation of output pulses so as to those relatively extend the.

[0010] In order to achieve the above object, a second aspect of the present invention is provided.
The strobe device of the first strobe device,
The power supply state detecting means is configured to detect that power is supplied to the specific load based on an output voltage of the power supply circuit.

In order to achieve the above object, a third aspect of the present invention is provided.
The strobe device of the first strobe device,
The power supply state detecting means is configured to detect that power is supplied to the specific load based on recognition of a system control unit that controls the power supply state in the flash device in a comprehensive manner. It is characterized by.

[0012] In order to achieve the above object, a fourth aspect of the present invention is provided.
The strobe device has a main capacitor for storing electric charge for causing a flash tube to emit light, a transformer having a secondary side connected to the main capacitor for charging the main capacitor, and a primary side for the transformer. An excitation pulse generation circuit for supplying a pulse voltage to excite the transformer;
A strobe device comprising the excitation pulse generation circuit and a power supply circuit for supplying power to another load, the power supply voltage detection means for detecting a supply voltage from the power supply circuit, and a specific power supply having a relatively low internal impedance. Power supply type detection means for detecting that the power supply has been applied, the excitation pulse generation circuit is configured to detect when the power supply voltage detection means detects a value greater than or equal to a predetermined value or when the power supply type detection means uses the specific power supply If it is detected that the pulse width of its own output pulse is specified to a predetermined maximum value or the pulse period is controlled to a predetermined minimum period, it is configured to control the generation of the output pulse It is characterized by.

[0013]

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

FIG. 1 is an electric circuit block diagram mainly showing the electric configuration of a camera having a strobe device according to a first embodiment of the present invention.

As shown in the figure, the camera is a so-called digital camera having a function of picking up a subject image from an image pickup lens (not shown) by a CCD 42 and appropriately processing the same, and includes the following strobe device.

This strobe device has a main condenser 2
9. A strobe device having a normal light-emitting function having a strobe discharge tube 26 that emits light by a charging voltage charged in the camera 9. A power supply 1 for supplying a power supply voltage to each circuit, and a power supply filter 104 of the power supply 1
An oscillation circuit 102 having a so-called separately excited flyback system configuration for generating a pulse voltage for charging the main capacitor 29; the strobe discharge tube 26; and the main unit for charging the light emission voltage of the strobe discharge tube 26. A capacitor 29; a trigger circuit 103 for generating a trigger signal for light emission of the strobe discharge tube 26; an IGBT 27 which is a light emission control element of the strobe discharge tube 26;
A charge signal generating circuit 34, a strobe pulse signal generating circuit 35 for generating a signal for controlling the oscillation operation of the oscillation circuit 102 under the control of
A charging voltage detecting circuit 36 for detecting a charging voltage from the power supply 1 and a power supply voltage detecting circuit 50 for detecting a power supply voltage of the power supply 1
A light emission permission signal generating circuit 3 for generating a light emission permission signal for the strobe discharge tube 26 under the control of the CPU 101.
8 and a light emission stop signal generating circuit 40 for generating a light emission stop signal for the strobe discharge tube 26 constitute a main part.

The camera, in addition to the above-described strobe device, controls a CCD 42 for capturing an image of a subject from an imaging lens (not shown), a gain control amplifier 44 for controlling the amplification factor of the CCD 42, and a shutter speed (not shown). A shutter speed control circuit 43, a photometric circuit 41,
It has.

A first release button 61 for generating a photographing preparation start signal and a second release button 62 for generating a photographing operation start signal are connected to the CPU 101.

Further, the CPU 101 is connected to a zoom motor driving circuit 51 for a zoom motor 52 for driving a zoom lens (not shown) and a known distance measuring circuit 53.

A memory card 72 for storing predetermined information is connected to a CPU 10 via a memory card I / F circuit 71.
Connected to 1.

Note that the inside of the CPU 101 has a DR
A RAM 105 such as an AM is provided.

Hereinafter, the configuration of the above-described strobe device will be described.

The power supply 1 supplies a power supply voltage to each circuit of the camera in addition to the strobe device. The power supply filter 104 connected to the output terminal of the power supply 1 includes a coil 2 and a capacitor 3, and smoothes an output voltage of the power supply 1.

The oscillation circuit 102 is connected to the output terminal of the power supply filter 104. The oscillation circuit 102 has a so-called separately excited flyback circuit configuration, and is configured as follows.

The emitter of the PNP digital transistor 4 is connected to the positive terminal of the power supply 1 via the power supply filter 104. The base of the PNP digital transistor 4 is connected to the collector of the NPN transistor 30, and the base of the transistor 30 is connected to the output terminal of the charge signal generating circuit 34 via the resistor 33.
The collector of an NPN digital transistor 32 is connected to the base of the NPN transistor 30, and the output terminal of the strobe pulse signal generating circuit 35 is connected to the base of the transistor 32.

The output terminal of the strobe pulse signal generating circuit 35 is connected to the base of an NPN digital transistor 5, and the collector of the transistor 5 is connected to the PNP digital transistor 4 via a collector resistor 6.

Resistors 7 and 8 are connected to the collector of the NPN digital transistor 5, and the base and N of the NPN transistor 9 are respectively connected through these resistors.
It is connected to the base of the PN transistor 10.

The bases of the NPN transistors 9 and 10 are connected to GND via resistors 11 and 12, respectively. The collectors of the NPN transistors 9 and 10 are connected to the oscillation transformer 13.

The charge signal generating circuit 34 and the strobe pulse signal generating circuit 35 are both controlled by the CPU 101 to control the oscillating operation of the oscillating transformer 13. That is, under the control of the CPU 101, the oscillating circuit 102 is operated by the strobe pulse signal from the strobe pulse signal generating circuit 35, and a predetermined pulse voltage, that is, a pulse current is supplied to the primary side of the oscillating transformer 13. As a result, the oscillation transformer 13 is excited and the oscillating winding current exhibits a sharp change. The details of the operation will be described later.

The output terminal of the oscillation circuit 102 is connected to the anode of a rectifier diode 14 that rectifies the secondary AC output of the oscillation transformer 13. The cathode of the diode 14 is connected to the respective anodes of the main capacitor 29 and the strobe discharge tube 26 via the diode 15 for preventing leakage.

On the other hand, the cathode of the rectifier diode 14 is connected to the charging voltage detection circuit 36 via the resistor 16. The detection result of the charging voltage detection circuit 36 is
01 is input.

The trigger circuit 103 includes a resistor 21, a trigger capacitor 22, a trigger coil 23, a doubler capacitor 24, a resistor 25, a thyristor 20, a resistor 19, a capacitor 18, a resistor 17, and a trigger pulse generation circuit connected to the CPU 101. 37 are connected as shown. Then, under the control of the CPU 101, the trigger coil 2 is controlled by a control signal from the trigger pulse generation circuit 37.
3 generates a trigger pulse.

The IGB is connected to the cathode of the strobe discharge tube 26.
The collector of T27 is connected, and a resistor 28
The light emission permission signal generating circuit 38 is connected to the
9, a light emission stop signal generation circuit 40 is connected.

A power supply voltage detection circuit 50 for detecting the voltage of the power supply 1 is connected in parallel to the capacitor 3 at the output terminal of the power supply filter 104, and constantly detects the voltage of the power supply 1.

As described above, the charge signal generation circuit 34, the strobe pulse signal generation circuit 35, the charge voltage detection circuit 36, the trigger pulse generation circuit 37, the light emission permission signal generation circuit 38, and the light emission stop signal generation circuit 40
1 and controlled.

The gain control amplifier 44
And the shutter speed control circuit 43 and the photometry circuit 41 are also CPU
It is connected to 101 and controlled.

A basic charging operation in the strobe device of the first embodiment configured as described above will be described.

The charge signal generation circuit 34 and the strobe pulse signal generation circuit 35 are controlled by the CPU 101.
When predetermined charge signals and strobe pulse signals are output from the respective transistors 4, 5, 9, 10,
30, 32 and the resistors 6, 7, 8, 11, 12, 31 are operated, and the oscillation transformer 13 oscillates.

That is, under the control of the CPU 101,
When a low-active strobe pulse signal is output from the strobe pulse signal generation circuit 35 while an "H" level charge signal is being output from the charge signal generation circuit 34, each circuit of the oscillation circuit 102 operates. Then, a predetermined pulse voltage is supplied to the primary side of the oscillation transformer 13. The oscillation transformer 13 is excited by the pulse voltage, that is, the pulse current, and oscillates.

Then, the main capacitor 29 is charged via the rectifier diode 14 and the diode 15 by the secondary high voltage output generated by the steep change of the oscillation winding current of the oscillation transformer 13.

The strobe pulse signal generating circuit 3
By controlling the pulse width of the strobe pulse signal from No. 5, the pulse voltage applied to the oscillation transformer 13 can be controlled, and as a result, the amount of charge to the main capacitor 29 can be controlled.

On the other hand, the charging voltage detection circuit 36 is connected to the cathode of the rectifier diode 14 via the resistor 16 as described above, and detects the charging voltage of the main capacitor 29.

Next, a charging operation when various actuators and the like in the camera system having the strobe device of the first embodiment are driven will be described.

First, an example of charge control when the zoom motor operates will be described with reference to FIG.

FIG. 2 shows a power supply voltage drop, a charge signal from a charge signal generation circuit, and a signal from a strobe pulse signal generation circuit when a zoom motor is driven in a camera system having the strobe device of the first embodiment. 5 is a timing chart showing characteristics of a strobe pulse signal and a charging voltage VMC of a main capacitor.

As shown in the figure, a large current is required to drive the zoom motor 52, and at this time, the power supply voltage of the power supply 1 temporarily drops. When a large load is applied to the common power supply during zoom driving or the like, the CPU 101 detects this, and during this driving, the charge signal from the charge signal generation circuit 34 is set to the “L” level to temporarily stop the charging operation.

At this time, when the CPU 101 detects and recognizes that a large current load such as driving of a zoom motor occurs,
The charging signal is turned off slightly before the start of the driving, the strobe pulse signal is also turned off, and the charging is stopped.

As described above, when a relatively large load is applied to the common power supply, the charging operation is temporarily stopped before and after the control by the CPU 101.

As a result, it is possible to prevent the system from being inoperable or the like without overloading the common power supply.

Next, an example of charge control immediately after the first release button 61 is pressed will be described with reference to FIG.

FIG. 3 shows a camera system provided with the strobe device of the first embodiment, immediately after the first release button 61 is pressed, a power supply voltage drop due to auto-focus distance driving, etc., and a signal from the charge signal generation circuit. 5 is a timing chart showing characteristics of a charge signal, a strobe pulse signal from a strobe pulse signal generation circuit, and a charge voltage VMC of a main capacitor.

As shown in the figure, the first release button 6
When 1 is pressed, the distance is measured by the distance measuring circuit 53. Also at this time, the power supply voltage of the power supply 1 temporarily drops, and the CPU 101 detects this, as in the case of the zoom drive, and sets the charge signal from the charge signal generation circuit 34 to the “L” level to perform the charging operation. Is temporarily stopped.

In FIG. 3, the first release button 61
After the first trigger due to the pressing of the button, when the auto focus reaches the locked state, the power supply under the control of the CPU 101 exhibits a characteristic substantially equivalent to a dummy load (for example, when a recording operation or the like is executed). An appropriate load having such specifications is connected. The state of the drop in the power supply voltage with the dummy load connected is determined by the power supply voltage
0 and the CPU 101 detect and determine whether or not the normal operation can be executed even after the auto focus is in the locked state and the process shifts to the second trigger operation by pressing the second release button 62 subsequently.

Here, when it is determined that normal operation is difficult, a measure is taken in which shifting to the second trigger operation is not allowed. On the other hand, only when it is determined that the normal operation can be executed, the shift to the second trigger operation is permitted.

Next, an example of charge control when driving such as writing operation to the RAM 105 and data transfer in the CPU 101 will be described with reference to FIG.

FIG. 4 shows the RAM 1 in the CPU 101 after the second release button is turned on in the camera system including the flash device of the first embodiment.
05, data transfer, power supply voltage drop due to memory card writing, etc., charge signal from charge signal generation circuit, strobe pulse signal from strobe pulse signal generation circuit, charge voltage VMC for main capacitor
6 is a timing chart showing the characteristics of FIG.

As shown in FIG.
When driving for writing operation to 105, data transfer operation, writing operation to a memory card, and the like is performed, the load of the power supply becomes lighter than that in the case of the above-described zoom motor driving. Monitor the power supply voltage and only when the power supply voltage falls below a predetermined threshold,
The oscillation of the oscillation transformer 13 is controlled.

That is, for these relatively light loads,
The charge signal from the charge signal generation circuit 34 is "H"
The ON state is maintained at the level, and the charge amount is reduced only when the power supply voltage falls below the threshold value, for example, by narrowing the pulse width of the ON period (low active) of the strobe pulse signal.

As described above, even when a relatively light load is applied to the common power supply, if the load is equal to or more than a predetermined value, the amount of charge is reduced and the power supply is prevented from being overloaded.

Next, an example of charge control when an LCD (not shown) is turned on will be described with reference to FIG.

FIG. 5 shows a power supply voltage drop due to the turning on of the LCD, a charge signal from the charge signal generation circuit, and a strobe pulse from the strobe pulse signal generation circuit in the camera system having the strobe device of the first embodiment. 5 is a timing chart showing characteristics of a signal and a charging voltage VMC of a main capacitor.

As shown in the figure, although the power supply voltage drops even when the LCD is turned on, the load on the power supply when the LCD is turned on is lighter than that during the zoom driving, but the writing operation to the RAM 105 in the CPU 101 is performed. It becomes bigger than etc.

In this case, the LCD is turned on by the CPU 10
1, the CPU 101 controls the oscillation of the oscillation transformer 13 to reduce the charge amount by, for example, reducing the on-period pulse width of the strobe pulse signal from the strobe pulse signal generation circuit 35 in response to turning on the LCD.

As a result, it is possible to prevent a problem such as system inoperability without overloading the common power supply.

In the above description, the power supply state detecting means for detecting the presence or absence of power supply to the specific load employs a configuration in which the detection is performed based on the output of the power supply voltage detection circuit. The power supply state to the system may be controlled by the CPU as a whole, and the presence or absence of power supply to the specific load may be detected based on the recognition by the CPU at this time.

Next, a second embodiment of the present invention will be described.

The basic structure of the strobe device of the second embodiment is the same as that of the first embodiment.
As a power supply for charging the main capacitor or for driving each circuit of the camera system, a power supply system which can selectively use a commercial power supply such as a so-called AC adapter is provided. The other configuration is the same as that of the first embodiment, and the detailed description is omitted here.

Since the power supply such as the AC adapter generally has a low internal impedance, the power supply drop due to the load is smaller than that of the power supply used in the first embodiment.

Therefore, even if the charging operation of the main capacitor is overlapped during zoom driving, for example, when a large current load is applied to the power supply, the power supply voltage can be reduced by a small amount, but the power consumption is temporarily reduced. Since the value becomes high, there is a possibility that an adverse effect due to overcurrent may occur.

In view of such circumstances, the strobe device according to the second embodiment sets the maximum charging energy in each sequence and prevents overcurrent even when a power supply having a low internal impedance is used. Features.

That is, in the configuration of the strobe device of the first embodiment (see FIG. 1), a power supply type detection function for detecting that a specific power supply such as an AC adapter having a relatively low internal impedance is applied to the CPU 101 is provided. Provide. When the CPU 101 detects that the specific power supply is applied by the power supply type detection function, the CPU 101 sets the on-period pulse width of the strobe pulse signal from the strobe pulse signal generation circuit 35 to a predetermined maximum value, or Control is performed so that the cycle is defined as a predetermined minimum cycle.

According to this embodiment, by setting the maximum charging energy in each sequence, it is possible to prevent an overcurrent even when a power supply having a low internal impedance is used.

Next, a third embodiment of the present invention will be described.

The basic structure of the strobe device of the third embodiment is the same as that of the first embodiment.
A power supply having a large current supply capacity is used. The other configuration is the same as that of the first embodiment, and the detailed description is omitted here.

Even if the applicable power source is not a power source such as an AC adapter having a low internal impedance as in the second embodiment, even in the case of a power source having a large current supply capacity and capable of withstanding a large current load, the same as described above. There is a possibility that adverse effects due to the current may occur.

In view of such circumstances, the strobe device of the third embodiment sets the maximum charging energy in each sequence and prevents overcurrent even when a power supply having a large current supply capacity is used. It is characterized by.

That is, in the configuration of the strobe device of the first embodiment (see FIG. 1), the power supply voltage detection circuit 5
When the voltage of the power supply 1 is detected at 0 and the voltage drop is small even when a large load is applied, the on-period pulse width of the strobe pulse signal from the strobe pulse signal generation circuit 35 is specified to a predetermined maximum value. Alternatively, control is performed so that the pulse period is set to a predetermined minimum period.

According to this embodiment, since the maximum charging energy in each sequence is set, overcurrent can be prevented even when a power supply having excellent current supply capability is used.

[0079]

As described above, according to the present invention, when the transformer for charging the main capacitor is oscillated by the separately excited flyback method, the strobe device for preventing the common power supply of the strobe device from being overloaded. Can be provided.

[Brief description of the drawings]

FIG. 1 is an electric circuit block diagram mainly showing an electric configuration of a camera having a strobe device according to a first embodiment of the present invention.

FIG. 2 illustrates a camera system including the strobe device according to the first embodiment, in which a zoom motor is driven.
5 is a timing chart showing characteristics of a power supply voltage drop, a charge signal from a charge signal generation circuit, a strobe pulse signal from a strobe pulse signal generation circuit, and a charge voltage VMC of a main capacitor.

FIG. 3 is a diagram illustrating a camera system including the strobe device according to the first embodiment, a power supply voltage drop due to autofocus distance measurement drive, a charge signal from a charge signal generation circuit, and a strobe immediately after a first release button is pressed. Strobe pulse signal from the pulse signal generation circuit,
5 is a timing chart showing characteristics of a charging voltage VMC of a main capacitor.

FIG. 4 illustrates a camera system including the strobe device according to the first embodiment. In the camera system, a write operation to a RAM in a CPU, a data transfer, a power supply voltage drop due to a memory card write, a charge signal from a charge signal generation circuit, 5 is a timing chart showing characteristics of a strobe pulse signal from a strobe pulse signal generation circuit and a charging voltage VMC of a main capacitor.

FIG. 5 is a diagram showing a power supply voltage drop caused by turning on an LCD, a charge signal from a charge signal generation circuit, a strobe pulse signal from a strobe pulse signal generation circuit, 5 is a timing chart showing characteristics of a charging voltage VMC of a capacitor.

[Description of Signs] 1 Power supply 13 Oscillation transformer 26 Strobe discharge tube 29 Main capacitor 34 Charge signal generation circuit 35 Strobe pulse signal generation circuit 36 Charge voltage detection circuit 50 Power supply voltage detection circuit 52 Zoom motor 53: distance measuring circuit 61: first release button 72: memory card 101: CPU 102: oscillation circuit 103: trigger circuit

Claims (4)

[Claims] 1. A main capacitor for storing electric charge for causing a flash tube to emit light, a transformer having a secondary side connected to the main capacitor for charging the main capacitor, and a primary side connected to the transformer. A strobe device comprising: an excitation pulse generation circuit for supplying a pulse voltage to excite the transformer; and a power supply circuit for supplying power to the excitation pulse generation circuit and other loads. Power supply state detecting means for detecting that power is supplied to a specific one of the other loads is provided, and the excitation pulse generating circuit determines that the power supply state detecting means is supplying power to the specific load. During detection, the output pulse generation is controlled so that the pulse width of its own output pulse is made relatively narrow or the pulse period is made relatively elongated. A flash device which is characterized in that one that is. 2. The power supply state detecting means is configured to detect that power is supplied to the specific load based on an output voltage of the power supply circuit. 2. The strobe device according to 1. 3. The power supply state detecting means is configured to detect that power is supplied to the specific load based on recognition of a system control unit that controls the power supply state in the flash device in a comprehensive manner. The strobe device according to claim 1, wherein 4. A main capacitor for storing electric charge for causing a flash tube to emit light, a transformer having a secondary side connected to the main capacitor for charging the main capacitor, and a primary side connected to the primary side of the transformer. A strobe device comprising: an excitation pulse generation circuit for supplying a pulse voltage to excite the transformer; and a power supply circuit for supplying power to the excitation pulse generation circuit and other loads. A power supply voltage detecting means for detecting a supply voltage and a power supply type detecting means for detecting that a specific power supply having a relatively low internal impedance is applied are provided. When the value is equal to or more than the value or when the power supply type detecting means detects that the specific power supply is applied, the pulse width of its own output pulse is set to a predetermined A flash device which is characterized in that which has been configured to control the generation of output pulses so as to define a specified or pulse period to atmospheric value to a predetermined minimum period.