JP2001330873A - Stroboscope control system for camera - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a stroboscope control system for camera in which the charge voltage of a main capacitor can be charged to voltage near the limit of the withstand voltage of the capacitor regardless of the degradation degree of a power source and the reduction of the light quantity of the light emission of a stroboscope is small and moreover, which can be manufactured at a low cost. SOLUTION: A central processing unit CPU controls the charging of a main capacitor C3 and the light emission of a Xenon discharge tube in which the charged energy is used and also, detects that the charge voltage of the capacitor C3 reaches a light emittable voltage. Moreover, the CPU measures a charging time from a time when the charging of the capacitor C3 is started till a time when the charge voltage reaches the light emittable voltage and calculates a charge stopping time from a time when the charge voltage reaches the light emittable voltage till a time when the charging is properly stopped based the charging time. Furthermore, the CPU measures a time after the charge voltage reaches the light emittable voltage and stops the charging of the capacitor C3 based on a comparison with the charge stopping time.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to the control of an electronic flash, that is, a so-called strobe used in a camera, and more particularly to a strobe control system for a camera in which the influence of deterioration of a battery power source is reduced and the amount of emitted light is properly controlled. Things.

[0002]

2. Description of the Related Art In order to secure a sufficient amount of light emitted from a strobe, it is important to charge a main capacitor, which is a light emission energy source of the strobe light source, to a voltage near a withstand voltage limit. However, if the battery is charged beyond the withstand voltage, the main capacitor is destroyed. Therefore, it is necessary to protect the charged voltage from exceeding the withstand voltage. Conventionally, the following two methods have been mainly used as a method of protecting against the withstand voltage. The first withstand voltage protection method is to set the turn ratio of the primary winding and the secondary winding of the oscillation transformer to a small value, and to set the output voltage of the DC / DC converter to a voltage that does not exceed the withstand voltage of the main capacitor. It is a method of setting so that it becomes. However, this first withstand voltage protection method requires a long time to charge the main capacitor because the supply voltage is low. In general, a battery such as a dry battery is used as a power supply for charging the main capacitor of the strobe. However, when the battery used for this power supply is exhausted and the battery voltage decreases, DC / DC power is used. The output voltage of the converter also decreases, the main capacitor cannot be charged sufficiently, and the amount of emitted light becomes insufficient.

A method for compensating for such a drawback of the first withstand voltage protection method is a second withstand voltage protection method. In the second withstand voltage protection method, the winding ratio of the primary winding and the secondary winding of the oscillation transformer is set to a large value. This is a method in which the output voltage of the converter can be boosted to near the withstand voltage limit of the main capacitor. However,
This second withstand voltage protection method, when the battery is new,
The output voltage of the DC / DC converter may exceed the withstand voltage of the main capacitor, and may destroy the main capacitor. Therefore, in the second withstand voltage protection method, the charging voltage of the main capacitor is detected by some method, and the charging of the strobe is stopped when the main capacitor is charged to near the withstand voltage limit.
As a method of detecting the charging voltage of the main capacitor,
For example, there are the following methods (1) to (3).

(1) The voltage of the main capacitor is measured by an A / D converter, and charging is stopped when the voltage of the main capacitor approaches the withstand voltage limit. This method has the following problems. That is, the first problem is that when this method is employed, an expensive A / D converter is required. The second problem is that the charging voltage of the main capacitor is usually much higher than the input voltage of the A / D converter. That is, a conversion circuit is required. Therefore,
This method adds considerably to the manufacturing costs. FIG. 5 shows an example of a strobe control circuit using this method. The strobe control circuit shown in FIG.
T, capacitors C1, C2, C3, C4, C11, diodes D1, D2, D11, transistors Q1, Q2,
Q3, resistors R1, R2, R3, R4, R5, R6, R
7, R8, R10, R11, thyristor SCR, transformers T1, T2, xenon discharge tube (Xenon discharge tube) Xe, and central processing unit CPU.

The negative side of the battery power supply BAT, which is a low-voltage DC power supply, is connected to one power supply terminal VSS of the central processing unit CPU.
The positive side of the battery power supply is connected to the anode of a diode D11 having the illustrated polarity, and the cathode of the diode D11 is connected to the other power supply terminal V of the central processing unit CPU.
Connected to DD. The capacitor C11 is connected between the power supply terminals VDD and VSS of the central processing unit CPU. The positive side of the battery power supply BAT includes a resistor R1 and a resistor R
2 is connected to a terminal SPC of the central processing unit CPU via a series circuit. The connection point between the resistors R1 and R2 is connected to the base of the pnp transistor Q1, and the emitter of the transistor Q1 is connected to the positive side of the battery power supply BAT. The collector of the transistor Q1 is connected to the emitter of the npn transistor Q2 via a series circuit of the resistors R3 and R4. The base of the transistor Q2 is connected to a connection point between the resistors R3 and R4, and the collector of the transistor Q2 is connected to the base of the pnp transistor Q3. Transistor Q3
Is connected to the emitter of the transistor Q1, and the collector of the transistor Q3 is connected to the negative side of the battery power supply BAT (that is, the power supply of the central processing unit CPU) via the first winding N11 on the primary side of the transformer T1. Terminal V
SS).

[0006] The secondary winding of the transformer T1 is composed of a second winding N12 and a third winding N13 connected in series with each other, and the second winding N12 and the third winding N13 are connected to each other. Line N13
Is connected to the emitter of the transistor Q2. The other end of the second winding N12 is connected to the anode of the diode D1 having the illustrated polarity, and the other end of the third winding N13 is connected to the negative side of the battery power supply BAT via the resistor R5. The diode D1 is connected to the cathode of the diode D1.
2 is connected to the anode, and one end of the resistor R6 is connected to the cathode of the diode D2. Diode D1
Between the cathode of the battery power supply BAT and the negative side of the battery power supply BAT.
7 and a resistor R8 are connected in series, and a capacitor C4 is connected in parallel to the resistor R7 and resistor R8 series circuit. The connection point between the resistors R7 and R8 is connected to the A / D conversion input terminal ADIN of the central processing unit CPU. The other end of the resistor R6 is connected to the anode of the thyristor SCR, and the cathode of the thyristor SCR is connected to the negative side of the battery power supply BAT. The gate of the thyristor SCR is connected to the negative side of the battery power supply BAT via the capacitor C1, and the gate of the thyristor SCR is
It is connected to the trigger signal terminal TRG of the central processing unit CPU via the resistor R10. Further, the capacitor C
1, a resistor R11 is connected in parallel.

The anode of the thyristor SCR is connected to one end of a primary winding N21 of a transformer T2 via a capacitor C2, and one end of a secondary winding N22 of the transformer T2 is connected to a trigger terminal of a xenon discharge tube Xe. I have. The other end of the primary winding N21 and the other end of the secondary winding N22 are commonly connected to the negative side of the battery power supply BAT. A capacitor C3, which is a main capacitor, is connected between the cathode of the diode D and the negative side of the battery power supply BAT, and a discharge path of the xenon discharge tube Xe is connected in parallel with the capacitor C3. That is, the charging voltage of the main capacitor C3 is divided by a series circuit of the resistor R7 and the resistor R8, voltage-converted, and supplied to the A / D conversion input terminal ADIN of the central processing unit CPU. Central processing unit CPU
Is the voltage input to the A / D conversion input terminal ADIN,
It is converted into a digital value and taken in, and the charge voltage is determined and detected.

(2) If the voltage of the main capacitor becomes a voltage near the withstand voltage limit using a voltage detecting element such as a Zener diode without using the A / D converter,
Provide a circuit to stop oscillation. This method also uses an expensive voltage detecting element, so that the manufacturing cost increases. FIG. 6 shows an example of a strobe control circuit using this method.
Is shown in In the flash control circuit shown in FIG. 6, the same parts as those in FIG. 5 are denoted by the same reference numerals. The strobe control circuit shown in FIG. 6 includes a battery power supply BAT, capacitors C1, C2, C3, C11, diodes D1, D11,
Transistors Q1, Q2, Q3, Q4, Q12, Q1
4, resistors R1, R2, R3, R4, R5, R6, R9,
R10, R11, R12, R13, R14, R15, R
16, R17, R18, thyristor SCR, Zener diode ZD, neon tube (neon discharge tube) Ne, transformers T1, T2, xenon discharge tube Xe, and central processing unit CPU.

The negative side of the battery power supply BAT, which is a low-voltage DC power supply, is connected to one power supply terminal VSS of the central processing unit CPU.
The positive side of the battery power supply is connected to the anode of a diode D11 having the illustrated polarity, and the cathode of the diode D11 is connected to the other power supply terminal V of the central processing unit CPU.
Connected to DD. The capacitor C11 is connected between the power supply terminals VDD and VSS of the central processing unit CPU. The positive side of the battery power supply BAT includes a resistor R1 and a resistor R2.
Are connected to the collector of the npn transistor Q12 via a series circuit of The emitter of the transistor Q12 is connected to the negative side of the battery power supply BAT (that is, the power supply terminal VSS of the central processing unit CPU). The terminal SPC of the central processing unit CPU is connected to the base of the transistor Q12 via a resistor R12 and a resistor R13 in series, and a resistor R14 is connected between the base and the emitter of the transistor Q12. Resistance R1 and resistance R
2 is connected to the base of a pnp transistor Q1, and the emitter of the transistor Q1 is connected to the battery power supply B
Connected to the positive side of AT.

The collector of the transistor Q1 is connected to a resistor R3.
And a resistor R4 are sequentially connected in series to the emitter of the npn transistor Q2. The base of the transistor Q2 is connected to a connection point between the resistors R3 and R4, and the collector of the transistor Q2 is connected to a pnp transistor Q3.
Connected to the base. The emitter of the transistor Q3 is connected to the emitter of the transistor Q1, and the collector of the transistor Q3 is connected to the negative side of the battery power supply BAT via the first winding N11 on the primary side of the transformer T1. The secondary winding of the transformer T1 is composed of a second winding N12 and a third winding N13 connected in series with each other, and the second winding N12 and the third winding N13 are connected to each other.
Is connected to the emitter of the transistor Q2. The other end of the second winding N12 is connected to the anode of the diode D1 having the illustrated polarity, and the other end of the third winding N13 is connected to the negative side of the battery power supply BAT via the resistor R5. One end of a resistor R6 is connected to the cathode of the diode D1.

The other end of the resistor R6 is connected to the anode of the thyristor SCR via a resistor R9.
Is connected to the negative side of the battery power supply BAT. The gate of the thyristor SCR is connected to the negative side of the battery power supply BAT via the capacitor C1.
The gate of the CR is also connected to a trigger signal terminal TRG of the central processing unit CPU via a resistor R10. Further, a resistor R11 is connected in parallel with the capacitor C1. The anode of the thyristor SCR is connected to one end of a primary winding N21 of a transformer T2 via a capacitor C2, and one end of a secondary winding N22 of the transformer T2 is connected to a trigger terminal of a xenon discharge tube Xe. The other end of the primary winding N21 and the other end of the secondary winding N22 are commonly connected to the negative side of the battery power supply BAT. Diode D
1 and the negative side of the battery power supply BAT, a capacitor C3 as a main capacitor is connected, and a discharge path of a xenon discharge tube Xe is connected in parallel with the capacitor C3.

One end of a neon tube Ne is connected to the connection point between the resistors R6 and R9, and the other end of the neon tube Ne is connected to the cathode of a Zener diode ZD. The connection point between the resistors R12 and R13 is connected to the collector of the npn transistor Q14, and the emitter of the transistor Q14 is connected to the negative side of the battery power supply BAT. A resistor R15 is connected between the base and the emitter of the transistor Q14. The base of the transistor Q14 is connected to the anode of the Zener diode ZD via the resistor R16. The other end of the neon tube Ne and the cathode of the Zener diode ZD are connected to the negative side of the battery power supply BAT via a resistor R17 and a resistor R18 in series. The connection point between the resistors R17 and R18 is connected to the base of the npn transistor Q4, and the emitter of the transistor Q4 is connected to the negative side of the battery power supply BAT. The collector of the transistor Q4 is connected to the terminal READY of the central processing unit CPU. That is, the Zener diode ZD is used as a voltage detecting element, and when the charging voltage of the main capacitor C3 becomes a voltage near the withstand voltage limit, the oscillation is stopped.

(3) As an example other than the above, see JP-A-7-
Japanese Patent No. 22191 discloses that oscillation transformers having different turn ratios are provided and used by switching them, and booster circuits having different characteristics are provided and used by switching them. Also, JP-A-8-122869
In the publication, a tap is provided on the secondary winding of the oscillation transformer,
It is disclosed to switch and use it in a timely manner. on the other hand,
At the time of flash photography by a camera, the following two methods have been mainly used in order to keep the amount of light incident on the film surface constant. The first method for adjusting the amount of incident light is as follows.
Depending on the distance to the subject and film sensitivity, etc.,
This is a method of changing the size of the aperture of the stop without changing the amount of light emitted from the strobe. The second method for adjusting the amount of incident light is as follows.
In this method, the amount of light emitted from the strobe is changed in accordance with the distance to the subject at the time of shooting, the film sensitivity, and the aperture value.

The first method of adjusting the amount of incident light described above, that is, a method of adjusting the amount of incident light on the film surface by changing the aperture value, that is, the size of the aperture opening without changing the amount of light emitted from the strobe, is a flashmatic method. It is widely used for simple compact cameras and the like. This method does not need to control the amount of light of the strobe, so it can be configured and used at low cost. However, in this method, the aperture value is determined by the photographing distance and cannot be arbitrarily selected by the photographer, so that it is difficult to reflect the photographer's intention in the photograph. On the other hand, the second method of adjusting the amount of incident light, that is, a method of controlling and adjusting the amount of light emitted from a strobe in order to adjust the amount of incident light on the film surface, is usually an expensive insulated gate bipolar transistor (I
The light emission is stopped during light emission of the strobe by using an insulated gate bipolar transistor (GBT) and a thyristor. Therefore, this method
The circuit configuration becomes complicated and the manufacturing cost increases.

FIG. 7 shows an example of a flash control circuit using this method. 7, the same parts as those in FIG. 5 are denoted by the same reference numerals. The strobe control circuit shown in FIG. 7 includes a battery power supply BAT, capacitors C2, C3, C
6, C7, C11, diodes D1, D2, D3, D
4, D11, transistors Q1, Q2, Q3, Q5, Q
6, Q7, Q8, resistors R1, R2, R3, R4, R5,
R6, R7, R8, R21, R22, R23, R24,
R25, R26, R27, R28, Zener diode ZD, insulated gate bipolar transistor IGBT, transformers T1, T2, xenon discharge tube Xe, and central processing unit CPU.

The negative side of the battery power supply BAT, which is a low-voltage DC power supply, is connected to one power supply terminal VSS of the central processing unit CPU.
The positive side of the battery power supply is connected to the anode of a diode D11 having the illustrated polarity, and the cathode of the diode D11 is connected to the other power supply terminal VDD of the central processing unit CPU. The capacitor C11 is connected between the power supply terminals VDD and VSS of the central processing unit CPU. The positive side of the battery power supply BAT includes a resistor R1 and a resistor R
2 is connected to a terminal SPC of the central processing unit CPU via a series circuit. The connection point between the resistors R1 and R2 is connected to the base of the pnp transistor Q1, and the emitter of the transistor Q1 is connected to the positive side of the battery power supply BAT. The collector of the transistor Q1 is connected to the emitter of the npn transistor Q2 via a series circuit of the resistors R3 and R4. The base of the transistor Q2 is connected to a connection point between the resistors R3 and R4, and the collector of the transistor Q2 is connected to the base of the pnp transistor Q3.

The emitter of the transistor Q3 is connected to the emitter of the transistor Q1, and the collector of the transistor Q3 is connected to the first winding N11 on the primary side of the transformer T1.
Is connected to the negative side of the battery power supply BAT (that is, the power supply terminal VSS of the central processing unit CPU).
The secondary winding of the transformer T1 includes a second winding N12 and a third winding N13 connected in series with each other,
The connection point between the second winding N12 and the third winding N13 is connected to the emitter of the transistor Q2. The other end of the second winding N12 is connected to the anode of the diode D1 having the illustrated polarity, and the other end of the third winding N13 is connected to the negative side of the battery power supply BAT via the resistor R5.
The cathode of the diode D1 is connected to the anode of the diode D2, and the cathode of the diode D2 is connected to a resistor R
6 is connected to one end. A resistor R7 and a resistor R7 are connected between the cathode of the diode D1 and the negative side of the battery power supply BAT.
8 series circuits are connected.

The connection point between the resistors R7 and R8 is connected to the A / D conversion input terminal ADIN of the central processing unit CPU. The other end of the resistor R6 is connected via a capacitor C2 to one end of a primary winding N21 of a transformer T2, and one end of a secondary winding N22 of the transformer T2 is connected to a trigger terminal of a xenon discharge tube Xe. The other end of the primary winding N21 and the other end of the secondary winding N22 are commonly connected to the negative side of the battery power supply BAT. A capacitor C3, which is a main capacitor, is connected between the cathode of the diode D2 and the negative side of the battery power supply BAT. The second winding N12 on the secondary side of the transformer T1 is provided with an intermediate tap, and the anode of the diode D3 is connected to the intermediate tap. The cathode of the diode D3 is
The resistor R21 and the capacitor C6 are sequentially connected in series to the negative side of the battery power supply BAT. Capacitor C6
In parallel, a Zener diode ZD is connected as the illustrated polarity, that is, the anode is connected to the negative side of the battery power supply BAT. The base of an npn transistor Q5 is connected to a trigger signal terminal TRG of the central processing unit CPU via a resistor R22.
Are connected to the negative side of the battery power supply BAT.

A resistor R23 is connected between the base and the emitter of the transistor Q5. Zener diode Z
The cathode of D, that is, the connection point between the resistor R21 and the capacitor C6, is connected to the collector of the transistor Q5 via a resistor R24 and a resistor R25 in series.
The connection point between the resistors R24 and R25 is connected to the base of the pnp transistor Q6, and the collector of the transistor Q6 is connected to the negative side of the battery power supply BAT via the resistor R26. The emitter of the transistor Q6 is connected to a resistor R
21 and the connection point of the capacitor C6. The collector of the transistor Q6 has an npn transistor Q
7 and the base of the pnp transistor Q8 are commonly connected. The collector of the transistor Q7 is connected to a connection point between the resistor R21 and the capacitor C6, and the collector of the transistor Q8 is connected to the negative side of the battery power supply BAT. The emitter of the transistor Q7 and the emitter of the transistor Q8 are commonly connected to each other, and are connected to the gate of the insulated gate bipolar transistor IGBT.

Insulated gate bipolar transistor IGB
The emitter of T is connected to the negative side of the battery power supply BAT, and the collector of the insulated gate bipolar transistor IGBT is connected to the connection point between the resistor R6 and the capacitor C2. The cathode of the diode D2 is a xenon discharge tube C
3 is connected to one end of the discharge path, and the other end of the discharge path of the xenon discharge tube Xe is connected to the anode of the diode D4. The cathode of the diode D4 is connected to the collector of the insulated gate bipolar transistor IGBT. One end of a resistor R27 is connected to the anode of the diode D4, one end of a capacitor C7 is connected to the other end of the resistor R27, and the other end of the capacitor C7 is connected to the cathode of the diode D4. One end of a resistor R28 is connected to the anode of the diode D4, and the other end of the resistor 28 is connected to the negative side of the battery power supply BAT. With such a configuration, the insulated gate bipolar transistor IG
By using the BT, light emission can be stopped during light emission of the strobe. As examples other than the above, see JP-A-2-24.
Japanese Patent Publication No. 2242 discloses that the charging energy is selectively adjusted by selecting one charging time from a plurality of charging times according to the usage state of the camera.

[0021]

As described above, in order to secure a sufficient light emission amount of the strobe, it is desirable that the charging voltage of the main capacitor is charged to near the withstand voltage limit. Therefore, as a method of protecting the charging voltage from being higher than the withstand voltage, conventionally, the ratio of the number of turns of the primary winding to the secondary winding of the oscillation transformer is set to be small, and DC / DC is set.
A method of setting the output voltage of the converter so as not to exceed the withstand voltage of the main capacitor has been mainly used. However, such a method requires a long time to charge the main capacitor due to a low supply voltage. In general, a battery such as a dry battery is used as a power supply for charging the main capacitor of the strobe. However, when the battery used for this power supply is exhausted and the battery voltage decreases, DC / DC power is used. The output voltage of the converter also decreases, the main capacitor cannot be charged sufficiently, and the amount of emitted light becomes insufficient.

In order to compensate for the drawbacks of such a method, the ratio of the number of turns between the primary winding and the secondary winding of the oscillation transformer is set to a large value.
There has been proposed a method of increasing the output voltage of the DC / DC converter to near the withstand voltage limit of the main capacitor. However, in such a method, when the battery is new, the output voltage of the DC / DC converter may exceed the withstand voltage of the main capacitor, and the main capacitor may be destroyed. Therefore, in this method, the charging voltage of the main capacitor is detected by some method, and the charging of the strobe is stopped when the main capacitor is charged to near the withstand voltage limit. On the other hand, at the time of flash photography with a camera, in order to keep the amount of light incident on the film surface constant,
Depending on the distance to the subject and film sensitivity, etc.,
A method of changing the size of the aperture of the aperture and a method of changing the amount of light emitted from the strobe in accordance with the distance to the subject at the time of shooting, the film sensitivity, and the aperture value have been mainly used.

The former method, that is, the method of adjusting the incident light amount on the film surface by changing the aperture value, ie, the size of the aperture opening without changing the light emission amount of the strobe, is called a flashmatic, and is a simple compact camera. Widely used for etc. This method does not require control of the amount of light of the strobe, so it can be configured and used at low cost, but since the aperture value is determined by the shooting distance and the photographer cannot select it arbitrarily, It is difficult to reflect the photographer's intention in the photograph. In addition, the latter method, that is, the method of controlling and adjusting the amount of light emitted from a strobe to adjust the amount of light incident on the film surface, usually uses an expensive insulated gate bipolar transistor and a thyristor, etc. Since the configuration is such that light emission is stopped, the circuit configuration becomes complicated and the manufacturing cost increases.

The present invention has been made in view of the above circumstances, and can charge the main capacitor to a voltage near the withstand voltage limit regardless of the degree of deterioration of the power supply such as a battery. It is a first object of the present invention to provide a camera strobe control system that can be manufactured at a low cost with a small decrease in the amount of emitted light. Another object of the present invention is to provide a strobe control system for a camera, which can control the amount of emitted light in accordance with a change in a photographing distance, a film sensitivity, and an aperture value of a photographing lens, and can be manufactured at low cost. The purpose is.

[0025]

According to the first aspect of the present invention, there is provided a strobe control system for a camera according to the present invention, wherein an output of a low voltage DC power supply is converted into a high DC voltage to achieve the above object. A strobe control system for a camera that controls a strobe device that uses a charge of a capacitor and emits a xenon discharge tube using the energy charged in the main capacitor to irradiate a subject with light, controls start and stop of charging of the main capacitor. Charge control means for controlling light emission of a strobe using charging energy of the main capacitor, light emission control means for detecting that the charging voltage of the main capacitor has reached a light emission enabled voltage, The charging from the start of charging the main capacitor by the charging control means to the reaching of the light emission enabling voltage. A first time counting means for measuring time,
Based on the time measured by the first timing means,
Calculating means for calculating a charging stop time from when the charging voltage of the main capacitor reaches the voltage capable of emitting light until the charging is properly stopped; and by means of the voltage capable of emitting light, the charging voltage of the main capacitor is reduced to the voltage capable of emitting light. Second time measuring means for measuring the time after the time has reached,
Comparing the time measured by the time measuring means with the charging stop time obtained by the calculating means, and when the time measured by the second time measuring means is equal to or longer than the charging stopping time obtained by the calculating means, the charge controlling means And a comparison control means for stopping charging of the main capacitor.

According to a second aspect of the present invention, there is provided a strobe control system for a camera according to the present invention, wherein photographing distance information generating means for generating photographing distance information to a subject of a camera, and an aperture value of a photographing lens for photographing the subject are set. Aperture value setting means, film sensitivity setting means for setting the film sensitivity of the camera, and the charging stop time obtained by the calculating means,
The image processing apparatus further includes a correction control unit that changes based on at least one of the information on the shooting distance, the aperture value of the shooting lens, and the film sensitivity.

According to a third aspect of the present invention, a strobe control system for a camera according to the present invention instructs preparation for photographing of a camera by an on-operation of a first stage, and instructs a shutter release operation by an on-operation of a second stage. A release switch of a two-stage operation type, wherein the comparison control means is configured to: (1) when the first stage of the release switch is off at the time when the voltage of the main capacitor reaches a voltage capable of emitting light; The charging of the main capacitor is stopped, and when the first stage of the release switch is turned on, the charging of the main capacitor is restarted.From the time when the voltage of the main capacitor reaches the voltage at which light emission is possible again, After charging the main capacitor for the charging stop time determined by the calculating means, the charging is stopped, and (2) the first stage of the release switch Means that the charging of the main capacitor is stopped only after the charging of the main capacitor is performed for the charging stop time calculated by the arithmetic unit without stopping the charging of the main capacitor. Features.

According to a fourth aspect of the present invention, there is provided a strobe control system for a camera according to the present invention.
Means for metering the subject in response to the on operation of the step, wherein the comparison control means restarts charging only when it is determined that strobe light emission is necessary based on the result of light measurement by the light metering means It is characterized by including. The flash control system for a camera according to the present invention according to claim 5, further comprising a flash mode setting means for setting a flash operation mode of the flash, and wherein the comparison control means comprises a first stage of the release switch. In response to the ON operation, the state of the strobe mode setting means is checked, and the apparatus is characterized in that means for restarting charging only when it is determined that strobe light emission is necessary is included.

According to a sixth aspect of the present invention, in the camera strobe control system according to the present invention, even when the second stage of the release switch is turned on by the comparison control means, the release operation is performed during the charging operation of the strobe. Is further included. According to a seventh aspect of the present invention, there is provided a camera strobe control system according to the present invention, further comprising a storage unit for storing a calculation result in the calculation unit. The flash control system for a camera according to the present invention according to claim 8 is characterized by further comprising means for deleting the calculation result of the calculation means stored in the storage means after emission of the flash. According to a ninth aspect of the present invention, in the camera strobe control system according to the present invention, the storage unit is a volatile storage unit, and the storage contents of the storage unit are erased when the power of the camera is turned off. I have.

According to a tenth aspect of the present invention, in the camera strobe control system according to the present invention, the first time-measuring means is charged when the charging stop time, which is a calculation result of the calculating means, is stored in the storage means. It is characterized in that the comparison control means does not measure time and includes means for performing charge stop control using the charge stop time stored in the storage means. The strobe control system for a camera according to the present invention as set forth in claim 11, wherein the light emission control means applies a voltage higher than the voltage of the main capacitor to the xenon discharge tube to trigger the xenon discharge tube. It is characterized by including. 13. The flash control system for a camera according to claim 12, further comprising first reference time holding means for holding a first reference time, and wherein the calculating means measures the first reference time. When the charging time from the start of charging of the main capacitor to the reaching of the light emission enabling voltage is shorter than the first reference time, the charging is stopped by using the first reference time instead of the charging time. It is characterized by including means for obtaining time.

According to a thirteenth aspect of the present invention, in the camera strobe control system according to the present invention, the first reference time holding means has substantially the highest performance as the low-voltage DC power supply used for charging the main capacitor. It is characterized in that it includes means for holding a time set substantially equal to the charging time from the start of charging to the voltage at which light emission is possible when a high power supply is used as the first reference time.
15. The flash control system for a camera according to claim 14, further comprising a second reference time holding unit that holds a second reference time longer than the first reference time, and the comparison control unit. Means that the charging time from the start of charging of the main capacitor to the voltage at which light emission is possible
When the time is longer than the reference time, a means for stopping the charging of the main capacitor when the second reference time is reached is provided. According to a fifteenth aspect of the present invention, in the camera strobe control system according to the present invention, the charging control means has already reached the light emission enabling voltage based on the detection signal of the light emission enabling voltage detection means. In this case, it is characterized by further including means for avoiding charging of the main capacitor.

According to a sixteenth aspect of the present invention, in the camera strobe control system according to the present invention, the second time counting means includes a means for subtracting a charging stop time calculated by the calculating means with a lapse of time, and The comparison control means is characterized by including means for detecting that the subtraction result is either zero or negative. The strobe control system for a camera according to the present invention described in claim 17, wherein the calculating means uses time information separately calculated and stored in advance as a charging stop time based on the first reference time. It is characterized by including means.

According to a eighteenth aspect of the present invention, in the camera strobe control system according to the present invention, the arithmetic unit includes the first flash unit.
A charging stop time based on the charging time measured by the time measuring means is separately calculated in advance, and selected from a plurality of charging stop times stored in correspondence with the charging time in accordance with the charging time. It is characterized by including a means for outputting the data.

According to a nineteenth aspect of the present invention, in the camera strobe control system according to the present invention, the arithmetic unit includes the first flash unit.
The present invention is characterized in that the charging time measured by the time measuring means is multiplied by an arbitrary constant to obtain a charging stop time. 21. The strobe control system for a camera according to claim 20, wherein the calculating means multiplies the charging time measured by the first time measuring means by a constant proportional to the charging time. It is characterized by including means for determining the stop time. The strobe control system for a camera according to the present invention as set forth in claim 21, further comprising a third reference time holding means for holding a third reference time, and wherein the calculating means sets the calculated charging stop time to the third reference time. When the third reference time is longer than the third reference time, a means for outputting the third reference time as the charging stop time is included.

[0035]

The strobe control system for a camera according to the first aspect of the present invention converts the output of the low-voltage DC power supply into a high DC voltage and uses it for charging the main capacitor, and uses the energy charged in the main capacitor. In a strobe control system for a camera, which controls a strobe device that emits light from a xenon discharge tube to irradiate a subject, charging control means controls start and stop of charging of the main capacitor, and emission control means controls the start and stop of the main capacitor. While controlling the light emission of the strobe using the charging energy, the light emission possible voltage detecting means detects that the charging voltage of the main capacitor has reached the light emission possible voltage, and the first time measuring means causes the charge control means to perform the light emission. At the time of charging from the start of charging of the main capacitor until the voltage at which light emission is possible is reached Is calculated, and a charging stop time from when the charging voltage of the main capacitor reaches the voltage at which light emission is possible to when charging is appropriately stopped is calculated by the calculating means based on the time measured by the first timing means. ,
The second time measuring means measures the time after the charging voltage of the main capacitor reaches the light emitting possible voltage by the light emitting possible voltage detecting means, and measures the time measured by the second time measuring means and the calculating means. The calculated charging stop time is compared by the comparison control means, and when the time measured by the second timing means is equal to or longer than the charging stop time obtained by the calculation means, the comparison control means sets the charge control means. To stop charging the main capacitor.

Also, in the camera strobe control system according to claim 2 of the present invention, the photographing distance information generating means includes:
Generating photographing distance information to a subject of the camera, setting an aperture value of a photographing lens for photographing the subject by aperture value setting means, setting a film sensitivity of the camera by film sensitivity setting means, The charge suspension time obtained in step (c) is changed by the correction control means based on at least one of the shooting distance, the aperture value of the shooting lens, and the film sensitivity.

A strobe control system for a camera according to a third aspect of the present invention is a two-stage operation in which the first stage of the ON operation instructs the camera to prepare for photographing, and the second stage of the ON operation instructs the shutter release operation. Equipped with a release switch,
And, when the voltage of the main capacitor reaches the voltage at which light emission is possible, (1) when the first stage of the release switch is off, the comparison control means stops charging the main capacitor, When the first stage of the release switch is turned on, the charging of the main capacitor is restarted. From the point in time when the voltage of the main capacitor reaches the voltage at which light emission is possible again, only for the charging stop time obtained by the calculating means. After charging the main capacitor, the charging is stopped, and (2) when the first stage of the release switch is on, the charging of the main capacitor is stopped without stopping the charging of the main capacitor. Means for charging the main capacitor for the charging stop time determined by the above, and then stopping the charging.

A strobe light control system for a camera according to a fourth aspect of the present invention includes a light metering means for metering an object in response to an ON operation of a first stage of the release switch, and the comparison control means includes a light metering means. A means for restarting charging only when it is determined that strobe light emission is necessary based on the photometric result of the means is included. The strobe control system for a camera according to claim 5 of the present invention further comprises a strobe mode setting means for setting a flash operation mode of the strobe, and the comparison control means controls a first-stage ON operation of the release switch. Responsively, the status of the strobe mode setting means is confirmed, and a means for restarting charging only when it is determined that strobe light emission is necessary is included. In the camera strobe control system according to a sixth aspect of the present invention, the comparison control means further includes means for prohibiting the release operation during the charging operation of the strobe even when the second stage of the release switch is turned on. Contains.

The camera strobe control system according to claim 7 of the present invention further includes storage means for storing a result of the calculation by the calculation means. The flash control system for a camera according to claim 8 of the present invention further includes means for erasing the calculation result of the calculation means stored in the storage means after the strobe light is emitted. In a camera strobe control system according to a ninth aspect of the present invention, the storage means is a volatile storage means, and the stored contents of the storage means are erased when the power of the camera is turned off. According to a tenth aspect of the present invention, in the camera strobe control system, the first time measuring means does not measure the charging time when the charging stop time, which is the result of the calculation by the calculating means, is stored in the storage means. The comparison control means includes means for performing charge stop control using the charge stop time stored in the storage means. An electronic flash control system according to claim 11 of the present invention, wherein the light emission control means includes means for applying a voltage higher than the voltage of the main capacitor to the xenon discharge tube to trigger the xenon discharge tube. .

A strobe control system for a camera according to a twelfth aspect of the present invention further includes first reference time holding means for holding a first reference time, and wherein the calculating means measures the first reference time. When the charging time from the start of charging of the main capacitor to the reaching of the light emission enabling voltage is shorter than the first reference time, the charging is stopped by using the first reference time instead of the charging time. Includes means to determine time. According to a thirteenth aspect of the present invention, in the camera strobe control system according to the thirteenth aspect, the first reference time holding unit uses a power supply having substantially the highest performance as the low-voltage DC power supply used for charging the main capacitor. And means for holding a time set approximately equal to the charging time from the start of charging to the voltage at which light emission is possible in the first reference time as the first reference time. A strobe control system for a camera according to claim 14 of the present invention comprises:
A second reference time holding unit for holding a second reference time longer than the first reference time, wherein the comparison control unit sets a charging time from a start of charging of the main capacitor to a time at which a light emission enabling voltage is reached; Means for stopping the charging of the main capacitor when the second reference time is reached when the second reference time is longer than the second reference time.

In a flash control system for a camera according to a fifteenth aspect of the present invention, the charge control means has already reached the light emission enabling voltage based on the detection signal from the light emission enable voltage detection means. In such a case, a means for avoiding charging of the main capacitor is further included. 17. The flash control system for a camera according to claim 16, wherein the second time counting means includes means for subtracting the charging stop time calculated by the calculation means with the passage of time, and the comparison control means performs the subtraction. It includes means for detecting that the result is either zero or negative. The strobe control system for a camera according to claim 17 of the present invention includes a means in which the calculating means uses time information separately calculated and stored in advance as a charging stop time based on the first reference time. In.

[0042] In the strobe control system for a camera according to the eighteenth aspect of the present invention, the calculating means separately calculates a charging stop time based on the charging time measured by the first time measuring means in advance, and calculates the charging stop time as the charging time. It includes means for selecting and outputting from a plurality of charging stop times stored in association with each other according to the charging time. According to a nineteenth aspect of the present invention, in the camera strobe control system, the arithmetic means includes means for obtaining a charging stop time by multiplying the charging time measured by the first timing means by an arbitrary constant. . According to a twentieth aspect of the present invention, in the camera strobe control system according to the twentieth aspect, the calculating means multiplies the charging time measured by the first time measuring means by a constant proportional to the charging time to thereby reduce the charging stop time. Includes means to seek.

A strobe control system for a camera according to a twenty-first aspect of the present invention further includes a third reference time holding means for holding a third reference time, and wherein the calculating means determines that the determined charging time is equal to the third charging time. If the third reference time is longer than the reference time, a means for outputting the third reference time as the charging stop time is included. With such a configuration, the first
The main capacitor can be charged to a voltage near the withstand voltage limit regardless of the degree of deterioration of the power supply such as a battery, and there is little reduction in the amount of strobe light and it can be manufactured at low cost. Becomes possible. Also,
The above-described second object is achieved, and the amount of emitted light can be controlled in accordance with variations in the photographing distance, the film sensitivity, the aperture value of the photographing lens, and the like, and the production can be performed at low cost.

[0044]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a strobe control system for a camera according to the present invention will be described in detail based on embodiments with reference to the drawings. FIG. 1 shows a configuration of a main part of a camera strobe control system incorporated in a camera according to a first embodiment of the present invention. In FIG. 1, the same parts as those in FIG. 5 are denoted by the same reference numerals. The strobe control system for a camera shown in FIG.
Is provided. The strobe circuit unit 1 includes a capacitor C
1, C2, C3, diode D1, transistor Q1,
Q2, Q3, Q4, resistors R1, R2, R3, R4, R
5, R6, R9, R10, R11, R17, R18, thyristor SCR, transformers T1, T2, xenon discharge tube Xe and neon tube Ne. Central processing unit 2
Comprises a central processing unit CPU. The power supply unit 6 has a battery power supply BAT, a capacitor C11, and a diode D11.

The negative side of the battery power supply BAT, which is a low-voltage DC power supply of the power supply unit 6, is connected to the central processing unit CP of the central processing unit 2.
U is connected to the power supply terminal VSS on one low voltage side, the positive side of the battery power supply is connected to the anode of a diode D11 having the illustrated polarity, and the cathode of the diode D11 is connected to the other high voltage of the central processing unit CPU. Power supply terminal VDD
It is connected to the. The capacitor C11 is connected between the power supply terminals VDD and VSS of the central processing unit CPU. In the strobe circuit unit 1, the positive side of the battery power supply BAT of the power supply unit 6 is connected to a strobe power control output terminal SPC (Strobo) of the central processing unit CPU of the central processing unit 2 via a series circuit of the resistors R1 and R2. Power Contr
ol). The connection point between the resistors R1 and R2 is connected to the base of the pnp transistor Q1, and the emitter of the transistor Q1 is connected to the battery power supply BA
It is connected to the positive side of T. The collector of the transistor Q1 is connected to np through a series circuit of a resistor R3 and a resistor R4.
It is connected to the emitter of n transistor Q2.

The base of the transistor Q2 is connected to the connection point between the resistors R3 and R4, and the collector of the transistor Q2 is connected to the base of the pnp transistor Q3. The emitter of the transistor Q3 is
The collector of the transistor Q3 is connected to the negative side of the battery power supply BAT of the power supply section 6 (ie, the central processing section of the central processing section 2) via the first winding N11 on the primary side of the transformer T1. Power supply terminal VSS of unit CPU)
It is connected to the. The winding on the secondary side of the transformer T1 includes a second winding N12 and a third winding N connected in series with each other.
The connection point between the second winding N12 and the third winding N13 is connected to the emitter of the transistor Q2. The other end of the second winding N12 is connected to the anode of the diode D1 having the illustrated polarity, and the third winding N1
The other end of 3 is connected to the negative side of battery power supply BAT via resistor R5. One end of a resistor R6 is connected to the cathode of the diode D1.

The other end of the resistor R6 is connected to a neon tube Ne, a resistor R
17 and a resistor R18 in series and a battery power supply BA
It is connected to the negative side of T. The connection point between the resistors R17 and R18 is connected to the base of the npn transistor Q4, and the collector of the transistor Q4 is connected to the terminal READY of the central processing unit CPU. The emitter of the transistor Q4 is connected to the negative side of the battery power supply BAT. One end of a resistor R9 is connected to a connection point between the resistor R6 and the neon tube Ne. At the other end of the resistor R9,
The thyristor SCR anode is connected to the thyristor SCR.
The cathode of the CR is connected to the negative side of the battery power supply BAT. The gate of the thyristor SCR is connected to the negative side of the battery power supply BAT via the capacitor C1, and the gate of the thyristor SCR is also connected to the trigger signal terminal TRG of the central processing unit CPU via the resistor R10. Further, a resistor R11 is connected in parallel with the capacitor C1.

The anode of the thyristor SCR is connected to one end of a primary winding N21 of a transformer T2 via a capacitor C2, and one end of a secondary winding N22 of the transformer T2 is connected to a trigger terminal of a xenon discharge tube Xe. I have. The other end of the primary winding N21 and the other end of the secondary winding N22 are commonly connected to the negative side of the battery power supply BAT. Between the cathode of the diode D1 and the negative side of the battery power supply BAT,
A capacitor C3 as a main capacitor is connected, and a discharge path of a xenon discharge tube Xe is connected in parallel with the capacitor C3. The photographing distance information generating means 3 includes at least one of an auto-focus distance measuring unit of the camera and a distance setting unit in a manual focusing operation, and subjects distance information between the subject image forming surface and the subject, ie, photographing distance information. Is generated and input to the central processing unit CPU of the central processing unit 2. The distance information generated by the photographing distance information generating means 3 corresponds to the extension amount of a photographing lens (not shown). The film sensitivity information generating means 4 detects the sensitivity information of the loaded film in a film loading unit or the like of the camera, or generates film sensitivity information in response to a sensitivity setting operation of a setting operation unit by a user, and generates the film sensitivity information. It is input to the central processing unit CPU of the processing unit 2.

The photographing lens aperture information generating means 5 includes at least one of an AE (automatic exposure) metering section of the camera and an aperture operation section (for example, an aperture ring) for manually setting an aperture, and is adapted to the subject light amount at the time of photographing. An aperture value corresponding to the size of the aperture opening of the photographing lens, that is, aperture information is generated, and the central processing unit CPU of the central processing unit 2 generates the aperture value.
To enter. The central processing unit 2 controls the strobe and controls various operations of the camera (not shown in detail) by the central processing unit CPU.
The photographing distance information generating means 3 operates in association with the operation of the photographing lens, and generates photographing distance information corresponding to the positional information of the photographing lens. The film sensitivity information generating means 4 obtains film sensitivity information by detecting a so-called DX code displayed on a film case such as a film cartridge. The photographic lens aperture information generating means 5 generates aperture information by obtaining the open F value of the photographic lens, aperture value information when the aperture is stopped down, and the like. In order to achieve only the above-described first object of the present invention, the photographing distance information generating means 3, the film sensitivity information generating means 4, and the photographing lens aperture information generating means 5 do not necessarily need to be provided. Therefore, in the description of the first embodiment, a detailed description of the photographing distance information generating means 3, the film sensitivity information generating means 4, and the photographing lens aperture information generating means 5 will be omitted.

As is apparent from FIG. 1, the portion of the strobe circuit section 1 has substantially the same configuration as that of the conventional strobe which did not control the charging voltage. In the case of the present invention, however, it is set to be larger than in the prior art. Since there is almost no difference in the manufacturing cost of the oscillating transformer due to the difference in the number of turns, the present invention can be realized at substantially the same manufacturing cost as that of a conventional strobe which does not control the charging voltage. Next, the operation of the camera strobe control system according to the first embodiment of the present invention will be described in detail with reference to a control flowchart shown in FIG. FIG. 2 is a flowchart for achieving the first object of the present invention described above.
This is achieved by executing a program stored in advance in the central processing unit CPU of the central processing unit 2. In FIG. 1, to start charging the main capacitor C3, the central processing unit CPU sets the output terminal SPC for strobe power control to the "L (low potential)" level. As a result, the transistor Q1 is turned on, the transistor Q2 is turned on, the transistor Q3 for oscillation control of the DC / DC converter is turned on, oscillation starts, and the secondary winding N1 of the oscillation transformer T1 is started.
2, a high voltage is generated, and charging of the main capacitor C3 is started.

To stop charging the main capacitor C3, the output terminal SPC of the central processing unit CPU is set to "H".
(High potential) "level. As a result, the transistor Q1 is turned off, the transistor Q2 is turned off,
Then, the transistor Q3 for oscillation control is turned off,
The oscillation of the DC / DC converter is stopped, and the voltage on the secondary side of the oscillation transformer T1 disappears. As a result, charging of the main capacitor C3 is stopped. To fire the strobe, the trigger output terminal TR of the central processing unit CPU
G (Trigger) is set to the “H” level. When the trigger output terminal TRG becomes “H” level, a current flows through the gate of the thyristor SCR via the resistor R10, and the thyristor SCR
Is turned on, the electric charge accumulated in the trigger capacitor C2 flows through the primary winding N21 of the trigger transformer T2, and generates a high voltage on the secondary winding N22. This high voltage is applied to the trigger electrode of the xenon discharge tube Xe, and the xenon discharge tube Xe starts emitting light.

To detect that the charging voltage of the main capacitor C3 has reached the voltage at which light can be emitted, the level of the input terminal READY of the CPU is checked. When the charging voltage of the main capacitor C3 reaches the voltage at which light can be emitted, the neon tube Ne is turned on and a current flows. This current also flows to the base of the transistor Q4, turning on the transistor Q4, and setting the level of the input terminal READY of the central processing unit CPU to the “L” level. That is, by checking the level of the input terminal READY, the central processing unit CPU determines “H”
If it is at the level, it is uncharged, and if it is at the "L" level, it can be seen that it has been charged to the light emission enabling voltage. The first time measuring means for measuring the charging time from the start of charging the main capacitor C3 to the voltage at which light emission is possible is performed by the central processing unit C
This is achieved by executing a program on the PU. This program, for example, changes the level of the output terminal SPC,
The time from when the level is lowered to the “L” level until the level of the input terminal READY of the central processing unit CPU becomes the “L” level is measured, for example, by counting clocks having a constant period.

The charge stop time calculation for obtaining the charge stop time from the time when the main capacitor C3 starts to charge until the light emission voltage is reached until the light emission voltage is reached is calculated by the central processing unit. This is achieved by the CPU executing a prepared program. In this program, values calculated in advance for various values of the charging time are stored in a storage area as a table, and a value corresponding to a given charging time is selectively called from these stored values and used. (Claims 17 and 18). Alternatively, the charging time actually measured may be multiplied by an arbitrary constant (claim 19). Further, the program may multiply the actually measured charging time by an arbitrary constant (value) proportional to the charging time (claim 20).

The second timing means for measuring the time after the charging voltage of the main capacitor C3 reaches the voltage at which light emission is possible is also achieved by executing a program in the central processing unit CPU. The comparison control means for comparing the charging stop time obtained by the calculation means with the actual measurement time counted by the clock means is also achieved by executing the program in the central processing unit CPU. Next, the operation of the first embodiment of the present invention mainly relating to the first object of the present invention will be described with reference to the flowchart of FIG. (Step S1) The central processing unit CPU connects the terminal RE
The level of ADY is checked to determine whether or not the charging voltage of the main capacitor C3 has reached the light emission enabling voltage. (Step S2) If the charging voltage of the main capacitor C3 has reached the voltage at which light emission is possible, no charging is performed because charging has already been completed based on the strobe control method of the present invention (claim 15).

(Step S3) If the charging voltage of the main capacitor C3 has not reached the light emission enabling voltage, charging is started. (Step S4) It is checked whether or not the charging stop time, which is the result of the previous calculation means, is stored. (Step S5) If the charge stop time is stored, the stored charge stop time is used.
It is checked only whether the voltage has reached the light emission enabling voltage without performing the operations from 6 to step S15 (claim 10). (Step S6) If the charging stop time is not stored, the first time counting means starts measuring the charging time by the time counting of the time clock. (Step S7) It is checked whether the counted charging time is equal to or longer than a second reference time.

In the second reference time, the power supply of the camera, that is, the power supply battery BAT, which is a low-voltage power supply, has deteriorated and the main capacitor C3 cannot be charged to a voltage capable of emitting light, or has been charged. This is a reference time for stopping charging when it takes a very long time. (Step S8) If the counted charging time is equal to or longer than the second reference time, the charging is stopped (claim 14). (Step S9) If the counted charging time is less than the second reference time, the central processing unit CPU
The level of EADY is checked again, and it is checked whether or not the charging voltage has reached the voltage at which light emission is possible. If the charging voltage has not reached the light emission enabling voltage, the process returns to step S6 to continue counting the charging time.

(Step S10) If the charging voltage has reached the voltage capable of emitting light, it is checked whether or not the charging time counted is equal to or less than the first reference time. The first reference time is for dealing with a case where the power of the camera is turned off during charging of the main capacitor C3 or a case where the power of the camera is turned off after charging the main capacitor C3. When charging is started from a state where the voltage of the battery has dropped below the voltage at which light emission is possible, the previous charge stop time is not saved, and considerable charge is stored in the main capacitor. Charging time is faster. If this time is used as the measurement time, the time from the voltage at which light emission is possible to the stop of charging is too short, and a sufficient charging voltage cannot be obtained. Therefore, the time from the start of charging when the power supply having the highest performance is used as the power supply of the camera (power supply battery BAT) to the time when the voltage reaches the light emission enabling voltage is set as the first reference time. Determines that the charging has been performed halfway, and uses the first reference time instead of the measurement result of the charging time by the first time measuring means to perform the processing by the calculating means, thereby increasing the withstand voltage. Can be charged to a voltage close to.

Further, since the first reference time is determined based on the charging time when the power supply having the highest performance is used as the power supply, the charging time until the charging is stopped becomes longer and exceeds the withstand voltage of the main capacitor. It does not happen (claim 13). (Step S11) If the counted charging time is less than or equal to the first reference time, the charging stop time is calculated based on the first reference time (claim 12). The charge stop time based on the first reference time may be calculated in advance and stored (claim 17). (Step S12) If the counted charging time exceeds the first reference time, the calculating means calculates the charging stop time based on the charging time measured by the charging time measuring means (claim 1). In the calculation of the charging stop time by the calculating means, the time measured by the charging time measuring means may be multiplied by an arbitrary constant.

Alternatively, the calculating means may multiply the charging time measured by the charging time measuring means by a value (here, referred to as a constant) proportional to the charging time (claim 20). Further, in obtaining the charging stop time based on the charging time measured by the charging time measuring means, the results calculated in advance for various charging times are stored as a table in a storage area of the central processing unit CPU, and are given. The calculation means may be configured to selectively retrieve a result corresponding to the charged time from this table. The calculation method by the calculation means will be described later in detail. (Step S13) It is checked whether or not the charging stop time obtained by the calculating means is longer than a third reference time.

(Step S14) If the charging stop time obtained by the calculating means is equal to or longer than the third reference time, the third reference time is set as the charging stopping time without using the value obtained by the calculating means. (Claim 21). (Step S15) The obtained charging suspension time is stored (claim 7). (Step S16) The second timer measures the elapsed time from the time when the voltage reaches the light emission enabling voltage by the time counting of the time clock. (Step S17) The comparison control means compares the actual measurement time by the time count with the above-described charging stop time. When the actual measurement time by the time counting is shorter than the charging stop time, the process returns to step S16, and the time counting is continued.
As a method of comparison in the comparison control means, a method of detecting that the actual measurement time is equal to or longer than the charge stop time, or a method in which the set charge stop time is sequentially subtracted so that the charge stop time becomes zero. There is a method of detecting that the value has become negative (claim 16).

(Step S18) The charging is stopped when the actual time measured by the time counting becomes equal to or longer than the charging stop time (claim 1). (Step S19) After the charging is stopped, the shutter release operation based on the operation of the release switch is monitored. (Step S20) By the shutter release operation, a strobe light is emitted as necessary, and photographing is performed. (Step S21) After the strobe light is emitted, the previously stored charge stop time is erased (claims 8 and 9). (Step S22) When the power is turned off without performing the shutter release, the previously stored charge suspension time is erased.

By the above control, regardless of the degree of deterioration of the low-voltage power supply using a battery power supply such as a dry battery,
The main capacitor C3 is charged so as to obtain an optimal charging voltage, and is always charged to a voltage close to full charge.
The operation and effect according to the first object of the present invention in the configuration and operation according to the above-described first embodiment of the present invention will be described in detail. The amount of light emitted from the strobe is proportional to the charging voltage of the main capacitor C3. Main capacitor C3
Is a function of the voltage of the low-voltage power supply, which is the power supply of the DC / DC converter, and the charging time. As a low-voltage power supply, a battery power supply BAT such as a dry cell is usually used, so that the voltage decreases as power is consumed by use. When the voltage decreases, the output voltage of the DC / DC converter decreases, the charging voltage of the main capacitor C3 decreases, and the amount of light emitted from the strobe also decreases. Therefore, when the low-voltage power supply such as the battery power supply BAT weakens. In this case, the amount of light emitted in flash photography is insufficient. Furthermore, since the charging time becomes longer, the performance is deteriorated, for example, the timing of shooting is missed.

Therefore, the first winding N11 (the number of turns is also assumed to be N11) on the primary side of the oscillation transformer T1 used in the DC / DC converter and the second winding N12 on the secondary side.
By increasing the turns ratio (N12 / N11) of (the number of turns is also N12), the output voltage of the second winding N12 is increased, and the charging voltage of the main capacitor is increased even when the battery power supply BAT is deteriorated. Then, when the battery power is new, the charging voltage of the main capacitor C3 exceeds the withstand voltage of the main capacitor C3. Therefore, conventionally, for example, the charging voltage of the main capacitor C3 is measured and monitored using an A / D converter, and charging is stopped when the voltage reaches a voltage near the withstand voltage limit (FIG. 5). Alternatively, by using a voltage detecting element such as a Zener diode ZD, a circuit for stopping charging when the charging voltage of the main capacitor C3 reaches a voltage near the withstand voltage limit is added (FIG. 6), or the oscillation transformer T1 is used.
The secondary winding is provided with a tap so as to control the charging voltage of the main capacitor C3 by switching the tap according to the deterioration of the battery power source (Japanese Patent Laid-Open No. 8-12).
No. 2869).

However, any of these methods requires the addition of expensive parts and the like, which leads to an increase in manufacturing costs. The principle of the first embodiment of the present invention utilizes the fact that if the time from the start of charging to the voltage at which light emission can be obtained is known, the time until the withstand voltage limit voltage can be estimated and calculated based on this. ing. FIG. 8 schematically shows an equivalent circuit of a general strobe charging circuit. In FIG. 8, the output voltage E of the DC / DC converter is connected via a switch S in series with a resistor R indicating a resistance representing the current supply capability of the DC / DC converter.
And a main capacitor C. When the switch S is turned on, charging of the main capacitor C is started. The charging voltage of the main capacitor C is assumed to be Vc. The output voltage E is approximately expressed by Equation 1.

[0065]

(Equation 1)

Here, BAT is a camera and a strobe, or a battery power source B which is a low-voltage power source as a power source for the strobe.
AT indicates the voltage of the AT. As already described, N11 and N12 are the number of turns of the (primary side) first winding N11 and the (secondary side) second winding N12 of the oscillation transformer T1, respectively.
Is the number of turns. The charging voltage Vc of the main capacitor C after the switch S is closed is represented by Expression 2 where t is the elapsed time since the switch S was closed.

[0067]

(Equation 2)

The luminous voltage is Vs, the withstand voltage limit voltage of the main capacitor is Vf, the time from the start of charging to the luminous voltage (charging time) is Ts, and the time from the start of charging to the withstand voltage limit ( Charge limit time) to T
f, the charging time Ts and the charging limit Tf are respectively
Equations (3) and (4) are given.

[0069]

(Equation 3)

(Equation 4)

After the charging time Ts elapses, the time until the charging is completed, that is, the charging stop time Tx required from when the light emission enabling voltage Vs is reached to when the withstand voltage limit voltage Vf is reached.
Is the difference between the charging limit time Tf and the charging time Ts, and is expressed by Expression 5.

[0071]

(Equation 5)

The output voltage E of the DC / DC converter is expressed by Expression 6 based on Expression 2.

[0073]

(Equation 6)

The value of the voltage E is substituted into Expression 5. In the right-hand side of Equation 5, the resistance R is a value unique to the DC / DC converter, and the resistance R and the capacitance C of the main capacitor
Is a constant value, the time Tx corresponding to the charging stop time is a function of the charging time Ts, and it can be seen that the charging stop time Tx can be obtained based on the charging time Ts. The charge stop time Tx may be obtained each time, but since the calculation formula is complicated, the central processing unit CPU
The burden of is large. Therefore, the charging stop time Tx may be calculated in advance for various values of the charging time Ts, and may be stored as a table in the storage area of the central processing unit CPU. In order to approximately calculate the charging stop time Tx, a method of multiplying the charging time Ts by an arbitrary constant or a method of multiplying the time Ts by a value (constant) proportional to the time Ts itself can be considered.

Tables 1 to 3 show examples of the above calculation results. The conditions shown in Table 1, namely, the number of turns N11 of the first winding N11 on the primary side of the oscillation transformer T1 is 10 turns, the number of turns N12 of the second winding N12 on the secondary side is 1350 turns,
The capacity of the main capacitor C3 is 200 μF, DC / DC
The equivalent resistance R of the converter is 15 KΩ, and the light emission possible voltage Vs
To 250 V and the withstand voltage Vf of the main capacitor to 3
When set to 30V, the battery voltage changes from 3.2V to 2.3V.
V, the output voltage of the DC / DC converter, the charging time Ts until reaching the light emission enabling voltage Vs, the time Tf until reaching the withstand voltage limit voltage Vf, and the charging stop time Tx (each unit is ms). ) Was calculated.

In an actual camera, the value of the charging stop time Tx may be obtained by calculation, or a calculation result obtained in advance corresponding to the charging time Ts may be stored as a table and used for retrieval. In addition, an approximate calculation based on the first approximate calculation and the second approximate calculation described above may be performed. An example of the first approximation calculation is, as shown in Table 2, a time required to multiply the value of Tf / Ts (1.670) at the time of the battery voltage of 3.2 V by the value of Ts to charge to the withstand voltage limit voltage Vf. Tf is obtained, and the charging time is subtracted from the time Tf to obtain the charging stop time Tx. The lower the battery voltage, the lower the voltage at the time of stopping charging, but this is better than charging for a fixed time after the charging time Ts. As shown in Table 3, in the second approximation calculation, the value multiplied by the charging time Ts is increased in proportion to the charging time Ts.

By the way, in the examples of Tables 2 and 3, Tx = T
The calculation is s × (1.55 * Ts / Ts3.2). Note that Ts3.2 is the value of the charging time Ts when the battery voltage is 3.2V. According to Table 3, the first type shown in Table 2
It can be seen that the voltage at the time of charging stop is constant as compared with the approximate calculation of. DC / DC when battery voltage is below 2.4V
Since the output voltage of the converter does not reach the withstand voltage limit voltage Vf, the charge limit time Tf becomes ∞ (infinity). When the charging stop time Tx exceeds a certain time, charging is stopped in a predetermined time, for example, 10 seconds, as shown in Table 2.

[0078]

[Table 1]

[0079]

[Table 2]

[0080]

[Table 3]

Next, a description will be given of a camera strobe control system incorporated in a camera according to a second embodiment of the present invention. The configuration of the main part of the camera strobe control system according to the second embodiment of the present invention is the same as that of FIG. In FIG. 1, the operation of the strobe circuit is exactly the same as in the first embodiment. The difference from the first embodiment is that information on the photographing distance or the photographing lens position obtained by the photographing distance information generating means 3, the film sensitivity information obtained by the film sensitivity information generating means 4, and the photographing lens aperture information generating means 5 The charge stop time from when the charge voltage of the main capacitor C3 reaches the voltage at which light emission is possible to when the charge is stopped is changed using the photographing lens aperture information obtained by (1). That is, in the case of short-range shooting and shooting using a high-sensitivity film, the charging time is shortened, the charging voltage of the main capacitor C3 is reduced, and the amount of emitted light is reduced. On the other hand, in the case of long-distance shooting and shooting using a low-sensitivity film, on the other hand, control is performed so as to increase the charging voltage of the main capacitor by increasing the charging time and increase the amount of emitted light.

Next, the control operation of the electronic flash control system according to the second embodiment of the present invention will be described in detail with reference to the flowchart shown in FIG. FIG. 3 is a flowchart for achieving the above-described second object of the present invention. The operation in this case is also achieved by executing a program stored in advance in the central processing unit CPU of the central processing unit 2. Next, with reference to a flowchart of FIG. 3, an operation of the second embodiment of the present invention mainly relating to the second object of the present invention will be described. (Step P1) The state of the first stage of the release switch is checked, and the control waits until the first stage of the release switch is turned on. (Step P2) When the first stage of the release switch is turned on, the central processing unit CPU sets the input terminal READ
The signal level at Y is checked to determine whether or not the charging voltage of the main capacitor C3 has reached the voltage capable of emitting light.

(Step P3) If the charging voltage of the main capacitor C3 has reached the light emission enabling voltage, charging is not performed (claim 15). (Step P4) If the charging voltage of the main capacitor C3 has not reached the voltage at which light emission is possible and the photographing condition requires strobe light emission, charging is started (claims 4 and 5). The shooting conditions that require strobe lighting are as follows: if the subject is low-luminance and requires strobe lighting as a result of photometry, and if the strobe mode setting mode is set to a forced strobe mode Is one of (Step P5) It is checked whether or not the charging stop time, which is the result of the previous calculation means, has already been stored (claim 7).

(Step P6) If the charge stop time is stored, the stored charge stop time is used. Therefore, the operation from Step P7 to Step P20 is not performed, and only whether or not the light emission enabling voltage has been reached is obtained. (Claim 10). (Step P7) If the charging stop time is not stored, the first timing means starts a timing count for measuring the charging time. (Step P8) It is checked whether or not the counted charging time is equal to or longer than a second reference time. (Step P9) If the counted charging time is equal to or longer than the second reference time, the charging is stopped (claim 14). (Step P10) If the counted charging time is less than the second reference time, the central processing unit CPU sets the main capacitor C3 based on the level of the input terminal READY.
It is checked whether or not the charging voltage has reached the light emission enabling voltage. If the charging voltage of the main capacitor C3 has not reached the voltage at which light emission is possible, the process returns to Step P7, and the time counting is continued.

(Step P11) Main capacitor C3
If the charging voltage has reached the light emission enabling voltage, the state of the first stage of the release switch is checked. (Step P12) If the first stage of the release switch is off, charging is stopped (claim 3). (Step P13) Further, the state of the power switch is checked, and if the power is on, the process returns to Step P1. Claim 9). (Step P14) If the first step of the release switch is ON, the photographing distance information, the film sensitivity information, and the photographing lens aperture information are acquired. (Step P15) It is checked whether or not the charging time is equal to or less than a first reference time. (Step P16) If the charging time is equal to or shorter than the first reference time, the calculation means obtains a charging stop time based on the information acquired in Step P12 and the first reference time (claim 12).

(Step P17) If the charging time exceeds the first reference time, the calculating means obtains the charging stop time based on the information obtained in step P12 and the time measured by the first time measuring means. (Claim 2). (Step P18) It is checked whether or not the charging stop time obtained by the calculating means is longer than a third reference time. (Step P19) If the charge stop time is equal to or longer than the third reference time, the charge stop time is replaced with the third reference time (claim 21). (Step P20) In this way, if the charge stop time is shorter than the third reference time, step P17 is stored, and if the charge stop time is equal to or longer than the third reference time, step P19 stores the obtained charge stop time. (Claim 7). (Step P21) The time after the point at which the light emission enabling voltage is reached is counted by the second timer. (Step P22) The actual measurement time counted by the second timing means is compared with the set charging stop time.
While the actual measurement time is short, the time counting by the second time counting means is continued.

(Step P23) If the measured time exceeds the set charging stop time, charging is stopped. (Step P24) The state of the second stage of the release switch is checked, and if it is off, the process returns to Step P1. (Step P25) If the second stage of the release switch is on, a shutter release operation is performed. (Step P26) When flash emission is instructed, the flash is emitted in synchronization with the shutter release. (Step P27) The stored charge stop time data is erased (claims 8 and 9).

After executing Steps P3 and P9, the process jumps to Step P24 in any case. If the power switch is turned off in Step P13, the process jumps to Step P27. With the above control, it is possible to achieve strobe light emission control that controls the amount of emitted light in conjunction with the shooting distance, film sensitivity, and aperture value of the shooting lens. The operation and effect according to the second object of the present invention in the configuration and operation according to the above-described second embodiment of the present invention will be described in detail. In the case of flash photography, there are a method of controlling the light emission amount of the strobe by the distance to the subject, the sensitivity of the film, and the aperture of the lens at the time of shooting, and a method of changing the aperture of the lens without changing the light intensity of the flash. According to the present invention, the amount of light of the strobe can be easily controlled. The amount of light emitted from the strobe is GNo. (Guide number). GNo. Required for shooting Is expressed by Expression 7 using the aperture value F of the lens at the time of shooting, the distance L to the subject, and the film sensitivity I.

[0089]

(Equation 7)

The energy ef stored when the main capacitor C3 is charged to the withstand voltage limit voltage and the GNo. The relationship with f is given by Equation 8 where k is the proportionality constant.
Can be represented by

[0091]

(Equation 8) The energy ex of the main capacitor C3 at an arbitrary voltage Vx and the GNo. The relationship with x is expressed by Expression 9.

[0092]

(Equation 9) From Expressions 8 and 9, the voltage Vx is given by Expression 10.

[0093]

(Equation 10) That is, if the time Tx until the voltage of the main capacitor reaches Vx from Vs is known, the desired GNo. Charging can be stopped at a voltage corresponding to. The time Tx is
Similar to Equation 5, it is represented by Equation 11.

[0094]

[Equation 11] Therefore, the time Tx can be obtained by substituting Equation 6 into Equation 11. Tables 4 to 8 show examples of the above calculation results. Oscillation transformer T1 which is a condition for calculation
The number of turns N11 of the first winding N11 on the primary side, the number of turns N12 of the second winding N12 on the secondary side, the main capacitor C3
, The equivalent resistance of the DC / DC converter, and the withstand voltage of the main capacitor are the same as those in Table 1. In Table 4, the light-emitting voltage is 200 V,
When the main capacitor C3 is charged to the withstand voltage limit voltage and emits light, the GNo. Is set to 15.

Under these conditions, the output voltage of the DC / DC converter until the battery voltage drops from 3.2 V to 2.3 V, the time Ts until the light emission enabling voltage Vs is reached,
Desired GNo. , The charging voltages V15 and V14 (Table 5), V13 and V12 (Table 6), V11 and V10 (Table 7), V9 (Table 8), and the times T15 to T9 until reaching these voltages were calculated. . In this example, since the light emission enabling voltage Vs is set to 200 V, the GNo. Is 1
Values from 5 to about 9 are obtained. In an actual camera, the values of the times T15 to T9 may be obtained by calculation, or
An approximate expression as described in Table 3 may be used. In any case, the calculation result separately calculated may be stored in advance and read out by selection and used. If the charging time becomes longer when the battery voltage is 2.4 V or less, the charging is also stopped after a certain time. In addition, GNo. In the case where the charging time T9 becomes negative as in the case of FIG. 9, T9 is set to 0, and further charging is not performed when the charging time reaches the light emission enabling voltage Vs.

[0096]

[Table 4]

[0097]

[Table 5]

[0098]

[Table 6]

[0099]

[Table 7]

[0100]

[Table 8]

FIG. 4 shows a configuration of a main part of a camera strobe control system according to a third embodiment of the present invention, which is further improved so as to be suitable for achieving the second object of the present invention. 4, the same parts as those in FIG. 1 are indicated by the same reference numerals. The camera strobe control system shown in FIG. 4 differs from the camera strobe control system of FIG.
Only the strobe circuit section 11 corresponding to the strobe circuit section 1 is different, and FIG. 4 mainly shows only the strobe circuit section 11. The strobe circuit unit 11 includes capacitors C1, C2, C3, C5, diodes D1, D1
4, transistors Q1, Q2, Q3, Q4, resistor R1,
R2, R3, R4, R5, R6, R9, R10, R1
1, R17, R18, thyristor SCR, transformer T
1, T2, a xenon discharge tube Xe and a neon tube Ne. Although only a battery power supply BAT, which is a low-voltage DC power supply, is shown in the power supply unit, the power supply unit includes a diode D11 and a capacitor C11 and the like, similarly to the power supply unit 6 in FIG.

In the flash circuit section 1, the battery power source B
The positive side of the AT is connected to an output terminal SPC for strobe power control of the central processing unit CPU via a series circuit of a resistor R1 and a resistor R2. The connection point between the resistors R1 and R2 is connected to the base of the pnp transistor Q1, and the emitter of the transistor Q1 is connected to the battery power supply BAT.
Is connected to the positive side of The collector of the transistor Q1 is connected to a npn through a series circuit of a resistor R3 and a resistor R4.
It is connected to the emitter of transistor Q2. The base of the transistor Q2 is connected to a connection point between the resistors R3 and R4, and the collector of the transistor Q2 is connected to the base of the pnp transistor Q3. The emitter of the transistor Q3 is connected to the emitter of the transistor Q1, and the collector of the transistor Q3 is connected to the transformer T1.
Power supply BAT through the primary winding N11 on the primary side of the battery
(That is, the power supply terminal VSS of the central processing unit CPU).

The secondary winding of the transformer T1 is composed of a second winding N12 and a third winding N13 connected in series with each other. Line N13
Is connected to the emitter of the transistor Q2. The other end of the second winding N12 is connected to the anode of the diode D1 having the illustrated polarity, and the other end of the third winding N13 is connected to the negative side of the battery power supply BAT via the resistor R5. One end of a resistor R6 is connected to the cathode of the diode D1. The other end of the resistor R6 is connected to a neon tube N
e, a resistor R17 and a resistor R18 are sequentially connected in series to the negative side of the battery power supply BAT. The connection point between the resistors R17 and R18 is connected to the base of the npn transistor Q4, and the collector of the transistor Q4 is connected to the terminal READY of the central processing unit CPU. The emitter of the transistor Q4 is connected to the negative side of the battery power supply BAT.

One end of a resistor R9 is connected to a connection point between the resistor R6 and the neon tube Ne. At the other end of the resistor R9,
The thyristor SCR anode is connected to the thyristor SCR.
The cathode of the CR is connected to the negative side of the battery power supply BAT. The gate of the thyristor SCR is connected to the negative side of the battery power supply BAT via the capacitor C1, and the gate of the thyristor SCR is also connected to the trigger signal terminal TRG of the central processing unit CPU via the resistor R10. Further, a resistor R11 is connected in parallel with the capacitor C1. The anode of the thyristor SCR is connected to one end of a primary winding N21 of a transformer T2 via a capacitor C2, and one end of a secondary winding N22 of the transformer T2 is connected to a trigger terminal of a xenon discharge tube Xe. The other end of the primary winding N21 and the other end of the secondary winding N22 are commonly connected to the negative side of the battery power supply BAT. Between the cathode of the diode D1 and the negative side of the battery power supply BAT,
A capacitor C3 which is a main capacitor is connected, and a series circuit of a discharge path of the xenon discharge tube Xe and a diode D14 having the illustrated polarity is connected in parallel with the capacitor C3.

The other end of the xenon discharge tube Xe having one end connected to the cathode of the diode D1 is connected to the anode of the diode D14. The cathode of the diode D14 is connected to the negative side of the battery power supply BAT. One end of a capacitor C5 is connected to the anode of the thyristor SCR, and the other end of the capacitor C5 is
Discharge path of xenon discharge tube Xe and diode D with polarity shown
14; that is, the anode of the diode D14. In the configuration of FIG. 4, a capacitor C5 and a diode D14 are added in order to widen the control range of the amount of emitted light. The light emission enabling voltage is reduced so as to be higher (claim 11).

That is, in the calculation examples shown in Tables 4 to 8, GNo. Was set as low as 200 V in order to obtain a wide control range. The luminescable voltage is determined by the characteristics of the xenon discharge tube Xe, and may not be reduced to 200 V in some cases. In such a case, as shown in FIG. 4, by adding a capacitor C5 and a diode D14 to the trigger circuit, the light emission enabling voltage is reduced. By adding the capacitor C5 and the diode D14 to the trigger circuit in this way, when triggering the xenon discharge tube Xe, it is possible to apply a voltage twice as large as that of the main capacitor C3 to the xenon discharge tube Xe. The possible voltage can be reduced. The present invention is not limited to the embodiment described above and shown in the drawings, and can be implemented in various modifications without departing from the spirit and scope of the invention.

[0107]

As described above, according to the present invention, the charging voltage of the main capacitor can be charged to a voltage near the withstand voltage limit regardless of the degree of deterioration of the power supply such as a battery, and the strobe light emission can be achieved. It is possible to provide a strobe control system for a camera that can be manufactured at a low cost with a small decrease in light quantity, and can control the light emission quantity according to changes in the shooting distance, film sensitivity, and aperture value of the shooting lens. It is possible to provide a camera strobe control system that can be manufactured at a low cost. That is, the camera strobe control system according to claim 1 of the present invention converts the output of the low-voltage DC power supply into a DC high voltage and uses it for charging the main capacitor, and discharges xenon using the energy charged in the main capacitor. In a camera strobe control system that controls a strobe device that emits light to a tube to irradiate a subject, charging control means controls start and stop of charging of the main capacitor, and emission control means controls charging energy of the main capacitor. In addition to controlling the emission of the used strobe, the light emission possible voltage detection means detects that the charging voltage of the main capacitor has reached the light emission possible voltage, and the first clocking means detects the main capacitor by the charge control means. Measure the charging time from the start of charging until reaching the light emission possible voltage Based on the time measured by the first time measuring means, the charge stopping time from when the charging voltage of the main capacitor reaches the light emission enabling voltage to when the charging is appropriately stopped is obtained by the calculating means, Means for measuring the time after the charging voltage of the main capacitor reaches the light emission enabling voltage by the light emission enabling voltage detection means, and measuring the time measured by the second time counting means and the charging obtained by the arithmetic means. The stop time is compared by the comparison control means, and when the time measured by the second time measurement means is equal to or longer than the charge stop time obtained by the calculation means, the comparison control means causes the charge control means to execute the main capacitor operation. Stop charging.

According to a second aspect of the present invention, there is provided a strobe control system for a camera, wherein shooting distance information generating means generates shooting distance information to a subject of the camera, and aperture value setting means sets the shooting of the subject. The aperture of the lens is set, the film sensitivity of the camera is set by film sensitivity setting means, and the charging stop time obtained by the arithmetic means is calculated by the correction control means, the shooting distance, the aperture value of the shooting lens and The change is made based on at least one of the information on the film sensitivity. A strobe control system for a camera according to a third aspect of the present invention is a two-stage operation type release that instructs the camera to prepare for shooting by a first-stage ON operation and instructs a shutter release operation by a second-stage ON operation. A switch, and the comparison control means, when the voltage of the main capacitor reaches a voltage capable of emitting light,
(1) When the first stage of the release switch is off, charging of the main capacitor is stopped, and when the first stage of the release switch is turned on, charging of the main capacitor is restarted. And after the voltage of the main capacitor again reaches the voltage at which light emission is possible, the main capacitor is charged for the charging stop time calculated by the arithmetic means, and then the charging is stopped. (2)
When the first stage of the release switch is on, the charging of the main capacitor is performed only for the charging stop time calculated by the arithmetic unit without stopping the charging of the main capacitor. Means for stopping the operation.

A flash strobe control system according to a fourth aspect of the present invention includes a photometric unit for measuring a subject in response to an ON operation of a first stage of the release switch, and the comparison control unit includes the photometric unit. A means for restarting charging only when it is determined that strobe light emission is necessary based on the photometric result of the means is included. The camera strobe control system according to claim 5 of the present invention further comprises a strobe mode setting means for setting a flash operation mode of the strobe, and wherein the comparison control means performs a first-stage ON operation of the release switch. Responsively, the status of the strobe mode setting means is confirmed, and a means for restarting charging only when it is determined that strobe light emission is necessary is included.

According to a sixth aspect of the present invention, in the camera strobe control system, the comparison control means inhibits the release operation during the charging operation of the strobe even if the second stage of the release switch is turned on. Means are further included. The camera strobe control system according to claim 7 of the present invention further includes storage means for storing the calculation result in the calculation means. The camera strobe control system according to claim 8 of the present invention further includes means for erasing the operation result of the operation means stored in the storage means after the strobe light is emitted. In a flash control system for a camera according to a ninth aspect of the present invention, the storage means is a volatile storage means, and the stored contents of the storage means are erased when the power of the camera is turned off.

According to a tenth aspect of the present invention, in the camera strobe control system according to the first aspect of the present invention, the first timing means measures the charging time when the storage means stores a charging stop time as a result of the calculation by the calculating means. And the comparison control means includes means for performing charge stop control using the charge stop time stored in the storage means. The flash control system for a camera according to claim 11 of the present invention, wherein the light emission control means includes means for applying a voltage higher than the voltage of the main capacitor to the xenon discharge tube to trigger the xenon discharge tube. . The strobe control system for a camera according to claim 12 of the present invention further includes first reference time holding means for holding a first reference time, and wherein said arithmetic means is configured to measure said first time measured by said first timekeeping means. If the charging time from the start of charging of the main capacitor to reaching the light emission enabling voltage is shorter than the first reference time, the first reference time is used in place of the charging time to determine the charging stop time. Includes means.

According to a thirteenth aspect of the present invention, in the camera strobe control system according to the thirteenth aspect, the first reference time holding means uses a power supply having substantially the highest performance as the low-voltage DC power supply used for charging the main capacitor. Means for holding a time set substantially equal to the charging time from the start of charging to reaching the light emission enabling voltage when used as the first reference time is included. The camera strobe control system according to a fourteenth aspect of the present invention further includes a second reference time holding unit that holds a second reference time longer than the first reference time, and the comparison control unit includes a main control unit. Means for stopping charging of the main capacitor when the charging time from the start of charging of the capacitor to the voltage at which light emission is possible is longer than the second reference time when the second reference time is reached. I have. According to a fifteenth aspect of the present invention, in the camera strobe control system according to the first aspect, when the charging control unit determines that the charging voltage of the main capacitor has already reached the light emission enabling voltage based on the detection signal of the light emission possible voltage detection unit. And means for avoiding charging of the main capacitor.

17. The flash control system for a camera according to claim 16, wherein said second timing means includes means for subtracting the charging stop time calculated by said calculation means with the passage of time, and said comparison control means. Includes means for detecting whether the result of the subtraction is 0 or negative. The strobe control system for a camera according to claim 17 of the present invention includes a means in which the calculating means uses time information separately calculated and stored in advance as a charging stop time based on the first reference time. In. Claim 1 of the present invention
In the camera strobe control system of No. 8, the calculation means separately calculates in advance a charging stop time based on the charging time measured by the first time measuring means, and stores it in correspondence with the charging time. Means is provided for selecting and outputting from a plurality of charging stop times in accordance with the charging time. According to a nineteenth aspect of the present invention, in the camera strobe control system, the arithmetic means includes means for obtaining a charging stop time by multiplying the charging time measured by the first timing means by an arbitrary constant. .

According to a twentieth aspect of the present invention, in the camera strobe control system, the arithmetic means multiplies the charging time measured by the first time measuring means by a constant proportional to the charging time. Includes means to determine stop time. 22. The strobe control system for a camera according to claim 21, further comprising third reference time holding means for holding a third reference time, and wherein said calculating means calculates the charging time obtained by said third reference time. If it is longer than the time, the third
Means for outputting the reference time as the charging stop time. With such a configuration, the first object described above is achieved, and the charging voltage of the main capacitor can be charged to a voltage near the withstand voltage limit regardless of the degree of deterioration of the power supply such as a battery. It can be manufactured at a low cost and at a low cost. Further, the above-described second object is achieved, and the amount of emitted light can be controlled in accordance with a change in a photographing distance, a film sensitivity, an aperture value of a photographing lens, and the like.

[Brief description of the drawings]

FIG. 1 is a circuit diagram showing a configuration of a main part of a camera strobe control system according to a first embodiment of the present invention.

FIG. 2 is a flowchart for explaining a control operation of the camera strobe control system of FIG. 1;

FIG. 3 is a flowchart illustrating a control operation of a camera strobe control system according to a second embodiment of the present invention.

FIG. 4 is a circuit configuration diagram showing a configuration of a main part of a camera strobe control system according to a third embodiment of the present invention.

FIG. 5 is a circuit diagram showing a configuration of a main part of an example of a conventional camera flash control system.

FIG. 6 is a circuit diagram showing a configuration of a main part of another example of a conventional flash control system for a camera.

FIG. 7 is a circuit diagram showing a configuration of a main part in another example of a conventional camera flash control system.

FIG. 8 is a circuit diagram showing an equivalent circuit of a general flash capacitor charging circuit.

[Explanation of symbols]

REFERENCE SIGNS LIST 1 strobe circuit section 2 central processing section 3 photographing distance information generating means 4 film sensitivity information generating means 5 photographing lens aperture information generating means 6 power supply section 11 strobe circuit section C1, C2, C3, C5, C11 capacitors D1, D11, D14 diodes Q1, Q2, Q3, Q4 Transistors R1, R2, R3, R4, R5, R6, R9, R10,
R11, R17, R18 Resistance SCR Thyristor T1, T2 Transformer Xe Xenon discharge tube Ne Neon tube BAT Battery power supply CPU Central processing unit

Claims (21)

[Claims] 1. A strobe device for converting the output of a low-voltage DC power supply into a DC high voltage and charging the main capacitor, and using the energy charged in the main capacitor to emit light from a xenon discharge tube to irradiate an object. In a camera strobe control system for controlling, a charge control unit that controls start and stop of charging of the main capacitor; a light emission control unit that controls light emission of a strobe using charging energy of the main capacitor; Light-emission-capable voltage detection means for detecting that the charging voltage has reached the light-emission-possible voltage; And, based on the time measured by the first timing means,
Calculating means for calculating a charging stop time from when the charging voltage of the main capacitor reaches the voltage at which light emission is possible to when the charging is appropriately stopped; and A second time measuring means for measuring a time after the arrival, and comparing the time measured by the second time measuring means with the charging stop time obtained by the arithmetic means, and measuring the time measured by the second time measuring means. And a comparison control means for stopping the charging of the main capacitor by the charge control means when the charge stop time is equal to or longer than the charge stop time calculated by the calculation means. 2. A photographing distance information generating means for generating photographing distance information to a subject of a camera, an aperture value setting means for setting an aperture value of a photographing lens for photographing the subject, and setting a film sensitivity of the camera. Film sensitivity setting means, the charging stop time determined by the calculating means, the shooting distance,
2. The flash control system for a camera according to claim 1, further comprising: a correction control unit that changes based on at least one of the information on the aperture value of the photographing lens and the film sensitivity. 3. A comparison control means comprising a two-stage operation type release switch for instructing a camera to be ready for photographing by a first-stage ON operation and instructing a shutter release operation by a second-stage ON operation. When the voltage of the main capacitor reaches a voltage at which light emission is possible, (1) when the first stage of the release switch is off, charging of the main capacitor is stopped, and When the first stage is turned on, the charging of the main capacitor is restarted, and from the time when the voltage of the main capacitor reaches the voltage at which light emission is possible again, the charging of the main capacitor is performed only for the charging stop time obtained by the arithmetic means. After that, the charging is stopped. (2) When the first stage of the release switch is on, the charging of the main capacitor is stopped. To,
3. The apparatus according to claim 1, further comprising means for charging the main capacitor for a charging stop time obtained by the calculation means, and then stopping the charging.
A strobe control system according to item 1. 4. A photometric device for photometrically measuring an object in response to an ON operation of a first stage of the release switch, and the comparison control device needs to emit strobe light based on a photometric result of the photometric device. 4. The strobe control system according to claim 3, further comprising: means for restarting charging only when it is determined that the charging is completed. 5. A strobe mode setting means for setting a light emission operation mode of a strobe, wherein said comparison control means responds to an ON operation of a first stage of said release switch, and said strobe mode setting means. 4. The flash control system according to claim 3, further comprising means for checking the status of the electronic flash and resuming charging only when it is determined that flash emission is necessary. 6. The comparison control means further comprising means for prohibiting a release operation during a charging operation of the strobe even if a second stage of the release switch is turned on. To any one of claims 5 to
The strobe control system according to the paragraph. 7. The strobe control system according to claim 1, further comprising a storage unit for storing a calculation result in said calculation unit. 8. The flash control system according to claim 7, further comprising means for erasing the operation result of said operation means stored in said storage means after the strobe light is emitted. 9. The flash control system according to claim 7, wherein the storage means is a volatile storage means, and the storage contents of the storage means are erased when the power of the camera is turned off. 10. The first time measuring means does not measure the charging time when the charging stop time, which is the result of the calculation by the calculating means, is stored in the storage means, and the comparison control means The strobe control system according to any one of claims 7 to 9, further comprising means for performing charge stop control using the charge stop time stored in the storage means. 11. The xenon discharge tube according to claim 1, wherein said emission control means includes means for applying a voltage higher than a voltage of said main capacitor to said xenon discharge tube to trigger said xenon discharge tube. A strobe control system according to any one of the preceding claims. 12. The apparatus further includes first reference time holding means for holding a first reference time, and wherein the calculation means includes a light emission enabling voltage from the start of charging of the main capacitor measured by the first time measurement means. When the charging time until the charging time is shorter than the first reference time, means for calculating the charging stop time by using the first reference time instead of the charging time. The strobe control system according to any one of claims 1 to 10. 13. The first reference time holding means reaches a light emission enabling voltage from the start of charging when a power supply having substantially the highest performance is used as the low-voltage DC power supply used for charging the main capacitor. 13. The flash control system according to claim 12, further comprising means for holding a time set substantially equal to the charging time until the first reference time. 14. The semiconductor device according to claim 1, further comprising a second reference time holding unit for holding a second reference time longer than the first reference time, wherein the comparison control unit changes the voltage from the start of charging of the main capacitor to a voltage capable of emitting light. The charging time to reach the second
14. The method according to claim 12, further comprising: means for stopping charging of the main capacitor when the second reference time is reached when the reference time is longer than the reference time.
A strobe control system according to item 1. 15. The charge control means, if the charge voltage of the main capacitor has already reached the light emission enabling voltage, based on the detection signal of the light emission enabling voltage detection means,
The strobe control system according to any one of claims 1 to 14, further comprising means for avoiding charging of the main capacitor. 16. The second time counting means includes means for subtracting the charging stop time calculated by the calculation means with the lapse of time, and the comparison control means sets the subtraction result to 0.
The strobe control system according to any one of claims 1 to 15, further comprising: means for detecting that the current value has become negative. 17. The apparatus according to claim 12, wherein said calculating means includes means for using time information separately calculated and stored in advance as a charging stop time based on said first reference time. The strobe control system according to claim 14. 18. The method according to claim 18, wherein the calculating means separately calculates a charge stop time based on the charge time measured by the first time measuring means, and stores a plurality of charge stop times corresponding to the charge time. 2. A device according to claim 1, further comprising means for selecting and outputting a time from the time according to the charging time.
The strobe control system according to claim 17. 19. The apparatus according to claim 1, wherein said calculating means includes means for obtaining a charging stop time by multiplying the charging time measured by said first timing means by an arbitrary constant. The strobe control system according to any one of claims 18 to 18. 20. The arithmetic unit includes a unit for obtaining a charging stop time by multiplying a charging time measured by the first time measuring unit by a constant proportional to the charging time. The strobe control system according to any one of claims 1 to 19. 21. The apparatus further comprising a third reference time holding means for holding a third reference time, and wherein the calculating means comprises: when the obtained charging stop time is longer than the third reference time, 21. The strobe control system according to claim 1, further comprising means for outputting the third reference time as a charging stop time.