JPH03287148A - strobe control device - Google Patents

Abstract

PURPOSE:To keep the consumption of a power source low and to accomplish appropriate strobe light emission by charging a main capacitor by the amount required for photographing with the aid of 1st and 2nd charging control means and controlling charging based on a value calculated by a light quantity arithmetic means and a voltage arithmetic means. CONSTITUTION:This controller is provided with a means 8 for measuring the voltage of the main capacitor 3, a 1st charging control means 16a for charging the capacitor 3 so that the voltage thereof attains a light emission performable voltage, and the light quantity arithmetic means 13 for calculating the light quantity required for photographing. It is also provided with the voltage arithmetic means 14 for calculating the voltage of the capacitor 3 required for photographing based on the calculated result form the means 13 and a 2nd charging control means 16b for charging the capacitor 3 so that the voltage of the capacitor 3 may be to the voltage obtained by the means 14. Then, the capacitor 3 is charged by dividing the voltage into the light emission performable voltage of a light emitting tube 4 by the means 16a and the voltage required for photographing by the means 16b. Thus, the consumption of the power source battery 1 is kept low and the appropriate strobe light emission is accomplished.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a strobe control device for controlling charging and light emission of a strobe for a camera.

(Prior art) As a camera strobe control device that automatically controls light emission, the flashmatic method, which fully charges the main capacitor and determines the aperture value (F value) of the photographing lens according to the subject distance, performs strobe photography. Alternatively, an auto strobe method is known in which strobe light emission is stopped when the integrated light reflected from the subject reaches a predetermined value.

(Problem to be solved by the invention) However, with the conventional two-legged flashmatic method, the power supply battery is often consumed because it is always fully charged and emits full light.
It takes a long time to charge because it fires repeatedly, and when shooting at close range, the aperture becomes extremely small, resulting in dark scenery.

Furthermore, the conventional auto strobe method requires a high-speed, high-sensitivity photodetector, or a high-precision integration circuit.
This results in an increase in cost and space.

Furthermore, there is a problem of overexposure or underexposure due to differences in reflectance between the subject and the film.

The purpose of the present invention is to have a simple configuration, low power consumption,
Another object of the present invention is to provide a strobe control device that can perform proper strobe light emission.

(Means for Solving the Problems) In order to achieve the object of item 142, the present invention provides a strobe control device that illuminates a subject by causing an arc tube to emit light based on the voltage charged in a main capacitor. , a voltage measuring means for measuring the voltage of the main capacitor, a first charging control means for charging the voltage of the main capacitor to a voltage capable of emitting light, a light amount calculating means for calculating the amount of light necessary for photographing, and a light amount calculating means for calculating the amount of light necessary for photographing; The present invention is characterized by comprising a voltage calculation means for calculating the voltage of the main capacitor necessary for photographing based on the calculation result, and a second charging control means for charging the voltage of the main capacitor to the voltage determined by the voltage calculation means. .

(Function) Since the above-mentioned means are adopted, the main capacitor is charged separately into the voltage at which the arc tube can emit light by the first charging control means and the voltage necessary for photographing by the second charging control means. Since only the required amount is charged at a certain time, wasteful consumption of the power source is suppressed, and charging control is performed based on the voltage value necessary for photography calculated by the light amount calculation means and the voltage calculation means, and - corresponding to the photography conditions. Appropriate strobe light emission can be performed, and furthermore, the measurement and calculation means can be integrated into an integrated circuit.

(Example) Embodiments of the present invention will be described below based on the drawings.

FIG. 1 is a block diagram of an embodiment of the present invention, in which 1 is a power supply battery, 2 is a booster circuit consisting of a DC/DC converter, etc.
3 is a main capacitor, 4 is an Xe (xenon) tube which is an arc tube, 5 is a trigger means for starting the Xe tube 4, 6
is an X contact, 7 is a voltage divider circuit consisting of series resistors R□ and R2 connected in series to the main capacitor 3, 8 is a voltage divider circuit 7
An A/D (analog/digital) converter is connected to the connecting portion 7a of the series resistor R1°R2 and is a voltage measuring means for measuring the voltage of the main capacitor 3, and 9 is a film that outputs information related to film sensitivity. Sensitivity information output section, 10 is an aperture information output section that outputs aperture information of the photographic lens, 1] is a subject distance information output section that outputs distance information to the subject, 12 is a base guide number (GNo.)
GNo., an information output section that outputs information, and (3) the film sensitivity information output section 9. Aperture information output unit 10. a light amount calculation means that receives data from the object distance information output unit 11 and calculates the amount of light necessary for illuminating the object; 14 is the GNo.;
Information output unit 12. A voltage calculation means receives data from the light amount calculation means I3 and calculates the voltage of the main capacitor 3 necessary for photographing; 15 is a photometry means for measuring the brightness of external light;
Reference numeral 16 denotes a carving charging control means 16a which receives the measurement result of the photometry means 15 and charges the voltage of the main capacitor 3 to the voltage at which the Xe tube 4 can emit light, and the measurement and calculation from the voltage measurement means 8 and the voltage calculation means 14. The charging control means includes a second charging control means 16b that receives the result and charges the voltage of the main capacitor 4 to the voltage necessary for photographing.

The operation of the above embodiment will be explained with reference to the flowchart of FIG.

When the main switch (not shown) is turned on and the power source battery is turned on (S-1), the photometry means 15 gives external light photometry data to the charge control means 16, and the charge control means 16 performs strobe photography. If it is determined that there is no need to perform (
S-2 NO), after being released (S-3a YES)
), exposure calculation is performed (S-4), and shutter operation is performed (S-5).

On the other hand, if the charging control means 16 determines that strobe photography is necessary (YES in S-2), the booster circuit 2 is operated. The voltage of the power supply battery 1 is boosted to several hundred square meters by the booster circuit 2, and the charge is stored in the main capacitor 3. At this time, the charging voltage of the main capacitor 3 is the resistance R□ of the voltage dividing circuit 7.
, R2, input to the A/D converter 8, output as a digital value to the charge control means 16, and stored. That is, the charging voltage V MC determined by the A/D converter 8 is stored as data M in the charging control means 16 (S-6). And second charging control means 16a
As a result, the voltage of main capacitor 3 becomes a value that allows light emission■□
. The charging operation is performed (S-8) until it is determined that the voltage is 7 or more (M≧vlloK) (S-7), and M≧■11
When OK is reached (YES in S-7), the charging operation is stopped.

When the release is released (YES in S-9), the light amount calculation means 3 calculates the amount of light (G NO, X) necessary for photographing (S-10), and the voltage calculation means 14
Calculate the voltage VHX of the main capacitor 3 required for strobe light emission from the required light amount calculated from step 3 (S-11
,).

At this time, if the voltage of the main capacitor 3 (M=VMC) is larger than the voltage VMX calculated by the voltage calculation means J4 (YES in S-12), the aperture area of the photographing lens according to the subject distance is calculated (S -1, 3), a shutter operation is performed (S-5).

However, when M<VIIX (NO in S-12), the second
The charging control means 16b performs additional charging to the main capacitor 3 until M≧VMX (S-14).
, after which the shutter operation will be performed (S-5
).

Next, the calculation method of each calculation means in the two-legged embodiment will be explained.

The amount of light necessary for illuminating the subject in the light amount calculation means 13 is determined by the aperture value F of the photographing lens and the distance I to the subject.
] is the guide number (GNo8) found by G No, = F -1) ...... (
It is determined by the relational expression 1). However, when the film sensitivity (ISO sensitivity) changes, the value of G No. changes.

In the following description, 15O100 is used unless otherwise specified.

Further, although the distance is determined, the aperture value F can be set freely. The smaller this aperture value F, the more necessary GNo.
Therefore, it is desirable to obtain the aperture value F near the maximum aperture value of the photographic lens.

Next, a method for determining the voltage of the main capacitor 3 necessary for flash photography using the voltage calculation means 14 will be explained.

The voltage of main capacitor 3 when fully charged is V
M 01 The residual voltage of the main capacitor 3 after full light emission is v17. The voltage V□. Light emission starts at voltage V1. GN is the amount of light emitted when light emission stops at
o. , determine the distance from the camera to the subject, set the aperture value of the lens to F, and set the maximum aperture value of the lens to C. , If the amount of light emitted for photographing is GNo,X, then from the above (1), GNo,X=D −F.

・・・・・・(2) Then, if we try to give the same amount of light to a unit area with strobe light, and when the energy emitted by the strobe is E, then D2 of E...(3) Also, from equation (2), DocGNo.

...(4) Because it is, EccGNo,” ・(5) becomes.

The energy emitted by the voltage VHo, V is E. , if the capacitance of the main capacitor 3 is C1 and the proportionality constant is K, then the following equation is obtained.

The voltage of any main capacitor 3 before the start of light emission, which shows a change as shown in the explanatory diagram of FIG. 9 If the residual voltage of the main capacitor 3 after the end of light emission is vl, then from VHX ■
1. The energy EX released by emitting light is as follows.

Here, the reference G No, is G No,. On the other hand, if X is the ratio of G No, which is the G No required for photographing, then x = G No, x/G No. --(8)
Therefore, when solving equation (9) for the voltage V tax after the end of light emission, VH/=VH,' + x2・(Vllll' Vl
, ”) −・−・(I O) or is the voltage of the main capacitor 3 necessary for this VHX shooting, and VIIo + Vl,, GNo, is the base G No, information, and the G No , are stored in the information output section 12.

In this embodiment, the voltage VHX is obtained by dividing the voltage of the main capacitor 3 by the resistors R, , R7 of the voltage dividing circuit 7.
Since it is input to the /D converter 8, if this person's direct position is V, then the following is obtained.

Here, in order to simplify the above equation (10), V t =
V' V on ・・・・・・(13) Then, VHX'=y'・V ) Ill '+ X 2・(↓-
y2)・■□. ...(14)1. ■□. is the voltage of main capacitor 3 when fully charged, and ■. Since is the voltage of the main capacitor 3 at the end of full light emission, for example, ■.

330V, V,. = 40■, then y = 40 /
Since 330 yen is 0.12, it becomes 1-y2 or 1,
The formula (t4) is V, lx"=(y"+X2) 'V
Hl...(15), and further V
Since MX is set above the voltage that allows light emission, X cannot be an extremely small value, so y2(x2...(16), and equation (15) is V Hx' ”
There are only 0, 11 and V 1111, and the calculation becomes simple QL.

2 Although the above V H11 was explained as the voltage when the main capacitor 3 is fully charged, ■□. is not limited to the voltage at the time of full charge, but any voltage that can emit light, that is, a voltage that corresponds to a known guide number, can be used. do not have.

Also, the aperture value F for determining G No. and X is also the open aperture value F 1
It is not limited to 1.

In the above embodiment, it is determined whether or not to perform charging based on the output of the photometric means 15, but the photometric means 15 may not be provided and charging may be performed manually by the user. It is also conceivable that the first charging control means 16a performs charging immediately when the power source battery is turned on.

Further, in the embodiment shown in "-", the first charging control means 16a performs charging to a voltage that allows light emission. However, as mentioned above, when the sensitivity of the film changes, it is necessary to change the G No. Therefore, if the voltage charged by the first charging control means 16a is constant, additional charging by the second charging control means 16b will be required frequently when the sensitivity of the film is high, and conversely, when the sensitivity of the film is high, Additional charging is rarely required.

Therefore, when the sensitivity of the film is low, the control voltage for charging the main capacitor 3 of the first charge control means 16a is set high, and when the sensitivity of the film is high, the control voltage of the first charge control means 16a is set high. When configured to lower
The frequency of additional charging is reduced, and the waiting time for additional charging is also shortened. However, even if the charging voltage is changed as described above, it goes without saying that the voltage must be equal to or higher than the minimum light emission voltage.

By the way, as a guideline for the charging voltage, it is desirable to use a voltage that provides a GNo that allows shooting up to a certain distance regardless of the sensitivity of the film, and a GNo that can be obtained at ISO100.

If GNo is 100, then GNOoX of GNo, which is desired to be obtained with DingSOX, which is an arbitrary ISO value, is,
The charging voltage is determined from the above equations (10) and (11).

In addition, a power supply voltage measuring means (not shown) is provided for measuring the voltage of the power supply battery 1, and when the power supply voltage decreases, the control voltage for charging the main capacitor 3 of the first charging control means 16a is increased. Furthermore, charging speed detection means (not shown) is provided for detecting the charging speed of the main capacitor 3 during operation of the first charging control means 16a, and when the charging voltage decreases, the main capacitor 3 of the first charging control means 1.6a is One possibility is to increase the control voltage for charging.

By providing a power supply voltage measuring means and a charging speed detecting means, the waiting time for additional charging is reduced both in frequency and time.

Furthermore, if a high-performance battery such as a lithium battery is used as a power supply battery, the waiting time can be more effectively reduced.

” - When changing the charging voltage by the first charging control means 1.6a in response to changes in film sensitivity, power supply voltage, and charging speed of the main capacitor, each charging r, i r1
The G No. for 1f pressure is stored in advance and set to 1.
5 may be used, or GNo obtained by solving the above equation (9) for GNo and X and substituting the charging voltage for vHx in this equation (20) may be used.

As explained above, in this embodiment, charging is enabled only when the brightness is necessary for strobe photography, and in this chargeable state, the first charging control means 16a reaches a voltage that allows light emission.
The second charging control means 16b performs the first charging until the required voltage is reached only when the amount of light is insufficient in the first charging during shooting.
The second charging can be carried out more easily, the charging required for flash photography is kept to a minimum, and the power battery 1 is consumed less.
Also, when the distance to the subject is short, the flash can be emitted with only the first charge, so you won't have to shoot with an extremely small aperture. Furthermore, there is no need for a high-speed, high-sensitivity light-receiving element or a high-precision integration circuit, and the A/D converter 8.
Light amount calculation means 13. Voltage calculation means 14. Charging control means 1
6 etc. can be built into a one-chip CP6-U (central processing unit), so the cost is significantly lower than that of conventional devices. There is no increase in space.

(Effects of the Invention) According to the present invention, the main capacitor is charged by the first and second charge control means to an amount necessary for photographing, and the charge control is calculated by the light amount calculation means and the voltage calculation means. Since it is performed based on the value, it is simple, tt5. It is possible to create a strobe control device that has a simple configuration, consumes little power, and performs suitable strobe photography.

[Brief explanation of drawings]

FIG. 1 is a configuration diagram of an embodiment of the strobe control device of the present invention, FIG. 2 is a flowchart related to the operation of this embodiment, and FIG.
The figure is an explanatory diagram of charging and discharging the main capacitor. ↓... Power supply battery, 2... Boost circuit, 3... Main capacitor, 4... Luminous tube, 5... 1-Riga means, 6... X contact, 7... Voltage divider circuit,
8...Voltage measurement means, 9...Film sensitivity information output section, 10...Aperture information output section, 1■...Subject distance output section, 12-GNo. information output section, 13-Light amount calculation means, 14 . . . Voltage calculation means, 15 . . . Photometry means, 16a . . .
Charging control means.

Claims (4)

[Claims] (1) In a strobe control device that illuminates a subject by causing an arc tube to emit light based on the voltage charged in the main capacitor, there is a voltage measuring means for measuring the voltage of the main capacitor, and a voltage measuring device that measures the voltage of the main capacitor up to the voltage that enables light emission. A first charging control means for charging, a light amount calculation means for calculating the amount of light necessary for photographing, a voltage calculation means for calculating the voltage of the main capacitor necessary for photographing based on the calculation result from the light amount calculation means, and a main capacitor. a second charging control means for charging the voltage up to the voltage determined by the voltage calculation means. (2) Claim (1) characterized in that the control voltage of the first charging control means is changed in order to change the charging voltage of the main capacitor at a voltage higher than the voltage that allows light emission depending on the sensitivity of the film. strobe control device. (3) A power supply voltage measuring means for measuring the voltage of a power supply that charges the main capacitor is provided, and when the power supply voltage decreases, the control voltage by the first charging control means is increased. (1) or (2
) strobe control device. (4) Charging speed detection means for detecting the charging speed of the main capacitor during operation of the first charging control means, and configured to increase the control voltage by the first charging control means when the charging speed decreases. A strobe control device according to claim 1 or 2, characterized in that: