JP2000232242A - Light-emitting element measuring device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To measure the optical characteristics of a light-emitting element in a short time, with high accuracy and with good reproducibility. SOLUTION: A diffusion plate 23 is arranged facing a fixing jig 22 for fixing a light-emitting diode 21 and a radiant flux from this diode 21 is projected on the plate 23. A first camera 24 is provided behind the plate 23 and the transmitted image of an exposure pattern projected on the plate 23 is picked up by the camera 24. A half mirror 26 is provided between the jig 22 and the plate 23 and the reflecting image of a projection image on the plate 23 is picked up by a second camera 25 via the half mirror 26. The images captured by the cameras 24 and 25 are processed by an image processing unit 28 and an adjustment of the center of a luminous intensity and a directional angle and a pattern matching are made.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a light emitting element measuring device for measuring optical characteristics of a light emitting element such as a light emitting diode.

[0002]

2. Description of the Related Art FIG. 7 is a front view showing a light emitting element measuring device 1 for measuring a directivity angle of a light emitting element such as a light emitting diode, and FIG. 8 is a plan view thereof. Light emitting element measuring device 1
Comprises a fixing jig 4 for fixing a lens-shaped light emitting diode 2 as a light emitting element, and a light receiving device 5 having a photodiode or a solar cell. The fixing jig 4 is provided on the rotary stage 3 that rotates around a vertical rotation axis L1. The light emitting diode 2 is fixed to the fixing jig 4 such that the center is located on the rotation axis L1 of the rotary stage.
A slit 6 is formed in the light receiving portion 9 of the light receiver 5, and the radiant flux of the light emitting diode 2 is linearly received through the slit 6.

In order to measure the directivity angle of the light emitting diode 2 using the light emitting element measuring device 1, first, the light emitting diode 2 attached to the fixing jig 4 is turned on, and as shown in FIG. The rotary stage 3 is rotated around the axis L1 within a range of -90 ° to 90 °. The radiation intensity at this time is plotted.

[0004] Next, the light emitting diode 2 is removed from the fixing jig 4, rotated 90 ° around the optical axis L2 and fixed again to the fixing jig 4, and as shown in FIG. The radiation intensity is plotted while rotating the light emitting diode 2 in the range of 90 ° to 90 °. In this way, the radiation intensities of the light emitting diode 2 in the two directions are measured through the slit 6, and the directional angle of the light emitting diode 2 is measured based on these.

However, such a light emitting element measuring device 1 can measure only the directivity angle, and cannot measure the light distribution pattern and the center of the light emission intensity. Further, since it is necessary to measure the radiation intensity in at least two directions, the light emitting diode 2 must be replaced at the time of measurement, and the reproducibility is reduced. In addition, since the measurement is performed by rotating the light emitting diode 2, it is difficult to perform the measurement in a short time.

In order to solve such a problem, Japanese Patent Application Laid-Open No. Hei 10-26716 discloses a light-emitting element measuring apparatus using a measuring television camera for imaging a luminous flux distribution pattern. FIG. 10 is a block diagram showing a configuration of the light emitting element measuring device 10. As shown in FIG. The radiant flux from the light emitting module 11 is collected by the converging lens 13 into the measuring television camera 1
The image data of the camera 12 is processed by the image processing device 14 and the light distribution pattern of the light emitting module 11 is displayed on the monitor television 15. Thus, the light distribution pattern of the light emitting module 11 can be obtained.

[0007]

In such a light emitting element measuring apparatus 10, all the radiant flux from the light emitting module 11 is collected and taken into the camera 12, so that the light amount is large and the maximum radiant intensity is locally increased. The difference between the minimum radiation intensity and the minimum radiation intensity becomes excessively large, and it becomes impossible for the camera to clearly distinguish the bright and dark portions of the light distribution pattern of the radiant flux. This makes it difficult, for example, to distinguish non-defective products from defective products from the light distribution pattern.

It is an object of the present invention to provide a light emitting element measuring device capable of clearly identifying a light distribution pattern of a radiant flux and measuring characteristics of the light emitting element in a short time.

[0009]

According to a first aspect of the present invention, there is provided a fixing jig for detachably fixing a light emitting element, and a light emitting element arranged and projected to face the light emitting element fixed to the fixing jig. A light-emitting element measuring device comprising: a diffusion plate that diffuses a radiant flux from an element; and a camera that captures an image of the radiant flux projected on the diffuser plate.

According to the present invention, the light distribution pattern of the radiant flux from the light emitting element is projected on the diffusion plate, and the projected image is taken by a camera to measure the optical characteristics of the light emitting element. Since the radiant flux from the light emitting element is diffused by the diffuser,
In the radiant flux projected on the diffuser, the difference between the maximum radiant intensity and the minimum radiant intensity is relaxed, a stable light amount with little variation is obtained, and the light distribution pattern can be clearly imaged. Based on this, a plurality of optical characteristics such as a directivity angle, a light emission intensity center, and an alignment pattern can be measured with a single measuring device while the light emitting element is fixed, and reproducibility is also improved. Further, since it is not necessary to measure the radiation intensity by rotating the light emitting element, the measurement can be performed in a short time.

According to a second aspect of the present invention, a half mirror is provided between the diffusion plate and a fixing jig, and the camera is disposed behind the diffusion plate, and projects a radiant flux transmitted through the diffusion plate. It is characterized by comprising a first camera that captures an image and a second camera that captures a projected image of the radiant flux reflected by the diffusion plate via a half mirror.

According to the present invention, the light distribution pattern of the radiant flux projected on the diffusion plate is captured by the first camera as a transmitted image, and the second camera is captured as a reflected image via a half mirror. Since the transmitted image can obtain a stable and constant light amount with little variation due to the diffusion effect, it is possible to perform measurement with more stable reproducibility in the emission intensity center measurement. Further, a sharp light distribution pattern having no diffusion effect is formed on the diffusion plate with respect to the image reflected by the diffusion plate, and pattern matching of the measured light distribution pattern of the directional angle can be performed with high accuracy.

According to a third aspect of the present invention, there is provided an image processing circuit for measuring characteristics of a light emitting element based on image data captured by a first camera and a second camera.

According to the present invention, the image data captured by the first and second cameras is processed by the image processing circuit to instantaneously match the center of the light emission intensity, the directional angle, and the pattern matching with a predetermined light distribution pattern. It can be carried out.

According to a fourth aspect of the present invention, the image processing circuit comprises:
The position of the center of gravity of the projected image of the radiant flux is obtained based on the image data captured by the camera or the second camera.

According to the present invention, the center of gravity of the projected image of the emitted light beam, that is, the center of the emitted light intensity, can be accurately obtained by the image processing circuit based on the multi-valued level of the emitted light intensity received by each pixel of the camera.

According to a fifth aspect of the present invention, the image processing circuit calculates the radius of the projected image of the radiant flux based on the image data captured by the first camera or the second camera to obtain the directional angle. It is characterized by.

According to the present invention, since the projected image of the radiant flux on the diffusion plate has a clear light distribution pattern, the radius can be accurately obtained by the image processing circuit. The directivity angle of the light emitting element can be calculated instantaneously based on the distance between the children.

The image processing circuit according to claim 6, wherein image data of a projected image of the radiant flux is stored in advance, and the image data captured by the first camera or the second camera and the image data stored in advance are stored. And comparing with.

According to the present invention, it is possible to clearly capture an image by projecting the light distribution pattern of the radiant flux onto the diffusion plate. Therefore, any radiation such as a non-defective or defective product stored in the image processing circuit in advance can be obtained. By comparing the light distribution pattern of the projected image of the flux with the light distribution pattern of the captured radiation flux, it is possible to accurately evaluate whether the light emitting element is a good product or a defective product.

According to a seventh aspect of the present invention, the light emitting device is a light emitting diode. According to the present invention, a light emitting diode can be suitably used as a light emitting element.

[0022]

FIG. 1 is a block diagram schematically showing a configuration of a light emitting device measuring apparatus 20 according to an embodiment of the present invention. The light emitting element measuring device 20 includes a fixing jig 22 for fixing a light emitting diode 21 which is a light emitting element, a diffusion plate 23 arranged facing the fixing jig 22, and a first jig arranged behind the diffusion plate 23. The camera 24 includes a half mirror 26 disposed between the fixing jig 22 and the diffusion plate 23, a second camera 25, an image processing device 28, and a monitor 29. The first and second cameras 24 and 25 are charge coupled device (CCD) cameras, and the captured image is processed by the image processing device 28 and the monitor 29.
Will be displayed.

The light-emitting diode 21 fixed to the fixing jig 22, the half mirror 26, the diffusion plate 23, and the respective light receiving portions of the first and second cameras 24 and 25 are provided in a dark box 27, respectively. The light emitting diode 21 is a light emitting diode having a lens shape, and the fixing jig 22 is detachably fixed so that the optical axis is substantially directed toward the first camera 24 based on the lead frame or the resin package of the light emitting diode 21. Fixed to.

The diffusion plate 23 is disposed substantially perpendicular to the optical axis of the light emitting diode 21 in the dark box 27, and is formed by kneading diffusion particles into a translucent synthetic resin such as acrylic resin or polyvinyl chloride, or Alternatively, it is formed by coating diffused particles on a translucent resin substrate, or by using opal glass. Further, a matting treatment may be applied to both surfaces to prevent surface reflection. The half mirror 26 is disposed in the dark box 27 so as to form an angle of 45 ° with the diffusion plate 23 between the diffusion plate 23 and the fixing jig 22.
The second camera 25 is arranged on the side of the half mirror 26 so as to face the half mirror 26 so that a reflected image from the diffusion plate 23 can be captured via the half mirror 26.

When the light emitting diode 21 is turned on, the radiant flux is transmitted through the half mirror 26 and projected on the diffusion plate 23. The first camera 24 captures a projected image of the radiant flux projected on the diffusion plate 23 from the back side of the diffusion plate 23. Since the transmitted image has a stable and constant light amount with little variation due to the diffusion effect, it is possible to perform measurement with stable reproducibility secured in emission intensity center (center of gravity) measurement.

The image reflected by the diffusion plate 23 is picked up by a second camera 25 via a half mirror 26. Since the reflected image has a small amount of diffused light and an image of a sharp light distribution pattern can be obtained, the measurement of the directional angle and the light distribution pattern can be performed with high accuracy.

FIG. 2 shows the image processing circuit 3 of the image processing device 28.
FIG. 3 is a block diagram showing a configuration of a 0. The image processing circuit 30 includes a center-of-gravity measuring circuit 31, a directional angle measuring circuit 32, and a pattern matching circuit 33.
The images captured at 4 and 25 are processed by the image processing circuit 30 and displayed on the monitor 29.

FIG. 3 is a diagram showing an example of a transmitted image captured by the first camera 24. Image signals from the cameras 24 and 25 are taken into the image processing circuit 30 and A / D-converted and multi-valued in accordance with the radiation intensity received by each pixel of the CCD. The image data is stored in the memory. The center-of-gravity measurement circuit 31 calculates the position of each pixel from the image data captured from the first camera 24,
The center of gravity, that is, the emission intensity center, is calculated based on the multi-valued level.

FIG. 4 is a diagram schematically showing the measurement of the directivity angle θ. The diagram shown on the left side of FIG. 4 is an example of the reflection image, and FIG. 5 shows another example of the reflection image. As described above, a sharp light distribution pattern with a small amount of diffused light is obtained in the reflection image, and therefore, as shown in the reflection image of FIG.
5A, or a plurality of concentric circles having different light emission intensities as shown in FIG.
As shown in (b), the shadow of the chip may be projected at the center of the light emitting pattern.

The directing angle measuring circuit 32 has a fixing jig 22 in advance.
The distance L between the tip of the light emitting diode 21 and the diffusion plate 23, which is fixed to the light emitting diode 21, is stored. The directivity angle measuring circuit 32 first obtains the diameter D of the outer circle from the light distribution pattern of the radiant flux imaged on the diffusion plate 23. The diameter D is calculated based on at least three positions at which a transition from a white pixel to a black pixel is made. Based on the distance L stored in advance and the calculated diameter D, the directivity angle θ is calculated by substituting into the following equation θ = tan ⁻¹ {(D / 2) / L}.

FIG. 6 is a diagram showing a light distribution pattern having a ring shape. As shown in the figure, the light emitting diode 21 has a defective light distribution pattern having a ring shape. In the pattern matching circuit 33, for example, a light distribution pattern of a non-defective product as shown in FIG. 3 is registered in advance, and the image data of the light distribution pattern of the reflected image captured by the second camera 25 and the distribution of the registered non-defective product are used. Pattern matching is performed based on the image data of the light pattern, that is, the degree of coincidence of each image data is determined to determine whether the product is good or defective. Thereby, the light emitting diodes having the light distribution pattern having a ring shape as shown in FIG. 6 can be selected.

The monitor 29 displays a transmission image from the first camera 24 and a reflection image from the second camera 25 based on the image data captured by the image processing circuit 30, and calculates a center of gravity measurement circuit 31. The position of the center of gravity (light emission intensity center), the directional angle θ calculated by the directional angle measuring circuit 32, and whether or not a non-defective product is the result of the determination by the pattern matching circuit 33 are instantaneously displayed.

Whether to use the transmission image or the reflection image in the center of gravity measurement, the directional angle measurement and the pattern matching may be appropriately changed according to the light emitting diode 21 and the diffusion plate 23.

[0034]

According to the first aspect of the present invention, the luminous flux distribution pattern projected on the diffusion plate is imaged and the characteristics of the luminous flux are measured to measure the characteristics of the luminous flux. This eliminates the need to rotate and perform the measurement, and the measurement can be performed in a short time with high reproducibility. Further, since the projection image has a stable light amount with little variation due to the diffusion effect of the diffusion plate, it is possible to clearly capture the light distribution pattern and measure the optical characteristics of the light emitting element with high accuracy.

According to the second aspect of the present invention, a transmission image and a reflection image can be simultaneously obtained by the first and second cameras, thereby making it possible to measure the characteristics of the light emitting element with high accuracy. Become.

According to the third aspect of the present invention, it is possible to instantaneously measure the emission intensity center, the directional angle, the pattern matching, and the like based on the image captured by the image processing circuit.

According to the present invention, the center of gravity, that is, the center of the light emission intensity can be obtained with high accuracy based on the projected image.

According to the fifth aspect of the present invention, since the radius can be calculated with high accuracy based on the projected image, the directional angle can be calculated with high accuracy based on this.

According to the present invention, by performing pattern matching in the image processing circuit, it is possible to sort out defective products with high accuracy.

According to the present invention, it is possible to suitably measure the optical characteristics of a light emitting diode having a lens shape.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a configuration of a light emitting element measuring device 20 according to one embodiment of the present invention.

FIG. 2 is a block diagram of an image processing circuit 30.

FIG. 3 is a diagram showing a transmission image captured by a first camera 24;

FIG. 4 is a diagram showing a method of measuring a directivity angle θ.

FIG. 5 is a diagram illustrating an example of a reflection image.

FIG. 6 is a diagram showing a light distribution pattern having a ring shape.

FIG. 7 is a front view showing a conventional light emitting element measuring device 1.

FIG. 8 is a plan view of the light emitting element measuring device 1.

FIG. 9 is a diagram showing a measurement trajectory at the time of measurement by the light emitting element measurement device 1.

FIG. 10 is a block diagram showing a configuration of a conventional light emitting element measuring device 10 using a television camera.

[Explanation of symbols]

 Reference Signs List 20 light emitting element measuring device 21 light emitting diode 22 fixing jig 23 diffusion plate 24 first camera 25 second camera 26 half mirror 27 dark box 28 image processing device 30 image processing circuit

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 2G065 AA04 AA11 AB22 AB23 AB28 BA04 BB05 BB23 BC11 BC14 BC28 BC33 BD01 DA05 DA18 2G086 EE03 5F041 AA46 EE25

Claims (7)

[Claims] 1. A fixing jig for detachably fixing a light emitting element, a diffusion plate arranged facing the light emitting element fixed to the fixing jig, and diffusing a radiant flux from the projected light emitting element; A light-emitting element measuring device, comprising: a camera that captures an image of the radiant flux projected on the plate. 2. A half mirror is provided between the diffusion plate and a fixing jig. The camera is disposed behind the diffusion plate, and captures a projection image of a radiant flux transmitted through the diffusion plate. The light-emitting element measuring device according to claim 1, further comprising: a camera; and a second camera configured to capture, via a half mirror, a projected image of the radiant flux reflected by the diffusion plate. 3. The light-emitting element measuring device according to claim 1, further comprising an image processing circuit for measuring characteristics of the light-emitting element based on image data captured by the first camera and the second camera. . 4. The image processing circuit according to claim 3, wherein a position of a center of gravity of a projected image of the radiant flux is obtained based on image data captured by the first camera or the second camera.
The light-emitting element measuring device according to claim 1. 5. The image processing circuit according to claim 1, wherein a directional angle is calculated by calculating a radius of a projected image of the radiant flux based on image data captured by the first camera or the second camera. 5. The light emitting element measuring device according to 3 or 4. 6. The image processing circuit stores image data of a projected image of a radiant flux in advance, and compares image data captured by a first camera or a second camera with the image data stored in advance. 6. The method according to claim 3, wherein
The light-emitting element measuring device according to any one of the above. 7. The light emitting element measuring device according to claim 1, wherein said light emitting element is a light emitting diode.