JP2015206850A - Luminaire - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a luminaire capable of reducing uneven light distribution without using a complicated mechanism.SOLUTION: The luminaire comprises: a light emission member: and a Fresnel-shaped optical member including a first region of a first focal distance, a second region of a second focal distance different from the first focal distance, and a third region held between the first and second regions and having a plurality of continuously changeable focal distances.

Description

  The present invention relates to a lighting device.

  Conventionally, as a light emitting optical system of a zoom strobe device that can change the irradiation angle in a strobe device that is an illumination device, a mechanism that swings a side reflector in synchronization with a change in the distance between a light source and a reflector is provided. It has been proposed (see, for example, Patent Document 1). In addition, a configuration has been proposed in which the reflector is moved in the optical axis direction with respect to the fixed Fresnel lens, and the flash discharge tube is swung in synchronism with this (see, for example, Patent Document 2).

Japanese Patent Laid-Open No. 09-080593 JP 2005-78011 A

  However, in the prior arts disclosed in Patent Documents 1 and 2, since a plurality of operations are performed synchronously, not only the mechanism is complicated, but also a high-accuracy drive system is required to obtain predetermined optical characteristics. I need. Moreover, since there are many components, an apparatus will become expensive and will also become heavy.

  In view of such a problem, an object of the present invention is to provide an illumination device that can reduce uneven light distribution without using a complicated mechanism.

  An illumination device according to an aspect of the present invention includes a light emitting member, a first region that is a first focal length, a second region that is a second focal length different from the first focal length, An optical member formed with a Fresnel shape having a first region and a third region sandwiched between the second region and having a plurality of continuously changing focal lengths. To do.

  ADVANTAGE OF THE INVENTION According to this invention, the illuminating device which made it possible to reduce light distribution nonuniformity without using a complicated mechanism can be provided.

It is a perspective view of the main optical system of the light emission part of the strobe device which concerns on embodiment of this invention. It is a center sectional view of the main optical system of the light emission part of a strobe device. It is horizontal direction sectional drawing of the main optical system of the light emission part of a strobe device. It is shape explanatory drawing of a reflective umbrella. It is characteristic explanatory drawing of an optical panel. It is shape explanatory drawing of the peripheral part of an optical panel. It is a light distribution characteristic figure which shows the state before a light distribution nonuniformity countermeasure. It is a ray trace figure of the state before light distribution nonuniformity countermeasures. It is a light distribution characteristic figure which shows the state after light distribution nonuniformity countermeasures. It is a light ray trace figure of the state after light distribution nonuniformity countermeasures. It is a perspective view of the main optical system of the light emission part of the strobe device of a well-known technique. It is a center sectional view of the main optical system of the light emitting part of a known strobe device. It is a horizontal direction sectional view of the main optical system of the light emission part of the strobe device of a well-known technique.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In each figure, the same members are denoted by the same reference numerals, and redundant description is omitted. The strobe device, which is the illumination device of the present embodiment, is used by being detachably attached to an imaging device (not shown), for example, as a strobe device disclosed in Japanese Patent Application Laid-Open No. 2005-284095. The strobe device of the present embodiment is different from Japanese Unexamined Patent Application Publication No. 2005-284095 in the main optical system and the irradiation angle variable mechanism, but the other parts related to light emission are the same, and detailed description thereof is omitted.

  First, in order to clarify the operation and effect of the present invention, a method for reducing the size of a zoom strobe device capable of changing the irradiation angle and the disadvantages thereof will be described using the known techniques shown in FIGS.

  11 is a perspective view of a main optical system of a light emitting unit of a known strobe device, FIG. 12 is a central longitudinal sectional view of the main optical system, and FIG. 13 is a horizontal sectional view of the main optical system. 12A and 13A show the case where the imaging device is in the wide state, and FIGS. 12B and 13B show the case where the imaging device is in the tele state.

  The first and second optical panels 101 and 105 are fixed to the strobe body. The first optical panel 101 is disposed on the light emitting member side constituted by the reflector 102 and the flash discharge tube 103. On the subject side surface of the first optical panel 101, a horizontal Fresnel shape with power in the vertical direction is formed at the center, and a ring-shaped Fresnel shape is formed at the left and right peripheral portions. A vertical Fresnel shape is formed only on the left and right peripheral portions on the surface on the subject side of the second optical panel 105 disposed on the subject side. A plurality of cylindrical lenses are formed on the surfaces of the first and second optical panels 101 and 105 on the light emitting member side so as to be parallel to the flash discharge tube 103. The reflector 102 is made of a high reflectivity material or a mold member having a high reflectivity material deposited on the inner surface. The flash discharge tube 103 is a light source, and the protective panel 104 is formed of a glass material having high heat resistance.

  12 and 13, the reflector 102 and the flash discharge tube 103 move independently with respect to the first and second optical panels 101 and 105, respectively. Specifically, in the wide state shown in FIGS. 12A and 13A, the light emitting member is closest to the optical panel 101. At this time, the irradiation angle in the vertical direction is the widest. At this time, the flash discharge tube 103 is farthest from the reflector 102, and the distance between the rear end of the reflector 102 and the center of the flash discharge tube 103 is the largest value G1 '. On the other hand, in the tele state shown in FIGS. 12B and 13B, the light emitting member is farthest from the optical panel 101. At this time, the flash discharge tube 103 is closest to the reflector 102, and the distance between the rear end of the reflector 102 and the center of the flash discharge tube 103 is the smallest value G2 '.

  In general, in a zoom strobe optical system that changes the irradiation angle by changing the positional relationship between the flash discharge tube and the reflector, the irradiation angle can be changed significantly in a small space in the optical axis direction. Is extremely effective. However, there is a problem that the control is not easy because the irradiation angle is greatly changed by a slight change in the positional relationship. As a method for alleviating this problem, a method can be considered in which the shape of the reflector is made relatively large so that the relative position change between the flash discharge tube and the reflector is apparently reduced. The opening area of the reflector which occupies the opening area becomes large. As a result, it is necessary to adopt a configuration in which the optical path in the tele state and the wide state use the same region, and independent light flux control cannot be performed. For this reason, the best state cannot be realized in either position, and only halfway optical characteristics can be obtained. In addition, when the reflector is enlarged, the weight increases and the load on the drive system also increases, so that it takes a long time to move.

  Next, the light distribution characteristic in the left-right direction of a known technique will be described. In the wide state, the use area of the first and second optical panels 101 and 105 is slightly larger than the opening area of the reflector 102, the vertical direction is almost the entire surface, and the horizontal direction is limited to the central area. . At this time, the first optical panel 101 is in a state in which the horizontal Fresnel-shaped region having power in the vertical direction at the center of the subject side and a part of the right and left ring-shaped Fresnel-shaped regions affect the optical characteristics. Become. In the vicinity of the central portion, there is a lateral Fresnel lens extending in the left-right direction, but there is no light collecting property in the left-right direction. For the ring-shaped Fresnel shape, only the region where the refractive power is weak at the center of the ring zone is related, but the light collecting effect to the left and right is weak. The second optical panel 105 has a flat surface on the subject side and does not exert a condensing function. As a result, the influence of the refractive power of each Fresnel lens in the left-right direction is extremely weak, resulting in a light distribution characteristic in a wide angle range. On the other hand, in the tele state, the light is condensed under the influence of the entire surface of the first optical panel 101. Further, for the second optical panel 105, the vertical Fresnel lenses formed on the left and right, which did not function in the wide state, will newly function, and the light distribution characteristic condensed most near the center is obtained.

  In general, in a zoom strobe device in which the distance between the Fresnel lens and the light emitting member is short, in order to obtain a sufficient light collecting effect, two Fresnel lenses are used, and a greater light collecting effect is obtained by the combined power. It is However, the use of a plurality of Fresnel lenses increases the number of times of entering and exiting the optical panel, and the efficiency decreases due to surface reflection. Moreover, since the number of parts increases, it becomes expensive, and harmful effects such as an increase in weight also occur.

  The present invention is a compact zoom strobe optical system that prevents the above-described various problems from occurring. A detailed description will be given below, including differences from the conventional zoom strobe device.

  First, the main optical system of the light emitting unit of the strobe device according to the embodiment of the present invention will be described. 1 is a perspective view of a main optical system of a light emitting unit of a strobe device according to an embodiment of the present invention, FIG. 2 is a central sectional view of the main optical system, and FIG. 3 is a horizontal sectional view of the main optical system. 2A and 3A show the case where the imaging device is in the wide state, and FIGS. 2B and 3B show the case where the imaging device is in the tele state.

  The strobe device has an optical panel 1, a reflector 2, a flash discharge tube 3, and a protection panel 4. The optical panel 1 is fixed to the front surface of a light emitting member of a strobe device composed of a reflector 2 and a flash discharge tube 3. The optical panel 1 can collect and uniformly diffuse the light beam emitted from the flash discharge tube 3. The reflector 2 uniformly irradiates the luminous flux emitted from the flash discharge tube 3 with respect to a predetermined angle. The reflector 2 is formed of a bright aluminum material having a high reflectivity on the inner surface side where the flash discharge tube 3 is disposed, or a mold material on which a high reflectivity material is deposited. The protective panel 4 is disposed immediately in front of the light emitting member, prevents dust and dust from entering the light emitting member to prevent deterioration of optical characteristics, and radiant heat from the flash discharge tube 3 is applied to the optical panel 1. Preventing direct hits. The protective panel 4 is formed of a material having high heat resistance such as a glass material. The reflector 2, the flash discharge tube 3, and the protection panel 4 are integrally held in a state where the positional relationship is fixed, and can be moved along the optical axis of the optical panel 1. The strobe device converts the strobe light into an irradiation angle corresponding to the angle of view of the image pickup device by changing the relative distance between the optical panel 1 and the light emitting unit according to the focal length of the photographic lens attached to the image pickup device. To do. In this embodiment, since the reflector 2 and the flash discharge tube 3 are not moved independently, the mechanism is simplified. Each optical member is held by a holding member (not shown). The holding member is formed of a heat-resistant mold member, holds the drive unit of the reflector 2 and the flash discharge tube 3, and prevents the luminous flux from being emitted in an unnecessary direction.

  As shown in FIG. 2, the vertical opening RH of the reflector 2 is about ¼ of the vertical opening H of the optical panel 1. In the present embodiment, for example, the upper and lower openings H are set to 32 mm, and the upper and lower openings RH are set to 8.6 mm. As for the left and right openings, as shown in FIG. 3, the left and right openings RW of the reflector 2 are about half as long as the left and right openings W of the optical panel 1. In this embodiment, for example, the opening W in the left-right direction is 64 mm, and the left-right opening RW is 33 mm. As a result, the opening area of the reflector 2 is an extremely small opening area of about 13% with respect to the opening area of the optical panel 1, which is sufficiently smaller than that of the known technique. With this configuration, it is possible to use only a part of the Fresnel-shaped weakly weak central portion of the optical panel 1 in the wide state, and use almost the entire opening area of the optical panel 1 in the tele state. It is possible to efficiently perform a large change in irradiation angle in the vertical and horizontal directions. That is, this embodiment is superior to the known technique in that ideal light distribution control can be performed in each of the wide state and the tele state.

  FIG. 4 is an explanatory view of the shape of the reflector 2. This figure is a central sectional view of the light emitting section of the present embodiment, and also shows a ray trace from the center of the light source. Direct light directly emitted from the central portion of the flash discharge tube 3 without passing through the reflector 2 is subjected to angle regulation by the opening of the reflector 2. In the present embodiment, the shape of the opening is regulated so that the maximum angle Θ1 is regulated by 40 ° in the vertical direction. Therefore, with respect to direct light, irradiation with uniform intensity can be performed for each angle in the range of 40 ° above and below. The reflector 2 is formed so that the light beam traveling backward in the optical axis direction out of the luminous flux emitted from the light source center is reflected and passes through the optical axis center again. The reflector 2 is formed so that each reflected light is uniformly distributed according to the angle emitted from the center of the light source, and the maximum angle Θ2 reflected near the opening coincides with the maximum angle Θ1 of the direct light. . By configuring the reflector 2 in this way, it is possible to uniformly irradiate the light beam emitted 360 ° uniformly from the center of the light source in the range of 40 ° both above and below.

  In the optical arrangement in the wide state in which the distance between the front end of the optical panel 1 and the rear end of the reflector 2 is D1, the single optical panel 1 is arranged at a close distance immediately before the reflector 2, Since the influence of the refractive power of the optical panel 1 is minimized, the upper and lower light distribution characteristics are uniform. In the wide state, only an extremely small area of the optical panel 1 is used, and the light distribution characteristic is regulated by the reflector 2 only. As a result, uniform and extremely wide light distribution characteristics can be obtained.

  In the telescopic optical arrangement in which the distance between the front end of the optical panel 1 and the rear end of the reflector 2 is D2, the reflector 2 is sufficiently small, so that the direct light from the flash discharge tube 3 and the reflection by the reflector 2 are reflected. The difference in the angle of light can be apparently reduced, and can be efficiently controlled by the single optical panel 1. As a result, each light beam hits the entire surface of the optical panel 1 and can be efficiently condensed due to the influence of a very powerful Fresnel lens formed on the optical panel 1.

  Next, the Fresnel shape formed on the subject side that is the light emission side of the optical panel 1 will be described in detail with reference to FIGS. As shown in FIG. 5, the optical panel 1 includes a plurality of regions having different focal lengths. The center region 1a is a circular region at the center of the optical panel 1, and is a Fresnel-shaped region having a relatively long focal length. The center region 1a corresponds to a range that substantially covers the opening 2a of the reflector 2. In the present embodiment, the focal length is 35 mm. The peripheral region 1b is a Fresnel-shaped region that is formed on the outer peripheral portion of the optical panel 1 and has a short focal length. The focal length is set so as to substantially coincide with the distance (D2-G) from the subject-side surface of the optical panel 1 in the telephoto state to the center of the flash discharge tube 3. In this embodiment, the focal length is 25 mm. The intermediate region 1c is a region sandwiched between two regions. The focal length is set so as to continuously change a focal length intermediate between the focal length of the central region 1a and the focal length of the peripheral region 1b.

  In order to have a large irradiation angle change in a state where the optical panel 1 and the light emitting member are extremely close to each other, a Fresnel lens having a very short focal length is required. As described above, in the known technique, in order to obtain a sufficient light collecting effect, a plurality of Fresnel lenses are used and the power is divided and arranged. In the present invention, the Fresnel shape having a very short focal length is formed on one optical panel 1 by forming a large inclination angle in the intermediate region 1c connecting the Fresnel shaped regions (the central region 1a and the peripheral region 1b). ing. In the present embodiment, the Fresnel lens angle in the peripheral region 1b of the optical panel 1 exceeds 70 °. FIG. 5 shows this partial shape. In addition, since the moving distance is limited to be short, the incident angle of the light beam reaching the peripheral region 1b is considerably limited, and only the component incident at an extremely steep angle exists in the vicinity of the peripheral region 1b. For a light beam having a large incident angle, the refracted light after the incident is also limited to a specific angle.

  In the present embodiment, paying attention to the light beam incident on the peripheral region 1b of the optical panel 1, the angle of the intermediate region connecting the respective Fresnel-shaped regions is changed to be optimal according to the position of the optical panel 1. Yes. For this reason, it is possible to efficiently guide the light beam even to a Fresnel lens surface having a large angle such that the inclination of the Fresnel lens surface exceeds 70 °. As an angle of the efficient intermediate region 1c, the light beam after entering the optical panel 1 and being refracted does not directly enter the intermediate region 1c, and the light beam after exiting from each Fresnel-shaped region is the intermediate region 1c. It is desirable that the angle is not incident again.

  In the present invention, in consideration of the moldability of the optical panel 1, the angle of the intermediate region 1 c is regulated so that the Fresnel lens apex angle formed by each Fresnel-shaped region and the intermediate region 1 c is 45 ° or more. It is desirable. In the present embodiment, the apex angle of the Fresnel lens composed of the Fresnel lens and the coupling surface is set to be about 50 °.

  As described above, by appropriately setting the angle of the intermediate region 1c of the optical panel 1, it becomes possible to change the irradiation angle with a large refractive power, and to eliminate the unnecessary stray light as much as possible and to perform efficient light irradiation. It becomes possible to do.

  In an optical system with a short focal length and a small amount of movement due to variable illumination angle, a phenomenon occurs in which the image of the flash discharge tube 3 is formed on the subject surface in the tele state. The flash discharge tube 3 is generally arranged in a horizontally long shape, and there are many cases in which the light is irradiated horizontally in the required irradiation range. In the present invention, a flash discharge as a diffusing surface is provided on the light emitting member side of the optical panel 1 so as to convert the left and right and up and down angle ranges into the required angle range, specifically, to widen the upper and lower irradiation ranges. A plurality of cylindrical lenses are formed in parallel with the tube 3. Thereby, the right and left and up and down balance is good, and uniform light distribution characteristics can be obtained. The power of the cylindrical lens may be weaker than that of the conventional lens, and the light amount loss necessary for diffusion in the tele state can be minimized. For this reason, a more efficient optical system can be configured.

  Next, the shape of the intermediate region 1c will be described with reference to FIGS. As described above, the intermediate region 1c is a region sandwiched between the central region 1a and the peripheral region 1b, which are fixed focal regions, and the focal length is set so as to continuously change between the focal lengths of the two regions. ing.

  In order to make a large light distribution characteristic change with one optical panel 1, in the wide state, it corresponds to the relatively long focal length of the central region 1a, and in the tele state, the region of the peripheral region 1c is added to the central region 1a. It is desirable to form a Fresnel shape so as to have the strongest refractive power. However, the zoom region is not limited to the two states of the wide state and the tele state, and it is desirable that the light distribution characteristics continuously change even with the focal length in the intermediate state.

  The state of FIGS. 7 and 8 shows one method of changing the focal length of the intermediate region 1c, and is continuously performed once in the region from the focal length of 35 mm in the central region 1a to the focal length of 25 mm in the peripheral region 1b. The focal length is changed.

  FIG. 7 is a light distribution characteristic diagram at the time of wide. As shown in the figure, after darkening once in the left-right direction, it can be seen that there is a region A brighter than the surroundings outside. This state will be described with reference to the ray trace diagram of FIG. In the peripheral portion of the Fresnel lens, the amount of change in the emission angle from the Fresnel lens tends to become extremely small from a certain angle. As shown in FIG. 8B, in a lens having an extremely short focal length, the change in the angle of the Fresnel lens is reduced in the periphery thereof, and there is a phenomenon that the light flux after the Fresnel lens exits is easily aligned at a certain angle. . This phenomenon occurs only in the optical arrangement in the wide state. Originally, in the wide state, it is desirable that the irradiation angle is uniformly scattered. However, due to the above phenomenon, the luminous flux is concentrated at a certain angle, and uneven light distribution occurs in this part. May occur.

  In order to eliminate the above-described light distribution unevenness, as shown in FIG. 10, a region in which the focal length intermediate between the focal length of the central region 1 a and the focal length of the peripheral region 1 b continuously changes in the intermediate region 1 c. A plurality of layers are formed. By doing so, as shown in FIG. 10D, the luminous flux is uniformly diffused, and as shown in FIG. 9C, uneven light distribution is improved, and uniform light distribution characteristics can be obtained. .

  In the present embodiment, it is possible to prevent the uneven light distribution in the wide state unique to the present invention by appropriately changing the way of changing the focal length of the intermediate region 1c. In the present embodiment, the intermediate region 1c in which the focal length continuously changes is repeated three layers, but is not necessarily limited to three layers, and may be more or less than this.

  As described above, with the above-described configuration, a zoom strobe optical system that is small and has a wide range of change in irradiation angle can be realized.

  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. For example, in the present embodiment, an example of a strobe device that is detachably attached to an imaging device has been described. However, the present invention is applied to a strobe device built in the imaging device, that is, an imaging device incorporating the strobe device. You may apply.

1 Optical panel (optical member)
1a Central region (first region)
1b Peripheral area (second area)
1c Intermediate region (third region)
2 Reflector umbrella (light emitting member)
3 Flash discharge tube (light emitting member)

Claims (9)

A light emitting member;
It is sandwiched between a first region that is a first focal length, a second region that is a second focal length different from the first focal length, and the first region and the second region. And an optical member formed with a Fresnel shape having a third region having a plurality of focal lengths that change in a moving manner.   The lighting device according to claim 1, wherein the Fresnel shape is formed on a light emission side of the optical member. The first region is formed at a central portion of the optical member,
The second region is formed on the outer periphery of the optical member,
The lighting device according to claim 1, wherein the second focal length is shorter than the first focal length.   4. The focal length in the third region continuously changes at a focal length between the first focal length and the second focal length. 5. The lighting device described in 1.   5. The illumination according to claim 4, wherein the third region has a plurality of regions that continuously change at a focal length between the first focal length and the second focal length. apparatus.   The lighting device according to any one of claims 1 to 5, wherein the light emitting member is formed integrally with a flash discharge tube and a reflector.   The lighting device according to claim 6, wherein the third region is formed outside an outer peripheral portion of the reflector when viewed from the optical axis direction.   The illumination device according to claim 1, wherein a diffusion surface is formed on the light emitting member side of the optical member. An imaging apparatus comprising the illumination device according to claim 1.