JPS62196635A - Flash device - Google Patents

Abstract

PURPOSE:To set up an irradiation angle to a wide angle when a subject is positioned on a near range and to prevent the subject from uneven urradiation based upon the shear between the optical axis of a lens and a light emitting optical axis by connecting a switching circuit for making an adjusting circuit execute irradiation angle adjusting operation on the basis of irradiation angle information. CONSTITUTION:When a set distance is a near range, e.g. <1m, the output of a resistor 1 is increased higher than a reference voltage Vref, so that the output of a comparator 2 is turned to the high level and a transistor (TR) 6 is turned on. Thereby, a voltage impressed to a terminal (c) becomes a constant voltage from a Zener diode 5 independently of the value of the resistor 4. Since the constatn voltage is previously set up so as to be a value corresponding to the shortest focal distance, a cover 26 is moved in the lens 28 direction independently of the set zoom information and light distribution characteristics on the most wide side can be obtained. Since the irradiation angle is automatically set up to the wide side when the subject is positioned on a near range, the subject can be prevented from uneven irradiation.

Description

[Detailed description of the invention] <Industrial application field> The present invention relates to a flash device.

<Prior art> Conventionally, the angle of view of the photographic lens and the illumination angle were matched by detecting the focal length information of the photographing lens and automatically adjusting the illumination angle to a value corresponding to the focal length information. This flash device is known.

Although this type of device is advantageous in that the angle of view and the angle of illumination match, it suffers from the following disadvantages.

That is, when a long focal length lens is attached, the illumination angle becomes narrow, so there is no problem when the subject is located far away, but in this state, the subject is close! ! (for example, within 1 m), a part of the subject screen will be located outside the irradiation angle due to the misalignment between the lens optical axis and the flash device's light emission axis, resulting in uneven irradiation of the subject. There are drawbacks that arise.

<Purpose> The present invention has been developed in view of the above-mentioned matters, and has a configuration in which focal length information of a photographing lens is detected, and the irradiation angle of a flash device is automatically adjusted according to the detected focal length information. A flash device equipped with an adjustment circuit that adjusts to a value includes a detection circuit that detects object distance information and generates an output when the object distance is shorter than a predetermined distance, and a detection circuit that responds to the output of the detection circuit. A switching circuit is provided for transmitting predetermined wide-angle illumination angle information to the adjustment circuit in place of the focal length information of the photographing lens, and causing the adjustment circuit to perform an illumination angle adjustment operation based on the illumination angle information. However, when the subject is located at a close distance, the illumination angle is widened to prevent uneven illumination of the subject due to misalignment between the lens optical axis and the light emitting optical axis.

<Embodiment> FIG. 1 is a circuit diagram showing an embodiment of a flash device according to the present invention.

In the figure, reference numeral 1 denotes a variable resistor that is linked to a distance ring of a lens (not shown), and is configured such that the output of the intermediate terminal becomes lower as the set distance becomes longer. 2 is a comparator to which the intermediate terminal of the above variable resistor is connected to the human power, and a reference voltage V ref is applied to the - human power. have.

Reference numeral 4 denotes a variable resistor that is linked to a zoom mechanism of a lens (not shown), and the intermediate terminal output is configured such that the closer the zoom setting is to the short focal length side, the lower the output becomes. 6 is its base'
is connected to the output of the comparator 2 via a resistor 3, and has a collector connected to the intermediate terminal of the resistor 4 and an emitter connected to the Zener diode 5. Each of the elements 1 to 6 above is arranged on the lens and camera side.

Reference numeral 7 denotes a variable resistor that is linked to the reflective shade 26, and is configured such that the farther the reflective shade 26 is from the Fresnel lens 28 (the narrower the irradiation angle), the higher the output of the intermediate terminal becomes. A flash discharge tube 27 fixed to the reflective shade is arranged on the reflective shade,
The irradiation angle is made variable by changing the distance between the Fresnel lens 28 at a fixed position and the reflective shade.

10.11 is a comparator, and the output of resistor 4 and resistor 7
A comparison is made between the output of the resistor 7 and the voltage divided by the voltage dividing resistor 8.9 against the output of the resistor 7.

Part A is a known motor forward/reverse rotation control circuit, which includes inverters 12, 24 and transistors 17, 18, 2.
0.21, and rotates the motor 19 in forward and reverse directions based on the outputs of comparators io and z. Moreover, the motor 1
9, the TL 29 is moved in the front-rear direction with respect to the lens 28. The circuit elements 7 to 21 are built into the strobe device, and the elements on the lens and camera side and the circuit on the strobe device side are connected through terminals c and d.

Next, the operation of the embodiment shown in FIG. 1 will be explained.

First, a state where the subject distance is set to a long distance will be explained.

In this case, the output of the resistor 1 is low, so the comparator 2 outputs a low level, and the transistor 6 is turned off. Therefore, the output of the resistor 4 is applied to the comparator 10's 10-man power and the 11-man power. The output of the resistor 4 is the zoom information (
Focal length tI! The output of the resistor 4 and the output of the resistor 7 are compared.

Now, for the focal length set by resistor 4, lens 28
Assume that the irradiation angle of the strobe, which is determined by the distance between the reflector 27 and the reflector 27, is narrow. In this case, the output of the resistor 7 becomes higher than the output of the resistor 4, so the output a of the comparator IO becomes a low level, and the output of the comparator 11 becomes a high level. Therefore, transistor 20.
18 is turned on, current flows through the motor 19 in the direction of the arrow, and the reflective shade 26 moves forward. In addition, the output of the resistor 7 decreases in conjunction with the displacement of the reflective shade, and when the positional distance between the reflective shade and the lens reaches a value corresponding to the set focal length of the lens, the output of the comparator 11 decreases. The light changes to a low level, the power supply to the motor 19 is stopped, and the displacement of the reflective shade 26 is stopped, so that the irradiation angle automatically matches the set zoom information.

Furthermore, when the strobe illumination angle is wide relative to the set focal length of the lens, the output a of the comparator 10 is at a high level and the output of the comparator -ll is at a low level. When current flows in the opposite direction, the reflector is displaced backward, and the irradiation angle is controlled in the direction of narrowing. In this case, the irradiation angle also automatically matches the zoom information of the lens.

In this way, in this embodiment, the reflector of the flash discharge tube moves according to the focal length of the lens, and when the focal length of the lens is short, the reflector becomes close to the Fresnel lens, providing wide light distribution characteristics. When the focal length is long, the reflective shade is farther away than the Fresnel lens, resulting in narrow light distribution characteristics.

Next, a case where the set distance is a short distance (for example, within 1 m) will be explained.

In this case, the output of the resistor 1 becomes higher than the reference voltage V ref, so the output of the comparator 2 becomes high level, and the transistor 6 is turned on. Therefore, the voltage applied to the terminal C becomes a constant voltage from the Zener diode 5 regardless of the value of the resistor 4. Since the constant voltage is set to a value corresponding to the shortest focal length, the cap 26 is set to a value corresponding to the shortest focal length.
It moves in 8 directions and has the widest light distribution characteristic.

As described above, according to the present invention, since the illumination angle is automatically set to the wide side when the subject is at a short distance, it is possible to prevent uneven illumination of the subject.

FIG. 2 is a circuit diagram showing another embodiment of the present invention, which differs from the embodiment in FIG. 1 only in that the processing circuit is a digital circuit. .

In the figure, REl is a register, and the register RE
1 is the distance Il of the lens (not shown)! The digital value corresponding to the set distance is manually input from the code board linked to the ring. The code plate is set so that the digital value becomes smaller as the distance increases.

C0M1 is a digital comparator, and the six inputs of this comparator are manually inputted from the output of the register RE1,
A digital value corresponding to a distance a1m is manually input to the B input, and the digital values to inputs A and B are compared, and when A2B, the output is set to high level.

This resistor RE and comparator C0M1 are resistors 1 and 1 in the embodiment of FIG. This corresponds to comparator 2, and when the set distance is within 1 meter, a high level signal is sent from comparator C0M1.

RE2 is a register into which a digital value from a code plate linked to a zoom mechanism of a lens (not shown) is input manually, and the code plate is set so that the digital value of register RE2 becomes smaller as the set focal length becomes shorter. There is. RE3
is a register in which a digital value corresponding to the shortest focal length of the lens is manually input, and C0M2 is a register in which the digital value corresponding to the shortest focal length of the lens is manually input, and C0M2 is the register R in which the digital value corresponding to the shortest focal length of the lens is manually input.
Transfer the digital value of E2 to the register RE3 manually to B.
A data selector which inputs a digital value sends out the digital value of human power B when the human power S of the selector is at a high level or manually, and when the human power S of the selector is at a low level, it sends out the digital value of human power A.

The registers RE2, R, E3, selector S
L is the resistor 4 in Figure 1. Diode 5. transistor 6
With the above configuration, when the subject distance is within 1 m, the digital value corresponding to the shortest focal length of the lens is in register RE3, and when the subject distance is 1 m or more, the digital value is in register R.
A digital value corresponding to the set focal length of E2 is output.

CSW is a code plate, and the code plate is the reflective shade 26 in FIG.
In conjunction with this, a digital value corresponding to the irradiation angle determined by the distance between the reflective shade and the lens 28 is formed.

The code plate CSW is configured to form a larger digital value as the irradiation angle becomes narrower.

C0M2 is a digital comparator, and this comparator sends out a low level from its output a when the relationship between inputs A and B is A2B, and also sends out a low level when B≦A. Above coated plate CSW, comparator C0M
2 are the resistor 7 and diode 29 in FIG. Corresponds to comparator 10.2, and with the above configuration the set focal pressure it! When the irradiation angle (corresponding to the focal length) is narrow with respect to f, a low level is sent from the output a of the comparator, and a high level is sent from the output a, and conversely, when the irradiation angle is wide with respect to the focal length, the comparator's output A low level is sent from the output C, and a high level is sent from the output C. A is a circuit having the same configuration as the control circuit shown in the first diagram.

Since it is configured as above, the strobe illumination angle corresponds to the set focal length, and the set distance is 1 m.
When it is within the range, the irradiation angle is forcibly adjusted to the wide side based on the digital value from the register RE3.

<Effects> As described above, in the present invention, in a flash device that automatically adjusts the irradiation angle according to the focal length of the photographic lens, when the subject is located at a close distance, the flash device is forced to Since the irradiation angle is set on the wide side, even if the lens is a long focal length lens and the subject is located at a short distance, uneven irradiation on the subject can be prevented.

In the embodiment, the reflection shade is moved when the irradiation angle is made variable, but instead of this, a Fresnel lens or a flash tube may be moved.

Further, in the embodiment, the circuit elements are arranged separately on the lens and camera side and on the flash device side, but the camera and the flash device may be integrated. Further, although the camera is switched to the widest side when the subject distance is within 1 m, it may be within a predetermined distance of 1 m or more, and the lens may be set to a wide side other than the shortest focal length.

[Brief explanation of drawings]

FIG. 1 is a circuit diagram showing one embodiment of a flash device according to the invention, and FIG. 2 is a circuit diagram showing another embodiment of the invention. 1.4.7---Resistance 2.10. t t----Comparator 6----Transistor

Claims (1)

[Claims] In a flash device equipped with an adjustment circuit that detects the focal length information of the photographing lens and automatically adjusts the illumination angle of the flash device to a value according to the detected focal length information, the flash device detects the subject distance information. a detection circuit that generates an output when the subject distance is shorter than a predetermined distance; and a detection circuit that responds to the output of the detection circuit and replaces the illumination angle information on the predetermined wide side with the focal length information of the photographic lens for the adjustment. A flash device comprising: a switching circuit for transmitting information to a circuit and causing the adjusting circuit to perform an illumination angle setting operation based on the illumination angle information.