JP2010139268A - Pattern light emitting device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a pattern light emitting device for measuring a three-dimensional shape for which working of manufacturing such as wiring is less troublesome. <P>SOLUTION: An LED chip includes an element array having a plurality of string LED elements arranged in a direction perpendicular to an extending direction of the elements. The element array is produced by a semiconductor process. Each of the string LED elements has a p-side electrode 108 extending like a string and the electrodes are separated by element separation grooves 110 from one another. The string LED elements are formed on a common substrate 120 and an n-side electrode 130 commonly used by all of the elements is formed at the lower side of the substrate 120. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a pattern light emitting device that emits pattern light for three-dimensional shape measurement.

  A system (also called an active range finder) that measures the three-dimensional position of each point on the surface of an object by the active stereo method has become widespread. In this type of system, light is projected onto an object in order to specify a point on the surface of the object, and the object in a state where the light is projected is photographed with a camera. For example, in the light cutting method, an object is scanned with slit light formed by a laser light source or the like. In the spatial encoding method and the phase shift method, for example, a striped pattern light is formed by a light source and a liquid crystal shutter and projected onto an object.

  However, the method of scanning the slit light increases the size of the light source unit due to the scanning mechanism. In addition, even in a method in which pattern light is formed by a light source and a liquid crystal shutter, it is necessary to provide a certain distance from the light source to the liquid crystal shutter.

  On the other hand, Patent Document 1 discloses a pattern light emitting device in which light emitting diode (LED) elements functioning as point light sources are arranged in a matrix. In this apparatus, pattern light is formed by controlling the light emission intensity for each column of LED elements.

JP 2002-195812 A

  However, in the case of a light-emitting device in which LED elements that function as point light sources are arranged in a matrix, it is complicated to connect a large number of LED elements to a substrate during manufacturing.

  The present invention relates to a pattern light emitting device that emits pattern light for measuring a three-dimensional shape, in which a linear light emitting diode having a linear light emitting layer is perpendicular to the extending direction of the linear light emitting diode. Further, there is provided a pattern light emitting device comprising a plurality of light emitting array units arranged and a switching circuit for switching each linear light emitting diode of the light emitting array unit according to a predetermined switching pattern.

  In one aspect, the continuous electrode is formed in the surface of each said linear light emitting diode over the substantially full length of the extending | stretching direction of the said linear diode, respectively.

  In a further preferred aspect, the plurality of linear light emitting diodes are formed on one surface of a common substrate, and an electrode common to the plurality of linear light emitting diodes is formed on the other surface of the substrate. ing.

  ADVANTAGE OF THE INVENTION According to this invention, the pattern light generator with little complexity of manufacturing work, such as wiring, can be provided.

  Embodiments of a patterned light emitting device according to the present invention will be described below with reference to the drawings.

  In this embodiment, the LED chip 10 shown in FIG. 1 is used as a pattern light source for three-dimensional shape measurement. The LED chip 10 includes an element array in which a plurality of linear light emitting diode (hereinafter “LED”) elements 100 are arranged along a direction Q perpendicular to the extending direction P (that is, a line extending direction) P of the diode 100. . The number of linear LED elements 100 formed in one chip is, for example, 128 (however, this is only an example). The linear LED element 100 has, for example, a width of about 0.2 mm and a length of about 10 mm (however, this is only an example).

  A top view of the corner portion R of the LED chip 10 is shown in FIG. As shown in this figure, the individual linear LED elements 100 are separated from each other by element separation grooves 110. As elements constituting the linear LED element 100, FIG. 2, which is a top view, shows the top surfaces of the linear p-side electrode 108 and the p-type semiconductor layer 102. The p-side electrode 108 extends continuously over almost the entire length of the linear LED element 100, and a pad portion 108a for wire bonding is formed at the end thereof. The pad portion 108a is connected to the control circuit by wire bonding.

  In the illustrated example, the pad portions 108a of the p-side electrodes 108 of all the lines are provided on the same side (lower side in the figure), but this is only an example. Instead, for example, the pad portion 108a may be provided at the upper end of the odd-numbered line and the lower end of the even-numbered line may be provided at the lower end. Alternatively, pad portions 108a may be provided at both ends of the p-side electrode 108, and the same power supply voltage may be applied to both pad portions 108a. Since the potential at each position along the longitudinal direction of the linear p-side electrode 108 decreases according to the distance from the pad portion 108a to which the power supply voltage is applied, the emission intensity also decreases accordingly. If the power supply voltage is applied from both sides of the p-side electrode 108, the difference in potential at each position of the electrode 108 can be reduced and the variation in emission intensity can be reduced compared to the case where the power supply voltage is applied from one side.

  FIG. 3 shows a portion where four linear LED elements 100 are arranged in the cross section taken along the line AA in FIG. As shown in FIG. 3, the substrate 120 of the LED chip 10 is based on the substrate 120. The material of the substrate 120 is not particularly limited. For example, a material such as GaAs (gallium arsenide) may be used.

  An n-side electrode 130 is formed over the entire surface of the substrate 120. The n-side electrode 130 is a common electrode for all the linear LED elements 10.

  On the other surface of the substrate 120, an n-type semiconductor layer 106, a light emitting layer 104, and a p-type semiconductor layer 102 are stacked in the order closer to the substrate 120. A plurality of linear p-side electrodes 108 are formed on the p-type semiconductor layer 102. One p-side electrode 108 is provided for each linear LED element.

  The n-type semiconductor layer 106, the light emitting layer 104, and the p-type semiconductor layer 102 are separated for each element by an element isolation groove 110. In the illustrated example, the element isolation trench 110 has a depth from the upper surface of the p-type semiconductor layer 102 to the middle of the n-type semiconductor layer 102, but this is only an example. The depth of the element isolation groove 110 may be equal to or greater than the depth at which the light emitting layer 104 is completely cut.

  The materials of the n-type semiconductor layer 106, the light emitting layer 104, and the p-type semiconductor layer 102 are not particularly limited due to the configuration of this embodiment. Various things normally used for LED can be used. The n-side electrode 130 and the p-side electrode 108 may be formed of a material (for example, gold) that is usually used for an LED electrode.

  An example of the manufacturing procedure of such LED chip 10 is shown in FIG.

  (A) First, an n-side electrode 130 is formed on one surface of a wafer-shaped substrate 120 by gold vapor deposition or the like, and an LED operation layer is formed on the other surface of the substrate 120 by a technique such as an epitaxial crystal growth method. That is, the n-type semiconductor layer 106, the light emitting layer 104, and the p-type semiconductor layer 102 are formed in this order from the bottom (that is, from the substrate 120 side).

  (B) Next, a plurality of linear p-side electrodes 108 arranged at predetermined intervals are formed on the upper surface of the p-type semiconductor layer 102 by a method such as gold vapor deposition. If the p-side electrode 108 is a transparent electrode, the light emitting area of the linear LED element 100 can be increased as compared with the case where an opaque electrode such as gold is used. A known transparent conductive material may be used for the transparent electrode.

  (C) Then, an element isolation groove 110 is formed by dicing cut. The element isolation trench 110 is formed to a position deeper than the light emitting layer 104. However, the n-side electrode 130 is not cut.

  After element isolation is performed in this manner, a protective film is formed on the entire wafer (excluding the portions of the electrodes 108 and 130) and cut for each chip size. Then, the LED chip 10 is completed by connecting the n-side electrode 130 and the p-side electrode 108 of the chip thus formed to the control circuit by wire bonding.

  Next, an example of a configuration for controlling the light emission pattern of the LED chip 10 will be described with reference to FIG.

  The example of FIG. 5 is a circuit configuration that can be used for three-dimensional shape measurement by the phase shift method. In the figure, only 16 of the linear LED elements 100 on the chip 10 are shown to avoid complexity.

  One terminal of each linear LED element 100 is connected to the power supply Vcc, and the other terminal is connected to the ground via the switches sw0, sw1, sw2,. Each of the switches sw0, sw1, sw2,..., Sw7 is connected to every eight elements in the element array. The adjacent switches sw0, sw1, sw2,..., Sw7 are connected to the adjacent elements 100 in the element array. For example, sw0 is connected to the 8,100,..., 8nth element 100 (n is a natural number) from the left, and sw1 is connected to the 7,15,..., (8n-1) th element 100 from the left.

  The switches sw0, sw1, sw2,..., Sw7 are on / off controlled by the control circuit 200. An example of the switching pattern of these switches for the phase shift method is shown in FIG.

  The switching pattern of this example repeats four time phases I, II, III, and IV. Each time phase pattern is a periodic pattern that is alternately turned on / off every two lines (ie, two elements) of the element array, and the periodic pattern is one line per time phase, ie, π / 2. Moving. For example, in time phase I, switches sw0 and sw1, and sw4 and sw5 are turned on and the remaining switches are turned off. In time phase II, switches sw1 and sw2, sw5 and sw6 are turned on and the remaining switches are turned off.

  FIG. 6B shows a light emission pattern of the element array in each time phase, and FIG. 6C shows a projection pattern of pattern light projected on a plane according to the light emission pattern in each time phase. The light emission pattern is a distinct on / off pattern in units of lines, that is, two adjacent linear LED elements 100, but when it is projected, the on / off pattern becomes dull due to the spread of the light emission itself. Thus, a light intensity distribution close to a sine curve can be obtained.

  In the phase shift method, a fringe pattern light having a sine-like intensity distribution is typically projected onto a target, and the pattern light is photographed with a camera while shifting the phase by π / 2, and photographed at each time phase. The depth information of the object is obtained from the image. The apparatus illustrated in FIGS. 5 and 6 can project pattern light that can be used in such a phase shift method.

  Since the phase shift method itself is a well-known method, description thereof is omitted. If necessary, Japanese Patent Application Laid-Open No. 06-109438, Ryosuke Mitaka and Nagao Hamada “High-speed and high-accuracy three-dimensional measurement technology using the phase shift method” Matsushita Electric Works Technical Report (Aug. 2002) pp.10-15, 2002 Please refer to August (http://www.mew.co.jp/tecrepo/78j/pdfs/78_02.pdf).

  The embodiment of the present invention has been described above. Since the pattern light generator of this embodiment is an array of linear LED elements 100 formed by a semiconductor process, the manufacturing and wiring are less complicated than a light source in which LED elements of point light sources are arranged in a matrix. When a large number of LED elements of individual point light sources are used, the emission intensity distribution becomes irregular for each line due to variations in the characteristics of the individual elements. In this embodiment, the linear LED element 100 formed by a semiconductor process is used. Therefore, such line-by-line variations are not great. In addition, since the n-side electrode 130 is shared by all the linear LED elements 100, wiring and other configurations for the n-side electrode 130 can be simplified.

  In this embodiment, a light emission pattern for the phase shift method can be generated by relatively simple wiring and control.

  In addition, the application destination of the LED chip 10 of the said embodiment is not necessarily restricted to a phase shift method. Those skilled in the art will readily understand that although the wiring and switching logic are somewhat complicated, binary code patterns and gray code patterns for spatial coding methods can also be generated.

It is a perspective view which shows typically schematic structure of the LED chip of embodiment. It is a partial top view of the LED chip of embodiment. It is a fragmentary sectional view of the LED chip of an embodiment. It is a figure which shows an example of the manufacturing process of the LED chip of embodiment. It is a figure which shows an example of the structure for the light emission pattern control of the LED chip of embodiment. It is a figure for demonstrating the on / off control pattern of a switch, the light emission pattern of the element array corresponding to this, and the projection pattern of the light emitted from the element array.

Explanation of symbols

  10 LED chip, 100 linear LED element, 102 p-type semiconductor layer, 104 light emitting layer, 106 n-type semiconductor layer, 108 p-side electrode, 110 element isolation groove, 120 substrate, 130 n-side electrode.

Claims (3)

A pattern light emitting device for emitting pattern light for three-dimensional shape measurement,
A light-emitting array portion formed by arranging a plurality of linear light-emitting diodes having a linear light-emitting layer in a direction orthogonal to the extending direction of the linear light-emitting diodes;
A switching circuit that switches the linear light emitting diodes of the light emitting array unit according to a predetermined switching pattern;
A pattern light emitting device comprising:   2. The pattern light emitting device according to claim 1, wherein an electrode is formed on the surface of each linear light emitting diode so as to be continuous over substantially the entire length in the extending direction of the linear diode.   The plurality of linear light emitting diodes are formed on one surface of a common substrate, and an electrode common to the plurality of linear light emitting diodes is formed on the other surface of the substrate. The patterned light-emitting device according to claim 2.

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