JP2641170B2 - Camera flash device - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a flash light emitting device for a camera which can change the light distribution and the amount of light.

(Background of the Invention) Conventionally, various types of strobe devices capable of changing light distribution have been proposed, but all of these devices disperse light by moving an arc tube and a lens (or a Fresnel lens) or a reflector. The configuration changes the angle or inserts a new lens or reflector into the optical path, that is, the configuration involves mechanical movement.

Such conventional types all have the following disadvantages.

1) When mechanically moving in an optical path, a motion transmission system from a drive source is complicated and incurs high cost. In particular, the combination of a so-called pop-up type strobe device that changes the distance between the photographing lens and the strobe device between the camera storage state and the photographing state and the mechanism for performing the light distribution variable has been further complicated.

2) In the conventional device, the light distribution was not efficient. That is, when the apparatus is mounted on a zoom camera of f = 35 to 70 mm, the area of the illuminated subject becomes 1/4 when f = 70 mm, compared to the light distribution at f = 35 mm. If the total amount of light at 35mm is condensed in a quarter area, the light density (GNo) near the center should be more than 4 times, but it is practically less than 2 times . The reason is that in order to efficiently condense the amount of light emitted from the arc tube, it is necessary to increase the size of the reflector or the Fresnel lens. Or, if you put in a diffuser, the size of the strobe device will be larger and it will not fit the camera.
This is because light collection was unavoidable.

However, from the user's point of view, the above f = 35 to 70
When using a zoom camera of mm, f = 35mm or f = 70mm
In view of the frequency of use, which is overwhelmingly large and only a few cases use the focal length in the middle range, the above characteristics are a major drawback.

3) The mechanical switching mechanism requires a light distribution switching time. In particular, the switching time is required for light distribution switching (switching for light distribution according to the lens extension position by AF) due to a change in subject distance. It was a release time lag.

4) Since the switching of the mechanism is performed by an electric motor such as a motor, energy for the switching is required, and the durability of the mechanism is also a problem.

(Object of the Invention) It is an object of the present invention to provide a flash light emitting device of a camera capable of performing flash photography with a desired light distribution characteristic according to a subject distance with a simple and small configuration.

(Features of the Invention) In order to achieve the above object, the present invention provides a first flash light emitting section, a second flash light emitting section having a light distribution narrower than that of the first flash light emitting section, A flash light emitting device of a camera having control means for controlling the light emitting operation of the second flash light emitting unit according to the subject distance.

Hereinafter, the present invention will be described in detail with reference to the illustrated embodiments.

1 (a), 1 (b) and 1 (c), reference numeral 1 denotes a camera body, and 2 denotes a zoom lens barrel, which controls the taking lenses 2a and 2b to predetermined positions. Reference numeral 3 denotes a strobe device which is always housed in the camera body 1 by a guide portion 3a, and has a structure protruding far away from the photographing lenses 2a and 2b during photographing as shown in the figure.

The strobe device 3 is composed of two light emitting units indicated by A and B in the figure. The angle of view of the light emitting unit A is substantially matched to the WIDE end of the photographing lens, and the angle of view of the light emitting unit B is the same as that of the photographing lens.
It is almost aligned with the TELE end. In the light emitting unit A, a WIDE reflector 3d, a WIDE lens 3c, and a xenon tube 3f are arranged. In the light emitting unit B, a TELE lens 3b, a TELE reflector 31e, and a xenon tube 3g are arranged. These light-emitting units A and B are controlled based on the focal length of the photographing lens (further, the brightness of the outside world and the subject distance) (details will be described later), and emit light at an appropriate ratio.

The TELE lens 3b is a reflective surface on which the remote surface 3h is aluminum-evaporated, and transmits light from an angle that does not enter the angle of view of the TELE lens 3b from the straight tube type xenon tube 3g on the front transparent surface.
It is configured so that it is totally reflected using a critical angle of 3k and re-reflected on the anti-slope surface 3h to be within the angle of view of the TELE lens 3b. Further, the light emitting units A and B are laid out by being inclined by the specified angle θ, respectively, and the light emitting direction is, as shown in the light distribution characteristic diagram described later, the optical axis of the photographing lens and the optical axis of the light emitting unit A. For example, to match at a subject distance of 1m,
The optical axis of the light emitting unit B and the optical axis of the photographing lens are set to coincide with each other, for example, at a subject distance of 3 m.

With this arrangement, the distribution can be determined not only by the distribution of the light distribution but also by the factor based on the distance. In addition, by arranging the light-emitting unit B on the TELE side, which has a higher light-condensing degree, in a direction far from the optical axis of the photographing lens, the so-called red-eye phenomenon in which light hitting the human retina is reflected on the film is less likely to occur.

In FIG. 1, reference numeral 3j denotes a flash circuit to be described later, 4 denotes a finder, and 5 denotes a release button.

FIG. 2 is a flowchart showing the operation of the camera having the light emitting units A and B.

When the photographer holds the camera and presses the release button 5 halfway, first, a known photometric circuit determines the luminance level of the object scene, and then the result (photometric data)
Is latched, and then the presence or absence of a bright or dark scene or a backlight scene in the object scene is determined. If a flash device is required for photographing, charging of the flash device is started. Thereafter, the distance measurement is performed, and the result (distance measurement data) is latched.

Next, zoom data indicating the current focal length of the photographing lens output from the lens barrel (further, the photometry,
Based on the distance measurement data), the light-emitting units A and
The light amount ratio (light distribution ratio) of B is determined, and at the same time, the light emission timing is stored. After that, various photographing modes are displayed by known display means, and the release button 5 is displayed.
Is expected to be pushed further.

When the photographer further presses the release button 5, the distance of the photographing lens is adjusted based on the above-mentioned distance measurement signal, and then the shutter blades are opened by known shutter means.

When the shutter is opened to the opening diameter obtained by dividing the total guide number (GNo) based on the determined light distribution ratio of the strobe by the object distance, the light emitting units A and B emit light at predetermined timings, respectively. When a proper exposure completion signal or a signal indicating the cutoff time is input, the shutter is closed, the film is wound up by one frame by a known winding mechanism, and the operation returns to the start state shown in FIG.

FIG. 3 shows an example of a circuit configuration of a main part of the present invention.

In the figure, 10 is a power supply battery used as a power supply for the entire camera, 11 is a known DC / DC converter circuit, 19 is a main capacitor, and the DC / DC converter circuit 11 boosts the voltage of the power supply battery 10, The capacitor 19 is charged.
18 and 22 are xenon tubes, and the xenon tube 18 corresponds to the xenon tube 3f in the light emitting unit A set to the WIDE angle of view,
The xenon tube 22 corresponds to the xenon tube 3g in the light emitting unit B set to the angle of view of TELE. Xenon tubes 18,22
Is connected in parallel with the main capacitor 19,
The energy stored in the device is discharged to perform a light emitting operation. A sub-capacitor 21 is connected to the xenon tube 22 in parallel. A parallel connection of the xenon tube 22 and the sub-capacitor 21 is connected in parallel to the main capacitor 19 via a diode 20. The diode 20 is connected in a direction in which current flows from the DC / DC converter circuit 11 or the main capacitor 19 to the parallel connection of the sub-capacitor 21 and the xenon tube 22.

Reference numerals 32 and 33 denote known first and second trigger circuits, respectively, which include a trigger capacitor, a trigger transformer, a switching thyristor, and the like. 29 is a mechanical or electrical synchro switch, and 30 is a trigger signal generating circuit for generating a trigger signal when the synchro switch 29 is turned on. 31 is a delay circuit, and 34 is an arithmetic circuit.

When the trigger signal is generated in the trigger signal generation circuit 30, the first trigger circuit 32 is activated and the delay timer of the delay circuit 31 is started. On the other hand, the arithmetic circuit 34
Determines the light emission timing of the light emitting unit B based on the above-described zoom information and the like, and the delay time of the delay circuit 31 is set based on this.

Next, the operation at the time of flash photography will be described with reference to FIGS. 2 and 3.

As a result of the photometric data, when a strobe device is used, a charging signal is generated in the DC / DC converter circuit 11, and the main capacitor 19 is charged. At the same time, the secondary capacitor
21 is also charged via the diode 20. When charging is completed and the photographer performs the release operation as described above, the synchro switch 29 is closed when the shutter opens to the opening value calculated based on the comprehensive guide number, and the trigger signal generation circuit 30 is triggered. When the signal is generated, the first trigger circuit 32 is activated, and the xenon tube 18 starts emitting light by consuming the charge of the main capacitor 19. At the same time, the delay timer of the delay circuit 31 starts. When the H level signal is output from the delay circuit 31 by the count up of the timer,
The second trigger circuit 33 is activated, and the xenon tube 22 emits light by consuming the electric charge of the main capacitor 19 via the diode 20. FIG. 4 shows an example of the light emission waveform of the light emitting units A and B at this time.

In this way, the voltage between both ends of the main capacitor 19 gradually decreases between the time when the xenon tube 18 starts emitting light and the time when the xenon tube 22 emits light. Generally, a xenon tube does not start emitting light unless a sufficient voltage is applied between the anode and the cathode. However, in the present configuration, the charging voltage before the xenon tube 18 emits light is stored in the sub-capacitor 21 via the diode 20, and the sub capacitor 21 is not discharged by the backflow preventing action of the diode 20 even after the xenon tube 18 emits light. Since the initial voltage is maintained in the sub-capacitor 21, even after the delay time elapses, the initial voltage is applied to the xenon tube 22 even if the voltage of the main capacitor 19 decreases, and light emission can be reliably performed. is there.

The xenon tube 18 and the xenon tube 22 have the same main capacitor.
The charge of 19 is divided at a ratio determined by the impedance of the xenon tube 18 and the xenon tube 22 to emit light. Therefore, for example, when the delay time is long, most of the electric charge of the main capacitor 19 is consumed by the xenon tube 18. On the other hand, when the delay time is short, the ratio of the xenon tube 18 becomes small.

Here, when the capacity of the sub-capacitor 21 is large, the change in the light amount ratio due to the variable delay time is small, but the sub-capacitor 21 only needs to be able to maintain the voltage until the xenon tube 22 is triggered and starts emitting light. Therefore, a small capacity that can be ignored is sufficient.

As described above, by varying the delay time by the arithmetic circuit 34, the light amount ratio between the light emitting units A and B can be varied. At this time, the variable light intensity ratio is determined by the xenon tube.
From the state where only 18 emits light, the xenon tube 18 and the xenon tube
After passing through a state in which light is emitted at a certain light amount ratio, the state changes to a state in which only the xenon tube 22 emits light. If the zoom data at this time is on the TELE end side or WIDE end side, only the corresponding light emitting unit is selected and emits light.

As a method of illuminating a subject with a plurality of light emitting units, in addition to a conventional light emitting unit, there is a method of using a two-light strobe device having a bounce light emitting unit.
It is not intended to change the light distribution and the light amount as in the present invention, but to obtain the effect of changing the light quality of the illumination light using the diffused light due to bounce. Different effects.

Next, light distribution examples of the light emitting unit A having the WIDE side light distribution and the light emitting unit B having the TELE side light distribution are shown in FIGS. 5 (a), (b) and 6, respectively.

FIG. 7 shows a total light distribution obtained by superposing the light distributions of FIG. 5 (a) and FIG. 6 at a predetermined ratio. FIG. 7 shows a state in which the ratio of the light distribution on the WIED side is large (result of the variable light amount ratio), a state in which the ratio of the light distribution on the TELE side is large, and an intermediate state.

By changing the light distribution ratio, as shown in FIG. 7 to, the total light distribution is varied, and a part in which the total light distribution is formed by both the WIDE side and the TELE side light, The amount of light can be rapidly increased or decreased near the boundary with the light-only portion on the WIDE side. For example, if the latitude of the film is relatively wide such as a color negative film, there is no practical problem, but if the latitude is small, such as a CCD image sensor used for a positive film or an electronic camera, This causes irradiation unevenness.

Therefore, the light distribution of FIG. 5B and the light distribution of FIG. In FIG. 5 (b), in the WIDE-side light distribution, the amount of light in the portion where the TELE light is superimposed is reduced so that the light distribution when superimposed is changed smoothly, thereby eliminating irradiation unevenness.

In the above embodiment, the light amount ratio of the two light emitting unit units A and B is switched in accordance with the focal length of the photographing lens to vary the light distribution, but there is also a system as shown in FIG.

FIGS. 9 (a) and 9 (b) show not only zoom data (focal length (angle of view)) but also the aforementioned photometric data (field luminance),
Lighting unit A, taking into account distance measurement data (subject distance)
FIG. 9A shows an example of determining the light amount ratio of B.
FIG. 9B shows the ratio of the light emission amount of each of the light emitting units A and B when the object field is relatively dark, and when the object field is relatively bright at the very end of the strobe light emission level.

The guide number of the light-emitting unit A at full light emission is set to "10", the guide number of the light-emitting unit B at full light emission is set to "28", and the photographing lens is set at the FIDE end at the WIDE end.
3.5, about F6.5 at TELE end, NOMAL is in the middle, 5m or more for long distance, 3.5m for long distance, 2m for medium distance, 1m for short distance, 0.88m or less for close distance It is.

Under the above conditions, this embodiment incorporates the following concept.

(I) Regardless of the position of the focal length of the taking lens, the light emitting unit A on the WIDE side mainly emits light during close-up shooting. (If the light-emitting unit B is the main, parallax will occur and irradiation unevenness (light distribution unevenness) will occur. If the light-emitting unit A has a low guide number but the subject distance is short, TELE
(II) Sufficient exposure can be obtained even on the side (F6.5). (II) If there is a certain level of field brightness, lower the strobe guide number slightly (increase the light emission ratio of the light emitting unit A) and increase the aperture of the camera as much as possible. Shoot with the camera open. (This lowers the luminance ratio between the main subject and the sub subject, preventing the background from darkening during flash photography.) (III) Basically, the light emitting unit A on the WIDE side and the light emitting unit on the TELE side The unit B emits light, and in the middle range, the emission ratio is adjusted to the angle of view.

10 to 18 show the light emitting units A and B shown in FIG.
1 shows another configuration example and the like.

In FIG. 10, reference numeral 51 denotes a main body of the strobe unit, and reference numeral 52 denotes a condenser lens for TELE. FIG. 11 shows a cross section of the condenser unit for TELE.

The condenser lens 52 is a lens and a reflection unit made of a transparent resin, and includes a convex lens 52a, a spherical surface 52b, reflection surfaces 52c and 52g on which a reflection film such as aluminum is deposited, and cylindrical irregularities detailed in FIG. It has an incident part 52d in which lens surfaces 52f and 52e are alternately provided on the circumference.

Reference numeral 53 denotes a well-known reflection shade, 54 denotes a straight tube type xenon tube for WIDE, and 55 denotes a bead ball type xenon tube shown in detail in FIG. A base portion 55a is made of ceramic or the like, and a xenon gas is sealed inside the glass tube 55e. 55d is an anode electrode, 55c is a cathode electrode,
A glass tube 55 having a transparent electrode processed by a known trigger circuit as shown in FIG. 3 in a state where a voltage is applied to both electrodes.
When a trigger signal is applied to e, electrons flow in the direction shown by the dotted line in FIG. 13 to emit light. Reference numeral 55b denotes a wall made of ceramic or the like which divides an internal space sealed by the glass tube 55e and the base 55a into four rooms, so that the four rooms are apparently connected in series (in the figure, The wall 55b, the glass tube 55e, and the base 5 (in such a way that electrons flow as shown by the broken lines)
A gap is provided only partially with 5a.

Reference numeral 56 in FIG. 11 denotes a holding ring for holding a bean ball type xenon tube 55, which is made of an insulator such as plastic and has a cylindrical shape having an elliptical shape in a natural state. Base portion 55a of xenon tube 55 and incident portion 51b of main body 51
(Both are in the shape of a perfect circular cylinder).

From this temporarily fixed state, the screw 60 is further inserted into the screw hole 51 of the main body 51.
Screw it into a and press down on the retaining ring 56 to deform it with a stronger force to fix the body and the xenon tube 55 (the screws may be glued).

The condenser lens 52 and the main body 51 are fixed with an adhesive.

FIG. 14 shows an example of another type of small xenon tube, in which a small straight tube is bent into a U shape, 57a is a base portion, 57c is an anode electrode, 57b is a cathode electrode,
Xenon gas is sealed in the inside of the glass tube 57d and the base portion 57a that have been subjected to the transparent electrode treatment.

With the above configuration, first, a small xenon tube 55 (or
57), the light emitted from the xenon tube 55 is reflected by O1 in the figure as shown in FIG.
The subject is illuminated through four optical paths of ~ O4.

The light beam passing through the optical path O1 is light that directly passes through the convex lens 52a and irradiates the subject, and the convex lens 52a is configured at a distance L from the light emitting surface to the lens with respect to the size X of the light emitting unit. In this arrangement, the light emitted from the light emitting unit is collected in the screen on the TELE side of the camera using the strobe device.

In this embodiment, the distance L and the power of the lens 52a are arranged such that an image of size X is substantially formed on a subject 3 m ahead with a size equivalent to the focal length f of the photographing lens f = 105 mm.

The light beam passing through the optical path O2 enters the lens from the incident portion 52d and undergoes total reflection by the lens spherical surface 52b (refractive index).
When a plastic lens of 1.49 is used, when light enters at an angle of about 42 ° or more, total reflection occurs.)
The light is reflected by c and is emitted again from the spherical surface 52b.

At this time, the spherical surface 52b forms a convex lens together with the incident portion 52d to collect the light beam, and OA, O having different angles at the time of total reflection.
It has the function of directing the luminous flux of B in the same direction.

The light beam passing through the optical path O3 enters from the incident portion 52d, is reflected by the reflection surface 52c, is totally reflected again by the spherical surface 52b, and is output as 52d to 52b. This light beam is also emitted to the subject at a narrow angle by the convex lens effect and the direction correcting effect at the time of total reflection, similarly to the light beam passing through the optical path O2 described above.

The light beam passing through the optical path O4 enters the lens from near the frontage of the entrance 52d, is reflected by the reflection surface 52g, and is output from the spherical surface 52b. Also at this time, the incident portion 52d and the spherical surface 52b serve as a convex lens, and the reflecting surface 52g also plays a role of condensing.

FIG. 16 shows the light condensing degree when illuminated by the above two light emitting units toward a plane at an object distance of 3 m.

In the drawing, the area to be photographed when the size indicated by a broken line and the like is f = 38 mm, 70 mm, and 105 mm is shown. The column shows the converging lens 52 and the xenon tube 55 on the TELE side. The light output from the light-emitting unit and the light represented by the prism are the light output from the light-emitting unit on the side of the reflector 53 and the xenon tube 54, and the height indicates the intensity of the light.

As can be understood from the above figure, of the light output from the conventional type WIDE-side light emitting unit, about 38% of the entire light is incident on the screen of f = 38 mm. This is effective for room effect or light distribution without unevenness of the intermediate focal length.

The volume of the cylinder and prism shown in Fig. 16 is larger than the volume of the prism (total light emission) of 0.65: 1, but the illuminance (height) at the center is 8: 1 and the TELE side (column side) Of the light emitting unit is larger (the guide number ratio is As described above, by giving a sufficient light-collecting action even with a small-sized and low-output light emitting body, it is possible to give a sufficient amount of light (guide number) to the screen on the TELE side.

Specifically, when a strobe device as in the above embodiment is attached to a zoom camera of f = 38 mm (F3.5) to f = 105 mm (F6), assuming that the guide number on the WIDE side is “10”, TELE
Side is "28", up to about 3m on the WIDE side, about 3m on the TELE side
Shooting is possible up to 5m.

Next, a structure for improving the illumination unevenness generated in the xenon tube 55 will be described with reference to FIG.

In the case of the bean ball type xenon tube 55 having the aforementioned four partition walls, there is extreme brightness unevenness between the light emitting portion and the wall portion 55b indicated by the dotted line in FIG. Is high, the high-brightness part is the incident part 52d.
By forming a concave lens 52e on the light incident surface and forming a convex lens 52f on a portion having low luminance and connecting these with a smooth surface, the above-mentioned illumination unevenness can be improved.

Further, by adopting the above shape, the plastic condensing lens 52 is kept away from a portion having a high emission luminance, that is, a portion where the temperature becomes high (FIG. 12 l).
m), the condenser lens is heated by heat while achieving compactness.
It also has the effect of preventing 52 from being attacked.

FIG. 17 is a view showing another structural example capable of eliminating illumination unevenness in the same manner as described above.
The light-emitting body 155 having the uneven brightness is turned into the lens light-emitting body 152 which does not cause the illumination unevenness.

FIG. 18 shows the U-shaped xenon tube 57 shown in FIG.
Uniform lens 70 having entrance surfaces 70a and 70b having the same effect
In which illumination unevenness is eliminated.

According to this embodiment, the light amount ratio of each light emitting unit having a different light distribution is changed according to the focal length information of the photographing lens and the like, and these strobe lights are superimposed and illuminated. As described above, it is possible to provide a highly efficient variable light distribution without using complicated moving parts, and to provide a system with no time lag due to the variable light distribution.

(Correspondence between the invention and the embodiment) In the above embodiment, the xenon tubes 3f, 55, the reflection shade 3d,
53 is a xenon tube 3g, 54 in the first flash light emitting portion of the present invention.
The reflection shade 3e and the condenser lens 52 correspond to a second flash light emitting section, and the trigger signal generation circuit 30, the delay circuit 31, and the arithmetic circuit correspond to control means.

(Effects of the Invention) As described above, according to the present invention, the light emission operation of the first and second flash light emitting units is controlled in accordance with the distance to the subject, so that the subject can be easily and compactly configured. It is possible to provide a flash light emitting device of a camera capable of performing flash photography with desired light distribution characteristics according to a distance.

[Brief description of the drawings]

1 (a), 1 (b) and 1 (c) are a top view, a front view and a side view of a camera equipped with an embodiment of the present invention, FIG. 2 is a flowchart showing the operation of the camera shown in FIG. 3 is a circuit diagram showing one embodiment of the present invention, FIG. 4 is a diagram showing a light emission waveform of each light emitting unit, and FIG. 5 (a) is a diagram showing a light distribution example of a light emitting unit A shown in FIG. FIG. 5 (b) is a diagram showing an improved example of the light distribution of FIG. 5 (a), FIG. 6 is a diagram showing an example of light distribution of the light emitting unit B shown in FIG. 1, and FIG. FIG. 8A shows a state in which the light distribution of FIG. 6 is superimposed, FIG. 8 shows a state in which the light distribution of FIG. 5B is superimposed on FIG. 6, and FIG. (B) is a diagram showing an example in which the light amount ratio of the light emitting units A and B is determined based on zoom data, photometry data, and distance measurement data, FIG. 10 is a perspective view showing another embodiment of the present invention, and FIG. Is the FIG. 10 is a sectional view of the TELE light collecting unit, FIG. 12 is a front view of the apparatus shown in FIG. 10, and FIG.
FIG. 11 is a perspective view of a bean ball type xenon tube illustrated in FIG. 14, FIG. 14 is a perspective view of another xenon tube of a bean ball type, FIG. 15 is a diagram illustrating a projection optical path in a TELE light collecting unit illustrated in FIG. 16
The figure is a diagram showing the light condensing degree from each light emitting unit shown in FIG. 10,
FIG. 17 is a diagram showing another example of the configuration for preventing the uneven brightness of the xenon tube shown in FIG. 13, and FIG. 18 is a configuration for preventing the uneven brightness when the xenon tube shown in FIG. 14 is employed. FIG. A: WIDE light-emitting unit, B: TELE light-emitting unit, 31: delay circuit, 34: arithmetic circuit, 52: condenser lens, 53: reflector, 54, 55 xenon tube .

 ──────────────────────────────────────────────────続 き Continuation of front page (56) References JP-A-55-144221 (JP, A) JP-A-63-182636 (JP, A) JP-A-57-81245 (JP, A) JP-A-58- 114025 (JP, A) JP-A-60-100125 (JP, A) JP-A-2-68533 (JP, A) JP-A-60-60729 (JP, U) JP-A-59-144636 (JP, U)

Claims (1)

(57) [Claims] A first flash light emitting section, a second flash light emitting section having a narrower light distribution than the first flash light emitting section, and a light emitting operation of the first and second flash light emitting sections set to a subject distance. Control means for controlling the flash light according to the camera.