JP2004069723A - Illuminator and photographing device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To mainly eliminate or reduce irregularities in the light distribution of exit light in a positive lens part. <P>SOLUTION: The illuminator is provided with a light source 13, a 1st optical member 12 for condensing the luminous flux emitted from the light source 13 on nearly the optical axis in a cross section including the radial direction of the light source 13, and a 2nd optical member 11 arranged near the optical axis center and equipped with the positive lens part 112 on which the luminous flux from the light condensing area by the 1st optical member 12 is made incident. And, a diffusion surface 112a for diffusing the exit light is formed on the front surface of the positive lens part 112. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a lighting device used for a photographing device such as a camera, and more specifically, to a structure of an optical member capable of eliminating or reducing uneven light distribution.
[0002]
[Prior art]
2. Description of the Related Art Various types of illumination devices used in photographing apparatuses such as cameras have been proposed in order to efficiently converge light beams emitted from light sources in various directions within a required irradiation range. In particular, in recent years, an illuminating device that improves the light-collecting efficiency and reduces the size by arranging an optical member using total reflection, such as a prism or a light guide, instead of a Fresnel lens arranged in front of a light source. Has been proposed.
[0003]
On the other hand, when an illuminating device having a fixed irradiation range is mounted on a photographing device capable of zooming a photographing lens, the illumination light is irradiated to an unnecessary range, particularly in a telephoto state where a necessary irradiation range is narrow. As a result, the energy loss increases or the light quantity becomes insufficient in the required irradiation range. In order to solve this inconvenience, there has been proposed an illuminating device capable of changing the irradiation range of the illuminating light according to the photographing angle of view.
[0004]
As an illumination device of a type in which the irradiation range is variable, as proposed in Japanese Patent Application Laid-Open No. 2001-66672, the illumination device is arranged in front of a light source and totally reflects at least a part of an incident light beam to condense the light most. An optical prism that forms a state in which the optical prism is formed, and first and second optical panels that are disposed on the object side of the optical prism, and that the irradiation range can be changed by changing the relative position of the two optical panels. There is something to say.
[0005]
Further, as in a strobe device proposed in Japanese Patent Application Laid-Open No. 7-270865, there is a device in which a diffusing plate and a reflecting mirror are arranged at the forefront in the irradiation direction for the purpose of widening the irradiation angle.
[0006]
[Problems to be solved by the invention]
However, in the illumination device proposed in Japanese Patent Application Laid-Open No. 2001-66672, it is necessary to arrange three optical members in front of the light source in order to converge and diverge light from the light source. There is a problem that is increased. In addition, as for the optical components, assembling position accuracy is required, so that there is a problem that as the number of optical components increases, the assembling work becomes complicated.
[0007]
Here, in the illumination device of the publication, the light from the light source is converted into substantially parallel light in a cross section including a radial direction of the light source (a cross section in the vertical direction of the device main body) by an optical prism that forms a condensing optical system, thereby obtaining a first light. It leads to the optical panel. However, in order to make the light from the light source substantially parallel, the size of the optical prism must be increased in the vertical direction of the device main body, and the optical panel on which the substantially parallel light emitted from the optical prism is incident also has a vertical direction. Must be bigger. For this reason, there is also a problem that the size of the lighting device is increased in the vertical direction.
[0008]
On the other hand, in the strobe device proposed in Japanese Patent Application Laid-Open No. 7-270865, there is a concern that the number of components increases due to the provision of the diffusion plate and the reflecting mirror, and the strobe device becomes large.
[0009]
Therefore, an object of the present invention is to provide an illumination device which is configured with a smaller number of components than the conventional technology and can be downsized (in particular, downsized in the vertical direction of the device main body), and an imaging device provided with the same. And Moreover, the present invention provides, in addition to the above objects, an illumination device which can use light energy from a light source with high efficiency and can obtain uniform light distribution characteristics within a predetermined irradiation range. The purpose is.
[0010]
[Means for Solving the Problems]
The lighting device according to the first aspect of the present invention is provided with a light source, a first optical member that condenses a light flux from the light source substantially on the optical axis in a cross section including the radial direction of the light source, and provided near the optical axis center. A second optical member having a positive lens portion on which a light beam from a light converging region by the first optical member enters, and a diffusion surface for diffusing the emitted light is formed on the front surface of the positive lens portion. It is characterized by the following.
[0011]
The illumination device according to the second invention of the present application includes a light source, a first optical member that condenses a light beam from the light source substantially on the optical axis in a cross section including the radial direction of the light source, and a light source near the optical axis center. A second optical member having a positive lens portion on which a light beam from a light converging region of the first optical member is incident, and a diffusing member for diffusing light emitted from the positive lens portion on a front surface of the positive lens portion. Is provided.
[0012]
In the above-described configuration of the illumination device of the present invention, only two optical members (a first optical member and a second optical member) need to be arranged in addition to the light source. The number of components can be reduced as compared with the case of disposing the optical members, the influence of the relative dislocation of the optical members on the optical characteristics is hardly caused, and the stability and reliability of the optical characteristics can be improved. It becomes possible.
[0013]
Further, since the light beam from the light source is condensed substantially on the optical axis by the first optical member, the light beam from the light source is converted into substantially parallel light and guided to an optical member in front of the device as in a conventional illumination device. Therefore, the size of the apparatus in the vertical direction can be reduced.
[0014]
In addition, since the diffusing surface or the diffusing member is provided on the front surface of the positive lens portion in the second optical member, the light emitted from the positive lens portion can be made to have a uniform light distribution, thereby preventing light distribution unevenness. In particular, in the above-described configuration of the illumination device of the present invention, uneven light distribution may occur in the emission light in a region near the center of the optical axis in the front surface of the positive lens unit. By forming the light near the center of the optical axis, or by disposing a diffusing member so as to diffuse the light emitted near the center of the optical axis among the light emitted from the positive lens, the light emitted from the positive lens can be evenly distributed. It can be a light distribution.
[0015]
On the other hand, a Fresnel lens portion for condensing a light beam from the condensing region is provided around the positive lens portion, and the light source and the first optical member are integrated with the second optical member in the optical axis direction. By moving the light source and the first optical member in the optical axis direction, the light irradiation range can be changed.
[0016]
In the present invention, since the light from the light source is condensed substantially on the optical axis by the first optical member, the light source and the first optical member are moved by a small amount in the optical axis direction with respect to the second optical member. Thereby, it is possible to make all the light beams from the light-converging region enter the positive lens portion, or enter the positive lens portion and the Fresnel lens portion. If the entire light beam from the light-converging region is incident on the positive lens portion, the irradiation range can be widened. If the light beam is incident on the positive lens portion and the Fresnel lens portion, the irradiation range can be narrowed. The irradiation range can be changed continuously and significantly with a small moving amount of the optical member.
[0017]
Here, a drive mechanism for moving the diffusing member to the front of the positive lens unit in accordance with the movement of the light source and the first optical member in the optical axis direction can be provided. With this driving mechanism, when the light source and the first optical member are at the first position with respect to the second optical member, that is, when all the light fluxes from the light condensing area are incident on the positive lens portion, the diffusing member Into the front surface of the positive lens portion, and when the light beam is at the second position, that is, when the light beam from the focusing area is incident on the positive lens portion and the Fresnel lens portion, the diffusing member is retracted from the front surface of the positive lens portion. It can also be done.
[0018]
When a discharge tube is used as a light source, the first optical member may be provided with a reflecting portion for condensing a light beam from the discharge tube in the optical axis direction in a cross section including the longitudinal direction of the discharge tube.
[0019]
Further, the lighting device of the present invention can be used for a photographing device mounted on a camera or a portable information terminal.
[0020]
BEST MODE FOR CARRYING OUT THE INVENTION
(1st Embodiment)
1 to 15 show a strobe device (illumination device) according to a first embodiment of the present invention, a configuration of a camera equipped with the strobe device, and light distribution characteristics of the strobe device, respectively.
[0021]
1 and 2 are longitudinal sectional views (sectional views including the radial direction of the tubular light source) of the optical system of the strobe device, and FIGS. 4 and 5 are horizontal sectional views (center in the longitudinal direction of the light source) of the optical system of the strobe device. FIG. 6 is a longitudinal sectional view showing a part of the optical system of the strobe device.
[0022]
Here, FIGS. 1 to 6 also show trace diagrams of light rays emitted from the center of the light source.
[0023]
FIG. 7 is an exploded perspective view showing an internal structure of a part of a camera equipped with a flash device, and FIGS. 8 and 9 are external perspective views showing an assembled state of the flash device. 10 and 11 are perspective views showing the appearance of a part of the camera in an assembled state.
[0024]
FIG. 12 is a detailed view of the front optical element in the strobe device, and FIGS. 13 to 15 are light distribution characteristics diagrams of the strobe device.
[0025]
As shown in FIGS. 10 and 11, the strobe device of the present embodiment is disposed above a camera body 21.
[0026]
In FIG. 7, when the photographing optical system provided in the lens barrel 25 of the camera body 21 moves in the photographing optical axis direction (front-back direction in the drawing) with the zoom operation, a driving mechanism of the photographing optical system is configured. The rectilinear pin 211 provided on the component to be moved moves along the rectilinear groove 212 formed on the upper surface of the lens barrel 25.
[0027]
A cam plate 23 is disposed above the lens barrel 25, and a drive cam (not shown) with which the rectilinear pin 211 is engaged is formed on the lower surface of the cam plate 23. For this reason, when the rectilinear pin 211 moves along the rectilinear groove 212, the cam plate 23 moves in the direction indicated by the arrow A in the figure.
[0028]
Further, on the cam plate 23, a flash drive cam 231 and a finder drive cam 232 are formed. The strobe drive cam 231 is engaged with a cam pin 151 (FIG. 8) provided on the light source unit main body 15 constituting the strobe device, and the finder drive cam 232 is connected to the finder of the finder base plate 22 fixed to the camera main body 21. A cam pin provided on a part of lenses of a finder optical system (not shown) stored in the storage part 222 is engaged.
[0029]
Therefore, when the cam plate 23 moves in the direction of arrow A, the light source unit main body 15 and the lens of the finder optical system move in the respective optical axis directions, and the strobe zoom operation and the finder zoom operation are performed.
[0030]
As shown in FIG. 6, the strobe device includes a front optical element (second optical member) 11, an intermediate prism (first optical member) 12, a discharge tube (light source) 13, a reflector 14, a light source unit main body 15, The holding rubber 16 is used.
[0031]
The front optical element 11 is fixed to the finder base plate 22 as a strobe light irradiation window. The discharge tube 13 and the reflector 14 disposed on the rear side of the discharge tube 13 are fixed to the light source unit main body 15 by pressing rubber 16, and the intermediate prism 12 is disposed in a state of being disposed on the front side of the discharge tube 13. Fixed to 15.
[0032]
The discharge tube 13 is connected to a power supply circuit (not shown) provided on the camera body 21 via a lead wire (not shown), and receives power supply from the power supply circuit to emit light as a light source. Emit. The reflector 14 reflects light emitted from the discharge tube 13 toward the rear of the strobe device and returns the light to the discharge tube 13 side. The discharge tube 13 is pressed against the reflector 14 by the elastic force of the pressing rubber 16. The light source unit 1 is constituted by the intermediate prism 12, the discharge tube 13, the reflector 14, and the light source unit main body 15.
[0033]
As described above, the light source unit 1 is moved forward and backward with respect to the front optical element 11 by the cam engaging action of the cam pin 151 provided on the light source unit main body 15 and the strobe drive cam 231 formed on the cam plate 23. Move in one direction. As a result, the distance between the front optical element 11 and the intermediate prism 12 changes, the degree of condensing or diverging light emitted from the discharge tube 13 changes, and the irradiation range of the strobe light changes with the zoom operation of the photographing lens. Be changed.
[0034]
FIG. 9 is a view of the light source unit 1 as viewed from below. On the lower surface of the light source unit main body 15, a cam pin 151 that engages with the flash drive cam 231 and a guide projection 152 are formed integrally with the light source unit main body 15. The guide protrusion 152 engages with a rail 221 formed on the finder base plate 22 shown in FIG.
[0035]
As shown in FIGS. 8 and 9, sliding protrusions 153 are integrally formed on the upper and lower surfaces of the light source unit main body 15 with the light source unit main body 15. When the light source unit 1 moves in the front-rear direction of the strobe device, the sliding protrusions 153 slide with respect to an upper cover (not shown) attached to the upper surface of the light source unit 1 and the finder base plate 22. The rattling of the light source unit 1 in the vertical direction is suppressed, and smooth movement is enabled.
[0036]
FIG. 10 is an external perspective view of the internal structure of the camera when the taking lens is in the wide state, and FIG. 11 is an external perspective view of the internal structure of the camera in the telephoto state. As shown in these figures, in the wide state, the front optical element 11 and the intermediate prism 12 are closest to each other, and in the telephoto state, the front optical element 11 and the intermediate prism 12 are farthest from each other. When the distance between the front optical element 11 and the intermediate prism 12 changes between the wide state and the tele state, the irradiation range of light emitted from the discharge tube 13 changes.
[0037]
Next, the operation and optical function of the strobe device will be described in detail with reference to FIGS.
[0038]
In these figures, the discharge tube 13 is constituted by a cylindrical xenon tube. The reflecting umbrella 14 reflects a component of the light beam emitted from the discharge tube 13 that is emitted to the rear of the strobe device toward the front of the strobe device. The reflecting surface has a metallic material such as bright aluminum having a high reflectance. Are adhered, or a metal evaporation surface with high reflectivity is formed.
[0039]
The intermediate prism 12 is an optical member for condensing a light beam emitted from the discharge tube 13 and controlling the light beam to a predetermined light distribution characteristic. Further, the front optical element 11 is disposed in front of the strobe device with respect to the intermediate prism 12, and as shown in FIGS. 4 and 5, the light-incident surface has a refractive power in the longitudinal direction of the discharge tube 13 on the light source side. Is formed.
[0040]
As shown in FIGS. 1 and 2, a cylindrical lens portion (having a positive refractive power in the vertical direction of the strobe device) is provided in a central region including the optical axis of the exit surface of the front optical element 11 on the subject side, as shown in FIGS. A positive lens portion 112 is formed. Further, Fresnel lens portions 113 and 114 having a positive refractive power in the device vertical direction are formed in a region in the device vertical direction adjacent to the cylindrical lens portion 112, respectively.
[0041]
In addition, as a material of the front optical element 11 and the intermediate prism 12, an optical resin material having a high transmittance such as an acrylic resin is preferable.
[0042]
The illumination device of the present embodiment configured as described above changes the positional relationship between the light source unit 1 (especially, the intermediate prism 12) and the front optical element 11 in the optical axis direction, so that the vertical direction of the strobe device and The irradiation range in the left-right direction is changed so as to correspond to the focal length (angle of view) of the photographing lens capable of performing a zoom operation.
[0043]
Hereinafter, setting of the optimum shape for changing the irradiation range in the vertical direction of the strobe device will be described with reference to FIGS.
[0044]
The reflecting surface of the reflecting umbrella 14 is a semi-cylindrical surface of a cylinder that is substantially concentric with the discharge tube 13. This is an effective shape for returning the light reflected by the reflecting surface of the reflector 14 to the vicinity of the center of the discharge tube 13. As a result, the discharge tube 13 is less likely to be adversely affected by refraction of glass, which is a component of the discharge tube 13. In addition, the light directly incident on the intermediate prism 12 from the discharge tube 13 and the light reflected by the reflector 14 can be treated as light emitted from substantially the same point (center point) of the discharge tube 13. The subsequent optical system as a whole can be reduced in size.
[0045]
FIG. 6 shows a radial cross section of the discharge tube 13, the reflector 14, and the intermediate prism 12, and also shows a ray trace diagram of a light beam emitted from the central portion of the discharge tube 13.
[0046]
In FIG. 6, an aspherical cylindrical lens portion 121 having a positive refractive power is formed in a central region including the optical axis in the incident region on the light source side of the intermediate prism 12. Further, peripheral incident surfaces 122 and 123 having a planar shape are formed in a peripheral region in the vertical direction of the device with the cylindrical lens portion 121 interposed therebetween. Further, reflection surfaces 124 and 125 each having an aspherical shape are formed above the device on the peripheral incident surface 122 (left side in the drawing) and below the device on the peripheral incident surface 123 (right side in the drawing).
[0047]
The cylindrical lens portion 121 and the reflecting surfaces 124 and 125 are formed in a shape that converges the light beam emitted from the discharge tube 13 toward substantially one point P, and thereby, is forward from the converging point P (in FIG. It becomes possible to narrow the spread angle of the light beam diverging upward (upward) to a predetermined angle α. The exit surface 126 of the intermediate prism 12 on the subject side is formed in a planar shape.
[0048]
Hereinafter, the optical function of the intermediate prism 12 in the vertical direction will be described in detail with reference to FIG. First, of the light flux emitted forward from near the center of the discharge tube 13, a component having a small angle with respect to the optical axis directly enters the cylindrical lens unit 121. This light flux is emitted from the exit surface 126 of the intermediate prism 12 by the positive refracting power of the cylindrical lens portion 121, and is then focused near the point P.
[0049]
In the light flux emitted from near the center of the discharge tube 13, a component having a relatively large angle with respect to the optical axis enters the intermediate prism 12 from the peripheral incidence surfaces 122 and 123, and is refracted at the time of incidence. It goes to the reflection surfaces 124 and 125. Since the reflecting surfaces 124 and 125 are formed in a shape that satisfies the condition of total reflection with respect to the light beams incident from the peripheral incident surfaces 122 and 123, almost all the light beams incident on the reflecting surfaces 124 and 125 are reflected.
[0050]
Further, the light beams reflected by the reflection surfaces 124 and 125 are condensed toward substantially the same point as the condensing point P due to the refracting power of the cylindrical lens portion 121.
[0051]
On the other hand, as described above, since the reflecting surface of the reflector 14 is a semi-cylindrical surface of a cylinder concentric with the discharge tube 13, the light flux from the center of the discharge tube 13 to the rear reflector 14 is again emitted. Then, the light returns to the center of the discharge tube 13 and follows the same optical path as the light directly incident on the intermediate prism 12 described above, and is condensed near the point P.
[0052]
As described above, all the light beams emitted from the center of the discharge tube 13 are collected near the point P. Further, the divergence angle range of the light beam after condensing is also suppressed to the angle α, and it is possible to convert the light beam into an easily handled light beam in the optical system described below.
[0053]
Here, the peripheral incident surfaces 122 and 123 of the intermediate prism 12 are formed as planes having a relatively large inclination angle with respect to the optical axis. This is because, as can be seen from the optical path shown in FIG. 6, when the light beams reflected by the reflecting surfaces 124 and 125 are directed to the converging point P, they are not efficiently reflected by the peripheral incident surfaces 122 and 123 and efficiently emitted. This is so that it can be guided to the surface 126.
[0054]
It is desirable that the inclination angles of the peripheral incident surfaces 122 and 123 be set so as to substantially coincide with the inclination angles with respect to the optical axis of the light rays reflected on the rearmost portions of the reflection surfaces 124 and 125, which is the most loss of light amount. This is the ideal angle to reduce.
[0055]
As described above, by setting the shape of each optical surface of the intermediate prism 12, the luminous flux emitted from the discharge tube 13 toward the entire periphery is converted into a luminous flux having an angle range α substantially exiting from the converging point P. Can be converted.
[0056]
Next, a description will be given of a change of the irradiation range using the above-described condensing at approximately one point P, with reference to FIGS. 1 and 2.
[0057]
FIG. 1 is an optical arrangement diagram of the strobe device when the taking lens is in a wide state. The state shown in FIG. 1 is also referred to as a wide state with respect to the flash device. As shown in the figure, in the wide state, the front optical element 11 and the intermediate prism 12 are closest to each other. In this state, the focal point P by the intermediate prism 12 and the position of the incident surface (cylindrical lens portion) 111 of the front optical element 11 are almost the same.
[0058]
However, the optimal positional relationship between the converging point P and the incident surface of the front optical element 11 is appropriately changed depending on the relationship with the focal length required for the photographing lens.
[0059]
Here, the shape of the front optical element 11 will be described in detail. The entrance surface (cylindrical lens portion 111) of the front optical element 11 does not have a lens effect in the vertical direction of the strobe device, and this surface is used for focusing light in the longitudinal direction of the discharge tube 13 as described later. are doing.
[0060]
On the other hand, the exit surface of the front optical element 11 is set to have various shapes in order to have a light collecting effect and a diffusion effect. The details of the exit surface of the front optical element 11 will be described with reference to FIG.
[0061]
First, an aspheric cylindrical lens portion 112 extending in the longitudinal direction of the front optical element 11 is formed in a central region including the optical axis on the exit surface of the front optical element 11. Extends in the longitudinal direction of the front optical element 11 with an appropriate width, and a diffusion portion (diffusion surface) 112a having a diffusion effect is formed.
[0062]
As the diffusing portion 112a, a material in which a mat (an uneven shape) is formed on the surface of the lens portion is used.
[0063]
The cylindrical lens portion 112 has a positive refractive power in the vertical direction of the device in a section orthogonal to the optical axis.
[0064]
Fresnel lens portions 113 and 114 having a positive refractive power in the vertical direction of the device in a cross section orthogonal to the optical axis are formed in a peripheral region of the exit surface of the front optical element 11 adjacent to the cylindrical lens portion 112 in the vertical direction. Have been.
[0065]
It is desirable that the exit surface side of the front optical element 11 be optically formed of a cylindrical lens surface. However, if all of the front optical element 11 is formed of a cylindrical lens surface, the refraction required in the outer peripheral area of the front optical element is required. Since the force is increased, the shape of the peripheral area is greatly reduced (recessed), which is unsuitable for use as a front window constituting an external part of the camera.
[0066]
For this reason, in the present embodiment, the central area of the exit surface of the front optical element 11 is constituted by the cylindrical lens surface, and the peripheral area adjacent to the central area is constituted by the Fresnel lens surface.
[0067]
The optical function of the front optical element 11 configured as described above will be described. In the wide state shown in FIG. 1, the light beam emitted from the center of the discharge tube 13 is emitted from a cylindrical lens portion 112 formed substantially at the center of the emission surface of the front optical element 11. Generally, light distribution characteristics in the wide state are most likely to cause uneven light distribution, as described later. However, in the present embodiment, all of the irradiation light beams in the wide state are formed by the continuous aspherical shape of the cylindrical lens unit 112 and the diffusion unit 112a. By controlling the light distribution, uneven light distribution caused by a discontinuous shape is eliminated as much as possible, so that substantially uniform light distribution characteristics can be obtained.
[0068]
Further, in the wide state, since the distance between the cylindrical lens portion 112 and the converging point P by the intermediate prism 12 is short, the condensing effect is weak, and it is possible to irradiate the strobe light to a relatively wide range.
[0069]
On the other hand, FIG. 2 is an optical arrangement diagram of the strobe device when the taking lens is in a telephoto state. The state shown in FIG. 2 is also referred to as a telephoto state with respect to the flash device. In the telephoto state shown in FIG. 2, the light beam emitted from the center of the discharge tube 13 and condensed by the intermediate prism 12 spreads sufficiently after passing through the converging point P, and is almost entirely on the exit surface of the front optical element 11. Is led to.
[0070]
The luminous flux passing through the converging point P is condensed in an extremely narrow angle range by the optical action of the cylindrical lens portion 112 and the Fresnel lens portions 113 and 114 formed on the exit surface of the front optical element 11, The luminous flux passing through the cylindrical lens section 112 and the diffusing section 112a is relatively lower than the luminous flux passing through the Fresnel lens sections 113 and 114. Therefore, in the telephoto state, the influence of the light beam diffused by the diffusion unit 112a is negligible.
[0071]
Here, the difference in the luminous flux depending on the presence or absence of the diffusion unit 112a will be described. FIG. 3 is an optical arrangement and an optical path diagram of the strobe device when the diffusion unit 112a is not formed, and FIG. 1 is an optical arrangement and an optical path diagram of the strobe device (this embodiment) when the diffusion unit 112a is formed. In FIGS. 3 and 1, the strobe device is in a wide state.
[0072]
In FIG. 3 (wide state), the light beams 102 and 104 are light beams reflected by the reflecting surfaces 124 and 125 of the intermediate prism 12 and passed through the cylindrical lens unit 112, and the light beam 103 is reflected by the reflecting surfaces 124 and 125. 3 shows a luminous flux directly passing through the cylindrical lens unit 112.
[0073]
Here, the luminous fluxes 102 and 104 regulated by the upper and lower reflecting surfaces 124 and 125 of the intermediate prism have an irradiation angle range that is hardly changed by changing the distance between the front optical element 11 and the intermediate prism 12, but the irradiation direction is not changed. Changes gradually.
[0074]
When the interval is widened, the light beams 102 and 104 are directed in a direction close to the optical axis center direction. In this case, since the light beam 103 converged by the cylindrical lens portion 121 formed at the center of the intermediate prism 12 overlaps, light distribution unevenness does not occur.
[0075]
On the other hand, when the interval is narrowed (wide state), the luminous fluxes 102 and 104 change their irradiation directions away from the optical axis. In this case, since the light flux 103 converged by the cylindrical lens portion 121 of the intermediate prism 12 changes in a direction in which a gap is generated, boundary areas 100 and 101, that is, light distribution unevenness occurs.
[0076]
FIG. 14 is a light distribution characteristic diagram at this time. In the vertical light distribution characteristics of the strobe device, a drop in light distribution (light distribution unevenness) is observed. As a method of reducing the uneven light distribution, there is a method of changing the shape of the intermediate prism 12, and the like. However, in this case, the intermediate prism 12 has a complicated shape, which is not preferable in design and processing.
[0077]
Therefore, as a method of easily reducing the light distribution unevenness, a diffusing portion 112a is provided on the front surface of the cylindrical lens portion 112 as in the present embodiment, so that the light flux passing through the cylindrical lens portion 112 is appropriately diffused. Thereby, the range of the boundary areas 100 and 101 can be reduced or eliminated.
[0078]
FIG. 13 is a light distribution characteristic diagram at this time. A remarkable improvement is seen in comparison with FIG.
[0079]
On the other hand, when the strobe device is in the telephoto state, since the light beams passing through the Fresnel lens units 113 and 114 are mixed as shown by the optical arrangement of the strobe device and the light beam path in FIG. 2, the light beam diffused by the diffusion unit 112a is mixed. The effect on the overall luminous flux is minor. Therefore, a decrease in the intensity of the central light beam, that is, Gno (guide number) is very small.
[0080]
Here, the position change amount (movement amount) of the intermediate prism 12 (light source unit 1) with respect to the front optical element 11 in the wide state and the telescopic state is about 2.0 mm. This moving amount is extremely small as compared with the moving amount in the illumination device of the related art.
[0081]
On the other hand, if the moving amount of the intermediate prism 12 is smaller than about 2.0 mm, the irradiation range largely changes with a very small moving amount, and thus it becomes difficult to design a mechanism. However, at the level of the movement amount as in the present embodiment, the dimensional relationship is the easiest to design in terms of the mechanism design.
[0082]
Next, the change of the irradiation range in the left-right direction of the strobe device (the longitudinal direction of the discharge tube 13) will be described with reference to FIGS. FIGS. 4 and 5 also show a ray trace diagram from the center of the discharge tube 13.
[0083]
FIG. 4 shows a light condensing state in the left-right direction of the strobe device when the lens barrel corresponding to FIG. 1 is in a wide state. As shown in the figure, the incident surface of the front optical element 11 is formed in various shapes in order to change the irradiation range in the lateral direction of the device.
[0084]
First, a cylindrical lens portion 111 is formed in a central region including the optical axis on the incident surface of the front optical element 11. In the present embodiment, the intermediate prism 12 approaches the front optical element 11 in the wide state and moves away in the telephoto state, so that a strong light-collecting effect can be obtained in the telephoto state. Also from the light ray trace diagrams shown in FIGS. 4 and 5, it can be seen that the light collecting power is stronger in the telephoto state than in the wide state.
[0085]
Here, the most characteristic feature of the light condensing in the left-right direction of the strobe device is the prism portions formed on both left and right ends of the cylindrical lens portion 111. This prism section has incident surfaces 115 and 116 and inner reflecting surfaces 117 and 118. The inner reflecting surfaces 117 and 118 are set so as to satisfy the condition for total reflection of incident light from the incident surfaces 115 and 116.
[0086]
In the present embodiment, by changing the position of the intermediate prism 12 in the optical axis direction with respect to the front optical element 11 within the range from the wide state to the telephoto state, the luminous flux region entering the intermediate prism 12 from the entrance surfaces 115 and 116 is changed. , The irradiation range in the left-right direction of the strobe device can be largely changed.
[0087]
In the wide state shown in FIG. 4, of the light beams emitted from the intermediate prism 12, the smallest light beams near the left and right ends enter the prism portion and are condensed on the optical axis side, and the other light beams are spread over a wide area by the cylindrical lens portion 111. Is irradiated.
[0088]
In the telephoto state shown in FIG. 5, the light flux incident on the prism section becomes maximum. That is, a part of the light emitted from the intermediate prism 12 enters the prism from almost the entire surfaces of the incident surfaces 115 and 116. Then, many of these light beams are converged on the optical axis side, and the other light beams are irradiated to a narrow range by the cylindrical lens unit 111. Therefore, sufficient light collection corresponding to the telephoto state of the photographing optical system is performed.
[0089]
As described above, by applying the light-collecting effect of the total reflection in the vertical direction of the strobe device shown in FIGS. 1 and 2 to the left-right direction of the strobe device, the efficiency is extremely low despite the small number of components. Light can be condensed well.
[0090]
FIGS. 13 and 15 show light distribution characteristics of the strobe device of the present embodiment configured as described above. FIG. 13 shows the vertical and horizontal light distribution characteristics of the strobe device in the wide state, and FIG. 15 shows the vertical and horizontal light distribution characteristics of the strobe device in the telephoto state. Note that both figures show an effective irradiation range defined by a light amount of 50% with respect to the center light amount.
[0091]
As can be seen from these figures, by shifting from the wide state to the telescopic state, the irradiation range (angle) is changed from 79.6 ° to 46.5 ° in the left-right direction of the strobe device, and the up-down direction of the strobe device is changed. Can be greatly changed from 41 ° to 18.7 °. In addition, the light distribution is maintained substantially uniform at any position, and uniform light distribution characteristics without unevenness can be obtained.
[0092]
In addition, the increase in the amount of light at the center of the optical axis due to the change in the irradiation range is twice or more, and the change in the irradiation range is achieved very efficiently.
[0093]
As described above, in the present embodiment, although the intermediate prism 12 (light source unit 1) moves only 2.0 mm with respect to the front optical element 11, the vertical direction and the horizontal direction of the strobe device are greatly increased. The irradiation range can be changed, the light distribution characteristics of the strobe light are good, and a large increase in the guide number can be expected.
[0094]
In this embodiment, the flash device of the type that can change the irradiation range of the strobe light has been described. However, the present invention can be applied to a flash device of a type in which the irradiation range is fixed. For example, the strobe device is configured to be fixed to the optical arrangement corresponding to the wide state shown in FIG. 1, and as the front optical element, a cylindrical lens unit in which the Fresnel lens units 113 and 114 are removed from the front optical unit 11 in the present embodiment. 112 and a diffusion unit 112a.
[0095]
Thus, it is possible to realize an illumination device capable of irradiating the strobe light evenly over a wide range while reducing the opening (front optical element) in the vertical direction of the strobe device.
[0096]
In the present embodiment, the strobe device mounted on a still camera has been described. However, the present invention can be applied to a lighting device used for a video camera or a photographing device mounted on a portable information terminal.
[0097]
(2nd Embodiment)
A second embodiment of the present invention will be described with reference to FIGS.
[0098]
FIG. 16 is an exploded perspective view showing the internal structure of a camera equipped with the strobe device of the present embodiment, FIG. 17 is an exploded perspective view of the camera in a wide state, and FIG. It is an exploded perspective view. Hereinafter, the configuration of the camera will be described with reference to FIG. The same members as those described in the first embodiment are denoted by the same reference numerals, and description thereof is omitted.
[0099]
Reference numeral 160 denotes a diffusion plate (diffusion member), which is formed integrally with the lever 161. Reference numeral 161a denotes a lever guide hole formed on a side surface of the lever 161. A guide shaft 164a formed in a convex shape on a guide 164 formed on the camera body is slidable in the lever guide hole 161a. Has been inserted.
[0100]
A rotation shaft 163 is formed in a two-way shape and has a circular portion at one end. The rotating shaft 163 is slidably inserted into a two-way lever sliding hole 161b formed on the lever 161 and rotatably inserted into a bearing 165a of a bearing 165 formed on the camera body. Is done. And it is fixed with the screw 168 through the lever receiving part 162 and the screw hole part 162a formed in the center part of the lever receiving part 162. Here, when the lever receiving portion 162 rotates, the lever 161 rotates by the sliding action of the rotating shaft 163 and the lever sliding hole 161b.
[0101]
A first spring coil (first SP) 167 is fitted around the outer periphery of the lever receiving portion 162. One end of the first SP 167 is engaged with the upper part of the lever 161. The other end of the first SP 167 contacts the holder projection 15a formed on the light source unit main body 15 when the strobe device is in the wide state, and does not contact when in the telephoto state.
[0102]
Reference numeral 166 denotes a second spring coil (second SP), one end of which engages with an engaging portion 161c formed at the rear end of the lever 161, and the other end engages with a projection (not shown) of the camera body. This urges the lever 161 to rotate clockwise in FIG.
[0103]
In the above-described configuration, the behavior of the lever 161 will be described with reference to FIGS.
[0104]
In the telephoto state shown in FIG. 18, when the light source unit main body 15 moves toward the subject (front of the strobe device) by the cam engaging action of the cam pin 151 and the strobe drive cam 231, the holder projection 15a pushes the other end of the first SP 167, The spring force of the first SP 167 causes the lever 161 to rotate counterclockwise in FIG. 18 against the spring force of the second SP 166.
[0105]
The upper end surface of the lever guide hole 161a of the lever 161 abuts on the guide shaft 164a. As a result, the diffusion plate 160 is disposed at the center of the cylindrical lens portion 112. In order to secure the above-described operation, the spring force of the second SP 166 is set to be weaker than the spring force of the first SP 167.
[0106]
In the wide state shown in FIG. 17, when the light source unit main body 15 moves to the film surface side (rearward of the strobe device), the contact state between the holder projection 15a and the other end of the first SP 167 is released, and the first SP 167 is free. It becomes. Therefore, the lever 161 rotates in the clockwise direction in FIG. 17 under the urging force of the second SP 166, and stops when the lower end surface of the lever guide hole 161a comes into contact with the guide shaft 164a. As a result, the diffusion plate 160 disposed on the front surface of the cylindrical lens unit 112 is retracted from the front surface of the front optical element 11 (cylindrical lens unit 112).
[0107]
【The invention's effect】
According to the present invention, it is only necessary to arrange two optical members (the first optical member and the second optical member) in addition to the light source, and therefore, compared with the case where three optical members are arranged as in the related art. As a result, the number of components can be reduced, the influence of the relative dislocation of the optical members on the optical characteristics is hardly affected, and the stability and reliability of the optical characteristics can be improved.
[0108]
Further, since the light beam from the light source is condensed substantially on the optical axis by the first optical member, the light beam from the light source is converted into substantially parallel light and guided to an optical member in front of the device as in a conventional illumination device. Therefore, the size of the apparatus in the vertical direction can be reduced.
[0109]
In addition, since the diffusing surface or the diffusing member is provided on the front surface of the positive lens portion in the second optical member, the light emitted from the positive lens portion can be made to have a uniform light distribution, thereby preventing light distribution unevenness. In particular, in the above-described configuration of the illumination device of the present invention, uneven light distribution may occur in the emission light in a region near the center of the optical axis in the front surface of the positive lens unit. By forming the light near the center of the optical axis, or by disposing a diffusing member so as to diffuse the light emitted near the center of the optical axis among the light emitted from the positive lens, the light emitted from the positive lens can be evenly distributed. It can be a light distribution.
[Brief description of the drawings]
FIG. 1 is a layout diagram and a light beam distribution diagram (wide state) of an optical member of a strobe device in a radial cross section of a discharge tube.
FIG. 2 is a layout diagram and a light ray distribution diagram (wide state) of an optical member of a strobe device having no diffusion portion (diffusion plate) in a radial cross section of a discharge tube.
FIG. 3 is an arrangement diagram and a light beam distribution diagram (tele state) of an optical member of the strobe device in a radial cross section of the discharge tube.
FIG. 4 is a layout diagram and a light beam distribution diagram (wide state) of an optical member of a strobe device in a longitudinal section of the discharge tube.
FIG. 5 is a layout diagram and a light beam distribution diagram (tele state) of an optical member of the strobe device in a longitudinal section of the discharge tube.
FIG. 6 is a layout diagram and a light beam distribution diagram of an optical member in a light source unit in a strobe device in a radial section of a discharge tube.
FIG. 7 is an exploded perspective view showing the internal configuration of a camera equipped with a strobe device according to the first embodiment.
FIG. 8 is an upper perspective view illustrating a configuration of a light source unit in the strobe device according to the first embodiment.
FIG. 9 is a lower perspective view illustrating a configuration of a light source unit in the strobe device according to the first embodiment.
FIG. 10 is an external perspective view (wide state) showing an internal configuration of a camera equipped with a strobe device according to the first embodiment.
FIG. 11 is an external perspective view (tele state) showing an internal configuration of a camera equipped with a strobe device according to the first embodiment.
FIG. 12 is an external perspective view of the front optical element according to the first embodiment.
FIG. 13 is a view showing light distribution characteristics of the strobe device according to the present invention in a wide state.
FIG. 14 is a diagram showing light distribution characteristics in a wide state when the front optical element has no diffusing portion.
FIG. 15 is a diagram illustrating light distribution characteristics of the strobe device according to the present invention in a telephoto state.
FIG. 16 is an exploded perspective view showing the internal configuration of the camera according to the second embodiment.
FIG. 17 is an external perspective view of the camera according to the second embodiment in a wide state.
FIG. 18 is an external perspective view of the camera according to the second embodiment in a telephoto state.
[Explanation of symbols]
1 light source unit
11 Front optical element
12 Intermediate prism
13 Discharge tube
14 Reflective umbrella
15 Light source unit body
15a Holder projection
16 Holding rubber
21 Camera body
22 Finder ground plane
23 cam plate
112a diffusion unit
151 cam pin
152 Guide protrusion
153 Sliding protrusion
160 diffuser
161 lever
166 Second spring coil
167 1st spring coil
221 rail

Claims (10)

A light source,
A first optical member that condenses a light beam from the light source substantially on the optical axis in a cross section including a radial direction of the light source;
A second optical member provided near the center of the optical axis, the second optical member having a positive lens portion on which a light beam from a light-converging region by the first optical member is incident;
A lighting device, wherein a diffusion surface for diffusing the emitted light is formed on a front surface of the positive lens unit. The lighting device according to claim 1, wherein the diffusion surface is formed in a region near a center of an optical axis on a front surface of the positive lens unit. A light source,
A first optical member that condenses a light beam from the light source substantially on the optical axis in a cross section including a radial direction of the light source;
A second optical member provided near the center of the optical axis, the second optical member having a positive lens portion on which a light beam from a light-converging region by the first optical member is incident;
A lighting device, wherein a diffusion member for diffusing light emitted from the positive lens unit is provided on a front surface of the positive lens unit. The lighting device according to claim 3, wherein the diffusing member diffuses outgoing light near the center of the optical axis out of the outgoing light from the positive lens unit. The second optical member has a Fresnel lens portion that has a light condensing action on the light beam from the light condensing region around the positive lens portion,
The light source and the first optical member are disposed so as to be integrally movable in the optical axis direction with respect to the second optical member,
The lighting device according to any one of claims 1 to 4, wherein a light irradiation range changes by movement of the light source and the first optical member. A drive mechanism for moving the diffusing member toward and away from the front surface of the positive lens unit in accordance with the movement of the light source and the first optical member in the optical axis direction;
The drive mechanism causes the diffusion member to enter the front surface of the positive lens unit when the light source and the first optical member are at the first position with respect to the second optical member, and the second position The lighting device according to claim 5, wherein the diffusing member is retracted from a front surface of the positive lens unit when the lighting device is in the position. When the light source and the first optical member are at the first position, the light irradiation range has a wide angle, and when at the second position, the light irradiation range has a narrow angle. The lighting device according to claim 6. The light source is a discharge tube extending in a direction perpendicular to the optical axis,
The lighting device according to claim 1, wherein the diffusion surface is formed along a longitudinal direction of the discharge tube. The light source is a discharge tube extending in a direction perpendicular to the optical axis,
The lighting device according to claim 3, wherein the diffusion member is arranged along a longitudinal direction of the discharge tube. An imaging device comprising the lighting device according to claim 1.

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