JP3854885B2 - Illumination device and photographing device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an illuminating device capable of changing the irradiation range of illumination light and an imaging device using the same, and more particularly to an illuminating device suitable for an imaging device having a small dimension in the thickness direction such as a card size camera. .
[0002]
[Prior art]
An illumination device used in a photographing device such as a camera is generally composed of optical components such as a light source, a reflector, and a Fresnel lens.
[0003]
In such an illuminating device, various proposals have been made in the past in order to efficiently change the luminous flux emitted from the light source in various directions in accordance with the required irradiation angle of view. In particular, in recent years, instead of the Fresnel lens that has been placed in front of the light source until now, optical members using total reflection such as prisms and light guides have been placed to improve the light collection efficiency and reduce the size. Have been proposed.
[0004]
As this type of proposal, there is one proposed in Japanese Patent Laid-Open No. 2000-298244. In this case, the components that are relatively close to the optical axis out of the light beam emitted from the center of the light source are refracted by the cylindrical lens of the optical prism, and the peripheral components that are away from the optical axis are respectively reflected by the reflecting surfaces formed above and below the cylindrical lens. After being converted into a light beam substantially parallel to the optical axis direction, the subject is irradiated with 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 arranged in front of the convex lenses. Is done.
[0005]
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 illumination device with high light collection efficiency is realized.
[0006]
By the way, in an imaging device, there is a tendency that the size and thickness of the device are further increased than ever before. Particularly in recent years, an unprecedented thin digital camera called a card size camera has been proposed.
[0007]
Along with this, it is essential to reduce the size and thickness of the illumination device, and there is a strong demand for practical use of an illumination optical system that does not deteriorate the optical performance.
[0008]
[Problems to be solved by the invention]
However, although the illuminating device proposed in the above publication is considerably thinner than the conventional type, the dimension in the optical axis direction is still too thick to be mounted on a card size camera or the like, and it is necessary to further reduce the thickness. There is.
[0009]
In view of the above, an object of the present invention is to provide an illuminating device that can sufficiently satisfy predetermined optical performance and can be thinned to the limit in the illumination optical axis direction.
[0010]
[Means for Solving the Problems]
  To achieve the above objectives,The present inventionThe lighting device includes a light source,TheAn optical member disposed on the front side of the light source, and a reflecting member disposed so as to cover the rear side of the light source and the front space between the light source and the optical member, and reflects light from the light source forward, and is optical On the incident surface side of the member, the optical axisCenter including locationA positive refracting portion that gives positive refractive power to light incident from the light source in FIG.A transmission part provided on the peripheral side of the positive refraction part and transmitting light reflected by a part of the reflection member covering the front space;, Positive refraction partProvided on the optical axis in the plane including the radial direction of the light source, having a refracting surface on which light from the light source is incident and a reflecting surface for reflecting light incident from the refracting surface forward. A pair or a plurality of pairs are arranged side by side across the optical axis in the orthogonal direction.With reflectionIs formedThe irradiation range of light emitted from the optical member can be changed by changing the relative positional relationship between the light source and the optical member in the optical axis direction.Characterized by.
[0011]
This makes it possible to achieve a significant reduction in thickness compared to conventional illumination range variable illumination devices, and uses the energy from the light source with high efficiency, resulting in uniform light distribution characteristics on the irradiated surface. The obtained illumination device can be realized.
[0012]
In the optical member, the reflective portion is provided so that one or more pairs are arranged with the optical axis in between in a direction orthogonal to the optical axis in a plane including the radial direction of the light source. It is possible to provide an illumination device that can obtain light characteristics.
[0013]
Here, the reflecting portion may be formed in a prism shape having a refracting surface on which light from the light source is incident and a reflecting surface that reflects light incident on the refracting surface forward.
[0014]
Further, 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 reflecting portion is
20 ° ≦ α ≦ 70 °
By making it fall within this range, it is possible to achieve both a reduction in thickness of the lighting device and a reduction in size in the vertical direction.
[0019]
Also,The above inventionTherefore, it is possible to divide the light flux from the light source into multiple components and control each light distribution characteristic independently, so that the light distribution characteristic can be finely set and a lighting device with a high degree of design freedom can be realized. is there.
[0020]
  In addition,The above inventionIs suitable for a photographing apparatus such as a still camera and a video camera, and a photographing apparatus having a sufficient thickness in the optical axis direction such as a card type camera.
[0021]
DETAILED DESCRIPTION OF THE INVENTION
(First embodiment)
1 to 4 show the configuration of the optical system of the illumination apparatus according to the first embodiment of the present invention. 1 and 2 are cross-sectional views of the optical system including the radial direction of the discharge tube. FIG. 1 shows a state where the irradiation angle range is narrow, and FIG. 2 shows a state where the irradiation angle range is wide. Yes.
[0022]
3 is a cross-sectional view taken along a plane including the central axis of the discharge tube of the optical system, and FIG. 4 is an exploded perspective view of the optical system. In addition, in FIG.1 (b)-FIG.3 (b), the ray trace figure of the representative ray inject | emitted from the center of the discharge tube which is a light source is also shown collectively.
[0023]
Further, FIG. 5 shows a compact camera (a) and a card-type camera (b) equipped with the lighting device.
[0024]
As shown in FIGS. 5A and 5B, the lighting device is disposed on the upper part of the camera body 11. In these drawings, 1 is an illumination device, 12 is a photographing lens, and 13 is a release button.
[0025]
In FIG. 5A, reference numeral 14 denotes an operation member for zooming the photographic lens 12. When the operation member is tilted forward, it can be zoomed in the tele direction, and when tilted rearward, it can be zoomed in the wide direction.
[0026]
5 (a) and 5 (b), 15 is an operation button for switching various modes of the camera, 16 is a liquid crystal display window for notifying the user of the operation of the camera, and 17 is measuring the brightness of outside light. A light receiving window of the photometric unit, and 18 is a view window of the viewfinder.
[0027]
Next, the configuration for determining the optical characteristics of the illumination device will be described in more detail with reference to FIGS.
[0028]
In these drawings, reference numeral 2 denotes a discharge tube (xenon tube) which is a light source having a cylindrical straight tube shape. Reference numeral 3 denotes a reflector that reflects the luminous flux emitted from the discharge tube 2 in the illumination light irradiation direction (front), and the inner surface is made of a metallic material such as bright aluminum formed with a high reflectance surface or the inner surface is high. It is comprised with the resin material etc. in which the metal vapor deposition surface of the reflectance was formed.
[0029]
Reference numeral 4 denotes an optical member integrally formed in a prism shape. On the incident surface side, refracting surfaces 4b and 4b 'having refractive power in a direction (vertical direction) substantially perpendicular to the longitudinal direction of the discharge tube 2, and this refracting surface. A pair of prism portions composed of reflecting surfaces 4c and 4c ′ satisfying almost the total reflection condition for the light incident from 4b and 4b ′ are formed above and below the emission optical axis L. As shown in FIG. 3, a prism row 4 p having refractive power in the longitudinal direction (left-right direction) of the discharge tube 2 is formed on the emission surface side of the optical member 4. As the material of the optical member 4, an optical resin material or glass material having a high transmittance such as an acrylic resin is suitable.
[0030]
In the above configuration, when the camera is set to “strobe auto mode”, for example, after the release button 13 is pressed by the user, it is loaded with the brightness of external light measured by a photometric device (not shown). A control circuit (not shown) determines whether or not the illumination device 1 emits light based on the sensitivity of the film and the characteristics of the image sensor such as a CCD.
[0031]
When the control circuit determines that “illuminate the lighting device”, the control circuit outputs a light emission signal and causes the discharge tube 2 to emit light via the trigger lead wire attached to the reflector 3.
[0032]
Among the light beams emitted from the discharge tube 2, the light beam emitted backward and laterally (see FIG. 3) in the irradiation optical axis (L) direction is emitted through the reflector 3 and forward in the irradiation optical axis direction. Is directly incident on the optical member 4 disposed in front of the discharge tube 2, is converted into a predetermined light distribution characteristic through the optical member 4, and is then irradiated on the subject side.
[0033]
Hereinafter, the setting of the optimum shape for keeping the light distribution characteristics of the necessary irradiation range uniform while making the illumination optical system extremely thin in the illumination device 1 will be described in more detail with reference to FIGS.
[0034]
First, 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. 1 and 2. Here, FIGS. 1A and 1B show a state corresponding to the narrowest irradiation angle range, and FIGS. 2A and 2B show a state corresponding to the widest irradiation angle range.
[0035]
(A), (b) of each figure is a figure when it cut | disconnects by the same cross section, (b) shows by adding a light trace part to sectional drawing of (a). Moreover, the code | symbol of each part in a figure respond | corresponds to FIGS.
[0036]
In these drawings, the inner and outer diameters of the glass tube are shown as the discharge tube 2. 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.
[0037]
First, the characteristic shape of the optical system of the illumination device will be described in order. The portion of the reflector 3 that covers the rear side of the discharge tube 2 has a semi-cylindrical shape (hereinafter referred to as a semi-cylindrical portion 3 a) that is substantially concentric with the discharge tube 2. This is an effective shape for returning the reflected light from the reflector 3 back to the vicinity of the center of the light source, and has the effect of making it less susceptible to adverse effects due to refraction of the glass part of the discharge tube 2.
[0038]
Further, by configuring in this way, it is easy to think because the reflected light from the rear of the reflector 3 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. Is also possible and convenient. Also, the reason why the shape is just a semi-cylindrical is that if it is smaller than this, the optical member 4 extends rearward in order to condense the light beam directed to the side, and the total reflection on the prism surface is used forward. This is because it is difficult to direct the light, and conversely, if it is larger than this, the luminous flux trapped inside the reflector 3 increases, resulting in a decrease in efficiency, which is undesirable.
[0039]
  On the other hand, the upper and lower peripheral portions 3b and 3b 'of the reflector 3 are reflected by the peripheral portions 3b and 3b' after the light beam emitted from the center of the light source is reflected on the peripheral portions of the optical member 4.(Transmission part)It is formed in a curved surface shape so as to be guided to 4d and 4d '. As will be described later, the light beam refracted at the peripheral portions 4d and 4d 'of the optical member 4 can obtain the light distribution characteristic in the most condensed state.
[0040]
Further, portions (hereinafter, referred to as plane portions) 3c and 3c ′ between the semi-cylindrical portion 3a and the peripheral portions 3b and 3b ′ of the reflector 3 are configured by a plane substantially perpendicular to the optical axis L. .
[0041]
Next, the detailed shape of the optical member 4 will be described. As shown in FIG. 1, when the discharge tube 2 and the optical member 4 are separated by a predetermined amount, the most condensed state is obtained.
[0042]
  First, as shown in FIG. 1A, near the optical axis center of the optical member 4(Center including the optical axis position)Is a portion where a direct light component having a relatively small angle with respect to the optical axis L is incident on the light beam emitted from the center of the light source, and the optical axis on the light source side of the optical member 4 is used to refract this component. Near the center, an aspherical cylindrical lens surface 4a is formed.
[0043]
Around the cylindrical lens surface 4a, there is a refractive surface 4b on which a component of the light beam emitted from the center of the light source that is not incident on the cylindrical lens surface 4a and has a slightly large angle with respect to the optical axis L is incident. , 4b ', and reflection surfaces 4c, 4c' for totally reflecting the refracted light incident on the prism portion from the refracting surfaces 4b, 4b '.
[0044]
  Further around thatNeighborhoodAs described above, the light beam is configured by a curved surface on which the light beams reflected by the reflectors 3b and 3b 'enter.Peripheral part4d, 4d 'Refracting surfaceIs formed. These cylindrical lens surfaces 4a, reflectors 3b, 3b ',Peripheral part4d, 4d 'Refracting surfaceThe reflecting surfaces 4c and 4c 'are shaped so that the light beam emitted from the center of the light source is substantially parallel to the optical axis in a state where the discharge tube 2 and the optical member 4 are separated by a predetermined amount.
[0045]
Then, the light beam incident on each part of the optical member 4 is refracted or totally reflected for conversion into a predetermined angle component, and then emitted from the same exit surface 4e.
[0046]
FIG. 1B shows a ray tracing diagram showing how light beams emitted from the center of the light source enter from each surface of the optical member 4 and pass through the respective optical paths. As shown in the figure, almost all of the light beam emitted from the center of the light source is converted parallel to the optical axis. That is, the most condensed state can be obtained by this optical arrangement.
[0047]
On the other hand, in the optical arrangement shown in FIG. 1, it can be seen that the light beam emitted from the center of the light source is emitted substantially parallel to the optical axis from almost the entire emission surface 4 e of the optical member 4. In other words, the emission direction of the light beam emitted from the center of the light source and the position on the emission surface 4e of the optical member 4 have a one-to-one correspondence, and the optical axis has no gap with respect to the given emission surface 4e. It can be said that the light condensing operation is most efficiently performed for a given exit aperture area.
[0048]
In addition, this figure adds only a light ray with respect to sectional drawing shown to the said Fig.1 (a), All other shapes are the same shape.
[0049]
On the other hand, the state shown in FIG. 2 is a state in which the discharge tube 2 and the optical member 4 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. is there. 2B is obtained by adding a ray trace emitted from the center of the light source to the cross-sectional view of FIG. 2A, and the shape of each part of the optical system is the same.
[0050]
In the case of such an optical arrangement, edge portions 4f and 4f ′ formed at the intersections of the refracting surfaces 4b and 4b ′ and the reflecting surfaces 4c and 4c ′ that determine the optical path of the light beam totally reflected by the reflecting surfaces 4c and 4c ′. Approaches the flat portions 3c and 3c ′ of the reflector 3. As a result, as shown in FIG. 2B, the peripheral portion of the reflector 3 from the gap between the reflectors 3c and 3c ′ and the edge portions 4f and 4f ′ of the optical member 4 out of the light rays emitted from the center of the light source. The luminous flux to be directed to 3b and 3b ′ is extremely reduced.
[0051]
Originally, the components directed to the peripheral portions 4d and 4d ′ of the optical member 4 via the peripheral portions 3b and 3b ′ are always in the optical axis direction because the light source 2 and the reflector 3 are integrally held. On the other hand, it is a condensed component to be converted into a component having a shallow angle. However, as described above, since the edge portions 4f and 4f ′ of the optical member 4 approach the flat surface portions 3c and 3c ′ of the reflector 3, this component is extremely reduced and is another optical path adjacent to this. The light is directed to the prism portion composed of the refracting surfaces 4b and 4b ′ and the reflecting surfaces 4c and 4c ′. At the same time, when the discharge tube 2 and the optical member 4 are separated from each other, a part of the light beam controlled by the reflecting surfaces 4c and 4c ′ is directly incident on the cylindrical lens surface 4a. The luminous flux component incident on the lens surface 4a also increases.
[0052]
Thus, originally, in the most condensed state shown in FIG. 1, the refraction area near the center of the optical axis, the reflection area by the optical member 4 (prism part) in the vicinity thereof, and the reflection by the surrounding reflector 3 in the vicinity. Whereas all three areas are condensed, each area is changed by changing the relative positional relationship between the discharge tube 2 (and the reflector 3) and the optical member 4 in the optical axis direction. It is possible to gradually change the condensing state by (that is, change the irradiation angle range).
[0053]
Hereinafter, the change in the light collection state will be described by dividing it into the above three regions. First, in the optical arrangement shown in FIG. 1, the refractive area near the center of the optical axis refracts a light beam emitted from the center of the light source so as to be substantially parallel to the optical axis. It is comprised by the surface 4a. In this case, as shown in FIG. 2, when the light source and the cylindrical lens surface 4a come close to each other, a defocused state is obtained, and the entire irradiation range acts. Further, in the state shown in FIG. 1, a part of the light beam guided in the direction of the reflecting surfaces 4c and 4c ′ newly enters this region in the state shown in FIG. 2, but this component is also refracted light. This is an extension of the light beam controlled by the region, and is converted into an angular component having the widest irradiation angle in this refraction region.
[0054]
However, since the angle change in this region is an effect due to refraction, there is no significant change in the irradiation angle range for a relatively small amount of movement as assumed this time. Only the light distribution near the very center is uniformly spread.
[0055]
Next, the reflection area by the optical member 4 (prism portion) will be described. This 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 4. This is because the irradiation direction can be greatly changed by changing the direction of the light beam by reflection, and the reflection phenomenon in the optical member 4 having a high refractive index is used, so that a larger angle conversion can be expected.
[0056]
As shown in FIG. 2B, the luminous flux component emitted from the center of the light source and reflected by the reflection area is converted into a component in a certain narrow angle area having a peripheral portion on the irradiation surface. The light flux component reflected by this reflection region seems to be converted into only a component having a predetermined angle with respect to the optical axis L in the trace diagram of FIG. 2 (b). Because the size exists, the reflection angle range also extends to some extent, and when viewed as a whole, it overlaps with the light flux component of the refraction region, so that a light distribution characteristic having a substantially uniform angular distribution over a wide angle range is obtained. be able to.
[0057]
Finally, as described above, the light beam component reflected by the reflection region by the outermost reflector 3 is moved closer to the light source and the optical member 4 from the state of FIG. 1 toward the state of FIG. Gradually, its components decrease.
[0058]
However, by leaving a certain amount of the reflection component in the reflection region, it is possible to suppress the decrease in the light beam component near the center of the optical axis due to the increase in the light beam component through the two reflection regions, and the amount of light near the center of the optical axis. Can be prevented.
[0059]
Thus, in the configuration of the present 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 2) and the optical member 4 in the optical axis direction. Each component divided into the three 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 little light loss with respect to the required irradiation range can be realized.
[0060]
On the other hand, as described above, the light beam emitted backward from the center of the discharge tube 2 is reflected by the semi-cylindrical portion 3a of the reflector 3 and is emitted forward through the center of the discharge tube 2 again. The behavior of the light beam after this is the same as that shown in FIGS. 1 (b) and 2 (b).
[0061]
Here, an optimal distribution ratio of the three regions of the refraction region, the reflection region by the prism portion of the optical member 4 and the reflection region by the reflector 3 will be described.
[0062]
Basically, a basic condensing optical system is formed by the area of the cylindrical lens surface 4a and the reflection area by the peripheral parts 3b and 3b 'of the reflector 3, and the minimum part of the connection between these areas is a prism part. It is desirable to be configured with a reflection region by
[0063]
In the most condensed state shown in FIG. 1, the angle α formed by the light beam from the center of the light source incident on the refracting surfaces 4b and 4b ′ of the prism portion and the optical axis is
20 ° ≦ α ≦ 70 ° (1)
It is desirable that
[0064]
Here, if the angle α is smaller than 20 °, which is the lower limit of the expression (1), it is difficult to form a reflection region by the prism portion itself. That is, the angles of the edge portions 4f and 4f ′ of the prism portion become extremely sharp, and at the same time, it is necessary to make the prism portion deep in the thickness direction, which makes it difficult not only to construct a thin optical system but also difficult to manufacture. It becomes.
[0065]
Further, when the angle α is larger than 70 ° which is the upper limit of the above expression (1), the light collection region by the reflector 3 is reduced, and the reflection region is divided into a reflection region by the reflector 3 and a reflection surface by the prism portion. The meaning itself decreases and various problems occur.
[0066]
That is, the distance between the light source and the optical member 4 necessary for changing the irradiation angle is reduced, and it becomes difficult to change the irradiation angle significantly, and the prism portion of the optical member 4 itself. However, the film becomes partially thick and long, so that the molding time becomes long and the production becomes difficult. As an ideal form, it is desirable to narrow the reflection area by the prism part to a necessary minimum and to collect the form without any 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.
[0067]
In the present embodiment, for the reason described above, the prism portion is formed corresponding to the light flux included in the range of about 30 ° between 30 ° and 60 ° with respect to the optical axis L for optimization. ing.
[0068]
Next, the optimum shape of the refracting surfaces 4b and 4b 'for guiding the light beam to the reflecting surfaces 4c and 4c' in the prism portion will be described. As shown in FIG. 1B and FIG. 2B, the light beam emitted from the center of the light source is largely refracted by the refracting surfaces 4b and 4b ′, and travels away from the optical axis L to the reflecting surfaces 4c and 4c ′. To reach. The ideal shape of the refracting surfaces 4b and 4b ′ is to adopt a shape that guides as much light flux emitted from the light source as possible to the reflecting surfaces 4c and 4c ′. For this purpose, the refracting surfaces 4b and 4b ′ are used. It is necessary to refract light suddenly.
[0069]
This also leads to shortening the length in the optical axis direction of the reflecting surfaces 4c and 4c ', that is, shortening the dimension in the thickness direction of the optical system, which is consistent with the gist of the present invention. As a specific shape, it is desirable that the refracting surfaces 4b and 4b 'be planes having an inclination with respect to the optical axis L of 0 °. However, it is difficult to obtain a plane of 0 ° due to the problem of moldability and processing accuracy of the optical member. In the present embodiment, considering the processing conditions, the refracting surfaces 4b and 4b 'are configured as a plane having an inclination with respect to the optical axis L of 10 ° or less or a curved surface that can be easily processed.
[0070]
On the other hand, by forming a light control region with a plurality of members and arranging them in an overlapping manner in the optical axis direction, an effect unique to the present invention that has not been possible in the past can be obtained.
[0071]
First, the configuration of the reflecting surfaces (the reflecting surfaces 4c and 4c ′ of the prism portion and the peripheral portions 3b and 3b ′ of the reflector 3) is configured by one surface that is continuous in the optical axis direction as in the prior art. Instead, it is composed of dissimilar dissimilar material surfaces, and one reflecting member (reflective umbrella 3) is integrated with the light source, and the other reflecting member (optical member 4) is used as the light source. They are configured to move with respect to each other, and are arranged so as to overlap in a direction (vertical direction) perpendicular to the optical axis.
[0072]
With this configuration, the thickness in the depth direction (optical axis direction) of the illumination optical system, which is the greatest feature of the present invention, can be extremely shortened. That is, with reference to the drawings of the first embodiment, the reflecting surfaces 4c and 4c ′ of the optical member 4 for performing the first reflection are first arranged, and the positions outside this and in the optical axis direction overlap. By disposing the peripheral portions 3b and 3b ′ of the reflector 3 for performing the second reflection at the position where the reflection is performed, it is possible to reduce the thickness of the reflection region in the optical axis direction as a whole.
[0073]
Second, the optical member 4 itself can be made extremely thin. That is, the optical action part required for the optical member 4 includes a cylindrical lens surface 4a having a positive refractive power near the center of the optical axis, and a refractive surface for separating direct light from the light source and reflected light from the reflector 3 Only the acute-angle prism portion composed of 4b and 4b ′ and the reflecting surfaces 4c and 4c ′. Therefore, the optical member 4 can perform a sufficient optical function while the optical member 4 has a simple shape, and the overall thickness of the optical member 4 can be extremely reduced.
[0074]
This not only improves the moldability of the optical member 4 made of resin, but can also minimize the reduction in the amount of light due to the transmittance of the resin material, and contributes to the weight reduction of the illumination device and thus the photographing device.
[0075]
Furthermore, since the shape of the outermost peripheral surface of the optical member 4 is extremely simple and is configured with a surface with few optical restrictions, the optical member 4 can be easily held and is special even when mounted on a photographing apparatus. There is no need to adopt a holding structure, and the form is very easy to handle.
[0076]
Thirdly, by configuring the reflection region with a plurality of reflection members in this way, there is a problem with conventional light guide type strobes, that is, when an optical member generally formed of a resin optical material is disposed near the light source, The problem that the optical member is melted by the generated heat and the original optical characteristics cannot be obtained depending on the light emission conditions can be avoided.
[0077]
That is, by forming the reflection region with the reflection surfaces of the plurality of members in this manner, the edge portions 4f and 4f ′ that are the boundary portions between the refracting surface and the reflection surface of the optical member 4 that is most susceptible to heat are arranged away from the light source. can do. Further, the space around the discharge tube 2 can be expanded. For this reason, it is possible to minimize the influence of the radiant heat and convection heat generated during continuous light emission on the resin material, and it is possible to prevent deterioration of optical characteristics.
[0078]
As described above, according to the present embodiment, although it is a small component such as the reflector 3 and the optical member 4, the irradiation angle variable type that is small and has a small amount of light loss due to light irradiation outside the necessary irradiation range is very efficient. An illumination optical system can be configured.
[0079]
Next, the condensing action in the longitudinal direction of the discharge tube 2 in this embodiment will be described with reference to FIG.
[0080]
FIG. 3 is a cross-sectional view taken along a plane including the central axis of the discharge tube 2. FIGS. 3A and 3B show the same cross-sectional view, and FIG. 3B also shows a ray tracing diagram from the center of the light source.
[0081]
As shown in the figure, the exit portion of the optical member 4 includes a relatively obtuse prism array 4p formed near the center of the optical axis and having substantially equal angles on both inclined surfaces, and an acute-angle Fresnel lens portion formed on the periphery thereof. 4g and 4g ′.
[0082]
Further, side reflectors 3 d and 3 d ′ formed integrally with the reflector 3 are provided on both side surfaces of the optical member 4. The side reflectors 3d and 3d ′ are a part of a light beam that is emitted from the discharge tube 2 and does not enter the optical member 4 and escapes to the side, or a prism array formed on the exit surface side of the optical member 4. The object is to reflect the unnecessary reflection component generated by 4p and the Fresnel lens portions 4g and 4g ′ and re-enter the side surfaces 4h and 4h ′ of the optical member 4 for effective use.
[0083]
In the present embodiment, the apex angle of the prism row 4p near the center of the optical axis is set constant at 105 °. In the prism row 4p formed with such an angle setting, a component having a relatively large incident angle (a component in which the angle in the prism after incidence is around 30 ° to 40 °) remains as refracted at the incident surface. In this state, the light exits from the exit surface, i.e., exits from the exit surface with almost no influence of refraction at the exit surface, and the effect of condensing the incident light beam as a light beam in a certain irradiation angle range. is there.
[0084]
The apex angle of the prism row 4p is not limited to 105 °. If the angle is set to be smaller than this angle, for example, 90 °, the emission angle of the light beam from the optical member 4 can be set to be narrower. Is possible. Conversely, if the apex angle is set large, for example, 120 °, the distribution of the emission angles from the optical member 4 can be set wider.
[0085]
On the other hand, as shown in FIG. 3B, the luminous flux reaching the prism row 4p also includes a component that is reflected by the surface of the prism row 4p and returned to the light source side again. The light beam is reflected by the reflector 3 and then incident on the optical member 4 again, converted into a predetermined angle component by the prism array 4p or the Fresnel lenses 4g and 4g ', and then irradiated to the subject side.
[0086]
Thus, most of the light beam emitted from the center of the light source is converted into a distribution in a certain angle range and emitted from the optical member 4. The light distribution at this time depends only on the angle setting of the prism array 4p and is not affected by the pitch of the prism array. For this reason, the optical member 4 does not require a depth in the optical axis direction, and can perform condensing control in a very shallow region, and the entire optical system is greatly reduced in size (thinned) in the optical axis direction. can do.
[0087]
Further, as shown in the drawing, the Fresnel lens surfaces 4g and 4g 'around the optical member 4 are formed with an acute Fresnel lens surface. Although the optical member 4 is configured to be very thin, this peripheral portion is a region where a certain degree of light beam directivity can be obtained. By forming a Fresnel lens in this portion, a light collecting effect can be obtained efficiently. be able to.
[0088]
In the figure, no remarkable condensing action of this part is seen, but this is because only the light beam emitted from the center of the light source is shown. With respect to the light beam irradiated from the vicinity of the terminal portions at both ends of the discharge tube 2, A considerable luminous flux is converted into a component that collects in the vicinity of the optical axis.
[0089]
By setting the exit surface shape of the optical member 4 as described above, the emitted light beam is efficiently condensed in a certain angle range despite the extremely thin optical system in which the optical member 4 is disposed near the light source. be able to.
[0090]
Furthermore, the light distribution in the longitudinal direction (left-right direction) of the discharge tube 2 is determined by the light condensing action by the prism row 4p or Fresnel lens surfaces 4g, 4g ′ on the exit surface side of the optical member 4, and the discharge tube 2 The light distribution in the direction perpendicular to the longitudinal direction (vertical direction) of the optical member 4 includes a refractive area formed by the cylindrical lens surface 4a provided on the light source side (incident surface side) of the optical member 4, a reflective area formed by the reflector 3, and these areas. It is determined by a highly efficient light condensing action with the reflection region by the prism portion of the optical member 4 provided in the middle of the two regions. Therefore, according to the present embodiment, it is possible to obtain an illumination optical system that is thin and has excellent optical characteristics, which is unprecedented.
[0091]
An example of the light distribution characteristic obtained by the illumination optical system configured as described above is shown in FIGS.
[0092]
The light distribution characteristic shown in FIG. 6 is the light distribution characteristic in the most condensed state corresponding to the optical arrangement shown in FIG. 1, and the light distribution characteristic shown in FIG. 7 is the optical arrangement shown in FIG. Is the light distribution characteristic in the most diffused state corresponding to.
[0093]
By configuring as shown in the figure, a significant change in the irradiation angle can be obtained in the vertical direction. At the same time, a substantially uniform light distribution characteristic is obtained for each necessary irradiation angle range.
[0094]
In the state shown in FIG. 1, the shape of each surface is set so that all the light beams emitted from the center of the light source are emitted substantially parallel to the emission optical axis, and the angle is narrower than the light distribution characteristic shown in FIG. Although it is conceivable that the light can be condensed in a range, the light distribution characteristic actually has a certain extent depending on the size of the light source itself. As shown in FIG. 6, the irradiation angle determined by the half value with respect to the illuminance at the center portion extends to 12 °. Further, in the diffusion state shown in FIG. 7, this half-value irradiation angle spreads to 34 °, which is close to three times.
[0095]
On the other hand, there is no significant change in the angle in the horizontal direction due to the configuration of the optical system. However, although slightly, the angle range of the diffusion state corresponding to FIG. 2 is wider than the angle range of the light collection state corresponding to FIG. This is thought to be due to the fact that the light condensing and diffusing state near the center changes significantly according to the change in the light distribution in the vertical direction, while the distribution near the periphery does not change significantly. It can be understood that this change in the irradiation angle range occurs.
[0096]
In the present embodiment, light distribution control in a direction perpendicular to the longitudinal direction of the discharge tube 2 is performed on the cylindrical lens surface 4a provided on the light source side, the peripheral portions 3b and 3b ′ of the reflector 3, and the reflection surfaces 4c and 4c ′. The illumination device that changes the irradiation angle range by changing the relative distance between the light source and the optical member 4 based on the most condensed state as shown in FIG. 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.
[0097]
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 is a case where it is more convenient to intentionally make it different without condensing light.
[0098]
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 it cannot be said that there is no luminous flux that goes out of the necessary irradiation range even though it is the most optically focused optical arrangement.
[0099]
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.
[0100]
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 this cylindrical lens surface can be reduced. The distribution can be prevented from spreading more than necessary.
[0101]
In addition, 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 prism unit 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.
[0102]
In the present 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 symmetrical with respect to the optical axis center. Is not necessarily limited to such a symmetrical shape. For example, although the reflection surfaces 4c and 4c 'of the optical member 4 are configured symmetrically with the optical axis in between, they are not necessarily formed at the same position as described above, and may be asymmetrical. This is not only true for the reflective surface, but also for the shape of the reflector and the shape of the central cylindrical lens surface.
[0103]
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.
[0104]
In the present embodiment, the case where the cylindrical lens surface 4a formed in the central portion of the optical member 4 has an aspherical shape has been described. However, the cylindrical lens surface is not necessarily limited to an aspherical shape, You may form with a cylindrical surface. Further, in consideration of the light condensing property in the longitudinal direction of the discharge tube 2, a toric lens surface may be used.
[0105]
(Second Embodiment)
8 to 11 show the configuration of the optical system of the illumination apparatus according to the second embodiment of the present invention. 8 and 9 are cross-sectional views of the optical system including the radial direction of the discharge tube. FIG. 8 shows a state where the irradiation angle range is narrow, and FIG. 9 shows a state where the irradiation angle range is wide. Yes.
[0106]
FIG. 10 is a cross-sectional view taken along a plane including the central axis of the discharge tube of the optical system, and FIG. 11 is an exploded perspective view of the optical system. FIGS. 8B and 9B also show ray tracing diagrams of representative rays emitted from the center of the discharge tube as the light source.
[0107]
Further, the lighting device is mounted on the compact camera (a) and the card type camera (b) shown in FIG.
[0108]
The present embodiment is an illumination optical system that prioritizes the light distribution characteristics in a state where the irradiation angle range shown in FIG. 9 is widened, and is configured to obtain the most excellent light distribution characteristics with reference to this state.
[0109]
In each of the above figures, 2 is a discharge tube (xenon tube) which is a cylindrical straight tube-shaped light source. Reference numeral 23 denotes a reflector that reflects the luminous flux emitted from the discharge tube 2 in the illumination light irradiation direction (front), and the inner surface is made of a metallic material such as bright aluminum formed with a high reflectivity surface or the inner surface is high. It is comprised with the resin material etc. in which the metal vapor deposition surface of the reflectance was formed.
[0110]
An optical member 24 is integrally formed in a prism shape, and has refractive surfaces 24b, 24d, 24f, 24h, and 24b having refractive power in a direction (vertical direction) substantially orthogonal to the longitudinal direction of the discharge tube 2 on the incident surface side. ', 24d', 24f ', 24h', and reflecting surfaces 24c, 24e, 24g, 24i, 24c ', 24e', 24g ', 24i' satisfying almost total reflection conditions with respect to light incident from this refracting surface, A plurality of pairs of prism portions are formed above and below the emission optical axis L.
[0111]
As shown in FIG. 10, Fresnel lens portions 24q and 24q ′ having refractive power in the longitudinal direction (left and right direction) of the discharge tube 2 are formed on the left and right peripheral portions on the emission surface side of the optical member 24. .
[0112]
As the material of the optical member 24, an optical resin material or glass material having a high transmittance such as an acrylic resin is suitable.
[0113]
This embodiment is an illumination optical system that is thinner than the first embodiment, and with the minimum amount of positional change between the light source and the optical member while keeping the light distribution characteristics of the required irradiation range uniform. A large irradiation angle change can be obtained. Hereinafter, setting of the optimum shape of each component of the illumination optical system will be described in more detail with reference to FIGS.
[0114]
First, 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. 8A and 8B show a state corresponding to the narrowest irradiation angle range, and FIGS. 9A and 9B show a state corresponding to the widest irradiation angle range.
[0115]
Moreover, (a) and (b) of each figure are the figures when it cut | disconnects by the same cross section, (b) shows by adding the light ray trace part to sectional drawing of (a). Moreover, the code | symbol of each part in a figure respond | corresponds to FIGS.
[0116]
In these drawings, for the same reason as in the first embodiment, 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 drawings. As an actual light distribution characteristic, the light distribution characteristic changes in a slightly spreading direction as a whole by the light beam emitted from the peripheral portion of the discharge tube 2 in addition to the representative light beam as shown in the figure, but the tendency of the light distribution characteristic Therefore, the following explanation will be given according to this representative light flux.
[0117]
First, the characteristic shape of the optical system configured as described above will be described in order. A portion of the reflector 23 that covers the rear side of the discharge tube 2 has a semi-cylindrical shape (hereinafter referred to as a semi-cylindrical portion 23 a) that is substantially concentric with the discharge tube 2. This is an effective shape for returning the reflected light from the reflector 23 again to the vicinity of the center of the light source, and has the effect of making it less susceptible to adverse effects due to refraction of the glass portion of the discharge tube 2.
[0118]
On the other hand, the peripheral portions 23b and 23b ′ extending in the vertical direction of the reflector 23 are inclined surfaces (24j and 24j ′) formed in the peripheral portion of the optical member 24 after the light beam emitted from the center of the light source is reflected by the peripheral portion. ) To be curved. As will be described later, after the light is refracted at the peripheral portions 24j and 24j 'of the optical member 24, a light distribution characteristic in a state where light is condensed to some extent is obtained.
[0119]
The region between the semi-cylindrical portion 23a and the peripheral portions 23b and 23b 'of the reflector 23 is configured by planes 23c and 23c' that are substantially perpendicular to the optical axis (hereinafter referred to as plane portions).
[0120]
Next, the detailed shape of the optical member 24 that most affects the light distribution characteristics of the illumination device of the present embodiment will be described. The state shown in FIG. 8 is a state in which the distance between the discharge tube 2 and the optical member 24 is separated by a predetermined amount, and the shape and optical arrangement of each part are set so that a predetermined condensing state is obtained.
[0121]
First, as shown in FIG. 8 (a), in the vicinity of the optical axis center of the optical member 24, a portion in which a direct light component having a relatively small angle with respect to the optical axis L is incident on the light beam emitted from the light source center. In order to refract this component, a cylindrical lens surface 24a made of a part of a cylindrical surface is also formed on the light source side near the center of the optical axis of the optical member 24.
[0122]
On the peripheral side, refractive surfaces 24b and 24b ′ are formed for allowing components having a slightly larger angle with respect to the optical axis L to be incident on the cylindrical lens surface 24a out of the light beam emitted from the center of the light source. On the rear side thereof, reflecting surfaces 24c and 24c ′ satisfying almost total reflection conditions for the refracted light are formed. Up to this point, the optical system is almost the same as that of the first embodiment.
[0123]
The feature of this embodiment is that a plurality of pairs of prism portions including the refracting surfaces 24b and 24b 'and the reflecting surfaces 24c and 24c' are formed in addition to the upper and lower pairs. That is, from the refracting surfaces 24d, 24d 'and the reflecting surfaces 24e, 24e' on the peripheral side of the pair of upper and lower prism parts composed of the refracting surfaces 24b, 24b 'and the reflecting surfaces 24c, 24c' provided near the optical axis L. A pair of upper and lower prism portions is formed, and a pair of upper and lower prism portions including refracting surfaces 24f and 24f ′ and reflecting surfaces 24g and 24g ′ are formed on the peripheral side thereof. Further, refracting surfaces 24h and 24h ′ are formed on the peripheral side thereof. In addition, a pair of upper and lower prism portions made up of the reflecting surfaces 24i and 24i ′ are formed.
[0124]
The shapes of the reflecting surfaces 24c, 24c ′, 24e, 24e ′, 24g, 24g ′, 24i, and 24i ′ are set so that the light flux reflected here has a light distribution characteristic in a predetermined condensing state. ing.
[0125]
  Further, as described above, the light flux reflected by the peripheral portions 23b and 23b 'of the reflector 23 is incident on the further periphery of the most peripheral prism portion on the light source side of the optical member 24.Peripheral part (transmission part)24j, 24j 'Inclined surfaceIs formed. The peripheral portions 23b and 23b 'of the reflector 23 and the abovePeripheral part24j, 24j 'Inclined surface (refractive surface)Also, like the optical path through the prism portion, the shape is set so as to obtain a light distribution characteristic in a predetermined condensing state.
[0126]
The light flux that has entered each part of the optical member 24 is converted into a predetermined angle component by refraction or reflection, and then exits from the same exit surface 24k.
[0127]
Thus, by forming a plurality of pairs of prism portions on the optical member 24 so as to be stacked in the vertical direction across the optical axis L, the depth of the illumination optical system in the optical axis direction can be extremely shortened. There is. At the same time, when applied to an illumination device capable of changing the irradiation angle, the amount of change in the relative positional relationship in the optical axis direction between the light source and the optical member 24 when changing the irradiation angle can be greatly shortened. There is also. This can be said to be an extremely effective form for realizing an illumination optical system having a minimum volume and a variable irradiation angle that can obtain desired light distribution characteristics while being very thin.
[0128]
FIG. 8B is 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 24 and passes through each optical path. As shown in the figure, most of the luminous flux emitted from the center of the light source is converted into a component having a relatively small angle with respect to the optical axis L. That is, the most condensed state in the optical system of the present embodiment can be obtained by this optical arrangement.
[0129]
On the other hand, the state shown in FIG. 9 is a state in which the discharge tube 2 and the optical member 24 are brought close to each other, and a state where the irradiation angle range is wider than the state shown in FIG. 8 is obtained. In the present embodiment, the light distribution characteristic in this state is optimized to obtain the most uniform light distribution characteristic while corresponding to the light distribution characteristic when the wide-angle lens is mounted, and is set as a design reference state. .
[0130]
In such an optical arrangement, the edge portions 24l, 24l ′, 24m, 24m ′, 24n, 24n ′, 24o, 24o ′ formed at the intersections of the refracting surface and the reflecting surface of each prism portion are the planes of the reflector 23. The parts 23c and 23c ′ are approached. As the optical member 24 approaches the reflector 23 in this way, as shown in FIG. 9B, the component incident on the cylindrical lens surface 24 a out of the light rays emitted from the center of the light source increases. The luminous flux to be directed to the peripheral portions 23b and 23b ′ is extremely reduced.
[0131]
In more detail, the component heading toward the peripheral portions 24j and 24j ′ of the optical member 24 through the peripheral portions 23b and 23b ′ is originally because the discharge tube 2 and the reflector 23 are integrally held. The angle formed with respect to the optical axis direction is always a small component to be collected. However, as described above, since the edge portions 24o and 24o 'of the optical member 24 approach each other, this component is extremely reduced and is sequentially directed to another prism portion adjacent thereto. At the same time, when the optical member 24 is away from the reflector 23, a part of the light beam controlled by the reflecting surfaces 24c and 24c ′ is directly incident on the cylindrical lens surface 24a formed near the center of the optical axis. As a result, the luminous flux component incident on the cylindrical lens surface 24a increases.
[0132]
Thus, originally, in the light collection state shown in FIG. 8, the refraction region near the center of the optical axis, the reflection region by the optical member 24 (prism portion) on the peripheral side, and the reflection by the reflector 23 on the most peripheral side. While the configuration is such that all of the light fluxes in the three regions are condensed within a certain range, the light emitting portion composed of the light source and the reflector 23 and the optical member 24 are brought close to the optical axis direction. As a result, it is possible to gradually change the condensing state of each region. This phenomenon is caused by the fact that the light beam component whose emission direction was controlled by refraction in the previous state can be changed in direction by reflection and the irradiation direction can be greatly changed. This is because a larger angle conversion can be expected because the reflection phenomenon is handled.
[0133]
As shown in FIG. 9B, the reflection component is converted into a component in a certain narrow angle region having a peripheral portion on the irradiation surface. In the trace diagram of FIG. 9 (b), this reflection component seems to be converted into only a predetermined angle component in a certain direction, but in reality, since the light source has a certain size, the angle region is When it extends to a certain region and as a whole, it overlaps with the components of the refractive region near the center of the optical axis, so that it is possible to obtain a light distribution characteristic having a substantially uniform angular distribution over a wide angle range.
[0134]
Further, as described above, the light flux component in the reflection region of the reflector 23 gradually decreases as the light source and the optical member 24 approach each other. Here, by leaving a certain amount of the light beam component in the reflection region, it is possible to suppress a decrease in the component having a small angle with respect to the optical axis direction, and to prevent the light beam from dropping near the center of the optical axis in light distribution characteristics. Therefore, it is effective to leave this component to some extent.
[0135]
As described above, in the configuration of the present embodiment, the irradiation angle range can be significantly changed by slightly changing the positional relationship between the light source and the optical member 24 in the optical axis direction. The light beam component can compensate for the change in the light distribution characteristics of other regions, and an optical system that is uniform as a whole and has little light loss with respect to the required irradiation range can be realized.
[0136]
In particular, by arranging a plurality of prism portions so as to be stacked in a direction (vertical direction) perpendicular to the optical axis direction, an illumination optical system having a very small depth in the optical axis direction can be realized.
[0137]
According to the configuration of this embodiment, the maximum dimension in the optical axis direction of the optical system shown in FIG. 8 can be shortened to 4.9 mm which is 5 mm or less. On the other hand, the state shown in FIG. 9 having the widest irradiation angle can be achieved by changing the positional relationship in the optical axis direction between the light source of only 0.6 mm and the optical member 24 with respect to the state of FIG.
[0138]
As described above, the configuration of the present embodiment has the following advantages because the irradiation angle range can be significantly changed with few components.
[0139]
1. The light from the light source can be irradiated without going through many parts, and it is efficient.
2. Ultra-compact size with a function to change the irradiation angle range
3. It can be made cheaper.
[0140]
Next, an optimal distribution ratio of the three areas, ie, the refraction area, the reflection area by the prism portion, and the reflection area by the reflector 23 will be described.
[0141]
Basically, the greatest feature of this embodiment is that a plurality of reflecting surfaces of the prism portion are formed and arranged so as to be stacked in layers in the direction perpendicular to the optical axis, thereby minimizing the thickness of the optical system in the optical axis direction. It was to suppress to. For this reason, unlike the idea of the first embodiment, it is determined how thin the reflection area by the prism portion provided with a plurality of layers can be made.
[0142]
In the most condensed state shown in FIG. 8, the angle α formed by the light beam from the center of the light source incident on the refractive surface of the prism portion and the optical axis is
20 ° ≦ α ≦ 80 ° (2)
It is desirable that
[0143]
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 prism portion itself. That is, the angle of the edge portion of the prism portion becomes extremely sharp, and at the same time, the prism portion needs to have a deep shape in the thickness direction. For this reason, it is not only difficult to construct a thin optical system that is the main focus of the present invention, but also it is difficult to manufacture, which is undesirable. On the other hand, when the angle is larger than 80 °, which is the upper limit, the light flux component collected by the reflector 23 is reduced. As a result, the light flux toward the center is reduced with the irradiation angle widened, and the light distribution is not necessarily uniform. The characteristic cannot be obtained.
[0144]
In the present embodiment, for the above reasons, a plurality of pairs of prism portions are formed corresponding to a light flux included in a range of about 50 ° from 25 ° to 75 ° with respect to the optical axis L for optimization. I am trying.
[0145]
As an ideal form, it is desirable to enlarge the reflection region by the prism portion as much as possible. As a result, the configuration in which the dimension in the thickness direction of the optical member 24 is shortened most can be taken, so that the optical system can be made extremely thin. In addition, the molding time when the optical member 24 is molded with a resin material can be shortened, and the form can be made inexpensive and easy to process.
[0146]
Next, refracting surfaces 24b, 24b ', 24d, 24d', 24f, 24f ', 24h, which guide the light beams to the reflecting surfaces 24c, 24c', 24e, 24e ', 24g, 24g', 24i, 24i 'in the prism portion, The optimum shape of 24h ′ will be described. As can be seen from the ray trace diagrams shown in FIGS. 8B and 9B, the light beam emitted from the center of the light source is largely refracted at each refracting surface, and the same prism portion in the direction away from the optical axis. Reach the reflective surface.
[0147]
The ideal shape of the refracting surface is to take as much light flux emitted from the light source as possible to the reflecting surface. For this purpose, it is necessary to refract light rapidly on the refracting surface. This also leads to shortening the length of each reflecting surface in the optical axis direction, that is, shortening the dimension in the thickness direction of the optical system, which is consistent with the gist of the present invention.
[0148]
As a specific shape, each of the refractive surfaces 24b, 24b ', 24d, 24d', 24f, 24f ', 24h, 24h' is preferably a plane having an inclination with respect to the optical axis L of 0 °. However, it is difficult to obtain a plane of 0 ° due to the problem of moldability and processing accuracy of the optical member. In the present embodiment, in consideration of processing conditions, the refractive surfaces 24b, 24b ′, 24d, 24d ′, 24f, 24f ′, 24h, and 24h ′ are flat or processed with an inclination with respect to the optical axis L of 10 ° or less. It is configured with a curved surface that is easy to do.
[0149]
On the other hand, in the present embodiment, a reflection region by a plurality of prism portions is formed on a single optical member, and the relative positional relationship between the optical member and the light source is changed, thereby providing an effect unique to the present invention that has not existed before. Obtainable.
[0150]
First, the volume required for the illumination optical system of variable irradiation angle type can be minimized. That is, the configuration of the reflective surface is not composed of a single curved surface (reflector umbrella or reflective surface) continuous in the optical axis direction as in the past, but a plurality of discontinuous reflective surfaces and total reflection are used. The plurality of reflecting surfaces are arranged so as to overlap in a direction perpendicular to the optical axis. With this configuration, the thickness of the illumination optical system in the depth direction (optical axis direction) can be extremely shortened, and the volume required for the illumination optical system can be minimized.
[0151]
Referring to FIGS. 8 and 9, the reflecting surfaces 24c and 24c ′ are first arranged on the side close to the optical axis, and the reflecting surfaces 24e and 24e ′ are arranged on the peripheral side and at positions overlapping in the optical axis direction. Deploy. Hereinafter, similarly, by arranging the reflecting surfaces 24g, 24g ′ and 24i, 24i ′ so that the positions in the optical axis direction overlap with each other, the overall thickness of the reflecting surface in the optical axis direction is extremely shortened. Yes.
[0152]
Second, since the shape of the optical member 24 is thin, it is excellent in moldability and can be manufactured at a low cost. In other words, the optical action unit required for the optical member 24 is only a cylindrical lens surface 24a having a positive refractive power near the center of the optical axis, and a plurality of acute angle prism portions including a refractive surface and a reflective surface. Therefore, the optical member 24 can perform a sufficient optical function while the optical member 24 has a simple shape, and the entire thickness of the optical member 24 can be extremely reduced.
[0153]
This not only improves the moldability of the optical member 24 by the resin, but also can minimize a decrease in the amount of light due to the transmittance of the resin material, and contributes to the weight reduction of the lighting device and thus the photographing device.
[0154]
Furthermore, since the shape of the outermost peripheral surface of the optical member 24 is extremely simple and is configured with a surface with few optical restrictions, the optical member 24 can be easily held, and even when mounted on a photographing apparatus, it is special. There is no need to adopt a holding structure, and the form is very easy to handle.
[0155]
Thirdly, by configuring the reflection region with a plurality of reflection members in this way, there is a problem with conventional light guide type strobes, that is, when an optical member generally formed of a resin optical material is disposed near the light source, The problem that the optical member is melted by the generated heat and the original optical characteristics cannot be obtained depending on the light emission conditions can be avoided.
[0156]
That is, by forming the reflection region with the reflection surfaces of the plurality of members in this manner, the edge portions 24l and 24l ′ that are the boundary portions between the refracting surface and the reflection surface of the optical member 24 that is most susceptible to heat are arranged away from the light source. can do. Further, the space around the discharge tube 2 can be expanded. For this reason, it is possible to minimize the influence of the radiant heat and convection heat generated during continuous light emission on the resin material, and it is possible to prevent deterioration of optical characteristics.
[0157]
As described above, according to the present embodiment, although it is a small component such as the reflector 23 and the optical member 24, the irradiation angle variable type that is small and has a small amount of light loss due to light irradiation outside the necessary irradiation range is very efficient. An illumination optical system can be configured.
[0158]
Next, the condensing action in the longitudinal direction of the discharge tube 2 in this embodiment will be described with reference to FIG.
[0159]
As shown in the drawing, in the present embodiment, a flat surface portion 24p is formed in the central portion of the emission portion of the optical member 24, and Fresnel lens portions 24q and 24q ′ are provided in the peripheral portion so that predetermined light distribution characteristics can be obtained. It is configured.
[0160]
Here, although the optical member 24 is configured to be very thin, the peripheral portion corresponding to the vicinity of the terminal portions at the left and right ends of the discharge tube 2 is a region where a certain degree of directivity of the light beam can be obtained. Then, by forming the Fresnel lens portions 24q and 24q 'in this portion, it is possible to produce a relatively good light collecting action.
[0161]
On the other hand, the vicinity of the center of the optical axis is constituted by the flat portion 24p, for the following reason. That is, in an illumination optical system that changes the irradiation angle in a wide field angle range corresponding to a relatively wide-angle lens as shown in this embodiment, it is difficult to control the light flux near the center of the optical axis. This is because uniform irradiation can be performed by using a flat surface rather than concentrating the light with a complicated surface configuration.
[0162]
In this way, by setting the shape of each part of the exit surface of the optical member 24, the emitted light flux is uniformly and efficiently collected in a certain angle range even though the optical member 24 is an extremely thin optical system close to the light source. Can be lighted.
[0163]
As described above, with respect to the longitudinal direction (left-right direction) of the discharge tube 2, light collection is controlled by the Fresnel lens portions 24 q and 24 q ′ on the exit surface side of the optical member 24, and the direction perpendicular to the longitudinal direction of the discharge tube 2 ( With respect to the vertical direction), a cylindrical lens surface 24a and a reflector 23 provided on the light source side of the optical member 24, and a plurality of reflecting surfaces (prism portions) of the optical member 24 provided in the middle of these two regions are provided. By using and controlling the light collection, it is possible to obtain a very thin illumination optical system with excellent optical characteristics that has not been obtained in the past.
[0164]
As described above, in this embodiment, the light distribution control in the direction perpendicular to the longitudinal direction of the light source is performed with three types 11 of the cylindrical lens surface 24a, the reflector 23, and the reflecting surfaces of the plural pairs of prism portions provided on the light source side. The irradiation angle is changed by changing the relative distance between the light source and the optical member 24 depending on the region of the layer. And like this embodiment, this invention can fully respond also to the optical system which changes the irradiation angle which gave priority to the light distribution characteristic of the wide angle side, and the optical member 24, the light source, and It is also possible to correspond to an illumination optical system that has a required light condensing action by moving the distance in the direction of separating a predetermined amount.
[0165]
In the present embodiment, the configuration of each surface on the light source side and the configuration of each surface on the emission surface side are all symmetrical with respect to the optical axis center. However, the present invention is not necessarily limited to such a symmetrical shape. Not. For example, the reflecting surface of the prism portion of the optical member 24 may be disposed asymmetrically with respect to the optical axis, and the number of the plurality of reflecting surfaces may be different above and below the optical axis. Further, not only the reflection surface but also the shape of the reflector and the shape of the cylindrical lens surface may be asymmetric. Similarly, with respect to the Fresnel lens surface formed on the exit surface side, the left and right light distribution characteristics may be changed by using Fresnel lenses with different angle settings on the left and right.
[0166]
In addition, the cylindrical lens surface 24a formed in the central portion of the optical member 24 is configured as a part of a cylindrical surface in this embodiment, but the cylindrical lens surface may be aspherical, and the longitudinal direction of the light source Considering the light condensing property, a toric lens surface may be used.
[0167]
  (Third embodiment)
  12 and 13 show the present invention.As an embodiment of the related inventionThe structure of the optical system of the illuminating device which is 3rd Embodiment is shown. FIG. 12 shows a condensing state where the irradiation angle range is narrowed, and FIG. 13 shows a diffusion state where the irradiation angle range is widened. The present embodiment is an illumination optical system that prioritizes the light distribution characteristics in a state where the irradiation angle range shown in FIG. 13 is narrowed, and the shape of each part is set so that the most excellent characteristics of light collection are obtained in this state It is a thing. FIGS. 12B and 13B also show ray tracing diagrams of representative rays emitted from the center of the light source.
[0168]
Further, the lighting device is mounted on the compact camera (a) and the card type camera (b) shown in FIG.
[0169]
In the figure, reference numeral 2 denotes a discharge tube (xenon tube) which is a cylindrical straight tube-shaped light source. Reference numeral 33 denotes a semi-cylindrical reflector that reflects the light beam emitted from the discharge tube 2 forward. The inner surface has a high reflectivity on a metal material such as bright aluminum formed with a high reflectivity surface or on the inner surface. It is comprised with the resin material etc. in which the metal vapor deposition surface was formed.
[0170]
Reference numeral 34 denotes an optical member in which a plurality of pairs of prism portions each having a refracting surface having a refractive power and a reflecting surface are formed in a direction (vertical direction) substantially orthogonal to the longitudinal direction of the discharge tube 2 on the incident surface side. As the material of the optical member 34, an optical resin material having a high transmittance such as an acrylic resin or a glass material is suitable.
[0171]
In this embodiment, particularly the overall shape of the illumination optical system is made extremely thin, and the light distribution characteristic of the necessary irradiation range at that time is kept uniform, and the irradiation angle is greatly increased with the minimum relative position change amount between the light source and the optical member 34. The most different point from the first embodiment is that the entire reflection portion of the optical member 34 is used without making the periphery of the reflector 33 wrap around the optical member 34. The light distribution control is performed.
[0172]
The shape of the discharge tube 2 in the axial direction is the same as that of the discharge tube 2 of the first and second embodiments. Hereinafter, setting of the optimum shape of the illumination optical system of the present embodiment will be described in more detail with reference to FIGS. 12 and 13.
[0173]
12 and 13 show the basic concept of changing the irradiation angle in the vertical direction in the present embodiment. 12A and 12B show a state corresponding to the narrowest irradiation angle range, and FIGS. 13A and 13B show a state corresponding to the widest irradiation angle range. Moreover, (a), (b) of each figure is a figure when it cuts in the same cross section.
[0174]
Further, in these drawings, for the same reason as described in the first embodiment, the light beam emitted from the center of the light source is considered as the representative light beam, and in the drawings, the light beam emitted from the center of the light source. Only shows.
[0175]
First, the characteristic shape of the illumination optical system will be described in order. The reflector 33 is formed so as to cover the rear side of the discharge tube 2 and has a semi-cylindrical shape that is substantially concentric with the discharge tube 2. This is for the same reason as described in the first embodiment.
[0176]
Next, the detailed shape of the optical member 34 will be described. The state shown in FIG. 12 is a state in which the distance between the discharge tube 2 and the optical member 34 is a predetermined distance, and in this state, the most condensed state is obtained in this embodiment.
[0177]
As shown in FIG. 12A, in the vicinity of the optical axis on the light source side of the optical member 34, a direct light component having a relatively small angle with respect to the optical axis is refracted in the light beam emitted from the light source center. In addition, a cylindrical lens surface 34a having an aspherical shape is formed. Due to the aspherical shape of the cylindrical lens surface 34a, the light beam emitted from the center of the light source is refracted so as to be substantially parallel to the optical axis with respect to this cross section.
[0178]
Refraction surfaces 34b and 34b for allowing a light beam component having a slightly larger angle with respect to the optical axis to be incident on the periphery of the cylindrical lens surface 34a without entering the cylindrical lens surface 34a out of the light beam emitted from the center of the light source. ', 34d, 34d', 34f, 34f ', 34h, 34h' and reflecting surfaces 34c, 34c ', 34e, 34e', 34g, 34g satisfying almost total reflection conditions with respect to light incident from these refracting surfaces. Plural pairs of prism portions composed of ', 34i, 34i' are formed vertically with the optical axis L in between.
[0179]
The shapes of the reflecting surfaces 34c, 34c ', 34e, 34e', 34g, 34g ', 34i, 34i' are set so that the light flux reflected here is in a predetermined condensing state.
[0180]
In this way, the light beam incident on each part of the optical member 34 is refracted or totally reflected by the optical member 34 and then exits from the same exit surface 34j.
[0181]
In the present embodiment, on the light source side of the optical member 34, a plurality of pairs of prism portions are arranged so as to be stacked in the vertical direction orthogonal to the optical axis L, so that the depth of the illumination optical system in the optical axis direction is extremely high. There is an advantage that it can be shortened. When this configuration is applied to an illumination optical system capable of changing the irradiation angle, the amount of change in the relative positional relationship in the optical axis direction between the light source and the optical member 34 at the time of changing the irradiation angle can be made extremely small. There is also an advantage of being able to do it. This is extremely effective for realizing an illumination optical system of a minimum volume irradiation angle variable type capable of obtaining a desired light distribution characteristic while being very thin.
[0182]
In addition, in this embodiment, there is no optical path due to the refraction of the optical member and the peripheral portion of the reflector located closest to the optical axis L shown in the first and second embodiments. There is no need to worry about the alignment accuracy with the member or worry about the mutual interference between the reflector and the optical member, and stable optical characteristics can be obtained easily.
[0183]
In FIG. 12B, the light beam emitted from the center of the light source is incident from each surface of the optical member 34.
It is a ray tracing diagram showing what kind of optical path to follow. As shown in the figure, most of the light beam emitted from the center of the light source is converted so as to be substantially parallel to the optical axis L. That is, the most concentrated state in the optical system of the present embodiment can be realized by this optical arrangement.
[0184]
On the other hand, FIG. 13 shows a state in which the discharge tube 2 and the optical member 34 are brought closer to the state shown in FIG. 12, and the optical arrangement is set so as to obtain a state where the irradiation angle range is expanded by a predetermined amount. In the present embodiment, the light distribution characteristic in this state is made to correspond to the light distribution characteristic when the wide-angle lens is mounted.
[0185]
First, in the case of such an optical arrangement, the edge portions 34k and 34k ′ formed at the intersections of the refracting surfaces 34b and 34b ′ that determine the optical path of the reflected light and the reflecting surfaces 34c and 34c ′ approach the reflector 33. become. As the optical member 34 approaches the reflector 33 in this way, as shown in FIG. 13B, the component incident on the cylindrical lens surface 34 a out of the light rays emitted from the center of the light source increases. The light beam incident on the peripheral refracting surfaces 34h and 34h 'is extremely reduced.
[0186]
In this way, in the condensed state shown in FIG. 12, all the light beams from the refraction area near the center of the optical axis and the reflection area by the prism portion on the peripheral side are substantially parallel to the optical axis. As shown in FIG. 13, the light collection state of the light from each of the above regions is gradually changed by bringing the positional relationship between the light-emitting unit including the light source and the reflector 33 and the optical member 34 close to each other in the optical axis direction. Can be made.
[0187]
Thereby, the irradiation angle range can be significantly changed by a slight change in the relative position between the light source and the optical member 34 in the optical axis direction. In particular, an illumination optical system having an extremely small depth in the optical axis direction can be realized by arranging a plurality of reflecting surfaces of the prism portion so as to overlap each other from the optical axis side to the peripheral side.
[0188]
In this embodiment, the upper and lower four reflective surfaces are formed on the optical member 34, but the present invention is not necessarily limited to four reflective surfaces. As the number of layers on the reflecting surface is increased, a thinner optical system can be configured.
[0189]
If the entire optical system is to be reduced in size, it is necessary to consider the pitch interval between the reflecting surfaces as well as the multilayered reflecting surfaces. In this embodiment, the pitch of the reflective layer in the region near the cylindrical lens surface 34a formed near the center of the optical axis of the optical member 34 is subdivided, and the pitch interval is increased toward the periphery, so that the overall shape We are trying to balance. This is due to the following reason.
[0190]
First, the incident angle on each refracting surface changes from the positional relationship between the light source and each refracting surface that guides the light flux to the reflecting surface, and the incident angle decreases as the distance from the optical axis increases. This is apparent from FIG. 12B, in which the light incident on the refractive surface 34b close to the optical axis has a very large incident angle, and the light incident on the peripheral refractive surface 34h has a small incident angle. . Thus, the difference in the incident angle of the light beam incident on each refracting surface greatly affects the shape of the reflecting surface provided corresponding to the refracting surface.
[0191]
That is, the reflecting surface corresponding to the refracting surface having a steep incident angle needs to be formed as a deeper surface, that is, a surface extending to the exit surface side. However, if the reflecting surface is extended in this way, it is difficult to reduce the thickness of the illumination optical system in the optical axis direction, which is the greatest object of the present invention.
[0192]
Therefore, in order to avoid this problem, in this embodiment, the incident area of the refractive surface near the center of the optical axis where the incident angle of the light beam is large is narrowed. In other words, the pitch interval of the prism portions near the center of the optical axis is narrowed so that the reflecting surface does not become deeper than a predetermined length.
[0193]
For this reason, by narrowing the pitch interval of the prism portion closer to the optical axis and widening the pitch interval of the peripheral prism portion, the optical axis direction position of the end of the reflecting surface on the exit surface side is substantially constant. Thus, the optical member can be thinned. For the same reason, by increasing the number of reflecting surfaces, the depth of each reflecting surface can be reduced, and the overall thickness of the optical member can be reduced. For this reason, if the purpose is to reduce the size of the entire illumination optical system to a minimum, it is desirable to reduce the pitch interval.
[0194]
If the number of reflecting surfaces is increased, the size in the optical axis direction can be reduced, but the vertical dimension perpendicular to the optical axis increases. Therefore, in this embodiment, this unnecessary increase in size is prevented by increasing the pitch interval of the reflecting surfaces as the distance from the optical axis increases. In particular, by covering the outermost refracting surfaces 34h and 34h 'and the reflecting surfaces 34i and 34i' to a large angle range with respect to the light source, the enlargement in the direction perpendicular to the optical axis is prevented.
[0195]
In the present embodiment, the case where the optical characteristics are optimized has been described with respect to the optical member 34 having four reflecting surfaces. However, the above-described device reduces the thickness in the optical axis direction and minimizes the vertical dimension. The miniaturization has also been achieved.
[0196]
The following effects can be given as specific effects of the present embodiment.
[0197]
First, the configuration is very simple. As the reflector 33, a minimum semi-cylindrical shape that is concentric with the discharge tube 2 that is a light source may be used. Further, the illumination angle range can be changed only by changing the positional relationship between the light source and the optical member 34, and an illumination optical system capable of changing the illumination angle range with a very simple configuration can be realized.
[0198]
Second, it is possible to efficiently irradiate the subject side with the light beam emitted from the light source. In the present embodiment, light distribution is controlled by refraction or reflection by the optical member 34 for all the light beams emitted from the light source to the front side (including light beams reflected by the reflector 33). For this reason, it is possible to guide the luminous flux more efficiently than the conventional reflection on the metal surface by the reflector, and it is possible to effectively use the limited energy.
[0199]
Thirdly, an air layer can be formed in a wide area around the reflector 33 and the optical member 34. Conventional light guide strobes often have a resin material arranged near the light source, and the optical member is deformed by heat emitted from the light source, and the original optical characteristics cannot be obtained depending on the light emission conditions. By adopting the configuration of this embodiment, the space around the discharge tube can be expanded, so that the influence on the resin material due to radiant heat and convection heat generated during continuous light emission can be minimized, and the optical characteristics Can be prevented.
[0200]
(Fourth embodiment)
14 and 15 show the configuration of the optical system of the illumination apparatus according to the fourth embodiment of the present invention. The present embodiment is a partial modification of the third embodiment. FIG. 14 shows a condensing state where the irradiation angle range is narrowed, and FIG. 15 shows a diffusion state where the irradiation angle range is widened. This embodiment is an illumination optical system that prioritizes the light distribution characteristics in a state in which the irradiation angle range shown in FIG. 14 is narrowed, and the shape of each part is set so that the most excellent light condensing characteristics can be obtained in this state. is doing. FIGS. 14B and 15B also show ray tracing diagrams of representative rays emitted from the center of the light source.
[0201]
In these drawings, reference numeral 2 denotes a discharge tube (xenon tube) which is a light source having a cylindrical straight tube shape. Reference numeral 33 denotes a semi-cylindrical reflector that reflects the light beam emitted from the discharge tube 2 forward.
[0202]
Reference numeral 44 denotes an optical member in which a plurality of pairs of prism portions each having a refractive surface having a refractive power in the vertical direction perpendicular to the longitudinal direction of the discharge tube 2 and a reflecting surface are formed on the incident surface side. It is fixed to. The reflecting plate 45 constitutes a reflecting surface having a function equivalent to the prism portion (34h, 34i) formed in the most peripheral portion in the third embodiment. The reflecting surface of the reflecting plate 45 is a parabolic metal reflecting surface. Further, as the material of the optical member 44, an optical resin material or glass material having a high transmittance such as an acrylic resin is suitable.
[0203]
In this embodiment, in particular, in the optical axis direction of the light source, the optical member 44 and the reflecting plate 45 while keeping the light distribution characteristics of the required irradiation range uniform while making the overall shape of the illumination optical system of the photographing apparatus extremely thin. This makes it possible to change the irradiation angle with a minimum amount of change in the positional relationship. The most different point from the third embodiment is that a part of the reflection surface of the optical member is replaced with a reflection member.
[0204]
The shape of the discharge tube 2 in the axial direction is the same as in the first and second embodiments. Hereinafter, the setting of the optimum shape of the illumination optical system of the present embodiment will be described in more detail.
[0205]
FIG. 14 and FIG. 15 are diagrams showing the basic concept of changing the irradiation angle in the vertical direction. 14A and 14B show a state corresponding to the narrowest irradiation angle range, and FIGS. 15A and 15B show a state corresponding to the widest irradiation angle range. . (A), (b) of each figure is a figure when it cut | disconnects by the same cross section, (b) adds the light ray trace part to sectional drawing of (a).
[0206]
14B and 15B, for the same reason as in the first embodiment, for ease of explanation, the light beam emitted from the center of the light source is considered as the representative light beam. Only the emitted light beam is shown.
[0207]
Here, the description will focus on the optical configuration that is different from the third embodiment. The state shown in FIG. 14 is a state in which the distance between the discharge tube 2 and the optical member 44 is a predetermined distance, and the most condensed state is obtained in the present embodiment.
[0208]
  First, as shown in FIG. 14 (a), a cylindrical lens surface 44a near the center of the optical axis and three pairs of prism portions (refractive surfaces 44b, 44d, 44f, 44b ′, 44d ′, 44f ′ and a reflecting surface near the center of the optical axis). 44c, 44e, 44g, 44c ′, 44e ′, 44g ′) is substantially the same shape as that of the third embodiment. In the present embodiment, the most peripheral region of the optical member 44 is a plane portion.(Transmission part)44h, 44h '.
[0209]
A reflecting plate 45 is formed integrally with the optical member 44 on the light source side surface of the flat portions 44h, 44h '. The shape of the reflecting plate 45 is a paraboloid that focuses on the center of the light source so that the light beam emitted from the center of the light source is converted into a light beam substantially parallel to the optical axis in the most condensed state shown in FIG. It is a surface.
[0210]
Thus, by setting the shape of each part, it is possible to have optical characteristics substantially similar to those of the third embodiment. Even in the wide irradiation angle state shown in FIG. 15, the reflector 45 functions to widen the irradiation angle range, and has substantially the same effect as the third embodiment.
[0211]
Here, in this embodiment, the reason for using the reflector 45 configured integrally with the optical member 44 will be described.
[0212]
First, as a first reason, since the thickness of the region of the reflective surface on the most peripheral side of the optical member of the third embodiment is large, it takes a long time to mold, which can be a factor of high cost. Can be mentioned. That is, in this embodiment, the entire thickness of the optical member 44 is made uniform in order to shorten the molding time.
[0213]
In the present embodiment, the reflective plate 45 having a metal reflecting surface is used, and a cost-priority configuration is used. However, the present invention is not necessarily limited to this form. A method of using this peripheral part as a reflective surface instead of a prism, that is, a method of using a thin material and a part of which is a vapor deposition surface, or a method of sticking a thin highly reflective material without using a highly reflective reflector Even if the configuration is adopted, substantially the same optical characteristics can be provided.
[0214]
The second reason is that the weight of the optical member is reduced. The weight of the optical member is largely due to the outermost prism part, and one of the purposes is to reduce the weight of this part.
[0215]
As described above, in this embodiment, the optical member 44 is provided with three pairs of reflecting surfaces (prism portions), and a pair of reflecting plates 45 is provided on the peripheral side thereof, so that the optical member 44 has four upper and lower reflecting surfaces as a whole. Although the system is configured, the present invention is not necessarily limited to such four layers. For example, the reflection plate may be divided into two or more layers, or a slightly inner reflection surface may be formed by the reflection plate instead of the outermost periphery. In addition, it is also possible to constitute a thinner optical system as the number of reflecting surfaces is increased. Further, as described in the third embodiment, the pitch interval of the reflecting surfaces may be changed.
[0216]
  (Fifth embodiment)
  16 and 17 show the present invention.As an embodiment of the related inventionThe structure of the illuminating device which is 5th Embodiment is shown. The present embodiment is a modification of the first embodiment. FIG. 16 is an exploded perspective view of the optical system of the illumination device, and FIG. 17 is a view of only the optical member as viewed from the back. Since the ray tracing diagram and the light distribution characteristics are substantially the same as those of the other embodiments, detailed description thereof is omitted.
[0217]
In the present embodiment, two pairs of reflecting surfaces of the illumination optical system of the illumination apparatus described in the first embodiment are formed, and the shape of the incident surface side of the optical member 54 is three-dimensionally deformed. The present embodiment is mainly aimed at improving the light distribution characteristics in the four corner directions on the subject surface.
[0218]
As an operation for changing the irradiation angle, as in the first to fourth embodiments, the discharge tube 52 and the reflector 53 are integrated and held, and the relative positional relationship in the optical axis direction between these and the optical member 54 is determined. Do by changing. About change of an irradiation angle range, it is the same as that of other embodiments.
[0219]
16 and 17, 52 is a discharge tube which is a light source having a cylindrical straight tube shape, 53 is a reflector, and 54 is an optical member integrally formed in a prism shape as a whole. The functions of these components are substantially equivalent to those of the first embodiment, but this embodiment is characterized by the shape of each surface of the optical member 54 on the discharge tube 52 side.
[0220]
In the drawing, a reflector 53 is formed in a semi-cylindrical shape (hereinafter referred to as a semi-cylindrical portion 53 a) that is substantially concentric with the discharge tube 52 and covers the rear side of the discharge tube 52. The toric surfaces 53b and 53b ′ that cover the back surfaces of the most peripheral reflecting surfaces 54e and 54e ′, and flat portions 53c and 53c ′ that connect the toric surfaces 53b and 53b ′ and the semi-cylindrical portion 53a are provided.
[0221]
On the other hand, a lens surface 54a having a positive refractive power in the direction orthogonal to the optical axis (vertical direction) is formed near the center of the optical axis on the incident surface side of the optical member 54, and in the peripheral portion on the incident surface side. The upper and lower two layers (two pairs) of the prism surface formed of the refracting surface and the reflecting surface are formed.
[0222]
This embodiment is different from the first embodiment in that the central lens surface 54a and the peripheral reflecting surfaces 54c, 54c ', 54e, 54e' are configured by a three-dimensional curved surface.
[0223]
Specifically, a toric surface as a lens surface 54a is formed in the vicinity of the center of the optical axis, and conical first refracting surfaces 54b and 54b ′ constituting a prism portion and a toric surface-like shape are formed on the peripheral side thereof. The first reflecting surfaces 54c and 54c ′ are formed symmetrically with respect to the optical axis.
[0224]
Furthermore, conical second refracting surfaces 54d and 54d 'and toric surface-like second reflecting surfaces 44e and 44e' forming the prism portion are formed symmetrically with respect to the optical axis in the vicinity thereof. A plurality of prism rows are formed on the exit surface 54h.
[0225]
The condensing operation and effect by making the optical member 54 in such a shape will be described.
[0226]
First, the toric lens surface 54a gradually changes its shape between the center of the optical axis and the peripheral portion in the left-right direction to reduce the vertical width, and the optical axis orthogonal direction (vertical direction) at each position in the left-right direction. The refracting power also changes gradually.
[0227]
As a result, the light distribution characteristics as a whole are made uniform, and curved light distribution unevenness on the subject irradiation surface that is likely to occur at the boundary edge portion between the refracting surface and the reflecting surface of the prism portion can be prevented. it can.
[0228]
In addition, the reflection surfaces 54c, 54c ′, 54e, and 54e ′ in the peripheral portion at the same time as the toric surface in the central portion are configured with toric surfaces in which the left and right and upper and lower cross-sectional shapes gradually change according to their positions. This makes it possible to make the light distribution characteristics up to the four corners of the irradiation range uniform.
[0229]
As described above, with respect to the light beam emitted from the center of the discharge tube 52, the light distribution distribution with a high light collecting property with a narrow irradiation angle range as a whole is obtained by the action of the toric lens surface 54a and the reflecting surfaces as the two pairs of toric surfaces. A holding illumination optical system can be configured.
[0230]
Further, by dividing the reflecting surface of the optical member 54 as compared with the conventional one and dividing and arranging it in the vertical direction, the optical member 54 can be made thin as in the first to fourth embodiments. Further, since the boundary edge portion between the refracting surface and the reflecting surface in the prism portion is separated from the center of the light source, it is difficult to be affected by the heat generated by the light source in the optical resin material, and adverse effects on the optical characteristics can be reduced.
[0231]
Further, as a specific effect of the present embodiment, an illumination optical system having a uniform light distribution considering the four corners of the irradiation range by configuring the lens surface and each reflecting surface near the center of the optical axis as toric surfaces. It can be easily configured without adding a special optical system.
[0232]
【The invention's effect】
As described above, according to the present invention, it is possible to achieve a significant reduction in thickness as compared with a conventional illumination range variable illumination device, and the energy from the light source is used with high efficiency on the irradiation surface. It is possible to realize an illumination device that can obtain uniform light distribution characteristics.
[0233]
Further, in the above optical member, the reflecting portions are provided so as to be arranged in a pair or a plurality of pairs with the optical axis in between in a direction orthogonal to the optical axis in a plane including the radial direction of the light source. It can be set as the illuminating device from which an optical characteristic is acquired.
[0234]
Further, 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 reflecting portion is
20 ° ≦ α ≦ 70 °
By making it fall within the range, it is possible to achieve both reduction in thickness of the lighting device and reduction in size in the vertical direction.
[0235]
According to the present invention, a lighting device capable of changing the irradiation range can be mounted on a small-sized photographing device, particularly a card-type photographing device.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view in the radial direction of a discharge tube of an illumination apparatus (condensing state) according to a first embodiment of the present invention.
FIG. 2 is a cross-sectional view of the illumination device (diffusion state) of the first embodiment in the discharge tube radial direction and a trace diagram of representative rays.
FIG. 3 is a cross-sectional view taken along a plane including the discharge tube central axis of the illumination device of the first embodiment.
FIG. 4 is an exploded perspective view of an optical system of the illumination device according to the first embodiment.
FIGS. 5A and 5B are perspective views of (a) a compact camera and (b) a card size camera on which the illumination device of the first embodiment is mounted.
FIG. 6 is a light distribution characteristic diagram of the illumination device (condensing state) of the first embodiment.
FIG. 7 is a light distribution characteristic diagram of the illumination device (diffusion state) of the first embodiment.
FIG. 8 is a cross-sectional view in the radial direction of a discharge tube of an illumination device (condensing state) according to a second embodiment of the present invention.
FIG. 9 is a cross-sectional view of the lighting device (diffusion state) of the second embodiment in the radial direction of the discharge tube and a trace diagram of representative rays.
FIG. 10 is a cross-sectional view taken along a plane including the discharge tube central axis of the lighting apparatus of the second embodiment.
FIG. 11 is an exploded perspective view of an optical system of the illumination device of the second embodiment.
FIG. 12 shows the present invention.As an embodiment of the related inventionSectional drawing of the discharge tube radial direction of the illuminating device (condensing state) which is 3rd Embodiment.
FIG. 13 is a cross-sectional view of the illumination device (diffusion state) of the third embodiment in the discharge tube radial direction and a representative ray trace diagram.
FIG. 14 is a cross-sectional view in the radial direction of a discharge tube of an illumination device (condensing state) according to a fourth embodiment of the present invention.
FIG. 15 is a cross-sectional view in the discharge tube radial direction and a trace diagram of representative rays of the illumination device (diffusion state) of the fourth embodiment.
FIG. 16 shows the present invention.As an embodiment of the related inventionThe disassembled perspective view of the optical system of the illuminating device which is 5th Embodiment.
FIG. 17 is a rear view of an optical member constituting the illumination device of the fifth embodiment.
[Explanation of symbols]
  2,52 discharge tube
  3, 23, 33, 53 Reflector umbrella
  4, 24, 34, 44, 54 Optical members
  4c, 4c ', 24c, 24e, 24g, 24i, 24c', 24e ', 24g', 24i ', 34c, 34c', 34e, 34e ', 34g, 34g', 34i, 34i 'Reflective surface
  45 Reflector
  11 Camera body
  12 Shooting lens
  13 Release button
  16 LCD window

Claims (6)

A light source;
An optical member disposed in front of said light source,
A reflective member that is disposed so as to cover a rear side of the light source and a front space between the light source and the optical member, and reflects light from the light source forward;
On the incident surface side of the optical member,
A positive refracting portion that gives positive refracting power to light incident from the light source in the central portion including the optical axis position ;
A transmission part that is provided on the peripheral side of the positive refraction part and transmits light reflected by a part of the reflection member that covers the front space ;
Wherein provided between the positive refracting portion and the transmissive portion, has a reflection surface for reflecting the light incident on the front from the refracting surface and the refractive surface which light from the light source is incident, the radial direction of the light source and a reflecting portion provided so as to be arranged one or more pairs are formed to sandwich the optical axis in a direction perpendicular to the optical axis in the plane containing,
An illumination device, wherein an irradiation range of light emitted from the optical member is variable by changing a relative positional relationship between the light source and the optical member in an optical axis direction. The lighting device according to claim 1 , wherein the refracting surface of the reflecting portion is configured by a plane having an inclination with respect to the optical axis of 10 ° or less. The reflecting surface of the reflecting portion, the lighting apparatus according possible to claim 1 or 2, characterized in that is constituted by a curved surface having a curvature in a plane including the radial direction of the light source. 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 reflecting portion is
20 ° ≦ α ≦ 70 °
Lighting device according to any one of to be within the scope of claims 1, wherein 3. Imaging apparatus comprising the illumination device according to claim 1, any one of four. Card-type imaging apparatus comprising the illumination device according to any one of claims 1 to 4.

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