JPH0216345Y2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an illumination angle control device for a flash device that is capable of changing the illumination angle of a flash device in accordance with the focal length of a photographic lens.

Conventionally, when using a flash device, when using a short focal length photographic lens with wide corners compared to the flash device's irradiation angle, the entire periphery of the photograph will be dark because both corners will not be illuminated sufficiently. In comparison, when a long focal length photographic lens with narrow angles is used, power consumption increases because irradiation is performed on areas other than both angles, and the distance to which the object can be irradiated cannot be increased. To solve this problem, a flash device has been proposed and implemented that can reduce the illumination angle when using a long focal length photographing lens and greatly change the illumination angle when using a short focal length photographic lens. There is.

However, this type of device has the following drawbacks.

For example, when using a photographic lens with a long focal length to photograph a subject that requires extremely uniform illumination, such as a painting, the automatic illumination angle adjustment device's illumination angle should be narrowed to correspond to the long focal length. Change. Even in this state, the entire subject is illuminated, but
In conventional systems, the relationship between the illumination angle and the focal length is gradual, so if the focal length of the lens used is just before or after the point of change, it is impossible to provide extremely uniform illumination. However, it had the disadvantage that it produced images that were contrary to the photographer's intentions. In addition, if you use a short focal length photographic lens to place the main subject at the center of a wide angle of view and want to illuminate only the main subject for a close-up, the automatic illumination angle variable device can be used to accommodate the short focal length of the photographic lens. Since the angle changes greatly, the subject is illuminated over the entire angle of view, making it impossible to illuminate only the main subject, resulting in photography that is contrary to the photographer's intention.
Furthermore, when the main subject is far away, the guide number decreases due to the wide irradiation angle, and there are cases where the main subject cannot be sufficiently illuminated.

In view of the above points, the present invention provides a hysteresis characteristic to changes in the illumination angle of the flash device, allowing the photographer to choose whether to give priority to the guide number or to shoot with priority to the illumination angle. This is an attempt to eliminate the shortcomings.

FIG. 1 is a block diagram of an embodiment of the present invention. In FIG. 1, 1 is a lens unit, 2 is a flash device, 3 is a zoom lens body with hysteresis characteristics, 4 is a contact that interlocks with the zoom ring of the zoom lens, and 5 is a resistor group selected by the contact 4, R ₁ , It is composed of resistors R ₂ and R ₃ each having a different resistance value. 6 is a power supply battery for the flash device and the zoom lens unit; 7 is a control circuit for the flash device; 8 is a switch that becomes conductive after the shutter front curtain has completed running; 9 is a light-emitting portion of the flash device; 10 is a device that changes the irradiation angle of the flash device. In this embodiment, a liquid crystal LCD is used as the means for making the image.

The operation of the embodiment configured as above will be explained. Since the liquid crystal LCD changes the irradiation angle of transmitted light depending on the applied voltage, the contact point 4 changes as the zoom ring of the zoom lens 3 having hysteresis characteristics is driven and the angle of view of the photographing lens changes.
However, within the resistor group 5, a voltage having a hysteresis characteristic corresponding to the focal length of the photographing lens is applied to the liquid crystal display, and the irradiation angle of the flash device has a hysteresis characteristic.

FIG. 2 is a sectional view showing the principle of the zoom lens body having the hysteresis characteristic shown in FIG. 1, and FIG. 3 is a plan view showing the principle of the zoom lens body. In FIGS. 2 and 3, reference numeral 10 denotes a zoom ring that changes the focal length of the photographic lens by moving parallel to the left and right in the drawings. 11 is a pin conductor plate 14 fitted into the horizontally long zoom ring groove 10a.
It is stuck to. The conductor plate 14 has electrodes 15, 16,
A contact 14-a that slides on the common electrode 17 is provided, and a contact 14-c that slides on the common electrode 18 is provided. Electrode 15,1
6 and 17 are connected to resistors having resistance values R ₁ , R ₂ , and R ₃ , respectively.

Next, the principle of the zoom lens body having hysteresis characteristics shown in FIGS. 2 and 3 will be explained.

For example, when the photographer moves the zoom ring 10 from the right end of the electrode 17 to the left in order to change the focal length of the zoom lens, the pin 11 is attached to the right end of the zoom ring groove 10a.
The zoom ring 10 moves to the left in a state in which the zoom ring 10 is in contact with the zoom ring 10.
If the zoom ring 10 is then moved to the position shown in FIGS. 2 and 3, the resistance value of the zoom lens is
Changes from R ₃ to R ₂ . When the photographer moves the zoom ring 10 to the right for fine adjustment, since the zoom ring groove 10aa is horizontally long, the pin 11 does not immediately move to the right as the zoom ring 10 moves, and the pin 11 zooms. After contacting the left end of the annular groove 10a, the pin 11 moves to the right. Therefore, first move the zoom ring to the left, move the pin 11 from above the electrode 17 to above the electrode 16, change the focal length of the zoom lens whose resistance value changes from R ₃ to R ₂ , and then move the zoom ring back The focal length of the zoom lens changes as the resistance value changes from R ₂ to R ₃ . Therefore, if the focal length and resistance value of the zoom lens are made to correspond, for example, as shown in FIG. 4, which is a correspondence diagram between the focal length and resistance value of the zoom lens, hysteresis characteristics can be provided.

FIG. 5 is a sectional view of a zoom lens body having hysteresis characteristics, and FIG. 6 is a plan view of a zoom ring 35 in which grooves are formed to provide hysteresis characteristics. In FIGS. 5 and 6, reference numeral 31 denotes a lens barrel fixing portion, to which a resistor group 39 is fixed and attached to a camera mount (not shown). 32 is a sliding guide tube that is integrally attached to the lens barrel fixing part 31;
A movable tube 3 that holds the lens group and the second lens group
3 and 34 are fitted so as to be able to slide inside the guide tube 32. As is well-known in the zoom lens, each movable barrel 33,
Each movable barrel 33,
34 slide back and forth to adjust the focal length. A long groove 35a passes through the zoom operation ring 35, and a contact member 41 that interlocks with a screwed pin 40a has a hysteresis in the relationship between the focal length and the resistance value depending on the direction of rotation of the zoom operation ring 35, as shown in the principle diagram above. can have properties.

FIG. 7 is a circuit diagram of a second embodiment of the present invention, which realizes the hysteresis characteristic in terms of an electrical circuit.

In FIG. 7, 1 is a lens section, and the others are flash devices. By driving the zoom ring 4 of the zoom lens 3, the contact point with the variable resistor V _R is moved, and the resistance value of the variable resistor V _R is changed. _S1 is a power switch for the flash device, B is a power battery, D is a booster circuit, and _C1 is a main capacitor. Resistor R ₃₀ and Zener diode Z ₂ constitute a constant voltage circuit. Resistor R ₆₁ , Capacitor C ₂ ,
Resistor R ₆₂ is connected in series, switch S ₂ , transformer L
The starting circuit for the flash discharge tube Xc is configured through this. Rf is a reflector that efficiently illuminates the subject with the light from the flash discharge tube. LCD is a liquid crystal that changes as the applied voltage increases, the diffusion effect becomes stronger and the illumination angle becomes larger. capacitor
C ₃ is charged with a voltage made constant by Zener diode Z ₁ via diode D, and the variable resistor _VR and the series connection of resistor R ₆₃ are connected in parallel.

The voltage of the capacitor C ₃ is divided by the variable resistor _VR and the resistor R ₆₃ and inputted to the inverting input terminals of the comparators C ₅₀ , C ₃₅ , and C ₇₀ . Each comparator C ₅₀ ,
The non-inverting input terminals of C ₃₅ and C ₇₀ have resistors R ₁₁ and
The voltage across capacitor _C3 divided by _R12 is applied to resistor _R13
capacitor C ₃ divided by resistors R ₁ and R ₂ through
The voltage of _the capacitor _C3 , which is divided by the resistors _R21 and _R22 , is inputted through the resistor _R23 . The output terminals of comparators C ₅₀ , C ₃₅ , and C ₇₀ are connected to the bases of transistors Tr ₅₀ , Tr ₃₅ , and Tr ₇₀ , respectively, and are also connected to the non-inverting input terminal via resistors R ₁₅ , R ₅ , and R ₂₅ . .

A voltage from a constant voltage circuit including the resistor R ₃₀ and the Zener diode Z ₂ is applied to the parallel connections of the resistors R ₃₁ , R ₃₂ , R ₃₃ , and R ₃₄ . The collector of Tr ₇₀ is connected to the connection point of resistors R ₃₁ and R ₃₂ , the collector of Tr ₅₀ is connected to the connection point of resistors R ₃₂ and R ₃₃ , and the collector of Tr ₃₅ is connected to the connection point of resistors R ₃₃ and R ₃₄ . Ru. _R31 , _R32 ,
The values of each resistor R ₃₃ and R ₃₄ are 35 mm and 50 mm, respectively, when the focal length of the zoom lens 3 changes the irradiation angle of the flash device.
The voltage of the variable resistor V _R is set to be equal to the non-inverting input voltage of the corresponding comparators C ₃₅ , C ₅₀ , and C ₇₀ at each point of mm and 70 mm.

FIG. 8 is a diagram of the focal length and the voltage applied to the liquid crystal in the second embodiment of the present invention.

The operation of the illumination angle control device for the flash device configured as above will be explained.

When the power switch _S1 of the flash device is turned on, the voltage boosted by the booster circuit D causes the main capacitor to
C ₁ is charged and the voltage of Zener diode Z ₂ is applied to the series connection of resistors R ₃₁ , R ₃₂ , R ₃₃ and R ₃₄ .
For example, if the photographer drives the zoom operation ring of the zoom lens 3 so that the focal length of the zoom lens becomes 85 mm, the resistance value of the variable resistor _VR becomes maximum. As a result, the voltage divided by the variable resistor V _R and the resistor R ₆₃ is minimized and is smaller than the voltage divided by R ₂₁ and _{R 22 ,} which is the voltage at the inverting input terminal of the comparator C _70. , C ₃₅ and C ₅₀ each become a positive output, and Tr ₇₀ , Tr ₃₅ and Tr ₅₀ all become conductive, and the voltage applied to the liquid crystal LCD becomes very small. The liquid crystal LCD of this embodiment has a property that the diffusion effect increases as the applied voltage increases, so the liquid crystal LCD has no diffusion effect and the irradiation angle of the flash device becomes small as shown at A in FIG. 8.

The photographer drives the zoom ring of the zoom lens 3,
By gradually shortening the focal length of a zoom lens,
The resistance value of variable resistor V _R gradually decreases, and the voltage divided by variable resistor V _R and resistor R ₆₃ gradually increases. When the focal length becomes slightly shorter than 70 mm and becomes higher than the voltage at the non-inverting input terminal of the comparator C ₇₀ , the output of the comparator C ₇₀ is inverted from the H level to the L level. Therefore the transistor
Tr ₇₀ is turned off and the Zener voltage V _Z2 divided by resistors R ₃₁ and R ₃₂ is applied to the liquid crystal display. (See Figure 8B).

In order to widen the angle of view, the photographer drives the zoom ring to further shorten the focal length of the zoom lens, and when the focal length becomes slightly shorter than 50mm, the comparator
C ₅₀ is inverted, and the voltage applied to the liquid crystal display becomes voltage V _Z2 , which is divided by resistor R ₃₁ and resistors R ₃₂ and R ₃₃ . (See Figure 8C). When the focal length becomes even shorter and slightly shorter than 35mm, Tr ₃₅ ,
Tr ₅₀ and Tr ₇₀ are all turned off, the voltage applied to the liquid crystal LCD becomes the highest, and the irradiation angle becomes the largest (see FIG. 8D). When the photographer returns the zoom ring to the long focal length side for fine adjustment of the angle of view immediately after the irradiation angle reaches its maximum, the output of comparator C ₃₅ is at L level, so the output of comparator C ₃₅ is at H level. The level at the non-inverting input terminal via resistors R ₅ and R ₃ is lower than in the case of heating. Therefore, the focal length at which the irradiation angle of the flash device changes while the zoom ring is being driven from the long focal length side to the short focal length side is the same as the focal length at which the irradiation angle of the flash device changes while the zoom ring is being driven from the short focal length side to the long focal length side. Unlike the focal length, which changes the irradiation angle of the flash device, the relationship between the focal length of the photographing lens and the stepwise change of the irradiation angle of the flash device has hysteresis characteristics.

Therefore, the photographer rotates the zoom ring of the zoom lens to the short focal length side and adjusts the focal length to f ₂ as shown in Figure 9.
When using a conventional device to place the main subject at the center of a wide angle of view, illuminate the main subject, and take a spot-light photo, the focal length of the zoom lens varies from f ₁ to f as shown in Figure 9. ₂ to the short focal length side, the flash device illumination angle will automatically change from C to D.
In this example, it was not possible to obtain a spot-lit photo by placing the main subject in the center of a wide angle of view and illuminating the main subject. According to
As shown in Figure 0, even if the angle of view is increased by rotating the zoom ring of the zoom lens from the focal length _f1 to _f2 , the illumination angle does not change, making it possible to take photographs that look like spot lighting. Also, when the focal length is _f2 , the irradiation angle becomes D, which is large, so the zoom ring of the zoom lens should be rotated once to the long focal length side, _f3 , and then conversely rotated to the short focal length side. If the focal length is set to _f2 for the desired angle of view, the illumination angle becomes C, allowing photography in a narrow condition.

In this example, the configuration of the flash device is basic, but it is of course possible to use a series control type flash device to save power. The means for doing this is not limited to using a variable resistor, but may also be a means for converting the focal length of the photographic lens into a digital signal. In that case, a magnitude comparator that compares digital values may be used instead of the comparator.

Further, according to this embodiment, since the configuration is like an electric circuit, it does not depend on the mechanical configuration of the photographing lens, and a complicated structure is not required. Therefore, it has the advantage of fewer failures and high reliability.

Furthermore, since a liquid crystal is used as a diffuser to change the flash device, there is no mechanical noise.

When it is necessary to irradiate the entire field of view extremely uniformly, for example, if you want to take a picture at the field of view of focal length f ₁ as shown in Figure 9, conventional devices automatically change the irradiation angle to D that corresponds to the focal length f ₂ . It becomes state C, which is smaller than that, and it is not possible to irradiate extremely uniformly,
As shown in FIG. 10, according to this embodiment, even if the focal length is changed from _f2 to _f1 by rotating the zoom ring of the zoom lens, the irradiation angle remains in the large state D. Also, if the angle of view is small at the focal length f ₁ , rotate the zoom ring of the zoom lens to the short focal length side (f ₄ ) and then turn it to the long focal length side to obtain the desired angle of view. If f is set to ₁ , the irradiation angle can be increased and irradiation can be extremely uniform.

Furthermore, by driving the zoom ring near the focal length where the irradiation angle is switched, the irradiation angle does not change frequently during the framing operation.

As described above, according to the present invention, the illumination angle control device of the flash device has a hysteresis characteristic, so that a photographer can use a variable illumination angle flash device or a zoom lens, and use a zoom lens that changes the illumination angle of the flash device. Even when the photographer finely adjusts the focal length of the zoom lens for zooming near the focal length, the illumination angle does not change frequently, which not only reduces power consumption, but also allows shooting by using hysteresis characteristics. The user can choose whether to give priority to the guide number of the flash device or to the irradiation angle, which is very effective.

[Brief explanation of the drawing]

FIG. 1 is a configuration diagram of an embodiment of the present invention, and FIG. 2 is a sectional view showing the principle of the zoom lens body of the present invention.
Figure 3 is a plan view showing the principle of the zoom lens body of the present invention, Figure 4 is a correspondence diagram of the focal length and resistance value of the zoom lens body of the present invention, and Figure 5 is a sectional view of the zoom lens body of the present invention. , FIG. 6 is a plan view of the zoom ring of the zoom lens body of the present invention, FIG. 7 is a circuit diagram of the second embodiment of the present invention, and FIG. 8 is the second embodiment of the present invention.
Fig. 9 is a diagram explaining the relationship between the focal length and the irradiation angle of the conventional device, and Fig. 10 is the relationship between the focal length and the irradiation angle of this embodiment. FIG. 10a, 35a...zoom ring groove, 11, 40...
…Pin, C ₃₅ , C ₅₀ , C ₇₀ … Comparator, R ₃ ,
_R5 , _R13 , _R15 , _R23 , _R25 ...Resistance.

Claims (1)

[Scope of Claim for Utility Model Registration] In an illumination angle control device that automatically varies the illumination angle of a flash device in stages according to changes in the focal length of a zoom lens in each predetermined range, 1. An irradiation angle control device comprising a switching means for changing the focal length depending on the direction of change in the focal length.