JP2009176471A - Lens for led light source - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To solve a problem that, when illumination is carried out with an LED in image reading of a sensing camera in conventional cases, the sensing camera needs more brightness at a peripheral part than a center part of the screen, so that a plurality of LEDs headed toward necessary directions must be combined to secure irradiation angles, which leads to plenty of power sources consumed of a digital camera and decrease of the photo-taking number. <P>SOLUTION: Power consumption for illumination is reduced by dividing light from an LED with an incident-face lens made in nearly a V shape so that it expands at an angle α in a length direction of the photo, and further focusing it with an irradiation-face lens as a convex lens with each divided center line as an axis, which enables to obtain a nearly rectangular irradiation range with light of just one LED. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a lamp used as a light source for a sensing camera using an LED as a light source, and more specifically, a range in which the camera captures light from one LED, in particular, a lack of light in a peripheral portion of a screen. The lens has been improved so that the range of light emitted from the LED matches the shooting range of the camera so that the actual range of surveillance is not narrowed in a surveillance camera or the like. The present invention relates to the configuration of the lens for the illumination device.

  FIG. 8 shows an example of the configuration of a conventional camera photographing LED, and nine LEDs 16 from LED 16A to LED 16I are attached to the front left shoulder of the camera 10. At this time, only the LED 16E at the center is directed in the same direction as the photographing lens 13, and the other LEDs 16, for example, the LED 16A, are inclined so as to appropriately irradiate the upper left side when viewed from the front.

  Further, the LED 16B is directed upward, the LED 16C is directed upward, and the LED 16D is directed leftward as appropriate, so that the viewing angle of the lens 13 is covered. At the same time, a preset current is applied to the other LEDs 16 (A, B, C, D, F, G, H, and I) with respect to the central LED 16E.

At this time, the current value applied to other than the LED 16E or the lighting time is, for example, an image of a gray plate having a reflectance of 16%. Are set to be the same, that is, the captured images are set to have the same density. At the same time, the inclination of each LED 16 (A, B, C, D, F, G, H, I) may be adjusted.
JP 2005-148200 A

  However, in the conventional illumination method described above, a large number of LEDs 16 (A to I) are turned on at the same time. Therefore, in a digital camera that is a portable device and does not have a sufficient battery capacity, battery consumption is severe. This causes a problem that the number of images that can be shot is drastically reduced at night.

  In recent years, the luminous efficiency of LEDs has dramatically improved, and for example, the sensitivity of CCD and CMOS photosensitive elements, which are films in digital cameras, can be easily increased by about 1600 to 3200 in terms of ISO. Also from this point, the necessity of using a large number of LEDs 16 as described above has been diminished.

  The present invention provides a projection lens for projecting light from a light source as a specific means for solving the above-described conventional problems, wherein the axis of the surface on the light emission side of the light source is the light source. The incident side surface from the light source is set to the same or substantially the same angle as the angle at which the emission side surface is inclined with respect to the light source. The problem is solved by providing a lens for an LED light source that is formed to be inclined.

  According to the present invention, by combining a lens that directs light in a desired direction with respect to one LED, there is no shortage in the amount of peripheral light, and excessive power is emitted by lighting a large number of LEDs. This product has excellent effects in reducing the power consumption of equipment that uses LEDs as its light source, such as reducing power consumption and reducing the number of images that can be taken at night. It is.

  Next, the present invention will be described in detail based on the embodiments shown in the drawings. 1 shows a first embodiment of an LED light source lens 1 according to the present invention. The LED light source lens 1 includes an exit surface lens 2, a flange 3, and an entrance surface. The lens 4 or the V-shaped cut 5 is configured to irradiate the light from the LED 6 placed on the center line of the LED light source lens 1 with an appropriate radiation angle.

  Here, in the first embodiment, in the present invention, the exit surface lens 2 is formed as a surface combining two spherical surfaces, and is used as, for example, an illumination device for taking a picture. In the case of a camera using a 35 mm film, the ratio of the long side to the short side is preferably about 3: 2.

  Therefore, in the present invention, the exit surface lens 2 is formed by two spherical surfaces 2a and 2b having two optical axes Z1 and Z2 that open α ° on the long side of the photographing screen when attached to a camera, for example. It is supposed to be. In the present invention, since the exit surface lens 2 is tilted so as to open to the long side, the entrance surface lens 4 (or V-shaped cut 5) is similarly tilted at the same angle.

  At this time, when the entrance surface lens 4 is concave and forms a meniscus lens shape with the exit surface lens 2, the entrance surface lens 4 is orthogonal to the optical axes Z1 and Z2. However, it may be formed as planes 5a and 5b orthogonal to the optical axes Z1 and Z2, and in this way, the shape of the entrance surface lens 4 is as follows: The cut surface 5 has a V-shape parallel to the short side of the irradiation range, and can perform substantially the same action as the tilted incident surface lens 4.

  Further, at this time, the focal point of the LED light source lens 1 composed of the exit surface lens 2 (a, b) and the entrance surface lens 4 or the V-shaped cut surface 5 (a, b). Is set in the LED 6 or in the vicinity thereof.

  With this configuration, the LED light source lens 1 of the present invention sets, for example, optical axes Z1 and Z2 that open horizontally, and the exit surface lens 2 (a and b) also has the optical axis Z1. In addition, the incident surface lens 4 or the V-shaped cut surfaces 5 (a, b) are provided in accordance with the inclinations of the optical axes Z1, Z2. As shown in FIG. 2, the LED light source lens 1 of the present invention emits light emitted from the light source (LED 6) as a substantially rectangular light distribution characteristic D1.

  FIG. 3 schematically shows the state of the light amount distribution in the cross-sectional line H1 along the long side in the light distribution characteristic D1 shown in FIG. The cross-sectional line H1 is attached to the camera so that its longitudinal direction coincides with the imaging range.

  According to the present invention, the configuration of the LED light source lens 1 is as described above. First, light emitted from the LED 6 as a light source is provided on the flange 3 as a concave surface when viewed from the LED 6. In addition, the light is divided by the incident surface lens 4 or the V-shaped cut 5 into light that travels in two horizontal directions from the center to the left and right.

  Further, the surface of the flange 3 opposite to the side where the entrance surface lens 4 and the cut surface 5 are provided is formed in the convex lens shape, and the entrance surface lens 4 and the cut surface 5 provide two directions. In correspondence with the divided angle α °, two exit surface lenses 2 (a, b) whose optical axes are inclined are provided (see FIG. 1). In this case, the light is emitted in the left and right peripheral directions). In general, there are many cases where an object for photographing exists in a position close to the front direction of the lens, and therefore, light is appropriately distributed in this front direction.

  As is apparent from the above description, the shape of the light distribution emitted from the exit surface lens 2 (a, b) may be any shape suitable for photography in this embodiment. For example, any shape such as an aspherical lens or a cylindrical lens can be freely used.

  FIG. 4 shows a second embodiment of the present invention. In the LED light source lens 1 of the first embodiment, for the purpose of use for illumination at the time of taking a photograph, The shape of the exit surface lens 2 and the entrance surface lens 4 has been set for the purpose of obtaining a substantially rectangular light distribution characteristic having a long side in the longitudinal direction of the photosensitive element. However, the present invention is not limited to this. For example, it is also possible to obtain light distribution characteristics as a general illumination lamp such as a home lamp or a lamp for other purposes such as a vehicular lamp.

  In FIG. 4, the flange 3 is combined with four convex spherical surfaces, aspherical surfaces and the like each having an axis Z (1 to 4) extending from the center (LED 6) at a predetermined angle. A four-sided exit surface lens 7 (a, b, c, d) is formed on the flange 3. Further, on the lower surface of the flange 3, four concave spherical surfaces are combined in a substantially quadrangular pyramid shape to direct the light emitted from the LED 6 in the direction of the respective axes Z (1 to 4). Lenses 8 (a, b, c, d) are provided. The quadrilateral entrance surface lens 8 (a, b, c, d) is constituted by a cut surface 9 (a, b, c, d) which is a flat surface in the form of a quadrangular pyramid as in the first embodiment. You can do it.

  The four-surface-type exit surface lens 7 (a, b, c, d) and the four-surface-type entrance surface lens 8 (a, b, c, d) corresponding to the four-surface-type exit surface lens 7 (a, b, c, d) The focal point generated by c, d) or the four-sided cut surface 9 (a, b, c, d) is set to the LED 6 or the vicinity thereof as in the first embodiment.

  FIG. 5 is a cross-sectional view taken along the axis Z2-Z4 of the second embodiment of the present invention configured as described above. By configuring in this way, light from one LED 6 is directed in a desired direction. It can be understood that irradiation can be performed. Further, as shown in FIG. 6, the light distribution characteristic D2 is also generally circular, and for example, a light distribution characteristic suitable for a signal lamp such as an indoor lamp or a tail lamp of a vehicle lamp can be obtained. .

  The light distribution characteristic D3 shown in FIG. 7 is substantially the same as the structure of the second embodiment described above, and the positions where the four-surface exit surface lens 7 provided on the flange 3 and the LED 6 are installed are as follows. As in the second embodiment, the position where the four-surface-type entrance surface lens 8 (cut surface 9) is provided is translated in the direction of the axis Z1 with respect to the four-surface-type exit surface lens 7 and the LED 6. It has been made.

  In this way, it is possible to apply applications such as distribution of a necessary amount of light in a required direction, or change of the shape of light distribution characteristics as necessary, and expansion of applications is possible. The description has been given for the case where the number of the exit surface lenses 2 and the number of the entrance surface lenses 4 are two and four respectively, but the present invention is not limited to this and is desired. It is possible to change freely according to the light distribution characteristics.

  In addition, when a positional difference is generated between the photographing lens and the illumination device using the LED light source lens of the present invention, the inclination of the four-sided incident surface lens 8 (cut surface 9) is appropriately determined depending on the position. For example, it is free to uniformly illuminate a subject that is likely to exist in the front. Therefore, in the present invention, the setting of the inclination of the exit surface lenses 2 and 7 or the entrance surface lenses 4 and 8 is not strictly limited. For example, the exit surface lenses 2 and 7 are within a range of ± 7 °. Further, the optical axes of the entrance surface lenses 4 and 8 may be shifted to finely adjust the light distribution.

It is explanatory drawing which shows the cross section in the 1st Example of the lens for LED light sources which concerns on this invention, and the advancing state of the light ray from a light source. It is a graph which similarly shows the light distribution shape in a 1st Example with an isoillumination curve. It is a graph which shows the illumination distribution along the H1-H1 line | wire of FIG. It is explanatory drawing shown in the state which looked at the 2nd Example of the lens for LED light sources which concerns on this invention from the front. It is sectional drawing which follows the BB line of FIG. It is a graph which shows the light distribution shape in the 2nd Example of the lens for LED light sources which concerns on this invention with an isoillumination curve. It is a graph which similarly shows an example when the light distribution shape in a 2nd Example is changed with an isoillumination curve. It is a front view which shows a prior art example.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... LED light source lens 2 (a, b) ... Output surface lens 3 ... Flange 4 (a, b) ... Incident surface lens 5 (a, b) ... Cut surface 6 ... LED
7 (a, b, c, d) ... Four-sided exit surface lens 8 (a, b, c, d) ... Four-sided entrance surface lens 9 (a, b, c, d) ... Four-sided cut surface

Claims (5)

  A projection lens for projecting light from a light source, wherein the axis of the lens surface on the light emission side from the light source is set to be inclined outward in two or four directions around the light source. The LED light source lens is characterized in that the light incident surface from the light source is also inclined at the same or substantially the same angle as the light emitting surface is inclined with respect to the light source. .   2. The LED light source lens according to claim 1, wherein a shape of an incident side surface from the light source is a plane orthogonal to the optical axis.   3. The LED light source lens according to claim 1, wherein the angles of the axes of the incident-side and emission-side surfaces inclined with respect to the light source are all the same angle.   The LED light source lens according to claim 1, wherein an angle of an axis of the surface inclined with respect to the light source is different from right to left or up and down.   The LED light source lens according to claim 1, wherein an angle of an axis of the surface inclined with respect to the light source is different in all surfaces.