JP4544513B2 - Illumination device and imaging device - Google Patents

Description

  The present invention relates to an illuminating device that efficiently irradiates a region to be illuminated with a light beam from a light source, and an imaging device having the illuminating device.

  An illumination device used in a conventional photographing apparatus such as a camera is composed of a light source and optical components such as a reflector and a Fresnel lens that guide a light beam emitted from the light source to a front (subject side) irradiated area. Has been.

Among the lighting apparatus as described above, the light beams emitted in various directions from a light source, a small lighting apparatus that is focused efficiently required irradiation angle of view have been various proposals from the prior art.

  In particular, in place of the Fresnel lens that has been placed on the front side (subject side) of the light source in recent years, optical components using total reflection such as prisms and light guides can be placed to improve light collection efficiency and reduce size. What has been proposed has been proposed.

  As a proposal of this type, the component close to the optical axis in the light beam emitted from the center of the light source is due to refraction of the cylindrical lens of the optical prism, and the peripheral components away from the optical axis are the reflecting surfaces formed above and below the cylindrical lens. Are converted into light beams substantially parallel to the optical axis direction, and then subject to an optical action by a plurality of convex lenses formed on the exit surface of the optical prism and a concave lens formed on the optical panel disposed in front of the convex lenses. Irradiated to the side.

  And the irradiation range (angle) of illumination light is changed by changing the optical axis direction distance of an optical prism and an optical panel. With such a configuration, the illumination light irradiation range can be changed, and a small-sized lighting device with high light collection efficiency is realized (see Patent Document 1).

  Patent Document 2 proposes an illumination device capable of changing the irradiation range with one optical member. FIG. 8 is a cross-sectional view of the illumination device, and FIG. 8B is a trace diagram of representative rays.

  The illuminating device is disposed so as to cover the light source 2, the optical member 4 disposed on the front side of the light source 2, the rear side of the light source 2 and the front space between the light source 2 and the optical member 4. And a reflecting member 3 that reflects light from the front.

Then, on the incident surface side of the optical member 4, a positive refracting portion 4 a that gives positive refractive power to light incident from the light source 2 in the vicinity of the optical axis L, and a reflecting member 3 that is on the peripheral side of the positive refracting portion 4 a Reflecting portions 4c and 4c ′ for reflecting light incident from the light source 2 forward are provided on the optical axis side of the region through which the light reflected by the portion covering the front space passes, and the light source 2 and the optical member The irradiation range of the light emitted from the optical member 4 is variable by changing the relative positional relationship in the optical axis direction with respect to the reference numeral 4 (see Patent Document 2).
JP 2000-298244 A (paragraphs 0100 to 0102, FIGS. 1 and 2 etc.) Japanese Patent Laying-Open No. 2003-287792 (paragraphs 0010 to 0014, FIGS. 1 and 2 etc.)

  However, the optical member in the illumination device of Patent Document 1 requires two members, an optical prism and an optical panel.

  In the illumination device disclosed in Patent Document 2, a component close to the optical axis of the light beam emitted from the center of the light source is refracted by the cylindrical lens of the optical member, and a peripheral component away from the optical axis is above and below the cylindrical lens. Because of the formed reflecting surface, the vertical component needs to be converted into a light beam substantially parallel to the optical axis direction by the reflecting part of the reflecting member that reflects the light beam forward, so that an optical member (optical prism) It was difficult to downsize the height direction of the opening.

  The objective of this invention is providing the illuminating device which is small and can obtain a favorable light distribution characteristic.

  In order to achieve the above object, an irradiation apparatus according to the present invention is a lighting device including a light source, an optical member for directing light from the light source in an irradiation direction, and a reflection member. An incident surface having a positive refractive power, an exit surface having a negative refractive power, and a reflective surface that reflects light traveling from the light source toward the peripheral side of the incident surface toward the exit surface.

  The reflecting member has a first surface that reflects light traveling from the light source to the peripheral side of the reflecting surface, and a second surface that reflects light from the first surface toward the exit surface. .

  According to the present invention, the light traveling from the light source can be efficiently collected by the reflecting surface provided on the optical member and the first surface and the second surface of the reflecting member, and the exit surface can be reduced. can do.

For this reason , the illuminating device which is small and can obtain a favorable light distribution characteristic is realizable.

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

  Hereinafter, the lighting apparatus according to the first embodiment of the present invention will be described with reference to FIGS.

  FIG. 1 is a schematic configuration diagram of this embodiment when the illumination device of this embodiment is mounted on the upper side of a camera (imaging device).

  Reference numeral 1 denotes a camera body, and 2 denotes a lens barrel, which holds a photographing lens (not shown). 3 is a viewfinder, and 4 is a release button. An illumination device (light emitting unit) 5 is provided in the upper right part of the camera body 1. In addition, since each function except an illuminating device is a well-known technique, detailed description is abbreviate | omitted here. The mechanical components of the present invention are not limited to the above-described configuration.

  FIG. 2 is a perspective view of the lighting device of the present embodiment, and FIG. 3 is a developed perspective view of the lighting device.

  This illuminating device emits light as a light source means, such as a cylindrical flash discharge tube (flash light discharge tube) 6 and a light beam emitted from the flash discharge tube 6 other than the front, for example, rearward (opposite to the subject side). A reflecting member (reflecting umbrella) 7 that reflects the reflected light beam toward the subject, and a directly incident light beam out of the light beam emitted from the flash discharge tube 6 and a light beam reflected and incident by the reflecting member 7 as a light beam having a predetermined shape It has an optical member (optical prism) 8 for guiding an illumination light beam that collects light and efficiently irradiates the subject side.

  Here, the reflecting member 7 is made of a metallic material such as bright aluminum whose inner surface is formed with a high reflectance surface, or a resin material where a highly reflective metal deposition surface is formed on the inner surface. As the material of the optical member 8, an optical resin material or glass material having a high transmittance such as an acrylic resin is suitable.

  In the configuration described above, the camera body 1 is a photometering (not shown) after the release button 4 is pressed by the user when the camera is set in the “strobe auto mode”, for example, as known in the art. A central processing unit (not shown) determines whether or not the illumination device emits light based on the brightness of external light measured by the device, the sensitivity of the loaded film, and the sensitivity of an image sensor such as a CCD sensor.

  If the central processing unit determines that the lighting device is to emit light under the current shooting conditions, the central processing unit issues a light emission signal and passes through a trigger lead wire (not shown) attached to the reflecting member 7. Then, the flash discharge tube 6 is caused to emit light. Of the emitted light beam, the light beam emitted in the direction opposite to the subject side is reflected by the reflecting member 7, and the light beam emitted to the subject side directly enters the optical member 8 disposed on the front surface, and this optical member After being converted to a predetermined light distribution characteristic via 8, the object side is irradiated.

  Hereinafter, the configuration for determining the optical characteristics of the illumination device will be described in more detail with reference to FIGS.

  4 and 5 show the configuration of the optical system of the illumination device 5 of this embodiment. 4 and 5 are cross-sectional views of the optical system including the radial direction of the flash discharge tube 6. FIG. 4 shows a state where the irradiation angle range is narrow, and FIG. 5 shows a state where the irradiation angle range is wide. Show. (A), (b) of each figure is a figure when it cuts with the same cross section, (b) is a trace figure which added the light ray trace part to sectional drawing of (a).

  The basic concept of the irradiation angle change in the vertical direction, which is the radial direction of the discharge tube (the direction perpendicular to the longitudinal direction), will be described with reference to FIGS.

  In the figure, the inner and outer diameters of a glass tube are shown as the flash discharge tube 6. As an actual light emission phenomenon of this type of discharge tube, in order to improve efficiency, light is often emitted to the full inner diameter, and it can be considered that light is emitted almost uniformly from the light emission point with the full inner diameter of the discharge tube. However, for ease of explanation, the light beam emitted from the center of the light source is considered as the representative light beam, and only the light beam emitted from the center of the light source is shown in the drawing. As for the actual light distribution characteristics, in addition to the representative light flux as shown in the figure, the light distribution characteristics change in a slightly widening direction as a whole by the light flux emitted from the periphery of the discharge tube, but the trend of the light distribution characteristics is as follows: Since they are almost the same, the following description will be made according to this representative light flux.

  First, as shown in FIG. 4, when the flash discharge tube 6 and the optical member 8 are separated by a predetermined amount, the most condensed state is obtained.

  A portion of the reflecting member 7 that covers the rear side of the flash discharge tube 6 has a semi-cylindrical shape (hereinafter referred to as a semi-cylindrical portion 7 a) that is substantially concentric with the flash discharge tube 6. This is an effective shape for returning the reflected light from the reflecting member 7 back to the vicinity of the center of the light source, and has the effect of making it less susceptible to the refraction of the glass portion of the flash discharge tube 6. By configuring in this way, it is easy to think because the reflected light from the rear of the reflecting member 7 can be handled as the emitted light substantially equivalent to the direct light from the light source, and the overall shape of the subsequent optical system can be reduced in size. It becomes convenient.

  Also, first reflecting surfaces (first surfaces) 7b and 7b ′ provided above and below the semi-cylindrical portion 7a of the reflecting member 7 are third reflecting surfaces 8b and 8b of the optical member 8 described later from the light source center. It is formed in a curved surface shape so as to reflect the light beam that has advanced to the peripheral side of '. Second reflective surfaces (second surfaces) 7c and 7c ′ provided in front of the first reflective surfaces 7b and 7b ′ will be described later with respect to the light beams reflected by the first reflective surfaces 7b and 7b ′. Similar to the first reflecting surfaces 7b and 7b ', it is formed in a curved surface shape so as to be reflected toward the exit surface 8e of the optical member 8 and to guide the luminous flux to the periphery of the optical member 8.

  Next, the detailed shape of the optical member 8 will be described.

  First, as shown in FIG. 4A, the light beam component in the vicinity of the emission optical axis center of the optical member 8 forms an angle smaller than the first angle with respect to the emission optical axis AXL among the light beams emitted from the light source center. In order to refract this component, an aspherical cylindrical lens surface (first incident surface) 8a is formed in the vicinity of the center of the emission optical axis of the optical member 8 on the light source side.

  In the periphery of the cylindrical lens surface 8a, the light beam emitted from the center of the light source does not enter the cylindrical lens surface 8a and travels to the peripheral side of the cylindrical lens surface 8a, and is incident on the emission optical axis AXL. On the other hand, second incident surfaces 8b and 8b 'on which a light beam having an angle larger than the first angle is formed are formed, and in the periphery thereof, the second incident surfaces 8b and 8b' enter the optical member 8 from the second incident surfaces 8b and 8b '. Third reflecting surfaces 8c and 8c ′ for reflecting (totally reflecting) incident light (refracted light) are formed.

  Further, in the vicinity thereof, there are formed third incident surfaces 8d and 8d 'which are formed into a curved surface and into which the light beam reflected by the second reflecting surfaces 7c and 7c' of the reflecting member 7 is incident.

  Here, the exit surface 8e of the optical member 8 is a concave surface having a negative refractive power, and the first incident surface 8a, the second incident surfaces 8b, 8b ′ and the third surface having a positive refractive power. The incident surfaces 8d and 8d ′ and the third reflecting surfaces 8c and 8c ′ allow the light beam emitted from the center of the light source to enter each part of the optical member 8 with the flash discharge tube 6 and the optical member 8 being separated by a predetermined amount. After being refracted or totally reflected for conversion to a predetermined angle component, the shape is set so as to be emitted from the same exit surface 8e and substantially parallel to the exit optical axis AXL.

  FIG. 4B shows a ray tracing diagram showing how the light beam emitted from the center of the light source enters from each surface of the optical member 8 and passes through each light path. As shown in the figure, almost all the light beam emitted from the center of the light source is converted in parallel to the emission optical axis AXL. That is, the most condensed state can be obtained by this optical arrangement, and the light condensing operation is performed most efficiently with respect to the exit aperture area.

  On the other hand, the state shown in FIG. 5 is a state in which the flash discharge tube 6 and the optical member 8 are brought closer to each other than the predetermined distance, and the optical arrangement is set so as to obtain a state where the irradiation angle range is expanded to some extent. It is.

  In the case of such an optical arrangement, the edge portions 8f and 8f ′ formed at the intersections of the second incident surfaces 8b and 8b ′ of the optical member 8 and the third reflecting surfaces 8c and 8c ′ are the first portions of the reflecting member 7. 1 reflective surface 7b, 7b '. As a result, the first reflecting surfaces 7b and 7b ′ of the reflecting member 7 from the gaps between the first reflecting surfaces 7b and 7b ′ and the edge portions 8f and 8f ′ of the optical member 8 out of the light flux emitted from the center of the light source. The luminous flux to be directed to decreases.

  Accordingly, as the edge portions 8f and 8f ′ approach the first reflecting surfaces 7b and 7b ′ of the reflecting member 7, this component is extremely reduced, and the second incident which is another optical path adjacent thereto. The surfaces 8b and 8b ′, the third reflecting surfaces 8c and 8c ′, and the cylindrical lens surface 8a are turned around.

  Here, the light beam reflected by the first reflecting surfaces 7b and 7b 'of the reflecting member 7 is always emitted optical axis because the flash discharge tube 6 as a light source and the reflecting member 7 are integrally held. It is converted to a component with a shallow angle with respect to the direction. For this reason, a decrease in the component (the light beam traveling from the light source toward the first reflecting surfaces 7b and 7b ′) reduces the light beam converged on the subject, so that the light near the center of the light distribution is reduced. The strength of will be weakened.

  Further, when the flash discharge tube 6 and the optical member 8 are brought closer to each other than the predetermined distance, a defocused state is reached, and the light beam reflected by the third reflecting surfaces 8c and 8c ′ of the optical member 8 is incident from the cylindrical lens surface 8a. The emitted light beam is diverged when exiting from the exit surface 8e.

  As described above, in the state where the light is most concentrated as shown in FIG. 4, originally, there are three refraction regions, ie, a refraction region near the center of the optical axis, a reflection region by the peripheral optical member 8, and a reflection region by the peripheral reflection member 7. Whereas the entire region is condensed, the relative position relationship between the flash discharge tube 6 (and the reflection member 7) and the optical member 8 in the direction of the emission (irradiation) optical axis is changed. It is possible to gradually change the light collection state by the region (that is, to change the irradiation angle range).

  Hereinafter, the change in the light distribution will be described by dividing it into the above three regions.

  First, the refractive region near the center of the optical axis refracts the light beam emitted from the center of the light source so as to be condensed at substantially one point on the optical axis of emission in the optical arrangement shown in FIG. The aspherical cylindrical lens surface 8a has a light source center as a focal position, and an exit surface 8e that is positioned in the middle of condensing and refracts this light beam so as to be substantially parallel to the exit optical axis AXL.

  Next, as shown in FIG. 5, when the flash discharge tube 6 and the optical member 8 are brought closer to each other than the predetermined distance, the light source and the cylindrical lens surface 8a approach each other to enter a defocused state, and the entire irradiation range is set. Acts to spread. Further, in the state shown in FIG. 4, a part of the light beam guided in the direction of the third reflecting surfaces 8c and 8c ′ of the optical member 8 newly enters this region in the state shown in FIG. This component is also an extension of the light beam controlled by this refracted light region, and is converted into an angular component having the widest irradiation angle in this refracted region.

  However, since the change in angle in this region is an effect due to refraction, a large change in the irradiation angle range does not occur for a small amount of movement. As a result, only the light distribution near the very center on the irradiated surface is uniformly spread.

  Next, the reflection area by the optical member 8 will be described. This reflection region is a region in which the irradiation angle range can be significantly changed by changing the positional relationship between the light source and the optical member 8. This is because in addition to the fact that the irradiation direction can be greatly changed by the conversion of the light beam direction by reflection, the reflection phenomenon in the optical member 8 having a high refractive index is used, so that a larger angle conversion can be expected.

  As shown in FIG. 4B, the luminous flux component emitted from the center of the light source and reflected by this reflection region is converted into a component in a certain narrow angle region at the periphery on the irradiation surface, and is emitted from the emission surface 8e. The light is refracted so as to be substantially parallel to the emission optical axis AXL.

  Next, as shown in FIG. 5, when the flash discharge tube 6 and the optical member 8 are brought closer than the predetermined distance, the light flux component reflected by this reflection region is diverged. In the trace diagram of FIG. 5 (b), it seems to be converted into only a component having a predetermined angle with respect to the emission optical axis AXL. However, in reality, the light source has a certain size, and therefore the reflection angle. The range also extends to some extent, and when viewed as a whole, it overlaps with the luminous flux component in the refraction region, so that it is possible to obtain a light distribution characteristic having a substantially uniform angular distribution over a wide angular range.

  Finally, as described above, the light beam component reflected by the reflection region by the outermost reflecting member 7 is moved closer to the light source and the optical member 8 from the state of FIG. 4 toward the state of FIG. Gradually, its components decrease.

  As described above, in this embodiment, a large change in the irradiation angle range can be obtained by a slight change in the relative positional relationship between the light source (discharge tube 6) and the optical member 8 in the optical axis direction. Each component divided into the two regions can compensate for the change in the light distribution characteristics of each part, and an optical system that is uniform as a whole and has a small amount of light loss with respect to the required irradiation range can be realized.

  On the other hand, although not shown, as described above, the light beam emitted backward from the center of the discharge tube 6 is reflected by the semi-cylindrical portion 7a of the reflecting member 7, and again passes through the center of the discharge tube 6 to the front. It is injected. The behavior of the subsequent light beam is the same as that shown in FIGS. 4B and 5B.

  Next, an optimal distribution ratio of the three areas, that is, the refraction area, the reflection area by the optical member 8, and the reflection area by the reflection member 7 will be described.

  Basically, a basic condensing optical system is formed by the refraction region of the cylindrical lens surface 8a and the reflection region by the first reflection surfaces 7b and 7b 'of the reflection member 7, and the minimum connection between these regions is formed. It is desirable that the portion is constituted by the reflection region of the optical member 8.

  First, as a material of the optical member 8, it is desirable to use an optical resin material such as an acrylic resin from the viewpoint of moldability and cost. However, in this type of lighting device, a large amount of heat is generated simultaneously with the generation of light from the light source. It is necessary to select the optical material and set the heat radiation space in consideration of the thermal energy generated in one light emission and the shortest light emission period.

  At this time, it is the respective incident surfaces of the optical member 8 closest to the light source that are actually most susceptible to heat, and it is necessary to first determine the minimum distance between the light source and the incident surface. In the present embodiment, the minimum distance between the light source and the first incident surface 8a that controls the angle component whose exit angle from the light source center is close to the exit optical axis AXL by direct refraction is d, and the angle component that is away from the exit optical axis AXL. The distance between the second incident surfaces 8b and 8b ′ on which light controlled by reflection (total reflection) is incident and the light source is defined as e, and the interval is regulated.

Here, if the distance between each incident surface and the light source is too large, the entire optical system becomes large. Therefore, if the diameter of the flash discharge tube 6 is φ, the minimum distances are d and e,
φ / 10 ≦ d ≦ φ / 2
φ / 10 ≦ e ≦ φ / 2 (1)
It is desirable to be in the range.

In the most condensed state shown in FIG. 4, the angle α formed by the light beam from the center of the light source incident on the second incident surfaces 8b and 8b ′ of the optical member 8 and the optical axis is
20 ° ≦ α ≦ 70 ° (2)
It is desirable that

  Here, when the angle α is smaller than 20 °, which is the lower limit of the expression (2), it is difficult to form a reflection region by the optical member 8. That is, the angles of the edge portions 8f and 8f ′ of the optical member 8 become extremely sharp, and the optical member 8 needs to be deep in the thickness direction, making it difficult to form a thin optical member (optical system). Not only is it difficult to manufacture.

  Further, when the angle α is larger than 70 ° which is the upper limit of the above expression (2), the condensing region by the reflecting member 7 decreases, and the reflecting region is reflected by the reflecting member 7 and the third reflecting surface by the optical member 8. The light collection efficiency, which has been improved by dividing into two, is reduced, and the following various problems occur.

  That is, the distance between the light source and the optical member 8 necessary for changing the irradiation angle is reduced, and it becomes difficult to change the irradiation angle significantly, and the optical member 8 itself is a partial problem. Therefore, there is a problem that the molding time becomes long and the manufacture becomes difficult. As an ideal form, it is desirable to narrow the reflection area by the optical member 8 to a necessary minimum and to collect it in a form with no light loss. By comprising in this way, it can make it easy to process with a simple structure also in shape, shortening the thickness direction to the shortest.

  In the present embodiment, for the reason described above, the optical member 8 is formed corresponding to the light flux included in the range of about 30 ° between 30 ° and 60 ° with respect to the optical axis AXL. I am trying.

  Next, in the optical member 8, the optimum shape of the second incident surfaces 8b and 8b 'for guiding the light beam to the third reflecting surfaces 8c and 8c' will be described. As shown in FIG. 4B and FIG. 5B, the light beam emitted from the center of the light source is largely refracted by the second incident surfaces 8b and 8b ′ and travels in the direction away from the emission optical axis AXL. It reaches the reflecting surfaces 8c and 8c ′.

  Here, it is desirable that the inclination between the second incident surfaces 8b and 8b 'and the exit optical axis AXL be an angle so that the light beam reflected by the third reflecting surfaces 8c and 8c' is not totally reflected again. Therefore, in this embodiment, considering the processing conditions, the second incident surfaces 8b and 8b 'are configured as a flat surface having an inclination with respect to the emission optical axis AXL of 5 ° or more or a curved surface that can be easily processed.

  As described above, according to the present embodiment, the reflection member 7 and the single optical member 8 are small components, but the size is small, and the amount of light loss due to light irradiation outside the necessary irradiation range is small. A variable illumination optical system can be configured.

  Furthermore, the angle α formed with respect to the optical axis of the light emitted from the center of the light source and incident on the third reflecting surfaces 8c and 8c ′ of the optical member 8 is included in the range of 20 ° ≦ α ≦ 70 °. Thus, the light collection efficiency by the first reflecting surfaces 8c and 8c ′ of the optical member 8, the first reflecting surfaces 7b and 7b ′ and the second reflecting surfaces 7c and 7c ′ of the reflecting member 7 is improved. .

  Therefore, since the emission surface 8e (injection opening) can be reduced, the lighting device can be made thinner and vertically smaller.

  Furthermore, the illumination angle variable illumination optical system according to the present embodiment has a high degree of design freedom, and it is easy to design an optimum illumination angle variable mechanism according to the size, mechanical accuracy, optical characteristics, etc. required for the product. it can.

  In addition, it is a highly versatile technology that has a small number of constituent elements and can be configured at low cost with a variable illumination angle mechanism, and has a wide range of applied optical systems.

  In addition, since the condensing in the optical member 8 is performed by using total reflection, the energy use efficiency for the same light source is high, and even if it is compact, it is irradiated within the angle of view without deteriorating the optical characteristics. The effective energy can be increased.

  In the illumination device of the present embodiment, the light distribution control in the direction perpendicular to the longitudinal direction of the discharge tube 6 is performed with the cylindrical lens surface 8a provided on the light source side, and the first reflecting surfaces 7b and 7b ′ of the reflecting member 7. The relative distance between the light source and the optical member 8 is changed based on the most condensed state as shown in FIG. 4 by the three types and five layers of the third reflecting surfaces 8c and 8c ′ of the optical member 8. To change the irradiation angle range. However, the present invention is not necessarily limited to this embodiment, and the reference state does not necessarily have to be a state in which the light beam in the entire region is most condensed.

  This is because all the light distribution in the reference state is the most because the light source is a light source with a certain size or more and the distance between each condensing control surface and the light source is different. This is because there are cases where it is more convenient not to focus the light but to make it different.

  As an example of this, when the size of the light source is large, the irradiation angle from the cylindrical lens surface located near the light source tends to be considerably widened. In particular, the luminous flux emitted from the front side of the center of the light source has a strong tendency to spread, and even in the most optically focused optical arrangement, there is no guarantee that there is no luminous flux going outside the necessary irradiation range.

  On the other hand, the luminous flux component controlled by the reflector farthest from the light source does not decrease the degree of light collection even if the size of the light source is increased to some extent, and its distribution is larger than the initially set irradiation angle distribution. It will not come off.

  For this reason, the cylindrical lens surface having a control surface close to the light source has a shape that forms a focal position slightly closer to the subject side than the center of the light source, so that the luminous flux emitted through the cylindrical lens surface can be reduced. The distribution can be prevented from spreading more than necessary.

  Even when changing the irradiation angle range with an emphasis on the wide-angle side, where the most focused state is not necessarily required, the luminous flux controlled by the reflector other than the central cylindrical lens surface and the reflecting surface of the optical member is uniform. In some cases, it may be more convenient to set the shape of each surface so as to obtain a slightly wider light distribution characteristic, instead of setting the light distribution to the most condensed state.

  In this embodiment, the configuration of each surface on the light source side (incident surface side) and the configuration of each surface on the exit surface side are shown as being symmetrical with respect to the center of the optical axis. Examples are not necessarily limited to such symmetrical shapes. For example, the third reflecting surfaces 8c and 8c 'of the optical member 8 are configured symmetrically with respect to the optical axis. However, the third reflecting surfaces 8c and 8c' do not have to be formed at the same position as described above, and may be asymmetrical. This is not only true for the reflecting surface, but the same applies to the shape of the reflecting member 7 and the shape of the cylindrical lens surface 8a.

  Further, with respect to the central prism row formed on the exit surface side, it is possible to change the light distribution characteristics in the left-right direction by using prism rows having different left and right angle settings. In addition, the degree of light collection may be changed with respect to the peripheral Fresnel lens portion, and the overall light distribution characteristics may be changed.

  In the present embodiment, the case where the cylindrical lens surface 8a formed at the center of the optical member 8 has an aspheric shape has been described. However, the cylindrical lens surface 8a is not necessarily limited to an aspheric shape, You may form with a cylindrical surface. Further, a toric lens surface may be used in consideration of the light condensing property in the longitudinal direction of the discharge tube 6.

  Next, a lighting device according to the second embodiment of the present invention will be described.

  Hereinafter, the configuration for determining the optical characteristics of the illumination device will be described in more detail with reference to FIGS.

  6 and 7 are cross-sectional views of the illumination optical system including the radial direction of the flash discharge tube. FIG. 6 shows a state where the irradiation angle range is narrow, and FIG. 7 shows a state where the irradiation angle range is wide. ing. (A), (b) of each figure is a figure when it cuts with the same cross section, (b) is a trace figure which added the light ray trace part to sectional drawing of (a).

  This embodiment can constitute a more efficient illumination optical system than the first embodiment.

  The illuminating device of the present embodiment is a cylindrical flash discharge tube (flash light emission tube) 9 that emits light as a light source means, and, for example, rear (opposite to the subject side) other than the front of the emitted light flux from the flash discharge tube 9 A reflecting member (reflecting umbrella) 10 that reflects a light beam radiated in the direction) to the subject side, a light beam directly emitted from a light beam radiated from the flash discharge tube 6, and a light beam reflected and incident by the reflecting member 10 are predetermined. It has an optical member (optical prism) 11 for guiding an illuminating light beam that condenses as a shaped light beam and efficiently irradiates the subject side.

  The basic concept of the irradiation angle change in the vertical direction, which is the radial direction of the discharge tube (the direction orthogonal to the longitudinal direction), will be described with reference to FIGS.

  In these drawings, the inner and outer diameters of the glass tube are shown as the flash discharge tube 9. As an actual light emission phenomenon of this type of discharge tube, in order to improve efficiency, light is often emitted to the full inner diameter, and it can be considered that light is emitted almost uniformly from the light emission point with the full inner diameter of the discharge tube. However, for ease of explanation, the light beam emitted from the center of the light source is considered as the representative light beam, and only the light beam emitted from the center of the light source is shown in the drawing. As for the actual light distribution characteristics, in addition to the representative light flux as shown in the figure, the light distribution characteristics change in a slightly widening direction as a whole by the light flux emitted from the periphery of the discharge tube, but the trend of the light distribution characteristics is as follows: Since they are almost the same, the following description will be made according to this representative light flux.

  First, as shown in FIG. 6, when the flash discharge tube 9 and the optical member 11 are separated by a predetermined amount, the most condensed state is obtained.

A portion of the reflecting mirror 10 that covers the rear side of the flash discharge tube 9 has a semi-cylindrical shape (hereinafter referred to as a semi-cylindrical portion 10 a) that is substantially concentric with the flash discharge tube 9. This is an effective shape for returning the reflected light from the reflecting mirror 10 again to the vicinity of the center of the light source, and has the effect of making it less susceptible to the refraction of the glass portion of the flash discharge tube 9. By configuring in this way, it is easy to think because the reflected light from the rear of the reflecting member 10 can be handled as the emitted light substantially equivalent to the direct light from the light source, and the overall shape of the subsequent optical system can be reduced in size. It becomes convenient.

On the other hand, reflecting surfaces (third reflecting surfaces) 10b and 10b ′ provided above and below the semi-cylindrical portion 10a of the reflecting member 10 are from first reflecting surfaces 11c and 11c ′ of the optical member 11 described later from the center of the light source. Is also formed in a curved shape so as to reflect the light beam traveling toward the peripheral side and guide it to the periphery of the optical member. Then, as will be described later, the light distribution characteristic in the most condensed state is obtained for the light beam incident from the peripheral portion of the optical member 11.

  Next, the detailed shape of the optical member 11 will be described.

  First, as shown in FIG. 6A, the light beam component in the vicinity of the emission optical axis center of the optical member 11 forms an angle smaller than the first angle with respect to the emission optical axis AXL among the light beams emitted from the light source center. In order to refract this component, an aspherical cylindrical lens surface (first incident surface) 11a having a positive refractive power is formed in the vicinity of the emission optical axis center of the optical member 11 on the light source side. ing.

  In the vicinity of the cylindrical lens surface 11a, a light beam emitted from the center of the light source is a component that does not enter the cylindrical lens surface 11a and forms a larger angle than the first angle with respect to the emission optical axis AXL. Second incident surfaces 11b and 11b ′ on which components are incident are formed, and refracted light (first first) incident on the optical member 11 (prism portion) from the second incident surfaces 11b and 11b ′ is formed around the second incident surfaces 11b and 11b ′. The first reflecting surfaces 11c and 11c ′ are formed for reflecting (totally reflecting) the light traveling toward the peripheral side of the incident surface 11a toward the exit surface 11f.

  Further, as described above, the third incident surfaces 11d and 11d ′ into which the light beams reflected by the reflecting surfaces 10b and 10b ′ of the reflecting member 10 are incident are formed in a curved shape in the vicinity thereof, and the third incident surface 11d. , 11d ′, the light beam from the reflecting member 10 is totally reflected by the second reflecting surfaces 11e and 11e ′ toward the exit surface 11f.

Here, the exit surface 11f of the optical member 11 is a concave surface having negative refractive power, and these cylindrical lens surface 11a, second incident surfaces 11b, 11b ′, and first reflecting surfaces 11c, 11c ′. the third incident surface 11d, 11d 'and a second reflecting surface 11e, 11e' in a state in which the flash discharge tube 9 and the optical member 11 is separated by a predetermined amount, the light beam emitted from the light source center of the optical member 11 After being refracted or totally reflected so as to be incident on each part and converted into a predetermined angle component, the shape is set so as to be emitted from the same exit surface 11f and substantially parallel to the exit optical axis AXL.

  FIG. 6B shows a ray tracing diagram showing how the light beam emitted from the center of the light source enters from each surface of the optical member 11 and passes through each optical path. As shown in the figure, almost all the light beam emitted from the center of the light source is converted in parallel to the emission optical axis AXL. That is, the most condensed state can be obtained by this optical arrangement. Therefore, it can be said that the light condensing operation is performed most efficiently with respect to the exit aperture area.

  On the other hand, the state shown in FIG. 7 is a state in which the flash discharge tube 9 and the optical member 11 are brought closer to each other than the predetermined distance, and the optical arrangement is set so that the irradiation angle range is expanded to some extent. It is.

  In the case of such an optical arrangement, the edge portions 11g and 11g ′ formed at the intersections of the second incident surfaces 11b and 11b ′ of the optical member 11 and the first reflecting surfaces 11c and 11c ′ are reflected by the reflecting member 10. The surfaces 10b and 10b 'will be approached. As a result, among the light rays emitted from the center of the light source, the light flux to be directed to the reflection surfaces 10b and 10b ′ of the reflection member 10 is reduced from the gap between the reflection surfaces 10b and 10b ′ and the edge portions 11g and 11g ′ of the optical member 11. Will do.

  Therefore, as the edge portions 11g and 11g ′ approach the reflecting surfaces 10b and 10b ′ of the reflecting member 10, this component is extremely reduced, and the second incident surfaces 11b and 11b, which are separate optical paths adjacent thereto. 'And the first reflecting surfaces 11c and 11c' are directed to the prism portion and the cylindrical lens portion 11a.

  Here, the luminous flux reflected by the reflecting surfaces 10b and 10b ′ of the reflecting member 10 is always held in the emission optical axis direction because the flash discharge tube 9 and the reflecting member 10 as the light source are integrally held. It is a component converted into a component with a shallow angle, and when this component decreases, the light flux converged on the subject decreases, so the intensity of light near the center of the light distribution is weak That is.

  When the flash discharge tube 9 and the optical member 11 are brought closer to each other than the predetermined distance, a defocused state is established, and the light beam reflected by the first reflecting surfaces 11c and 11c ′ of the prism portion is incident from the cylindrical lens surface 11a. The emitted light beam is diverged when exiting from the exit surface 11f.

  Thus, originally, in the most condensed state shown in FIG. 6, the refraction area near the center of the optical axis, the reflection area by the optical member 11 (prism part) in the vicinity thereof, and the reflection by the reflection member 10 in the vicinity. Whereas all three regions are condensed, the relative position relationship between the flash discharge tube 9 (and the reflecting mirror 10) and the optical member 11 in the optical axis direction is changed. It is possible to gradually change the light collection state by the region (that is, to change the irradiation angle range).

  On the other hand, although not shown, as described above, the light beam emitted backward from the center of the flash discharge tube 9 is reflected by the semi-cylindrical portion 10a of the reflecting member 10, and again passes through the center of the flash discharge tube 9. And injected forward. The behavior of the subsequent light beam is the same as that shown in FIGS.

  As described above, according to the present embodiment, the reflection member 10 and the optical member 11 are small components, but the size is small and the amount of light loss due to light irradiation outside the necessary irradiation range is small. An illumination optical system can be configured.

  Furthermore, the first reflecting surfaces 11c and 11c ′ and the second reflecting surfaces 11e and 11e ′ of the optical member 11 further improve the light collection efficiency and reduce the exit surface 11f (exit opening). However, an imaging device with good light distribution characteristics can be obtained.

It is a schematic block diagram of the camera carrying the illuminating device of this invention. It is a perspective view of the illuminating device in Example 1 of this invention. It is an expansion | deployment perspective view of the illuminating device in Example 1 of this invention. In the illuminating device of Example 1 of this invention, it is YZ sectional drawing at the time of the narrowest light distribution, (a) is a structure sectional drawing, (b) is a ray trace figure. In the illuminating device of Example 1 of this invention, it is YZ sectional drawing at the time of the widest light distribution, (a) is a structure sectional drawing, (b) is a ray trace figure. In the illuminating device of Example 2 of this invention, it is YZ sectional drawing at the time of the narrowest light distribution, (a) is a structure sectional drawing, (b) is a ray trace figure. In the illuminating device of Example 2 of this invention, it is YZ sectional drawing at the time of the widest light distribution, (a) is a structure sectional drawing, (b) is a ray trace figure. It is YZ sectional drawing of the conventional illuminating device, (a) is a structure sectional drawing, (b) is a ray trace figure.

Explanation of symbols

5 Illumination devices 6 and 9 Flash discharge tube (light source)
7, 10 Reflective member 8, 11 Optical member

Claims (5)

A lighting device having a light source, and an optical member and a reflecting member for directing light from the light source in the irradiation direction,
The optical member includes an incident surface having a positive refracting power, an exit surface having a negative refracting power, and a reflecting surface that reflects light traveling from the light source toward the peripheral side of the incident surface toward the exit surface. And
The reflecting member includes a first surface that reflects light traveling from the light source toward the periphery of the reflecting surface, and a second surface that reflects light from the first surface toward the exit surface. A lighting device comprising:   The illumination device according to claim 1, wherein the optical member is movable in an irradiation optical axis direction with respect to the light source. A lighting device having a light source, and an optical member and a reflecting member for directing light from the light source in the irradiation direction,
The optical member is configured to reflect an incident surface having a positive refractive power, an exit surface having a negative refractive power, and light that travels from the light source toward the periphery of the incident surface toward the exit surface. And a reflective surface of
The reflection member reflects light traveling from the light source toward the peripheral side of the first reflection surface, and the optical member further reflects light from the reflection member toward the emission surface. An illumination device having a reflective surface. The lighting device according to claim 3 , wherein the optical member is movable in an irradiation optical axis direction with respect to the light source. The lighting device according to any one of claims 1 to 4,
An imaging apparatus comprising: an imaging system for imaging a subject illuminated by the illumination apparatus.

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