JP5211084B2 - Strobe device - Google Patents

Description

  The present invention relates to a strobe device for irradiating an irradiation target with strobe light as auxiliary light for photographing.

  For example, a strobe device built in a digital camera or the like is a subject that is irradiated with strobe light in order to enable shooting within a predetermined effective shooting range in a dark environment such as at night or in the rain. A light source that emits strobe light, a reflector that reflects the strobe light from the light source toward the irradiation target, and a lens that covers the front opening of the reflector.

  In such a strobe device, in order to take a photograph with good color reproducibility, the strobe light emitted from the light source has a color tone that matches the sunlight.

  By the way, as a light source of a strobe device, a small and high illuminance xenon tube (Xe tube) is often used. This xenon tube is a transparent glass tube filled with xenon (Xe) gas. The optical characteristics (light quantity and wavelength distribution (color temperature)) depend on factors such as the pressure of the enclosed xenon gas, the spacing between the discharge electrodes, the glass material, and the coating film (nesa coating) coated on the outer wall of the glass tube. It is determined.

  In addition, resin molded products are mainly used for lenses, and their optical properties (elements such as resin materials used as base materials, additives such as pigments / dyes / phosphors / diffusion materials, lens shapes, and lens surface coatings) Light distribution control and color temperature control) are determined.

  Further, a high-luminance aluminum plate is mainly used for the reflector, and the light distribution of the strobe light emitted from the xenon tube is controlled by its shape.

  By the way, while the color temperature of sunlight is 5000 to 6000K, the color temperature of strobe light emitted from the xenon tube is as high as 6500 to 7000K, and the strobe light emitting unit adjusts the color temperature suitable for shooting. The color temperature is generally adjusted by a xenon tube and a lens. Specifically, the color temperature is adjusted by improving the gas pressure of the xenon tube, changing the coating film, changing the lens additive, increasing the amount, or the like.

Regarding the adjustment of the color temperature of the strobe light, Patent Document 1 discloses that a reflection film of SiO ₂ or TiO ₂ is formed on the reflection part of the reflector by vacuum deposition or sputtering, and the reflectance of the short wavelength light is suppressed to a low wavelength side. A strobe device has been proposed in which strobe light from a xenon tube is converted to a color temperature to emit radiation light having a low color temperature close to that of sunlight.

JP 2001-051326 A

  However, the method of adjusting the color temperature of the strobe light by using a xenon tube and a lens has a problem in that it tends to cause a problem of light emission startability, a decrease in light amount, or a problem of lens resin modification such as lens burning.

  In other words, when the gas pressure in the xenon tube is increased, the light emission startability decreases to prevent the discharge phenomenon due to electron avalanche, and when the coating film (nesa coating) is changed, the amount of light decreases due to the decrease in transmittance. To do. Further, lens burning is mainly caused by heating of pigments and dyes added to the lens. Here, the reason why the pigment or dye is added to the lens is to adjust the wavelength distribution (color temperature) of the light emitted from the light source by absorbing the wavelength in a specific region among the light rays from the light source.

  The present invention proposes a configuration different from that of Patent Document 1, and obtains a strobe light color temperature that is optimal for photographing regardless of the xenon tube or lens, while reducing the light emission startability of the xenon tube and insufficient light amount. An object of the present invention is to provide a strobe device that can prevent lens resin from being modified by heat.

In order to achieve the above object, the present invention provides:
A xenon tube that emits strobe light,
A reflector that includes a front reflecting portion that covers a part of the xenon tube from the back and a side reflecting portion formed on both sides thereof, and reflects the strobe light from the xenon tube toward the irradiation target;
A lens covering the exit surface of the reflector;
In a strobe device equipped with
The longitudinal cross-sectional shape of the front reflecting portion of the reflector is an ellipse or a free-form surface close to an ellipse, and the reflecting surface of the inner surface of the front reflecting portion is a main reflecting surface having different reflection spectral characteristics and a sub-surface disposed in the center in the width direction. With a reflective surface,
The main reflection surface is composed of bright alumina, white resin, or white alumina that exhibits a substantially high reflectance over the entire wavelength range of the visibility range from near ultraviolet to infrared, and the sub-reflection surface is from near ultraviolet to blue. In the short wavelength range, it is constituted by gold plating for color temperature adjustment with high heat dissipation and showing lower reflectance than the main reflecting surface .

According to the present invention, a portion of the strobe light in the wavelength range of the visibility range from near ultraviolet to infrared is reflected by the main reflecting surface of the reflector and exhibits high reflectance, and the short wavelength range from near ultraviolet to blue The strobe light is reflected by the sub-reflecting surface of the reflector and shows a low reflectance, and thus the mixed light in which the reflected light reflected by the reflector is mixed with the direct light directly irradiated without being reflected by the reflector, A photograph with good color reproducibility can be taken to show a color temperature close to that of sunlight. In this case, the xenon tube and the lens are not touched at all, so the strobe light color temperature optimal for shooting is obtained regardless of the xenon tube or lens, while the xenon tube emission startability is reduced, the light intensity is insufficient, and heat It is possible to prevent the lens resin from being modified.

Further, since the sub-reflecting surface of the reflector is made of gold plating with high heat dissipation, the lens resin is prevented from being denatured by overheating.

Furthermore, high bright alumina showing a substantially uniform high reflectivity in the wavelength range of visibility range to the near-ultraviolet to infrared as the main reflecting surface, using a white resin or white alumina, as a sub reflecting surface for color temperature adjustment Since gold plating showing a low reflectance in the short wavelength range from near ultraviolet to blue is used, it is possible to obtain a strobe light color temperature that is optimal for photographing irrespective of a xenon tube or a lens.

1 is a perspective view of a strobe device according to the present invention. 1 is a plan sectional view of a strobe device according to the present invention. It is the sectional view on the AA line of FIG. It is a figure which shows the spectral distribution of the light which a black body emits using temperature as a parameter. It is a spectral distribution map of sunlight. It is a spectral distribution map of a xenon tube. It is a reflection spectral distribution map of various materials.

  Embodiments of the present invention will be described below with reference to the accompanying drawings.

  1 is a perspective view of a strobe device according to the present invention, FIG. 2 is a plan sectional view of the strobe device, FIG. 3 is a sectional view taken along line AA in FIG. 2, and the strobe device 1 according to the present embodiment is A built-in digital camera or the like irradiates a subject (not shown), which is the subject of irradiation, with a strobe light to enable shooting within a predetermined effective shooting range even in dark environments such as at night or in rainy weather. As shown in FIGS. 1 and 2, a xenon tube 2 that is long in the width direction as a light source, a reflector 3 that reflects strobe light from the xenon tube 2 toward a subject, and a front surface of the reflector 3. A transparent resin lens 4 covering the (light emitting surface) is provided.

The reflector 3 is disposed so as to cover a part of the xenon tube 2 from the back side, and includes a front reflecting portion (vertical wall) 3a and side reflecting portions ( side walls) 3b formed on both side surfaces thereof. In order to control as much light as possible on the inner surface of the reflector 3, an ellipse or a free-form surface close to an ellipse is adopted as the longitudinal sectional shape of the front reflecting surface 3a, and the left and right side reflecting portions 3b are arranged in front (light It is formed in a tapered shape that opens toward the emission direction.

And Thus, in this embodiment, the reflector 3, as shown in FIG. 2, different from the main reflection surface 3A reflection spectral characteristics, and the secondary reflecting surface 3B arranged on the widthwise center of the main reflection surface 3A It consists of The main reflection surface 3A and the sub-reflection surface 3B have different reflection spectral characteristics, and the main reflection surface 3A covers the entire wavelength range (wavelength 380 to 780 nm) of the visibility range from the near ultraviolet to the infrared. The clothes reflecting surface 3B is a reflecting surface for adjusting the color temperature, and has a short wavelength range from near ultraviolet to blue (380 to 560 nm9). In FIG. 4, the heat-dissipating gold plating showing a lower reflectance than the main reflecting surface 3A is used.

  Further, the xenon tube 2 is configured by enclosing xenon gas inside the glass tube 2a of the discharge part, and a nesa coating 2b as a conductive coating film is formed on the entire circumference of the glass tube 2a. Coated. And this Nesa coating 2b is press-contacted to the front reflective surface 3a of the reflector 3, as shown in FIG.

  Here, the color temperature will be described. This color temperature is one of the indexes expressing the color of light emitted from the light source, and expresses a specific color with the temperature of a black body. FIG. 4 shows the spectral distribution of the black body as a parameter. As is clear from the figure, the spectral distribution of the light emitted by the black body changes with temperature, and if the temperature is low, there are many components on the long wavelength side. It emits reddish light, and if the temperature is high, it emits bluish light with many short wavelength components.

  Next, the spectral distribution of sunlight is shown in FIG. 5. As is clear from the figure, sunlight shows low energy intensity in a short wavelength region (380 to 560 nm).

  Thus, the strobe device 1 according to the present embodiment applies strobe light to a subject in order to enable photographing within a predetermined photographing effective range even in a dark environment such as at night or in rainy weather. When the brightness required for photographing is not ensured, strobe light is emitted from the xenon tube 2 of the strobe device 1 in synchronization with the operation of a shutter button (not shown).

  That is, a trigger voltage is applied to the xenon tube 2 through a contact portion between the aluminum vapor deposition layer of the reflector 3 and the nesa coating 2b of the xenon tube 2, and the xenon (Xe) gas enclosed in the xenon tube 2 is totally formed. When the emission current flows from the capacitor to the xenon tube 2, the xenon tube 2 discharges and emits light.

  Here, when the spectral distribution of the xenon tube 2 is X (λ), the reflection spectral characteristic of the reflector 3 is R (λ), the transmission spectral characteristic of the lens 4 is L (λ), and the coefficient relating to the number of reflections is ε, the strobe light The spectral distribution I (λ) of (mixed light) L is expressed by the following equation.

I (λ) = I ₁ (λ) + I ₂ (λ) + I ₃ (λ) + I ₄ (λ).
= X (λ) × εR (λ) × L (λ)
Where I ₁ (λ) = X (λ) × L (λ)
I ₂ (λ) = X (λ) × R (λ) × L (λ)
From the above equation, it can be seen that the color temperature (light emission color) of the strobe light can be adjusted if R (λ) can be arbitrarily adjusted in the reflection spectral characteristics of the reflector.

FIG. 6 shows the spectral distribution X (λ) of the xenon tube 2, and FIG. 7 shows the reflection spectral distribution R (λ) of various materials (polycarbonate, silver plating, gold plating, aluminum plate).

Thus, in the present embodiment, of the strobe light emitted from the xenon tube 2, the direct light L 1 shown in FIG. 3 is directly reflected toward the subject through the lens 4 without being reflected by the reflector 3. The The reflected light L2 reflected by the reflector 3 passes through the lens 4 and is irradiated toward the subject. However, the reflected light L2 in the wavelength range (380 to 780 nm) of the visibility range from near ultraviolet to infrared is obtained. Reflected by the main reflecting surface 3A of the reflector 3 and showing a high reflectance, the reflected light L2 in the short wavelength range (380 to 560 nm) from near ultraviolet to blue is reflected by the sub-reflecting surface 3B of the reflector 3 and is low. Reflectance is shown.

Therefore, the mixed light L obtained by mixing the reflected light L2 reflected by the reflector 3 and the direct light L1 directly irradiated without being reflected by the reflector 3 has a color temperature close to that of sunlight showing the spectral distribution shown in FIG. In order to show, a photograph with good color reproducibility can be taken. In this case, since the xenon tube 2 and the lens 4 are not touched at all, the emission startability of the xenon tube 2 is reduced while obtaining the optimum color temperature of the strobe light regardless of the xenon tube 2 and the lens 4. It is possible to prevent the resin of the lens 4 from being modified due to insufficient light quantity or heat.

Further, in the present embodiment, since the sub-reflecting surface 3B is made of gold plating with high heat dissipation, an effect that the resin lens 4 is prevented from being denatured by overheating is also obtained.

  The present invention can be applied to all strobe devices used in digital still cameras (DSC), digital video cameras (DVC), mobile phones and the like.

DESCRIPTION OF SYMBOLS 1 Strobe device 2 Xenon tube 2a Glass tube of xenon tube 2b Nesa coating of xenon tube 3 Reflector 3A Main reflection surface of reflector 3B Sub-reflection surface of reflector 3a Front reflection part (vertical wall) of reflector
Side reflector portion 3b reflector (side wall)
4 Lens L1 Direct light L2 Reflected light

Claims (1)

A xenon tube that emits strobe light,
A reflector that includes a front reflecting portion that covers a part of the xenon tube from the back and a side reflecting portion formed on both sides thereof, and reflects the strobe light from the xenon tube toward the irradiation target;
A lens covering the exit surface of the reflector;
In a strobe device equipped with
The longitudinal cross-sectional shape of the front reflecting portion of the reflector is an ellipse or a free-form surface close to an ellipse, and the reflecting surface of the inner surface of the front reflecting portion is a main reflecting surface having different reflection spectral characteristics and a sub-surface disposed in the center in the width direction. With a reflective surface,
The main reflection surface is composed of bright alumina, white resin, or white alumina that exhibits a substantially high reflectance over the entire wavelength range of the visibility range from near ultraviolet to infrared, and the sub-reflection surface is from near ultraviolet to blue. A stroboscopic device comprising a gold plate for color temperature adjustment having high heat dissipation and showing a lower reflectance than the main reflecting surface in the short wavelength range .

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