JPH0218973A - Testing device for light emitting diode - Google Patents

Abstract

PURPOSE:To seek to reduce cost and to improve processing capacity by making light emitting diodes to be measured emit lights successively in time series, and concentrating those emitted lights into one point through respective optical fibers so as to measure the optical characteristics of plural light emitting diodes with one optical characteristics measuring instrument. CONSTITUTION:The lights from three light emitting diodes 2-4 to be measured enter respective optical fibers 18-20, and the three light emitting diodes 2-4 to be measured are changed over for supply currents at high speeds and emit lights successively, but at a specific point of time the light of one light emitting diode irradiates a half mirror 23 passing through a bundled optical fiber part 21. And it irradiates a collimator mirror 30 (concave mirror), and the reflected light from a reflection type diffraction grating 31, though the reflection angle changes according to the wave length, are reflected at a condensing mirror 32 and irradiates an image sensor 33, and are measured for peak wave length. On the other hand, the reflection light from the half mirror 23 irradiates solar battery 25 passing through a condensing lens 24, and generates currents proportional to the quantity of light, and is input into a luminous intensity measurement result display 26, and the luminous intensity is indicated. Hereby, the cost can be reduced, and the processing capacity can be improved sharply.

Description

DETAILED DESCRIPTION OF THE INVENTION (1) Technical field to which the invention pertains The present invention relates to a method for measuring, testing, lead cutting, sorting, etc. of light emitting diodes during the production process of light emitting diodes, or during quality control and receiving inspections. It concerns an automatic device for carrying out such operations.

(2) Prior art and its problems FIG. 1(a) shows an example of a conventional light emitting diode testing device. Magazines 51, 52, 5 in which light emitting diodes using lead frames are housed as shown in FIG. 1(b)
3 is attached to the magazine tray 54, the magazine tray 54 is automatically transported to a predetermined position.

Light-emitting diodes using lead frames from each magazine 51.52.53 are simultaneously drawn into each measuring channel 55.56.57 and transported by intermittent feeding to the measuring section 5B and the cutting section 61.62.63 at 59° 60°. be done. The cut light emitting diodes are sorted by a sorter 64 according to the quality according to the measurement results, and are stored in product storage boxes 6 for each quality category.
It is accommodated in 5.66 and 67. The lead frame after the light emitting diode has been separated is stored in a lead frame storage box 68. When the number of light-emitting diomids housed in the product storage box reaches a preset number, the shutter of the storage box that has reached the set number is opened, and the storage box is packed by a bagging machine (not shown in Figure 1) and packed. Stored in a storage box.

In conventional light emitting diode test equipment, reverse current (ri).

Some devices measure luminous intensity at the same time as measuring electrical characteristics such as small current forward voltage (Vy+), large current forward voltage (■FZ), and forward current (I, ).

There was also a light-emitting diode tester that could simultaneously measure the luminous intensity and color tone of a light-emitting diode, although it was not a large-scale device like the one shown in FIG. 1(a).

Furthermore, the n
There was also a device that measured the characteristics of n light emitting diodes to be measured by simultaneously driving n measurement heads in parallel, but if you wanted to measure the color tone of a light emitting diode using this method, One color tone measuring device was required.

The number of processes per unit time can be increased by measuring using multiple color tone measuring instruments, but since color tone measuring instruments are expensive,
The disadvantage was that the cost was extremely high.

(3) Purpose of the Invention An object of the present invention is to provide a light emitting diode testing device with significantly improved throughput by shortening the measurement time including color tone measurement.

Another object of the present invention is to solve the problem that conventionally, when measuring the optical characteristics of a plurality (n) of light emitting diodes at the same time using a plurality (n) of measurement lines, n units of expensive optical characteristic measuring instruments are required. It is an object of the present invention to provide a light emitting diode testing device which is improved and can perform measurements in a short time almost as long as using n optical characteristic measuring devices with one optical characteristic measuring device.

(4) Structure of the Invention (4-1) Features of the Invention and Differences from the Conventional Technology The present invention uses a plurality of conveyance lines to chronologically transport light-emitting diodes to be measured that are simultaneously supplied to a plurality of measurement heads. The most important feature is that the optical characteristics of multiple light emitting diodes can be measured using a single optical characteristic measuring instrument by emitting light sequentially from each light emitting diode and concentrating the emitted light in one place through each optical fiber. do.

Conventionally, there was a light-emitting diode test device that operated multiple (n) measurement heads in parallel, each with a light-emitting diode to be measured, to perform simultaneous measurements, but it was not possible to measure color tone. .

In addition, there were measuring instruments that could measure luminous intensity and color tone at the same time as well as electrical characteristics, but they measured individual light emitting diodes one by one, and the measuring speed was too high for use on production lines. There was a problem with that.

In contrast, the present invention makes the light emitting diodes to be measured supplied to a plurality of measurement heads emit light sequentially in time series, and concentrates the emitted light to one place through each optical fiber. This method differs from conventional technology in that the optical characteristics of multiple light emitting diodes can be measured using a device. Simultaneous measurement of luminous intensity and color tone is also possible.

Furthermore, a gain adjuster is provided to obtain the same measurement result no matter which measurement point the light emitting diode to be measured is placed.

When measuring color tone, not only the absolute value measurement method but also
It is also possible to measure relative values compared to a reference product.

Furthermore, in a preferred embodiment, during the period of measuring the characteristics of a plurality of light emitting diodes to be measured, the work of individually separating and cutting the light emitting diodes that have been measured, and the management of the number of classified light emitting diodes, etc., are simultaneously performed simultaneously. .

(4-2) Example FIG. 2(a) is a diagram showing a first embodiment of the present invention.

An example of measuring the peak wavelength λ2 of a light emitting diode to be measured will be described. 3 drawn from 3 magazines
The light from the light emitting diodes to be measured 2°3.4 passes through the condenser lenses 6.7.8 and 10.11.1, respectively.
The optical fibers 1B, 19.20 enter through the optical fiber input ports 1415, 16 in the optical fibers 1415, 16 in the optical fibers 1415, 16, respectively. The three light emitting diodes 2, 3.4 to be measured are switched at high speed and emit light sequentially, but at a specific point in time, the light from one of the three light emitting diodes is bundled into an optical fiber section. 21 and from the optical fiber exit port 22 to the half mirror 2.
Irradiate 3. The transmitted light from the half mirror 23 passes through the condensing lens 28, enters the color tone measuring section 27, and enters the entrance slit 2.
9 to a collimator mirror 30 (concave mirror), and the reflected light is made into parallel light. The parallel light from the collimator mirror 30 is reflected by the reflective diffraction grating 31.
The reflection angle of the light from 1 changes depending on the wavelength, is reflected by the condensing mirror 32 and irradiates the image sensor 33, and the peak wavelength can be measured. A CCD sensor or the like is used as the image sensor.

On the other hand, the reflected light from the half mirror 23 is reflected by the condensing lens 23.
The solar cell 25 is irradiated through the solar cell 25 to generate a current proportional to the amount of light, which is input to the light intensity measurement result display device 26 to display the light intensity of the light emitting diode to be measured. Since it is the same as the embodiment, the second embodiment will be explained.

FIG. 2(b) is a diagram showing a second embodiment of the present invention.

An example in which color tone is measured using a color sensor will be described.

The light from the reference light emitting diode 1 and the three light emitting diodes to be measured 2°3.4 drawn in from the three magazines passes through condensing lenses 5 and 6.7°8, respectively, and enters the lens barrel 9.1.
Fiber optic entrance in 0.11.12 13.14.15
．． 16 to each optical fiber 17°18, 19.2
Enters 0. The three light-emitting diodes 2.3.4 to be measured and one reference light-emitting diode 1 emit light sequentially with the supply current switched at high speed, but instead of operating the reference light-emitting diode 1 every time in a series of measurements, an appropriate The operations may be performed at intervals. At a specific time, light from one of the four light emitting diodes 1.2.3.4 passes through the bundled optical fiber section 21 and illuminates the half mirror 23 from the optical fiber exit 22. half mirror
The transmitted light from 23 passes through a condensing lens 28 and further illuminates a color sensor 48. In this embodiment, the color sensor 48 uses a monolithic color sensor using a semiconductor pnp structure. The output from the color sensor 48 is
Each current/voltage converter 49 passes through an amplifier 50 and enters a logarithm calculator 70. The output passes through an analog/digital converter 71, undergoes arithmetic processing as described below in an arithmetic unit 72, and is then displayed on a display 73.

Although the color tone measurement may be an absolute value measurement, it is preferable to measure the color tone as a relative value with respect to a reference light emitting diode (reference LED). This is color sensor 48. This is because errors caused by the logarithm calculator 70 and the like, temperature changes, etc. do not directly result in measurement errors.

The measurement sequence is shown in Figure 4. First, a series of measurements begins with a start 1 pulse, which is an optical characteristic measurement start signal for the reference light emitting diode 1 (reference LED). First, a current is supplied to the reference light emitting diode 1 (reference LED) for a short period of time to emit light, and during that time, the color tone of the reference light emitting diode 1 (reference LED) is measured, and the measured value is defined as A.

Next, the light-emitting diode 2 (LED-1) to be measured is measured in the same manner as the reference light-emitting diode 1 (reference LED) using the start 2 pulse as the optical characteristic measurement start signal for the light-emitting diode 2 (LED-1) to be measured. The color tone is measured and the measured value is 81. Then, the difference C4 between A and B is calculated and output.

Next, the start 2 pulse as a light characteristic measurement start signal for the light emitting diode 3 (LED-2) to be measured causes the color tone B2 of the light emitting diode 3 (LED2) to be measured, as in the case of the light emitting diode 2 (LED-1) to be measured.
is measured, and the difference C2 between A and 82 is calculated and output. Similarly, the difference between A and 83 is output for the light emitting diode 4 (LED-3) to be measured. In this way, the plurality of light emitting diodes are sequentially switched and emit light, and the optical characteristics of each light emitting diode are measured each time by the same optical characteristics measuring device.

The light intensity measurement is the same as in the first embodiment (Fig. 2 (a)), but the reflected light from the half mirror 23 passes through the condensing lens 24 and irradiates the solar cell 25, and is proportional to the amount of light. A current is generated and inputted to the photointensity measurement result display device 26. Lenses 5 to 8 and optical fibers 17 to
Since it is not easy to completely equalize the light transmission characteristics of multiple optical systems consisting of 20, etc., it is difficult to make the light transmission characteristics of multiple optical systems completely equal. It is necessary to ensure that the measured values do not differ even if the device is attached.

For this purpose, a gain adjuster 37 is provided, as shown in the detailed view of the photometric result display 26 in FIG. adjusted to show the same measurement value. The details of the gain adjuster 37 are shown in FIG. Reference numeral 36 in FIG. 3 is a measurement range adjuster, and in this example, four measurement ranges can be selected. The gain adjuster 37 can be adjusted for each measurement channel and for each measurement range for each measurement channel, and the adjustment procedure will be explained below. First, a reference light emitting diode is attached to the measurement head of the first channel CHI, and switches 38 and 39 are connected.

Next, a measurement range is determined, for example 9.99 mcd, and the switch 34-A is closed, and the corresponding switch 44-A of the regulator for the measurement channel CHI is closed.

The forward current IF of the reference light emitting diode is set to a predetermined value, and the resistor R3 is adjusted so that the display on the display 46 at this time becomes the predetermined reference value.

Thereafter, corresponding gain adjustment is performed for each measurement channel, that is, the mounting location of the light emitting diode to be measured, and for each measurement range for each measurement channel, using changeover switches 40-41 and 42-43 that operate in the same manner. That is, 99.9mcd of measurement channel CHI
Switches 34-B and 44-B are connected to the measurement range of 999mcd, and switches 34-C and 44-C are connected to the measurement range of 999mcd.

When measuring the light emitting diode to be measured, selector switches 38-
The contacts of the interlocking switches 39, 40, 41, 42, and 43 become connected in chronological order, and the output of each channel becomes a digital signal through the A/D converter 45, and the respective luminous intensity is displayed on the display 46. , and are sent to a sorter (not shown in the drawing) where they are sorted according to quality.

In this way, the three light emitting diodes to be measured are sequentially switched and sequentially emit light, and the light is branched by the half mirror 23 as shown in FIGS. 2(a) and 2(b). Therefore, it is possible to measure the luminous intensity and color tone of each light emitting diode almost simultaneously.

FIG. 5 shows an example of the time course of electrical measurement and optical characteristic measurement for one light emitting diode.

First, IR (reverse current), ■F1 (small current forward voltage), VF2
Electrical characteristics such as (large current forward voltage) and IF (forward current) are measured. Next, we will measure the light characteristics of luminosity and color tone, but in order to remove the influence of external light, we first measure only with external light, then measure the sum of external light and the light emitted from the light emitting diode, and calculate the The optical characteristics of the light emitting diode alone, that is, the luminous intensity and color tone, are simultaneously measured by the above-described procedure while removing the influence of external light.

Figure 6 shows the start 1 pulse, which is the optical characteristic measurement start signal to the reference light emitting diode, which is fixed regardless of the machine transport during color tone measurement, and the optical characteristic measurement start signal to the three sighting diodes to be measured. This is a timing diagram of a certain start 2 pulse.

Figure 7 shows the details of the measurement time of about 0.65 seconds in Figure 6, and shows the electrical characteristics such as IR + VFII Vyz + It, the temporal relationship between the measurement of luminous intensity and color tone, and the optical characteristics for the light emitting diode to be measured. The timings of the start 2 pulse, which is the measurement start signal, and the measurement END pulse are also shown.

FIG. 8(a) shows the method of the first embodiment of the present invention; FIG.
b) shows the operating time of each measuring device in a three-head parallel drive system using one electrical measuring device and three optical property measuring devices. From FIGS. 8(a) and 8(b), the operating times of the electrical measuring device and the optical characteristic measuring device can be seen in comparison. The method shown in FIG. 8(b) requires three optical characteristic measuring instruments, whereas the method shown in FIG. 8(a) uses an optical fiber to collect the light from the light emitting diode to be measured at one location. Therefore, it can be seen that only one expensive optical property measuring instrument is required.

Figure 9 shows the single head system and the 3 method explained in Figure 8 (g)).
This is a comprehensive comparison of the timing diagrams of the head parallel drive systems. The processing time is approximately 173, indicating that the measurement time can be significantly shortened.

From FIG. 8 and FIG. 9, it can be seen that by adopting the embodiment method of the present invention, it can be operated in a short measurement time like the 3-head parallel drive method, and moreover, only one optical property measuring device is required. .

The mechanical movement of the light emitting diode to be measured when measuring the characteristics of a light emitting diode using a lead frame using the apparatus of the present invention is as follows.

A magazine containing light-emitting diodes using a lead frame is attached to a magazine tray, the magazine tray is automatically transported to a predetermined position, and the light-emitting diodes to be measured are simultaneously drawn into each channel from the magazine and transferred to the measuring section by intermittent feeding. After being transported to the cutting section and cut, the lead frame is placed in a lead frame storage box. Further, the separated light emitting diodes are classified and stored according to the measurement results. When the number of light emitting diodes reaches a predetermined value, the shutter of the storage box is opened, and the bags are packed by a bagging machine and stored in the bag storage box.

(5) Effects of the Invention When measuring the optical characteristics of a light-emitting diode, conventionally, one light-emitting diode to be measured was measured using one optical characteristic measuring device. If measurements are performed using multiple lines and multiple heads, the number of processes per unit time can be increased, but this requires multiple expensive optical property measuring instruments. If the light from a plurality of light emitting diodes is combined into one place using an optical fiber as in the present invention, and a single optical characteristic measuring device is used, a special effect that leads to a significant cost reduction can be obtained.

Furthermore, since photometric measurement and color tone measurement can be performed simultaneously, processing capacity is improved.

Conventionally, light emitting diodes were shipped without color tone measurement being performed on all the light emitting diodes mainly due to inspection costs, but by incorporating this technology into the production line, it becomes possible to perform color tone measurement on all light emitting diodes before shipping. By measuring the color tone of all light emitting diodes before shipping, when the light emitting diodes are arranged in a bar or panel shape, it is possible to eliminate variations in color tone as seen by the human eye.

[Brief explanation of the drawing]

Figure 1 shows a conventional light emitting diode test device, Figure 2 (a)
is a block diagram of the first embodiment of the present invention, FIG. 2(b) is a block diagram of the second embodiment of the present invention, FIG. 3 is an explanatory diagram of a gain adjuster used in the present invention, and FIG. 5 is a timing diagram for measuring the characteristics of one light emitting diode according to the present invention. FIG. 6 is a timing diagram of a measurement start pulse when measuring color tone according to the present invention. Figure 7 is a diagram showing details of one measurement cycle according to the present invention, Figures 8 (a) and (b)
9 is a comparison of the timing diagrams of the electrical characteristic measuring device and the optical characteristic measuring device using the method of the first embodiment of the present invention and the three-head parallel driving method, and FIG. 9 is a timing diagram of the three-head parallel driving method and the single head method. It is a diagram. 1... Reference light emitting diode, 2.3.4... Light emitting diode to be measured, 5.6.7.8... Condenser lens,
9, 10. IL 12... Lens barrel, 13.14.1
5.16...Optical fiber entrance, 17.18.19.
20... Optical fiber, 21... Bundled optical fiber portion, 22... Optical fiber exit, 23... Half mirror 24... Condensing lens, 25... Solar cell,
26... Photometric measurement result display device, 27... Color tone measurement section, 28... Condensing lens, 29... Incident slit, 30... Collimator mirror 31... Reflection type diffraction grating, 32... ...Condenser mirror 33...Image sensor, 34-A, 34-B, 34-C, 34
D...Switch, 36...Measurement range adjuster, 37
...Gain adjuster, 3B, 39.40.41.42
．． 43... switch, 44-A, 44-B, 44-
C, 44-D...Switch, 45...A/D converter, 46...Display device, 48...Color sensor, 49...Current/voltage converter, 50...Amplifier, 5L 52.53...Magazine, 54...Magazine tray 55.56.57...Measurement channel, 58.59.60...Measurement section, 61.62゜6
3... Cutting section, 64... Sorter 65.66
, 67... Product storage box, 68... Lead frame storage box, 70... Logarithm calculator, 71... Analog/digital converter, 72... Arithmetic unit, 73...
·display.

Claims (4)

[Claims] (1) The light-emitting diodes to be measured are supplied to multiple measurement heads in parallel by multiple conveyance lines, and are made to emit light sequentially in time series, and the emitted light passes through each optical fiber corresponding to each measurement head. concentrated in one place, 1
A light emitting diode testing device characterized in that the optical characteristics of a plurality of light emitting diodes can be measured using a single optical characteristic measuring device. (2) The light concentrated in one place by an optical fiber is split into two by a half mirror, and the luminous intensity and color tone of each branched light are measured simultaneously in claim (1).
) Light emitting diode test device described in . (3) means for measuring the color tone A of the reference light emitting diode using a specific light emitting diode as a reference light emitting diode;
means for measuring the color tone B_1 of a first light-emitting diode to be measured and then determining the difference between A and B_1; means for measuring the color tone B_2 of the second light-emitting diode to be measured and then determining the difference between A and B_2; Color tone B_3 of third light emitting diode to be measured
means for determining the difference between A and B_3 by measuring the color tone B_n of the nth light emitting diode to be measured; Claim (1) further comprising: means for specifying the measurement start time of each color tone of the light emitting diode to be measured.
Light emitting diode test equipment as described. (4) According to claim (1), each measurement head is provided with a gain adjuster so that the same measurement result can be obtained no matter in which measurement head the n light emitting diodes to be measured are placed. Light emitting diode test equipment.