JPH0719736U - Imager for measuring luminance distribution of LCD backlight - Google Patents

Abstract

(57) [Abstract] [Purpose] Use a Fresnel lens to shoot only vertical light from the entire emission surface of the LCD backlight, and move the luminance meter so that the luminance meter is perpendicular to the emission surface. Alternatively, the uniformity of the brightness distribution, which correlates with the evaluation of moving the table on which the object to be measured is fixed and photographing, is evaluated. [Configuration] LCD backlight emission surface 1 in dark box 10
1 is photographed by the television camera 13 through the Fresnel lens 12, oblique light is eliminated from the luminous flux from the light emitting surface 11 and only vertical light is received by the television camera 13, and the brightness of the light emitting surface 11 is obtained by the image processing means 14. Evaluate the uniformity of distribution.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to an image pickup device for measuring the brightness distribution of an LCD backlight, which measures the light emitting state of the light emitting surface of the LCD backlight and evaluates the uniformity of the brightness distribution.

[0002]

[Prior art]

 As shown in FIG. 4, vertical light A and oblique lights B and C having various kinds of angles are mixed in the light emission of the light emitting surface 1 of the LCD backlight. Therefore, when measuring the light emitting state, if the entire light emitting surface 1 is photographed from above with the TV camera 2 or the like, the vertical light A is predominant in the central portion of the light emitting surface 1 and the oblique light B, C in the peripheral portion. Therefore, the uniformity of the luminance distribution on the light emitting surface 1 is evaluated by moving the luminance meter so that the luminance meter is perpendicular to the light emitting surface, or by moving the table on which the DUT is fixed. In many cases, there is no correlation with the evaluation of shooting.

[0003]

[Problems to be solved by the device]

 However, the above-mentioned method requires a luminance meter or a driving mechanism for moving the object to be measured, and thus has a problem that the apparatus becomes complicated and takes a long time for photographing.

An object of the present invention is to solve the above-mentioned problems, and by using a Fresnel lens, it is possible to photograph only vertical light even in the peripheral portion of the light emitting surface. To provide.

[0005]

[Means for Solving the Problems]

 In order to achieve the above-mentioned object, a photographing device for measuring the brightness distribution of an LCD backlight according to the present invention is arranged toward the light emitting surface of the LCD backlight, and vertical light in the light flux from the light emitting surface is focused to a focal position. It is characterized in that it comprises a Fresnel lens for condensing light onto a light source and a television camera arranged at the focal point position of the Fresnel lens for taking an image of the light emitting surface.

[0006]

[Action]

 The image pickup device for measuring the luminance distribution of the LCD backlight having the above-described structure eliminates oblique light by passing the light flux emitted from the light emitting surface of the LCD backlight through the Fresnel lens, and only the vertical light is transmitted to the television. The light is condensed on the camera, and the output is subjected to image processing by the image processing means to measure the luminance distribution of the light emitting surface.

[0007]

【Example】

 The present invention will be described in detail with reference to the embodiments shown in FIGS. FIG. 1 shows a configuration diagram of this embodiment. A light emitting surface 11 of an LCD back light, which is an object to be measured, is arranged on a bottom surface of a dark box 10, and a Fresnel lens 12 for concentrating only vertical light to a television camera is provided in an intermediate portion. Is provided and a television camera 13 as a photographing means is arranged on the focal plane of the Fresnel lens 12, and the output of the television camera 13 is connected to an image processing means 14 for performing data analysis and the like.

The luminous flux emitted from the light emitting surface 11 is incident on the Fresnel lens 12 including oblique light B and C having various angles in addition to the vertical light A as shown in FIG. In the Fresnel lens 12, the oblique lights B and C are excluded, and only the vertical light A in the center and the peripheral part is incident on the television camera 13 and photographed, and the output is taken as the brightness distribution of the light emitting surface 11 via the image processing means. Is displayed.

FIG. 2 shows the operation when the Fresnel lens 12 is not used, and FIG. 3 shows the operation when the Fresnel lens 12 is used for comparison. That is, a plurality of nails 21 are vertically driven at predetermined size positions on an arbitrary plate 20 having the same size and shape as the light emitting surface 11. Then, in this state, the board 20 is photographed from directly above by the TV camera 22 and displayed on the TV monitor 23.

In the case of FIG. 2, the nail 21 in the central portion is photographed from directly above, but it can be seen that the nail 21 is photographed obliquely toward the outer peripheral portion of the plate 20.

On the other hand, when the Fresnel lens 12 is installed on the plate 20 as shown in FIG. 3 and an image is similarly taken by the TV camera 22, the nails 21 on all parts of the plate 20 on the TV monitor 23 are removed. It looks like it was shot from directly above.

According to such verification, by using the Fresnel lens 12 as in the embodiment, oblique light is eliminated from the light flux from the light emitting surface 11, and only the vertical light is mainly captured even in the peripheral portion. Therefore, the luminance meter is moved so that the luminance meter is perpendicular to the light emitting surface, or the luminance of the light emitting surface 11 that correlates with the evaluation of moving the table on which the DUT is fixed is taken. The uniformity of distribution can be evaluated.

[0013]

[Effect of device]

 As described above, the image pickup device for measuring the luminance distribution of the LCD backlight according to the present invention uses a Fresnel lens to eliminate oblique light, images only the vertical light from the entire light emitting surface, and processes its output for image processing. By doing so, it is possible to carry out the measurement according to the practical use.

[Brief description of drawings]

FIG. 1 is a configuration diagram.

FIG. 2 is an explanatory diagram of an operation when a Fresnel lens is not used.

FIG. 3 is an operation explanatory view when a Fresnel lens is used.

FIG. 4 is an explanatory diagram of a state of a light beam from a light emitting surface.

[Explanation of symbols]

 10 Dark Box 11 Light-Emitting Surface 12 Fresnel Lens 13 Television Camera 14 Image Processing Means

Claims (1)

[Scope of utility model registration request] 1. A Fresnel lens, which is arranged toward a light emitting surface of an LCD backlight and focuses vertical light of a light flux from the light emitting surface at a focal position, and the Fresnel lens is arranged at a focal position of the Fresnel lens to emit the light. An image pickup device for measuring the luminance distribution of an LCD backlight, comprising a television camera for taking an image of a surface.