GB2192753A - Light emitting diode device - Google Patents
Light emitting diode device Download PDFInfo
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- GB2192753A GB2192753A GB8715536A GB8715536A GB2192753A GB 2192753 A GB2192753 A GB 2192753A GB 8715536 A GB8715536 A GB 8715536A GB 8715536 A GB8715536 A GB 8715536A GB 2192753 A GB2192753 A GB 2192753A
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- 239000004065 semiconductor Substances 0.000 claims description 44
- 239000002184 metal Substances 0.000 claims description 23
- 229910052751 metal Inorganic materials 0.000 claims description 23
- 230000005540 biological transmission Effects 0.000 claims description 5
- 230000003287 optical effect Effects 0.000 description 12
- 229910001218 Gallium arsenide Inorganic materials 0.000 description 8
- 238000009792 diffusion process Methods 0.000 description 7
- 239000004020 conductor Substances 0.000 description 5
- 230000000694 effects Effects 0.000 description 5
- WABPQHHGFIMREM-UHFFFAOYSA-N lead(0) Chemical compound [Pb] WABPQHHGFIMREM-UHFFFAOYSA-N 0.000 description 5
- 230000001678 irradiating effect Effects 0.000 description 4
- 230000001105 regulatory effect Effects 0.000 description 4
- 238000006073 displacement reaction Methods 0.000 description 3
- PCHJSUWPFVWCPO-UHFFFAOYSA-N gold Chemical compound [Au] PCHJSUWPFVWCPO-UHFFFAOYSA-N 0.000 description 3
- 239000010931 gold Substances 0.000 description 3
- 229910052737 gold Inorganic materials 0.000 description 3
- 238000000034 method Methods 0.000 description 3
- 239000003795 chemical substances by application Substances 0.000 description 2
- 238000000151 deposition Methods 0.000 description 2
- 230000005284 excitation Effects 0.000 description 2
- 238000004519 manufacturing process Methods 0.000 description 2
- 238000004544 sputter deposition Methods 0.000 description 2
- 239000000758 substrate Substances 0.000 description 2
- 241000792765 Minous Species 0.000 description 1
- 101100400378 Mus musculus Marveld2 gene Proteins 0.000 description 1
- VRDIULHPQTYCLN-UHFFFAOYSA-N Prothionamide Chemical compound CCCC1=CC(C(N)=S)=CC=N1 VRDIULHPQTYCLN-UHFFFAOYSA-N 0.000 description 1
- 229910052581 Si3N4 Inorganic materials 0.000 description 1
- 239000011248 coating agent Substances 0.000 description 1
- 238000000576 coating method Methods 0.000 description 1
- 238000001514 detection method Methods 0.000 description 1
- 230000008030 elimination Effects 0.000 description 1
- 238000003379 elimination reaction Methods 0.000 description 1
- 230000008020 evaporation Effects 0.000 description 1
- 238000001704 evaporation Methods 0.000 description 1
- 230000004927 fusion Effects 0.000 description 1
- 238000003754 machining Methods 0.000 description 1
- 150000004767 nitrides Chemical class 0.000 description 1
- 229920000136 polysorbate Polymers 0.000 description 1
- 230000000007 visual effect Effects 0.000 description 1
Classifications
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
- H01L33/00—Semiconductor devices having potential barriers specially adapted for light emission; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof
- H01L33/36—Semiconductor devices having potential barriers specially adapted for light emission; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof characterised by the electrodes
- H01L33/38—Semiconductor devices having potential barriers specially adapted for light emission; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof characterised by the electrodes with a particular shape
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01D—MEASURING NOT SPECIALLY ADAPTED FOR A SPECIFIC VARIABLE; ARRANGEMENTS FOR MEASURING TWO OR MORE VARIABLES NOT COVERED IN A SINGLE OTHER SUBCLASS; TARIFF METERING APPARATUS; MEASURING OR TESTING NOT OTHERWISE PROVIDED FOR
- G01D5/00—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable
- G01D5/26—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable characterised by optical transfer means, i.e. using infrared, visible, or ultraviolet light
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
- H01L2924/00—Indexing scheme for arrangements or methods for connecting or disconnecting semiconductor or solid-state bodies as covered by H01L24/00
- H01L2924/0001—Technical content checked by a classifier
- H01L2924/0002—Not covered by any one of groups H01L24/00, H01L24/00 and H01L2224/00
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- Engineering & Computer Science (AREA)
- Manufacturing & Machinery (AREA)
- Computer Hardware Design (AREA)
- Microelectronics & Electronic Packaging (AREA)
- Power Engineering (AREA)
- Physics & Mathematics (AREA)
- General Physics & Mathematics (AREA)
- Optical Transform (AREA)
Description
GB2192753A 1 SPECIFICATION given to the light emitting diode device itself
in connection with this problem.
Light emitting diode device In particular, with a light emitting diode used for an indicator or the like, an appropriate dif The invention relates to a light emitting diode 70 fusion of light is rather desirable to enlarge device, and to photoelectric encoders incorpo- the visual field of the indicating light and be rating such diode devices. cause of this no consideration has convention Light emitting diodes, also known as photoally been given to regulation of the bundles of electric transducers, are widely used for vari- irradiating rays.
ous kinds of indicators and photoelectric sen- 75 On the other hand, a photoelectric sensor is sors. required to have a sharply converged light Of such light emitting diodes, diodes emitt- beam. Conventionally, the bundles of rays are ing visible light are used mainly for indicators, regulated outside the light emitting diode by and infrared diodes are mainly used for photo- providing a guide hole on the base substrate sensors such as photocouplers and photointer- 80 on which the light emitting diode is fixed. Al rupters. Various other kinds of light emitting ternatively, it is possible to obtain optical diodes are used for various purposes. beams sharply concentrated to a desired de In the accompanying drawings, Fig. 6 is a gree by using a collimator lens or the like.
perspective view showing a typical conven- However, light emitting diodes have recently tional semiconductor junction light emitting di- 85 been used for photoelectric sensor of very ode. Two semiconductor layers 10 and 12 high accuracy. This use has resulted in a having opposite polarities are placed one on problem because operation on the light beam top of the other, and a desired light emitting outside the light emitting diode to effect con function is obtained at the juncture of the vergence does not produce a desired resolu- layers 10 and 12. The first semiconductor 90 tion. In order to obtain a sufficiently high reso layer 10 is composed of a P-type GaAs semi- lution, it is necessary to design an external conductor, and the second semiconductor connected appliance, such as a collimator layer 12 is composed of an N-type GaAs lens, so that it has a long focal length, semiconductor, both having the form of thereby disadvantageously increasing the size square thin layers. 95 of the photoelectric sensor as a whole.
Metal film electrodes 14 and 16 are pro- Fig. 7 of the accompanying drawings shows vided on the exposed end surfaces of the a schematic perspective view of a. photoelec semiconductor layers 10 and 12 respectively, tric linear encoder given as an example of by evaporation or other suitable method. A such a high-accuracy photoelectric sensor.
high-voltage side lead wire 18 is connected to 100 The linear encoder of Fig. 7 includes a mea the electrode 14, and a low-voltage side lead suring grid 22 and a reference grid 24, both wire 20 is connected to the electrode 16. grids 22 and 24 having light transmission por Both metal film electrodes 14 and 16 are tions and light shielding portions arranged at a composed of a gold deposited film. predetermined grid pitch. Thus, if either of the Holes and electrons injected from the lead 105 grids 22 and 24 is moved in accordance with wires 18 and 20 respectively, are combined at a length to be measured, the device measures the junction of the semiconductor layers 10 the length in terms of the amount of relative and 12, where the electron excitation energy displacement of the grids.
produced causes a light emitting phenomenon. In order to electrically detect the amount of The metal film electrode 14 is provided subrelative displacement of the grids, a light em stantially in the shape of a cross in order to itting diode 100, which can correspond to the effectively inject holes, and the light emitted light emitting diode of Fig. 6, is provided on at the junction is projected upward from the one side of the pair of grids 22 and 24, and end surface of the semiconductor layer 10 as the irradiating light thereof is converged into a indicated by the arrow A. A desired indication 115 light beam by a collimator lens 26, being or photoelectric detection is enabled by use of thereafter transmitted through both grids 22 the light projected in this way. and 24.
In this conventional device, however, the On the other side of the grids 22 and 24, a light from the diode is projected outwardly photo detector 27, for example, a photo tran- from the end surface of the semiconductor 120 sistor, electrically detects a change in the layer 10 and the bundle of rays is rather apt brightness of the light transmitted through the to diffuse, so that it is difficult to obtain a grids and supplies a resultant electrical signal sharply converged light beam. Conventionally, through a preamplifier 28 to an external pro the only measure for solving the problem of cessing circuit.
diffusion of the emitted light from a light em- 125 Fig. 8 shows that the waveform of the out itting diode comprises condensing the rays put signal of the preamplifier 28 can be sub into light beams having a desired optical dia- stantially a sine wave related to the relative meter through a guide or a collimator lens displacement of the grids 22 and 24. The ex provided on an optical path on which the light ternal processing circuit can measure the dis- is to be directed. No consideration has been 130 placement to an accuracy determined by the I 2 GB2192753A 2 grid pitch and the number of divisions of the cerned with the reduction or elimination of the processing circuit by counting the sine wave abovedescribed problems with the prior art cycles. and with the provision of an improved light The waveform of Fig. 8 shows the output emitting diode which is capable of producing signal as comprising a DG component and an 70 light with little diffusion and which is easily AG component. In such a linear encoder, it is sharply converged by control of the light in desired that the ratio of the signal compo- the light emitting diode itself ' nents be a predetermined value, ordinarily not The present invention accordingly provides a less than -1.0". In other words, unless the light emitting diode in which an opening is ratio of the AC to the DC components is 75 provided at the central portion of the metal AC/DG > 1.0, it is impossible to carry out a film electrode on the side of projected light good measuring operation. beam, so as to restrict the cross-section of It is also known that this ratio depends on the bundles of light rags emitted therethrough.
the gap G between the grids 22 and 24. Fig. The present invention also provides a light 9 shows by the characteristic curve 200 how 80 emitting diode in which the junction of the the grid gap G varies with respect to the semiconductor layers, at which is effected the AG/DG ratio. As is clear from Fig. 9, it is light emitting operation of the diode, is ex conventionally necessary to-make the grid gap posed at the end surface of one of the layers G very narrow. For example, if the grid pitch and in that the junction has a predetermined is set at about 20 um, including a transmis- 85 configuration such as to control the configura sion portion/shielding portion width of 10 tion of the projected light beams.
Itm/10 um, it is the grid gap at not more than The present invention furthermore provides um. This means that it is necessary to a light emitting diode for a photoelectric enco support both grids 22 and 24 very precisely der comprising a measuring grid and a refer so as to be secured and slidable, so that 90 ence grid which are relatively movable in ac much care is required in machining -and as- cordance with the length of an object to be sembling the parts. measured and which have measuring slits for The present inventor has found that the grid light transmission or reflection arranged in gap G has a relation to the optical diameter of alignment on the surfaces thereof, a light em the light beam projected to the grids 22 and 95 itting diode disposed on one side of the grids 24, and has come to the conclusion that if for projecting light onto the measuring slit, the light beams are sufficiently concentrated and a photo detector disposed on the side of so as to have a small optical dimension or the grids remote from the light emitting diode diameter, it is possible to set the grid gap G for receiving transmitted or reflected light from less stringently. 100 the measuring slits, the light emitting diode The focal length F of the collimator lens 26 having a slit-shaped light emitting portion dis has a relationship with the concentration of posed so that the longitudinal direction thereof the light beam, as is known. As appears from corresponds to the longitudinal direction of the Fig. 10, the irradiating light projected from the measuring slits of the grids.
light emitting diode 100 is converged through 105 The invention will thus be seen to provide a the collimator lens 26 as indicated by the ar- light emitting diode device which has an im rows. The diffusion angle 0 of the light beams - proved structure to effect regulation or control is represented by the following formula, in of the emitted light to a predetermined confi which D is the diameter of the radiating surguration, which may comprise a bundle of face: 110 rays having a restricted diameter or dimension so as to be suitable in particular for use in a 0 = D/F photoelectric encoder. - Fig. 1 is a perspective view of an illustrative It will be understood that in order to make the light emitting diode embodying the present in diffusion angle small enough to obtain a suffi- 115 vention, in the shape of a thin square layer, as ciently long parallel beam, it is necessary is the diode shown in Fig7. 6.
either to make the diameter D of the light The light emitting diode of Figure 1 has emitting surface small or to make the focal semiconductor layers 30 and 32 of opposite length F long. polarities, with one layer placed on top of the However, the diameter of the surface D of 120 other to form a function surface for light emis the diode 100 is determined by the external sion therebetween. In this embodiment, the configuration of the semiconductor layers first semiconductor layer 30 consists of a P which constitute the diode, as-described type GaAs, the second semiconductor layer above. Consequently, it is conventionally 32 consists of an N-type GaAs, and near- necessary to make the focal length F of an 125 infrared light is mainly emitted, but it will be appropriate length, which brings about the dis- understood that GaP, (GaAI)As, etc. as well advantage of a light projecting portion which as GaAs can be used in the present invention is inconveniently large with respect to the as the semiconductors, and that it is possible grids 22 and 24. to effect emission of visible light, if desired. It The present invention is accordingly con- 130 is also possible to arrange the semiconductor 3 GB2192753A 3 - layers 30 and 32 so as to have reversed po- mensions of about 400 X 400 pm, and the larities, namely, N-type and P-type respecopening 34a is formed on the end surface of tively. the semiconductor layer 30 so as to have a Metal film electrodes 34 and 36 are pro- slit width W of 50 urn and a slit length L of vided on the exposed end surfaces of the 70 300pm.
semiconductor layers 30 and 32 respectively. Fig. 2 of the accompanying drawings is a In this embodiment, the metal film electrodes perspective view of the light emitting diode of 34 and 36 are formed by depositing gold, but Fig. 1 in use as part of a photoelectric linear they may be formed by sputtering or any encoder. This encoder has a structure similar other suitable method. 75 to that of the conventional device shown in A high-voltage side lead wire 38 and a low- Fig. 7, with a measuring grid 22 and a refer voltage side lead wire 40 are connected to ence grid 24 which are relatively movable in the metal film electrodes 34 and 36, respecaccordance with the length of an object to be tively, by bonding, and holes and electrons measured. When a light beam passes through are injected to the semiconductor layers 30 80 optical slits formed on the grids 22 and 24, and 32, respectively, through these elec- the change in the brightness is electrically de trodes. tected, whereby the amount of relative dis The injected holes and electrons are recom- placement of the grids 22 and 24 is mea bined at the junction surface of the semiconsured.
ductor layers 30 and 32, at which time the 85 The light beams are projected from a light electron excitation energy causes light emisemitting diode 100 and converged through a sion at a predetermined frequency. In this em- collimator lens 26. The light receiver consists bodiment, near-infrared light is emitted. of a photo detector 27 such as a photo tran One metal film electrode 34, that is, the sistor, and an electrical sigQai detected metal film electrode on the side from which 90 thereby is.supplied through a preamplifier 28 the emitted light is projected regulates the to an external processing circuit.
bundles of the light rays which are to be pro- As will be clear from Fig. 2, the opening jected outwardly of the light emitting diode. 34a of the light emitting diode 100 has a slit For this purpose, the metal film electrode 34 shape, the slit being arranged in alignment has an opening 34a of a predetermined confi- 95 with the optical grids of the measuring grid 22 guration at the central region thereof. and reference grid 24.
The light emitted from the junction surface 8ince the width of the opening 34a which is therefore projected outward through the corresponds to the direction X of the scale opening 34a of the metal film electrode 34, movement and which has influence on the and the configuration of the projected bundles 100 resolution of the encoder is short, the dia- of the light rays is determined by the configu- meter D of the light beams in the direction X ration of the opening 34a. of the scale movement is controlled to be The metal film electrode 36 on the other very small in the present invention, as will be side covers the entire end surface of the sem- clear from the diffusion angle 0 in Fig. 10.
iconductor layer 32, and the side surfaces of 105 More specifically, since the slit width of the the semiconductor layers 30 and 32 are thin opening 34a is about 50 pm in this embodi and orthogonal to the junction surface. Conse- ment, the diameter D of the light beam is quently, only a slight amount of the emitted reduced to 1/8th of the conventional dia light leaks out from these surfaces, and it is meter, so that it is possible to greatly reduce possible to effectively project the light emitted 110 the diffusion angle 0 or to shorten the focal at the junction surface through the opening length F of the collimator lens 26.
34a in the metal film electrode 34 to the out- Thus, as indicated in Fig. 2, it is possible to side. Needless to say, it is also preferable to greatly reduce the size of the light projector of shield the side surfaces from light by applying a linear encoder by using the light emitting thereto a black coating, or the like. 115 diode of Figure 1.
In the present invention, the- opening 34a In Fig. 2, the opening 34a in this embodi- may have any given configuration, for example ment has a sufficiently long length in the long a circular, rectangular or slit shape depending itudinal direction Y of the optical slits. In the on the intended purpose of the diode. case of a linear encoder, ffle length in the The light emitting diode shown in Fig. 1 is 120direction Y has no influence on the resolution.
formed for use in a photoelectric linear enco- It is rather necessary to have an opening in der. Therefore, the light beam in cross-section the longitudinal direction Y of the optical slit preferably has a long and narrow slit shape, which is sufficiently large to secure an ade and for this purpose, the opening 34a is quate quantity of light. Thus, the embodiment formed on the end surface of'the semiconduc- 125 shown in Figs. 1 and 2 is very useful because tor layer 30 so as to be narrow, and to exit provides sharply condensed light beams in tend along a diagonal thereof. the direction X of the scale movement while The upper and lower surfaces of the semi- securing an adequate quantity of light.
conductor layers which constitute the light Fig. 3 is a perspective view of another form emitting diode in this embodiment have di- 130 of light emitting diode embodying the present 4 GB2192753A 4 invention. A first semiconductor layer 130 and embodiment emits mainly near-infrared light, a second semiconductor layer 132 are com- but it will be evident that in the present inven posed of P-type and N-type semiconductor tion GaP, (GaAI)As, etc. as well as GaAs are layers, respectively. The upper and lower end usable as the semiconductors, and that it is surfaces of the semiconductor layers 130 & 70 possible to emit visible light, if necessary. It is 132 are rectangular and have dimensions of also possible to choose the semiconductor about 200 x 800 um, and an opening 134a layers 230 and 232 with reversed polarities, is formed in a metal film electrode 134 hownamely, N-type and P-type, respectively.
ever so as to extend in the longitudinal direc- Metal film electrodes 234 and 236 are pro- tion of the surfaces rather than diagonally as 75 vided on the end surfaces of the semiconduc in the first embodiment. tor layers 230 and 232, respectively. The Such a rectangular substrate is very useful metal film electrodes 234 and 236 are formed for a light emitting diode for projecting long by depositing gold, but they may be formed and narrow slit light beams. by sputtering or any other methods, if pre- In this way, according to the present inven- 80 ferred.
tion, it is possible to adequately condense the A high-voltage side lead wire 238 and a light beams from the light projector, thereby low-voltage side lead wire 240 are connected - advantageously enabling the gap G between to the metal film electrodes 234 and 236 re the grids 22 and 24 to be made compara- spectively by bonding, and holes and elec- tively large in, for example, the photoelectric 85 trons are injected to semiconductor layers 230 linear encoder shown in Fig. 2. and 232, respectively, through the respective In Fig. 9, which shows the AC/DC ratio of electrodes.
the wave form of an output signal with re- The injected holes and electrons at the junc spect to the grid gap G, the characteristic of tion surface B and the resulting electron exci- this embodiment is indicated by the curve 90 tation energy causes light emission of a pre 202. It is clear that it is possible to obtain a determined frequency, namely near-infrared sufficient output signal even if the grid gap G light.
is enlarged to about 50 gm. - An insulated film 242 is formed on the up As described above, in the conventional per surface of the second semiconductor layer light emitting diode, no consideration is given 95 232 so that the metal film electrode 236 is to the dimensions, diameter or the configura- conductive only with the second semiconduc tion of light beams within the light emitting tor layer 232. The insulated film 242 is made diode, and the light beams are regulated of, for example, Si3N4(S'licon nitride).
merely by a light shielding plate or a guide This embodiment is characterized in that the provided outside the light emitting diode. In 100 junction B is exposed to one end surface of contrast, according to the present invention, the light emitting diode, and in that the junc the light beams themselves projected from the tion B has a predetermined configuration light emitting diode are shaped, controlled or which determines the configuration of the light regulated, thereby facilitating miniaturization of beam emitted from the light emitting diode.
the apparatus and the improvement of its lu- 105 The light beams are produced by the recom minous efficiency. Furthermore, according to bination of the holes and electrons at the these embodiments, since an opening pro- junction B of the semiconductor layers 230 vided on a metal film electrode on the light and 232, and by making the junction B in the projecting side is utilized for such regulation of shape of, for example, a slit, it is possible to light beams, it is possible to produce a light 110 project outward a light beam with a corre emitting diode for good light beams very eas- sponding slit shape.
ily without increasing any manufacturing steps In the present invention, the junction B may or involving other complications. have any given configuration, for example, a Fig. 4 is a plan view of a third preferred round, rectangular or slit shaped configuration, light emitting diode embodying the present in- 115 depending on requirements.
vention and Fig. 5 is a sectional view of the The light emitting diode shown in Figs. 4 light emitting diode- shown of Fig. 4, taken and 5 is designed for use in a photoelectric along the line V-V of that Figure. linear encoder, so the light beam cross-section In the diode of Figs. 4 and 5, a first semi- has a long and narrow slit shape. For this conductor layer 230 consists of an N-type 120 purpose, the junction B is formed so as to be GaAs and a second semiconductor layer 232 long and narrow along the end surface of the is junctioned to the, first semiconductor layer diode.
230. The second semiconductor layer 232 The upper and lower surfaces of the semi consists-of a P-type GaAs, and is obtained conductor layers which constitute the light by, for example, doping Zn. It will therefore 125 emitting diode in this embodiment have di be understood that the semiconductor layers mensions of about 200 X 600 ym, and the 230 and 232 have opposite polarities and that junction B is formed so as to have a slit width light emission takes place at a junction B be- W of 50 /im and a slit length L of 400 jum.
tween the layers. For use with an encoder as described The combination of semiconductors in this 130 above, the junction B of the light emitting diGB2192753A 5 ode of Figures 4 and 5 is slit shaped, the slit trodes on the respective end surfaces of the being arranged in alignment with the optical semiconductor layers, whereby injected current grids of the relatively movable measuring and supplied from the electrodes effects light reference grids. Since the width of the slit, emission at the junction of the semiconductor which corresponds to the direction of scale 70 layers, an opening being provided in one of movement and which influences the resolution the metal film electrodes, the opening having of the encoder, is short, the dimension of the a predetermined configuration such as to con light beam in the direction of scale movement trol the irradiating light emitted from the junc- is regulated to be very small in the present tion through the opening.
invention. More specifically, since the slit 75 2. A light emitting diode device as claimed width of the junction is about 50 um in this in claim 1 wherein the opening is slit shaped.
embodiment, this dimension of the light beam 3. A light emitting diode device as claimed is reduced to 1/8th of the conventional di- in claim 2 wherein the semiconductor layers mension, so that it is possible to greatly re- are square shaped, and wherein the slit duce the diffusion angle or to shorten the fo- 80 shaped opening extends along one diagonal.
cal length of the collimator lens. 4. A light emitting diode device as claimed Thus, it is possible to greatly reduce the in claim 2 wherein the semiconductor layers size of the light projector of a linear encoder are rectangular and wherein the slit shaped by use of a light emitting diode of this em- opening extends centrally and parallel to the bodiment. 85 longer sides thereof.
The junction in this embodiment has a suffi- 5. A light emitting diode device comprising cient length in the longitudinal' direction of the semiconductor layers of opposed polarities optical slits. In the case of a linear encoder, placed one on the other, and metal film elec the length in the longitudinal direction of the trodes on respective end surfaces of the semi optical slits has no influence on the resolution. 90 conductor layers so that injected current sup It is rather necessary to have a light emitting plied from the electrodes effects light emission length in the longitudinal direction of the opti- at the junction of the semiconductor layers, cal slits sufficiently large to secure an ade- the junction being exposed to one end surface quate quantity of light. Thus, the embodiment of the diode in a predetermined configuration shown in Figs. 4 and 5 is very useful because 95 which determines the shape of the emitted it provides sharply condensed light beams in light.
the direction of the scale movement whilst se- 6. A light emitting diode device as claimed curing an adequate quantity of light. in claim 5 wherein the junction is exposed in a In this way, according to this embodiment, slit shaped configuration.
it is possible to adequately condense the light 100 7. A light emitting diode device as claimed beams from the light projector, thereby advan- in claim 7 wherein the semiconductor layers tageously enabling the gap G between the are rectangular and wherein the junction is ex grids of a photoelectric linear encoder to be posed centrally of one end face in alignment made comparatively large. with the longer sides.
Furthermore, since the configuration of the 105 8. A light emitting diode device substantially junction of the semiconductor layers is utilized as herein described with reference to Figure 1, for the regulation of light beams, it is possible Figure 3, or Figures 4 and 5 of the accom to produce a light emitting diode for good panying drawings.
light beams very easily without increasing any 9. A photoelectric encoder having a measur- manufacturing steps or the like. 110 ing grid and a reference grid which are rela- Thus in accordance with the present inventively movable in accordance with the length tion, it is possible to control or shape light of an object to be measured and which have beams by utilizing an opening provided on a measuring slits for light transmission slits for metal film electrode on the light projecting light transmission or light reflection arranged in side or by choosing the configuration of the 115 alignment thereon, a light emitting diode de junction of the semiconductor layers of a light vice disposed on one side of the grids for emitting diode. Thus, the present invention is projecting light onto the measuring slits, and a very advantageous in that it facilitates pro- photo detector disposed on the opposite side duction of a light emitting diode which can be of the grids from the light emitting diode for optimised for various uses. 120 receiving transmitted or reflected light from It will be understood that various modifica- the measuring slits, the light emitting diode tions may be made to the preferred embodi- having a light emitting portion shaped as a slit ments of the invention specifically described disposed with its length extending substan within the scope of the invention as defined tially in the direction of the length of measur by the appended claims. 125 ing slits of the grids.
10. A photoelectric encoder as claimed in
Claims (1)
- CLAIMS claim 9 wherein the light encoding diode is as1. A light emitting diode device comprising claimed in claim 2, 3, 4, 6, 7 or 8.semiconductor layers of opposed polarities 11. A photoelectric encoder having a mea placed one-on the other, and metal film elec- 130 suring grid and a reference grid which are 6 GB2192753A 6 relatively movable in accordance with the length of an object to be measured and which have measuring slits for light transmission or light reflection arranged in alignment thereon, a light emitting diode device disposed on one side of the grids for projecting light onto the measuring slits, and a photo detector disposed on the opposite side of the grids from the light emitting diode for receiving transmitted or reflected light from the measuring slits, the light emitting diode being as claimed in any one of claims 1-8.12. A photoelectric linear encoder substantially as herein described with reference to 15 Figure 2 of the accompanying drawings.Published 1988atThe Patent Office, State House, 66/71 High Holborn, London WC 1 R 4TP. Further copies may be obtained from The Patentoffice, Sales Branch, St Mary Cray, Orpington, Kent BR5 3RD. Printed by Burgess & Son (Abingdon) Ltd. Con. 1/87.b 1
Applications Claiming Priority (3)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP61156586A JPS6323375A (en) | 1986-07-02 | 1986-07-02 | Light emitting diode |
| JP61156585A JPS6323377A (en) | 1986-07-02 | 1986-07-02 | Light emitting diode |
| JP16743286A JPS6324127A (en) | 1986-07-15 | 1986-07-15 | Photoelectric encoder |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| GB8715536D0 GB8715536D0 (en) | 1987-08-12 |
| GB2192753A true GB2192753A (en) | 1988-01-20 |
Family
ID=27321023
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| GB8715536A Withdrawn GB2192753A (en) | 1986-07-02 | 1987-07-02 | Light emitting diode device |
Country Status (2)
| Country | Link |
|---|---|
| DE (1) | DE3721938A1 (en) |
| GB (1) | GB2192753A (en) |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US5155355A (en) * | 1991-04-25 | 1992-10-13 | Mitutoyo Corporation | Photoelectric encoder having a grating substrate with integral light emitting elements |
| EP1722200A1 (en) * | 2005-05-13 | 2006-11-15 | FAGOR, S.Coop | Optoelectronic measuring device |
Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4019196A (en) * | 1974-11-22 | 1977-04-19 | Stanley Electric Co., Ltd. | Indicating element and method of manufacturing same |
| GB2033155A (en) * | 1978-10-25 | 1980-05-14 | Int Standard Electric Corp | Light emissive diode structure |
| US4212021A (en) * | 1976-07-21 | 1980-07-08 | Hitachi, Ltd. | Light emitting devices |
| US4447822A (en) * | 1981-09-21 | 1984-05-08 | Bell Telephone Laboratories, Incorporated | Light emitting diode |
| US4507157A (en) * | 1981-05-07 | 1985-03-26 | General Electric Company | Simultaneously doped light-emitting diode formed by liquid phase epitaxy |
Family Cites Families (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US3900864A (en) * | 1973-05-17 | 1975-08-19 | Bell Telephone Labor Inc | Monolithic led displays |
| CA1023835A (en) * | 1974-07-08 | 1978-01-03 | Tadao Nakamura | Light emitting gallium phosphide device |
| US3964157A (en) * | 1974-10-31 | 1976-06-22 | Bell Telephone Laboratories, Incorporated | Method of mounting semiconductor chips |
| DE2725265A1 (en) * | 1976-06-04 | 1977-12-08 | Tokyo Shibaura Electric Co | SEMI-CONDUCTOR LIGHT DISPLAY DEVICE |
| DE3138687C2 (en) * | 1981-09-29 | 1986-03-06 | Siemens AG, 1000 Berlin und 8000 München | Light-emitting diode with a targeted distribution of light radiation for signal lights |
-
1987
- 1987-07-02 GB GB8715536A patent/GB2192753A/en not_active Withdrawn
- 1987-07-02 DE DE19873721938 patent/DE3721938A1/en not_active Withdrawn
Patent Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4019196A (en) * | 1974-11-22 | 1977-04-19 | Stanley Electric Co., Ltd. | Indicating element and method of manufacturing same |
| US4212021A (en) * | 1976-07-21 | 1980-07-08 | Hitachi, Ltd. | Light emitting devices |
| GB2033155A (en) * | 1978-10-25 | 1980-05-14 | Int Standard Electric Corp | Light emissive diode structure |
| US4507157A (en) * | 1981-05-07 | 1985-03-26 | General Electric Company | Simultaneously doped light-emitting diode formed by liquid phase epitaxy |
| US4447822A (en) * | 1981-09-21 | 1984-05-08 | Bell Telephone Laboratories, Incorporated | Light emitting diode |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US5155355A (en) * | 1991-04-25 | 1992-10-13 | Mitutoyo Corporation | Photoelectric encoder having a grating substrate with integral light emitting elements |
| EP1722200A1 (en) * | 2005-05-13 | 2006-11-15 | FAGOR, S.Coop | Optoelectronic measuring device |
Also Published As
| Publication number | Publication date |
|---|---|
| DE3721938A1 (en) | 1988-01-07 |
| GB8715536D0 (en) | 1987-08-12 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| WAP | Application withdrawn, taken to be withdrawn or refused ** after publication under section 16(1) |