JP2015055694A - Flash light emission device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a flash light emission device that enables not only prevention of thermal damage on a light transmission member of the flash light emission device but also prevention of increase in temperature inside the flash light emission device.SOLUTION: A flash light emission device comprises: a flash light emission source; and a first light transmission member. In an optical passage between the flash light emission source and the first light transmission member, an infrared reflection member is provided that transmits visible light and reflects infrared light, and out of light emitted from the flash light emission source, the visible light is caused to transmit a first light transmission member and the reflected infrared light is caused to be discharged from a second light transmission member to an outside of the flash light emission device.

Description

  The present invention relates to a flash light emitting device, and more particularly to a flash light emitting device that irradiates a subject with light from a flash light source via a light transmitting member.

  In recent years, with the increase in the number of frames that can be imaged by the imaging device per second, the number of continuous light emission of the flash light emitting device used at the time of imaging tends to increase. Along with this, thermal damage to the internal members including the light transmitting member has become a problem due to the heat generation of the electrical elements involved in the light emission of the flashlight emitting device.

  In conventional flash light emitting devices, in order to prevent damage to internal members including a light transmitting member made of a resin material due to heat generated by continuous light emission, the resin member is protected by limiting the light emission interval with an overheat prevention farm or the like. . However, if the light emission is limited in the firm, there is a problem that the interval at which the light can be emitted is greatly increased.

  As a means for preventing such thermal damage of the light transmissive member other than the limitation due to the farm, for example, in Patent Document 1, light is provided by providing a filter that does not transmit infrared light in the optical path between the flash light source and the light transmissive member. What protects a transmissive member is disclosed. Patent Document 2 discloses a device that protects by providing a filter that absorbs infrared light.

Japanese Patent Laid-Open No. 7-225415 JP 2009-210837 A

  However, in the conventional technology disclosed in the above-mentioned patent document, if continuous light emission is continued without being restricted by the farm, the heat due to the reflected or absorbed infrared light can be obtained even if the light transmitting member can be temporarily protected. Stays in the flashlight device. Therefore, the temperature inside the flash light emitting device gradually increases, and there is a risk of damaging the light transmitting member. Furthermore, the temperature inside the flash light emitting device rises, and there is a possibility that the resin member inside the flash light device is thermally damaged.

  Accordingly, an object of the present invention is to provide a flash light emitting device that can prevent not only thermal damage of a light transmitting member of the flash light emitting device but also temperature rise inside the flash light emitting device.

  In order to achieve the above object, the present invention comprises a flash light source and a first light transmission member, and visible light is transmitted through an optical path between the flash light source and the first light transmission member. In addition, an infrared light region reflecting member that reflects infrared light is provided, and among the light emitted from the flash light source, visible light is transmitted through the first light transmitting member, and reflected infrared light is second. The light transmitting member is discharged to the outside of the flash light emitting device.

  ADVANTAGE OF THE INVENTION According to this invention, the flash light-emitting device which not only prevented the thermal damage of the light transmissive member of a flash light-emitting device but also prevented the temperature rise inside a flash light-emitting device can be provided.

FIG. 2 is a central sectional view of a light emitting unit of the strobe device showing the first embodiment of the present invention. 1 is a perspective view of a strobe device showing a first embodiment of the present invention. The conceptual diagram which shows a mode that the strobe device which shows the 1st Embodiment of this invention is connected with the camera. The elements on larger scale which show the 1st Embodiment of this invention. The conceptual diagram of the infrared cut filter of embodiment of this invention. The diagram which shows the general spectral characteristic of the infrared cut filter of embodiment of this invention. The diagram which shows the general relative intensity when the xenon tube for photography of embodiment of this invention is light-emitted. The conceptual diagram at the time of light emission of the 1st Embodiment of this invention. The conceptual diagram of the cold mirror of embodiment of this invention. The diagram which shows the general spectral distribution of the cold mirror of embodiment of this invention. Sectional drawing which shows the mode of the angle change of the filter of the 1st Embodiment of this invention. The diagram which shows the change of the spectral distribution when changing the angle of the infrared cut filter of the embodiment of the present invention. The center sectional view of the strobe device which shows the 2nd embodiment of the present invention. The perspective view of the flash device which shows the 2nd Embodiment of this invention. FIG. 6 is a central sectional view showing a conventional strobe device.

  Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.

[Example 1]
Hereinafter, a strobe device for taking a picture as a flash light emitting device according to a first embodiment of the present invention will be described with reference to FIGS. First, the structure of each part is demonstrated based on FIGS. FIG. 1 is a central sectional view of a unit of a light emitting unit of the strobe device according to the first embodiment of the present invention. FIG. 2 is a perspective view of the light emitting unit of the strobe device according to the first embodiment of the present invention as seen obliquely from below. FIG. 3 is a conceptual diagram showing a state when the strobe device according to the first embodiment of the present invention is connected to a camera.

  1 is a Fresnel lens, 2 is a hinge, 3 is protective glass, 4 is a xenon tube for photography, 5 is a reflector, 6 is a reflector umbrella holder, 7 is an infrared cut filter, 8 is a cold mirror, 21 is a condenser, 22 is Hood, 23 diffuser panel, 24 coupling part, 25 capacitor cover, 26 exterior cover, 27 motor, 28 feed screw, 29 main body control unit, 30 metal contacts, 40 camera, 41 photographing lens Indicates.

  The light emitting unit shown in FIGS. 1 and 2 is coupled to the main body control unit 29 of FIG. 3 via a coupling unit 24 attached to the capacitor cover 25 so as to be rotatable in the horizontal direction. The main body control unit 29 is mounted with various operation members such as a control board for performing strobe light emission control (not shown), a battery box, a power supply circuit, a power switch, and a setting changeover switch. The main body control unit 29 is fixed to a camera 40 as an imaging device, and communicates by connecting the main body control unit 29 and the camera 40 with a metal contact 30, and is attached to the strobe emission amount or the camera 40. The strobe device is controlled based on information such as the focal length of the photographic lens 41 as a photographic optical system. Even when the camera 40 is not fixed, the control may be performed using wireless communication. The exterior lower cover 26a and the exterior upper cover 26b to which the Fresnel lens 1 as the first light transmission member is attached are coupled to the capacitor cover 25 so as to be rotatable in the vertical direction.

  Inside the exterior lower cover 26a and the exterior upper cover 26b, a photography xenon tube 4 as a flash light source, together with the protective glass 3, the reflector 5 and the reflector holder 6, is connected to a motor 27 via a feed screw 28. It is a mechanism driven by. Further, in the optical path between the Fresnel lens 1 and the protective glass 3, an infrared cut filter 7 as an infrared light region reflecting member that transmits visible light and reflects infrared light is provided through the hinge 2. The lower cover 26a is rotatably connected.

  FIG. 4 is a partially enlarged view showing the attachment part of the hinge 2 with the Fresnel lens 1 removed from the unit of the light emitting part of the strobe device according to the first embodiment of the present invention. 31 denotes a torsion coil spring, and 32 denotes a stopper. The infrared cut filter 7 is elastically biased by a torsion coil spring 31 attached to the hinge 2 so as to incline toward the photography xenon tube 4 side. The projection provided on the hinge 2 and the stopper 32 come into contact with each other, so that the tilt does not exceed a certain level.

  FIG. 5 is a conceptual diagram showing characteristics of the infrared cut filter in the unit of the light emitting unit of the strobe device according to the first embodiment of the present invention. FIG. 6 is a diagram showing the spectral transmittance of the infrared cut filter provided in the strobe device according to the first embodiment of the present invention. As shown in FIG. 5, the infrared cut filter 7 transmits visible light with a high transmittance out of the light emitted from the light source, and reflects the infrared light with little transmission. Infrared light is so-called heat rays that are converted into heat when absorbed. As shown in FIG. 6 which is a general spectral characteristic of the infrared cut filter, light having a wavelength of about 400 nm to about 700 nm in the visible light region is transmitted with a high transmittance of 90% or more and hardly reflected.

  However, light having a wavelength of about 800 nm to about 1100 nm, which is an infrared light region, is transmitted only with a low transmittance of 15% or less, and most of the light is reflected. In addition, although the general spectral characteristic was shown in FIG. 6, since the infrared cut filter can design the transmission wavelength range arbitrarily, it can use the best infrared cut filter by designing with the design value mentioned later. It is.

  FIG. 7 is a diagram showing the general relative intensity with respect to the wavelength of the xenon tube for photography of the strobe device according to the first embodiment of the present invention. The xenon tube 4 for photography can be supplied with power from a capacitor 21 and can emit flash light. The emitted light is reflected by a reflector 5 and passes through a protective glass 3, an infrared cut filter 7, and a Fresnel lens 1. Irradiate toward the subject. At this time, light that is not incident on the Fresnel lens 1 is diffusely reflected by the hood 22 so that more light can be directed toward the subject.

  Further, by pulling out the diffusing panel 23 accommodated between the outer cover 26b and the panel cover 26c, it is possible to make the focal length wider than the focal length that can be handled by the optical system of the Fresnel lens 1. As shown in FIG. 7, a large amount of light is generated from the xenon tube for photography, particularly in the infrared light region other than the visible light region. This light does not contribute to photography, and This is a cause of increasing the temperature of the constituent members.

  Next, the operation of the first embodiment of the present invention will be described with reference to FIGS. FIG. 8 is a conceptual diagram when a photo xenon tube emits light in the unit of the light emitting unit of the strobe device according to the first embodiment of the present invention.

  The light emitted from the xenon tube 4 for photography is transmitted through the protective glass 3 and then separated by being reflected by the infrared cut filter 7 and reflected by the infrared light. Of the separated light, visible light passes through the infrared cut filter 7 and is then irradiated to the subject through the Fresnel lens 1 to be used as illumination light at the time of photographing. Of the separated light, the infrared light is reflected by the infrared cut filter 7 and then discharged from the second light transmitting member provided in the exterior lower cover 26a to the outside of the strobe device. Thereby, the infrared light hardly reaches the Fresnel lens 1, the temperature rise of the Fresnel lens 1 can be suppressed, and damage from heat can be prevented. Furthermore, since infrared light is discharged to the outside of the strobe device, it is possible to prevent an increase in temperature due to heat remaining inside the strobe device.

  FIG. 9 is a conceptual diagram showing characteristics of the cold mirror in the unit of the light emitting unit of the strobe device according to the first embodiment of the present invention. FIG. 10 is a diagram showing general transmittance and reflectance with respect to the wavelength of the cold mirror provided in the strobe device according to the first embodiment of the present invention. As shown in FIG. 9, the cold mirror 8 reflects the visible light hardly transmitting among the light irradiated from the light source, and transmits the infrared light with high transmittance. As shown in FIG. 10, light having a wavelength of about 400 nm to about 700 nm, which is in the visible light region, is reflected with a high reflectance of 90% or more and hardly transmits, but is in the infrared light region of about 800 nm to Light having a wavelength of about 1100 nm is transmitted with a high transmittance of 90% or more and is hardly reflected. Although general spectral characteristics are shown in FIG. 10, the cold mirror can be designed to have an arbitrary transmission wavelength range as in the case of the infrared cut filter. Therefore, the cold mirror can be designed according to the design value of the infrared cut filter described later. Is possible.

  By providing a cold mirror 8 as an infrared light region transmitting member that does not transmit visible light but transmits infrared light instead of the second light transmitting member, the cold mirror 8 transmits only infrared light. The visible light diffused and reflected by the hood 22 without entering the Fresnel lens 1 can be prevented from leaking out of the strobe device from the second light transmitting member. That is, it is possible to prevent unintended light from appearing in the photograph. Needless to say, an infrared transmission filter may be used instead of the cold mirror 8 as long as it has an effect of transmitting only infrared light.

  FIG. 11 shows the change in the optical arrangement of the light emitting unit of the strobe device according to the focal length of the photographing lens attached to the camera in the first embodiment of the present invention, where (A) is the telephoto area, and (B) is the standard. Region (C) is a cross-sectional view showing a state in the wide-angle region. 11A shows the arrangement when the focal length is 200 mm as the telephoto area, FIG. 11B shows the arrangement when the focal length is 50 mm as the standard area, and FIG. 11C shows the focal length 20 mm as the wide angle area. FIG. 12 is a diagram showing the transition of the transmittance with respect to the wavelength when the arrangement angle of the infrared cut filter provided in the strobe device according to the first embodiment of the present invention is changed. As shown in FIGS. 11A to 11C, the state when the telephoto area is changed to the wide-angle area will be described in order.

  Between the focal length of 200 mm shown in FIG. 11 (A) and the focal length of 50 mm shown in FIG. 11 (B), the infrared cut filter 7 is elastically biased to the most inclined angle by the torsion coil spring 31, and the first In one embodiment, the infrared light is arranged at an angle at which it is easy to discharge out of the strobe device. Since the space between the Fresnel lens 1 and the protective glass 3 is narrowed between the focal length of 50 mm shown in FIG. 11B and the focal length of 20 mm shown in FIG. 11C, the infrared cut filter 7 is a reflector. While being pushed by the holder 6, it is urged to the most inclined angle that can be taken in the space between the Fresnel lens 1 and the protective glass 3, and the inclination gradually changes.

  When the focal length is 20 mm shown in FIG. 11C, the infrared cut filter 7 is vertical. The angle of the infrared cut filter 7 can be adjusted according to the size of the infrared cut filter 7 and the fixing position of the hinge 2. Even if the spectral characteristics of the infrared cut filter 7 and the size of the strobe device are changed, it is most effective. High condition can be designed. Further, by setting the position of the focal length that is assumed to emit light most continuously as in bounce shooting to the position where the infrared light is most effectively discharged as shown in FIG. The maximum discharge capacity can be utilized.

  For example, the position of the hinge 2 in the embodiment described with reference to FIG. 4 is determined by the relationship between the height and width of the Fresnel lens 1, the opening space in the hood 22, and the distance between the Fresnel lens 1 and the protective glass 3. With these spaces, the movable range of the infrared cut filter 7 is determined, and infrared light reflected from the infrared cut filter 7 by simulation is most exposed to the outside of the strobe device from the second light transmitting member provided on the exterior lower cover 26a. Analyze the discharge angle. And the hinge 2 is arrange | positioned in the position which can take the angle which the infrared cut filter 7 analyzed.

  At this time, it is necessary to make the size of the infrared cut filter 7 larger than the opening of the reflector 5 in a state where the infrared cut filter 7 is inclined. This is because the energy density of the heat received by the Fresnel lens 1 from the xenon tube 4 for photography is concentrated at the center of the Fresnel lens 1. That is, the infrared cut filter 7 needs to cover the center of the Fresnel lens 1 where heat energy is concentrated. According to the above design, the angle of the infrared cut filter 7 is determined with the angle inclined 45 degrees as the maximum. Incidentally, FIG. 4 shows an example in which the maximum displacement angle is 35 degrees.

  In FIG. 4, the hinge 2 is set at a position on the Fresnel lens 1, and this is a result of the above design. Visible light is blocked by the hinge 2, but the light incident on the Fresnel lens 1 is diffused in a Fresnel shape, so that the Fresnel shape can be designed so as not to affect the illumination light. Further, it is possible to prevent the visible light from being blocked by configuring the hinge 2 itself with a transparent member.

  However, in general, the infrared cut filter changes the transmittance and reflectance with respect to the wavelength depending on the incident angle of light. For example, in the first embodiment of the present invention, the infrared cut filter 7 exhibits the transmittance characteristics shown in FIG. 6 when arranged in the vertical direction shown in FIG. However, in response to the change in focal length from FIG. 11C to FIG. 11B, when the angle of the infrared cut filter 7 is inclined, the transmittance change shown in FIG. 12 is caused by the inclined angle. . For this reason, since the long wavelength end of the visible light region is cut, the color temperature of the flash of the strobe device increases and the guide number decreases.

  Therefore, it is desirable to design the transmission wavelength range of the infrared cut filter 7 in a wider range than the visible light range in order to prevent an increase in the color temperature of the flash of the strobe device and a decrease in the guide number. At this time, if the transmission wavelength region of the infrared cut filter 7 is excessively widened, the effect of protecting the Fresnel lens 1 is also reduced. Therefore, it is necessary to optimize the design in accordance with the movable range of the infrared cut filter 7.

  In particular, as shown in FIG. 7, since the relative intensity of the bright line spectrum in the infrared light region is large, it is preferable that the bright line spectrum is positively reflected by the infrared cut filter 7 and not transmitted through the Fresnel lens 1. For this reason, the infrared cut filter 7 is located between approximately 750 nm, which is the long wavelength end of the visible light region wavelength, and a local minimum point (near 800 nm in FIG. 7) on the shorter wavelength side of the peak line spectrum of FIG. It is preferable to design so that the half value of the transmittance on the long wavelength side of the visible light region is included. The half-wavelength of the transmittance of the cold mirror 8 is preferably designed to be equal to the half-wavelength of the transmittance of the infrared cut filter 7. Thereby, the infrared light reflected by the infrared cut filter 7 can be efficiently discharged outside the strobe device.

  The above description is summarized as follows. Although the present invention is completed by providing an infrared cut filter 7 and discharging infrared light to the outside of the strobe device, a cold mirror 8 is preferably added. Further, the angle of the infrared cut filter 7 may be changeable corresponding to the focal length. In that case, it is desirable to make the transmission wavelength range of the infrared cut filter 7 wider than the visible light range. Alternatively, the half value of the transmittance of the infrared cut filter 7 is preferably set between the minimum point on the shorter wavelength side than the emission line spectrum and the long wavelength end of the visible light region wavelength.

[Example 2]
A strobe device according to the second embodiment of the present invention will be described below with reference to FIGS. FIG. 13 is a central sectional view of the unit of the light emitting unit of the strobe device according to the second embodiment of the present invention. FIG. 14 is a perspective view of the light emitting unit of the strobe device according to the second embodiment of the present invention as seen obliquely from below.

  In the second embodiment of the present invention, members having the same functions as those in the first embodiment are denoted by the same reference numerals, description thereof is omitted, and only different points will be mainly described. In the light emitting section shown in FIGS. 13 and 14, the strobe device of the first embodiment has the cold mirror 8 disposed thereon, whereas the second embodiment replaces the cold mirror 8 with a heat absorbing member. And a heat radiation fin 10 as a heat radiating member attached in close contact with the metal plate 9. In other words, in the first embodiment, the infrared light reflected by the infrared cut filter 7 is transmitted through the cold mirror 8 and discharged to the outside of the strobe device. In this second embodiment, the metal plate is temporarily used. 9 absorbs infrared light into heat, and the heat is discharged to the outside of the strobe device by the radiation fins 10 attached to the metal plate 9.

  According to such an embodiment, it is possible to have substantially the same effect as the first embodiment, and at the same time, it becomes easy to handle by converting from infrared light to heat, and variations in heat transfer method and heat dissipation method. Can be increased. The metal plate 9 is preferably applied with a coating that easily absorbs heat, such as a black coat, in order to easily absorb heat. Alternatively, the metal plate 9 and the radiating fin 10 may be integrated, and the installation surface of the radiating fin 10 may be coated to easily absorb heat and disposed at the position of the metal plate 9. Furthermore, it goes without saying that a fan may be employed as the heat radiating member instead of the heat radiating fin 10 to radiate heat by forced air cooling.

  As mentioned above, although preferable embodiment of this invention was described, this invention is not limited to these embodiment, A various deformation | transformation and change are possible within the range of the summary.

1 ... Fresnel lens (light transmission member)
2 ... Hinge 3 ... Protective glass 4 ... Xenon tube (flash light source)
5 ... Reflective umbrella 6 ... Reflective umbrella holder 7 ... Infrared cut filter (infrared light region reflecting member)
8 ... Cold mirror (infrared light transmission member)
9. Metal plate (heat absorbing member)
10 ... Heat radiation fin (heat radiation member)
40 ... Camera (imaging device)
41 ... Shooting lens (shooting optical system)

Claims (6)

A flash light source (4) and a first light transmission member (1) are provided, and visible light is transmitted in an optical path between the flash light source (4) and the first light transmission member (1). The infrared light region reflecting member (7) for reflecting the infrared light is provided, and among the light emitted from the flash light source (4), the visible light is transmitted through the first light transmitting member (1). The flash light emitting device, wherein the reflected infrared light is discharged from the second light transmitting member to the outside of the flash light emitting device. The infrared light region reflecting member (7) that transmits the visible light and reflects the infrared light is changed in angle according to the focal length of the imaging optical system (41) attached to the imaging device (40). The flash light-emitting device according to claim 1, wherein The transmission wavelength region of the infrared light region reflecting member (7) that transmits visible light and reflects infrared light is a transmission wavelength region wider than the visible light region. The flash light-emitting device according to claim 2. The half value of the transmittance on the long wavelength side of the infrared light region reflecting member (7) that transmits the visible light and reflects the infrared light is infrared among the light emitted from the flash light source (4). 3. The flash light emitting device according to claim 1, wherein the flash light emitting device falls between a minimum point on a shorter wavelength side than an emission line spectrum in the light region and a long wavelength end of the visible light region. 2. The flash light emitting device according to claim 1, further comprising an infrared light region transmitting member (8) that does not transmit visible light but transmits infrared light, instead of the second light transmitting member. A flash light source (4) and a first light transmission member (1) are provided, and visible light is transmitted in an optical path between the flash light source (4) and the first light transmission member (1). The infrared light region reflecting member (7) for reflecting the infrared light is provided, and among the light emitted from the flash light source (4), the visible light is transmitted through the first light transmitting member (1). The reflected infrared light is absorbed by the heat absorbing member (9), and the heat is discharged to the outside of the flash light emitting device through the heat radiating member (10) attached to the heat absorbing member (9). Flash light emitting device.