CN101078637A - Photoelectric encoder - Google Patents
Photoelectric encoder Download PDFInfo
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- CN101078637A CN101078637A CN 200710128659 CN200710128659A CN101078637A CN 101078637 A CN101078637 A CN 101078637A CN 200710128659 CN200710128659 CN 200710128659 CN 200710128659 A CN200710128659 A CN 200710128659A CN 101078637 A CN101078637 A CN 101078637A
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Abstract
To provide a photoelectric encoder. In the light-receiving chip of the photoelectric encoder, a plurality of photodiodes are arranged in a shape of an array along a measuring axis X. A pitch of a PD and the width of the light-receiving surface 25 arranged at the end part of the array are made smaller than a pitch and the width arranged at a center part of the array, respectively.
Description
It is dividing an application of 200410043298.0 application for a patent for invention that the application's name that to be Mitsutoyo K.K. submit on May 17th, 2004 is called " optical-electricity encoder ", application number.
Technical field
The present invention relates to be used for the optical-electricity encoder (photoelectric encoder) of micrometric measurement.
Background technology
In the past, in the micrometric measurement of straight-line displacement and angle displacement etc., used optical-electricity encoder (below, be also referred to as ' scrambler ' sometimes).Scrambler is loaded on three dimensional measurer or the determining image instrument etc.Scrambler by light source (light source), comprise the scale (scale) of optical lattice (optical grating) and the light receiver of ground (relatively movable) configuration that can relative together scale with light source relatively moves constitutes.Light receiver comprises that different four of the phase place of light receiving surface (light detecting surface) configuration of four light receiving elements (for example photodiode (photodiode)) for example and corresponding each light receiving element demarcate grid (index grating).
The action of following simple declaration scrambler.Light source is relatively moved with respect to scale with light receiver, simultaneously, will demarcate grid to four of light receiver from the irradiation optical system (illuminating) of the light of the light source optical lattice by comprising scale.Promptly, the demarcation grid that makes light receiver relatively moves with respect to the optical lattice of scale, and the interference fringe that optical lattice generated (shading graphic (light-and-shade pattern)) that will be mapped to scale simultaneously from the illumination of light source shines the demarcation grid of light receiver.Thus, generate four light signals of the strong and weak sinusoidal wave shape ground variation of light.These light signals have different phase place mutually.Utilize these light signals to be received, and carry out the displacement that electric signal that light-to-current inversion (photoelectric conversion) produces is measured straight line etc. by the light receiving element of corresponding each phase place.
Four light signals that phase place is different are the light signal, phase place of A phase (0 degree) than the light signal of the B phase (90 degree) of A phase deviation 90 degree, phase place than the light signal of the AA phase (180 degree) of A phase deviation 180 degree and phase place than the BB of the A phase deviation 270 degree light signal of (270 degree) mutually.Use A with B reason mutually to be mutually, according to detection earlier be A mutually or the B phase, judge the direction that relatively moves of light receiver.In addition, except A mutually with B light signal mutually, use with the AA of their counter-rotatings mutually and the reason of BB light signal mutually be for: (1) is removed and is included in A mutually or the DC component in the light signal of B phase, and (2) guarantee that the reliability of light signal and (3) guarantee the high speed tracing property.
As long as the light receiving element of quantity of corresponding a plurality of light signals of out of phase is arranged, on principle, just can measure.Therefore, under the situation of four different light signals of phase place, there are four light receiving elements just passable.The scrambler of this 1st type (type) for example be disclosed in international disclose on No. 01/31292 fascicle (～the 6 page of the 7th row of the 5th page of the 19th row of instructions, Fig. 5).
, because of the light intensity distributions of light source and the reasons such as stain of scale face, on light quantity, produce deviation sometimes.According to the above-mentioned type, the light signal of each phase place is respectively a location detection, so be subjected to the influence of light quantity deviation easily.For example, when A is a little less than the light intensity of irradiation is compared at the configuration position of the light receiving element of usefulness with the configuration position of other light receiving elements mutually, because a little less than the output of A phase, so measure precise decreasing.
Therefore, the scrambler that following type is arranged, promptly, by light receiving element being cut apart tinily and the arrangement of array (array) shape ground, make it have both the function of demarcating grid, further with A mutually usefulness light receiving element, B mutually usefulness light receiving element, AA mutually usefulness light receiving element, BB mutually the light receiving element of usefulness as one group (set), along mensuration axle (measurement axis) direction of scrambler, with the scrambler of the 2nd type of a plurality of group pattern shapes ground configuration.This type for example be disclosed in the spy open flat 7-151565 communique ([0014] section, Fig. 4) in.Thus, because the position that will detect the light signal of each phase place is dispersed in the wide region, can reduce the influence (below, be referred to as ' average effect (averagingeffect) ') of light quantity deviation.
The light receiving element that has in the scrambler of the 2nd type is being measured the arranged spaced of direction of principal axis to equate.On the contrary, be disclosed in the light receiving element that has in the scrambler of the 3rd type in the special table 2004-501356 communique (Fig. 4) separately with the arranged spaced that equates measure direction of principal axis and with the direction of its quadrature.
Improving average effect measures on the precision very important in raising.But,, then produce the problem of the answer speed decline of scrambler if improve average effect simply.Relevant this problem explains below.
The such light receiving element of photodiode has the structure with n type semiconductor layer and p type semiconductor layer formation knot.If the electric capacity of this knot increases, then the answer speed of scrambler descends.Therefore, the increase of junction capacity produces harmful effect to the performance of scrambler.The length at (edge) has correlationship around the junction capacity of light receiving element and the area of light receiving surface and the light receiving surface.That is, if area or circumference increase, then junction capacity increases, if area or circumference diminish, then junction capacity reduces.
In the above-mentioned the 2nd and the 3rd type, even the area of the light receiving surface that adds up to is identical with the area of the 1st type, because the number of light receiving element is more than the 1st type, so the total of length increases on every side.Therefore, the 2nd compares its junction capacity with the 3rd type increases with the 1st type, so the answer speed of scrambler descends.As described above, in the prior art, if improve average effect, the total of junction capacity that then constitutes a plurality of light receiving elements of light receiver increases, and on the contrary, if reduce this total, then average effect reduces.
When making the optical lattice thin space of scale for accurate more mensuration, relative in this, light receiving element also must thin spaceization.Therefore, must dispose a plurality of light receiving elements that reduced the width of light receiving surface.In order to utilize light-to-current inversion to obtain to measure the electric signal of necessary intensity, it is a certain amount of that the area of the light receiving surface of total must reach.Therefore, when the light receiving element thin space, because the quantity of light receiving element increases, so the total of the light receiving surface circumference that adds up to also increases, thereupon, the junction capacity of a plurality of light receiving elements of total increases.Therefore, when the optical lattice thin space of scale, can not ignore the low problem of speed of replying of scrambler.
Summary of the invention
The present invention is the invention in view of this problem, and its purpose is to provide a kind of optical-electricity encoder, its improve average effect and reduce a plurality of light receiving elements total junction capacity this all can take into account aspect two.
Optical-electricity encoder of the present invention comprises: light source; Scale, it comprises by the light-struck optical lattice from described light source; A plurality of light receiving elements, its described relatively scale are configured to and can relatively move along measuring direction of principal axis, have the light receiving surface of incident based on the light signal that light generated that is radiated at described optical lattice respectively, and the different a plurality of light signals of detected phase; Described a plurality of light receiving element is configured to array-like, the size of the light receiving element that disposes in the array end is littler than the size of the light receiving element that the central portion at described array disposes, described a plurality of light receiving element is along the configuration of described mensuration axle, with regard to the axial size of described mensuration of described light receiving surface, little than at the light receiving element of the central portion configuration of described array of the light receiving element of the end of described array configuration.
According to optical-electricity encoder of the present invention, make the size of light receiving element less by end at array, can improve with respect to the light intensity distributions with light source in the end side of array be the average effect of variation of the light intensity of reason.On the other hand, at the central portion of array, because the size of light receiving element is bigger, so can suppress the increase of light receiving element quantity.Thus, the junction capacity that can prevent a plurality of light receiving elements of adding up to increases.
Along in a plurality of light receiving elements of measuring the axle configuration, can make the axial size of mensuration of the light receiving element that disposes on the end of array less.Thus, the size of light receiving element further can be reduced in the end side of measuring axial array, so, can be that the average effect of variation of the light intensity of reason further improves in end side with light intensity distributions with respect to light source.In addition, can make in the axial size of mensuration of the light receiving element of the central portion of array configuration bigger.Therefore, need not increase the quantity of light receiving element for the amount of necessity, so can suppress the increase of the junction capacity that a plurality of light receiving elements add up in order to ensure the aggregate value of the area of light receiving surface.
In optical-electricity encoder of the present invention, can comprise light-receiving chip, the demarcation grid that this light-receiving chip is also comprised have the light shielding part that partly covers described light receiving surface with described a plurality of light receiving elements.
Thus, though different at the central portion of array with the size of end light receiving surface, the light signal of the phase place that is assigned with in also can the receiving phase different a plurality of light signals of each light receiving element.
In optical-electricity encoder of the present invention, light-receiving chip can comprise: contact site, and it is being connected on this light shielding part below electric conductivity light shielding part, and contacts with light receiving surface; The wiring of light receiving element, it is connected with light shielding part.
Thus, the wiring by the light shielding part double as that makes the demarcation grid is connected with light receiving element can prevent that effective light receiving area of light receiving surface from reducing.
In optical-electricity encoder of the present invention, can make the direction configuration of described a plurality of light receiving elements edge and described mensuration axle quadrature, with regard to the size of the direction of described light receiving surface and described mensuration axle quadrature, little at the light receiving element of the central portion configuration of described array of the ratio of the light receiving element of the end of described array configuration.
Thus, about a plurality of light receiving elements of edge with the direction configuration of measuring the direction of principal axis quadrature, according to reason identical with along a plurality of light receiving element of described mensuration direction of principal axis configuration the time, the average effect with respect to the variation of light intensity of array end side is further improved, simultaneously, can suppress the increase of the junction capacity of a plurality of light receiving elements totals.
In optical-electricity encoder of the present invention, can utilize described a plurality of light receiving element to constitute different a plurality of groups of every group the size of light receiving element, the light receiving element that constitutes each group has with identical distance and disposes continuously and the light receiving element of a plurality of light signals that detected phase is different.
Thus, configurable light receiving element makes the size of the light receiving element in the group certain, the balance in obtaining organizing, and simultaneously, the end of array is littler than the interval of central portion.
In optical-electricity encoder of the present invention, in described a plurality of groups, in the group that is being configured in described array end and be configured in the group of pars intermedia configuration of the described array between the group of described array central portion, the size of light receiving element is bigger than the described size of the group of described array end, and littler than the described size of the group of described array central portion.
Thus, can according to the light intensity distributions of light source the variation of light intensity of reason, change the size of light receiving element.Thus, can not increase the quantity of light receiving element, in each end group, central portion group, pars intermedia group, obtain sufficient average effect intensity variation.
In optical-electricity encoder of the present invention, can set described a plurality of groups size separately, making light intensity distributions on the face of described array is that the variation of light intensity of reason is certain on each group.
Thus, can make with respect to the light intensity distributions on the array surface be reason light intensity variable quantity average effect each the group in identical.
More than be a kind of mode of optical-electricity encoder of the present invention, in addition also have following mode.That is, the another way of optical-electricity encoder of the present invention comprises: light source; Scale, it comprises by the light-struck optical lattice from described light source; Light-receiving chip, it is situated between by the rayed of described optical lattice quilt from described light source, simultaneously, can relatively move at described mensuration direction of principal axis by described relatively scale; A plurality of light receiving elements, it is configured to the two-dimensional array shape along the mensuration direction of principal axis on the described light-receiving chip and perpendicular to measuring axial direction; A plurality of demarcation grid, it is configured in described a plurality of light receiving element front separately; Described a plurality of demarcation grid disposes with specify offset along measuring direction of principal axis mutually, relatively moves by described, from the different a plurality of light signals of described a plurality of light receiving element output phases.
According to the another way of optical-electricity encoder of the present invention, because a plurality of light receiving elements are along measuring direction of principal axis and disposing with array-like perpendicular to measuring axial direction, so can improve average effect.In addition, by demarcating grid, prevented the increase of the total junction capacity of a plurality of light receiving elements in each described light receiving element former configuration.
Description of drawings
Fig. 1 is the figure of schematic configuration of the optical-electricity encoder of expression the 1st embodiment;
Fig. 2 is a planimetric map of schematically representing the light-receiving chip integral body of observing from the optical lattice side of Fig. 1;
Fig. 3 is the figure of the photodiode in the presentation graphs 2 schematically only;
Fig. 4 is a synoptic diagram of observing light-receiving chip shown in Figure 2 from IV (a)-IV (b) section;
Fig. 5 is the figure of variation that shows the demarcation grid of the 1st embodiment;
Fig. 6 is the curve map of intensity of light intensity that is presented at each position of the PD array that forms on the light-receiving chip;
Fig. 7 schematically is presented in the central portion of the PD array that forms on the light-receiving chip of optical-electricity encoder of the 2nd embodiment, a light receiving surface and demarcate the planimetric map of the configuration relation of grid;
Fig. 8 observes the synoptic diagram of structure shown in Figure 7 from VIII (a)-VIII (b) section;
Fig. 9 is the planimetric map of photodiode array of schematically representing the light-receiving chip of the 3rd embodiment observed from the optical lattice side;
Figure 10 is the planimetric map of the light-receiving chip part of the 3rd embodiment;
Figure 11 is the planimetric map of photodiode array of schematically representing the light-receiving chip of the 4th embodiment;
Figure 12 is the planimetric map with the 5th an embodiment light-receiving chip part relatively;
Figure 13 is the planimetric map of the light-receiving chip part of the 5th embodiment;
Figure 14 is the planimetric map of an example of the demarcation grid of the 5th embodiment;
Figure 15 is another routine planimetric map of the demarcation grid of the 5th embodiment.
Embodiment
Below, with reference to the 1st of description of drawings optical-electricity encoder of the present invention～the 5th embodiment.In addition, in the figure of explanation the 2nd～the 5th embodiment,, give same label and omit explanation the identical part of representing with the label of the embodiment that has illustrated of part.
The 1st embodiment
Fig. 1 is the figure of schematic configuration of the optical-electricity encoder 1 of expression the 1st embodiment.Present embodiment is a principal character with the structure of the light-receiving chip (photodetector chip) that comprises in light receiver, as the prerequisite of its understanding, optical-electricity encoder 1 is described.The structure of scrambler 1 at first, is described.Scrambler 1 is by light emitting diode (LED (light emitting diode)) 3, constitute with scale 5 and light receiver 7 along the arranged in order approaching with it.
Below, the mensuration action of briefly bright optical-electricity encoder 1.On the 1st optical lattice 11 that light L is shone scale 5 from light emitting diode 3 time, utilize optical lattice 11 on light-receiving chip 15, to produce shading graphic L1.This shading graphic L1 is irradiated on the light-receiving chip 15.In this state, detect the variation (sinusoidal wave light signal) of the shading graphic L1 that produces by edge mensuration axle X traversing carriage 21 by each photodiode (PD) that forms in the light-receiving chip 15.That is, the light signal of A phase (0 degree), phase place than B phase (90 degree) light signal of A phase deviation 90 degree, phase place than the light signal of the AA phase (180 degree) of A phase deviation 180 degree and phase place than the BB of A phase deviation 270 degree mutually the light signal of (270 degree) detect by the PD of correspondence respectively.Like this, each PD is received in the light signal of the phase place that is assigned with in the different a plurality of light signals of phase place.
Electric signal by each light signal generating is sent on the IC chip 19.In IC chip 19, A mutually and after B carries out predetermined process (removing DC component etc.) mutually, is being come the computing displacement according to the A phase after handling with B mutually.Its result is outputed to not shown display part.It more than is the action of optical-electricity encoder 1.
The principal character of the 1st embodiment is a light-receiving chip 15, below it is explained.Fig. 2 is the planimetric map of schematically representing from light-receiving chip 15 integral body of optical lattice side observation.Fig. 3 is the figure of the photodiode 23 in the presentation graphs 2 schematically only; Fig. 4 is a synoptic diagram of observing light-receiving chip 15 shown in Figure 2 from IV (a)-IV (b) section;
As shown in Figure 4, light-receiving chip 15 has n N-type semiconductor N substrate 37.In a face of this substrate 37, form the diffusion zone 39 of p type at interval.The junction surface of Semiconductor substrate 37 and diffusion zone 39 forms PD23.A plurality of PD23 are configured on the Semiconductor substrate 37 with array-like.
In a face of Semiconductor substrate 37, the zone that is formed with p type diffusion zone 39 is as light receiving surface 25.In addition, in order reliably p type diffusion zone 39 to be separated each other (that is, the element of each photodiode 23 separates), also can on diffusion zone 39 Semiconductor substrate 37 each other, form n
+The type diffusion zone.A face of Semiconductor substrate 37 is covered by the such dielectric film 41 of silicon oxide layer, to cover diffusion zone 39.
When plane earth is seen a plurality of PD23, as shown in Figures 2 and 3, with optical lattice mutually towards xy face upper edge measure an axle X and dispose a plurality of PD23 with array-like.In addition, the mensuration axle X's of x axle and Fig. 1 explanation towards consistent.
Form a group 27 with receiving the PD23 of the PD23 of A phase light signal, the PD23 that receives B phase light signal, reception AA phase light signal, the PD23 of reception BB phase light signal.Along measuring the axle directions X, configuration is a plurality of groups 27 on the central portion 29 of array.On the end 31 of the array of central portion 29 both sides of array, dispose a group 27 separately.Be formed in the interval P of the PD23 of the group 27 of configuration on the array end 31
1Than the interval P that is formed in the PD23 of the group 27 of configuration on the array central portion 29
2Little.On the other hand, in each group 27, dispose PD23 continuously with identical distance.Thus, respectively organized the balance of the PD23 in 27.
Incident is based on the light signal (A phase, B phase, AA phase, BB phase) of the correspondence that shines the photogenerated on the optical lattice on each light receiving surface 25.In other words, shading graphic L1 shown in Figure 1 is being shone under the state of light-receiving chip 15, the light signal of the phase place of distributing in will be by the phase place that traversing carriage 21 generates different a plurality of light signals incides on each light receiving surface 25.The shape of light receiving surface 25 is the rectangle of longitudinal direction on the y direction.The size of the mensuration axle directions X of light receiving surface 25 (width of light receiving surface 25 promptly) is different with end 31 at central portion 29.That is the width W of the light receiving surface 25 of the PD23 of configuration on array end 31,
1Corresponding each width W than array central portion 29
2Little.
Secondly, by Fig. 2 and Fig. 4 demarcation grid 33 is described.Light-receiving chip 15 has the demarcation grid 33 that is formed on the dielectric film 41, to cover each light receiving surface 25.Demarcate grid 33 and have a plurality of light shielding parts 35 that extend to the y direction of arranged spaced on each light receiving surface 25.As long as light shielding part 35 has lighttight character.Therefore, its material can be enumerated metal (for example chromium, aluminium) or resin.
Between light shielding part adjacent on the light receiving surface 25 35, form transmittance section (light transmittedportion) 40.Thus, we can say that demarcating grid 33 has the light shielding part 35 that partly covers light receiving surface 25.At least assemble two above light shielding parts 35,, constitute one and demarcate grid 33 by they being configured on the light receiving surface.
On each light receiving surface 25, transmittance section 40 is positioned at and the position of the light signal correspondence of the phase place of distributing, and light shielding part 35 is positioned at the position beyond it.Specifically describe as followsly, for example, in the PD23BB that receives BB phase light signal, transmittance section 40 is positioned at the position of light signal correspondence mutually with BB.Thus, PD23BB does not receive the light signal that A phase, B reach the AA phase mutually.The width of PD23 is different with end 31 at central portion 29, but can equate to prevent the skew of light signal phase place by the interval that makes light shielding part 35.
As shown in Figure 4, form silicon oxide layer or the such diaphragm 43 of silicon nitride film, demarcate grid 33 to cover.On whole of the another side of Semiconductor substrate 37, be formed with the common electrode (for example Au electrode) 45 of each PD23.
Below by Fig. 5 the variation of demarcating grid 33 is described.Fig. 5 is synoptic diagram and Fig. 4 correspondence of the section of light-receiving chip 15.Cover by light shielding part 35 between the adjacent light receiving surface 25.Become the reason that forms interference sometimes by the light that incides Semiconductor substrate 37 between the adjacent light receiving surface 25.According to this variation, can prevent that light is from inciding on the Semiconductor substrate 37 between the adjacent light receiving surface 25.
The optical-electricity encoder 1 of first embodiment has following main effect.
(1) according to the 1st embodiment, the total junction capacity that can prevent to constitute a plurality of PD23 of light-receiving chip 15 increases, and simultaneously in array end 31 sides, the light intensity distributions that can improve with respect to light source is the average effect of the intensity variation of reason.Below explain.Fig. 6 is the curve map of intensity of light intensity of each position of the PD array that forms on the display light receiving chip.The such light source of light emitting diode 3 has light intensity distributions shown in Figure 6 by control dimension of light source etc.Distributed as can be known by this, compare with the central portion of array, light intensity is little in the array end, and the variable quantity of light intensity (rate of curve) increases.Therefore, when the interval of PD was big, in the end of array, the difference of the DC component of the photocurrent that is produced by each PD increased.That is to say that the value of the DC component of A phase light signal, B phase light signal, AA phase light signal, BB phase light signal is different mutually, and difference is big.This becomes the obstacle of optical-electricity encoder high-precision measuring.
If adopt the less light-receiving chip in interval of PD, can eliminate described problem.But, when disposing a plurality of PD and make light-receiving chip with array-like in the zone of prescribed level, when the interval that makes PD hour, the quantity of PD will correspondingly increase, the total junction capacity that constitutes a plurality of PD of light-receiving chip will increase.
It is that the variable quantity (curve inclination) of the light intensity of reason is compared the big this point in the end of array with the central portion of array that inventor of the present invention is conceived to just with the light intensity distributions of light source.That is, as shown in Figure 3, in the 1st embodiment, the interval of the PD23 by making in the array end 31 configurations is less, has improved average effect with respect to intensity variation in array end 31 sides.And less by the interval that makes the PD23 that disposes at array central portion 29, in the average effect of 31 sides raising in array end with respect to intensity variation.On the other hand, the interval of the PD23 by making on array central portion 29 configuration is bigger, suppresses the increase of PD quantity, thus, can prevent to constitute the increase of total junction capacity of a plurality of PD23 of light-receiving chip.
(2) according to the 1st embodiment, as shown in Figure 3, the width W of the light receiving surface of the PD23 of configuration on array end 31
1Corresponding width W than the PD23 of configuration on central portion 29
2Little.Thus, the interval of the PD23 of end 31 sides is further reduced, so can further improve the average effect with respect to intensity variation of end 31 sides.On the other hand, with width W
1Compare width W
2Little amount, the width W of the light receiving surface of the PD23 of configuration on central portion 29
2It is bigger to form ground.Therefore, need not increase the quantity of PD23 for the amount of necessity, so can suppress the increase of the total junction capacity of a plurality of PD23 in order to ensure the aggregate value of the area of light receiving surface 25.
(3) in the 1st embodiment, as (2) illustrate, on the central portion 29 and end 31 of array, the width difference of light receiving surface 25.By demarcation grid 33 shown in Figure 2 is configured on the light receiving surface 25, but the light signal of the phase place of distributing in the different a plurality of light signals of each PD23 receiving phase.
The 2nd embodiment
Relevant the 2nd embodiment is that the center illustrates with the difference with the 1st embodiment.Fig. 7 schematically is presented in the central portion 29 of the PD array that forms on the light-receiving chip 15 of optical-electricity encoder of the 2nd embodiment, a light receiving surface and demarcate the planimetric map of the configuration relation of grid 33.Fig. 8 observes the planimetric map of structure shown in Figure 7 from VIII (a)-VIII (b) section.
In the 2nd embodiment, the light shielding part 35 of demarcating grid 33 is as a part that is connected the wiring on the photodiode 23.Below explain.Light shielding part 35 is the such conductive metal of aluminium.Four light shielding parts 35 of configuration are positioned at identical layer with wiring 47 on light receiving surface 25.They are formed by drawing (patterning) simultaneously.Two light shielding part 35-1 of central authorities are connected by drawing formation with wiring 47 in light shielding part 35.
On the dielectric film 41 between light shielding part 35-1 and the light receiving surface 25, be formed with contact hole (contacthole) 49.On contact hole 49, be formed with the contact site 51 that constitutes by conductive plug (for example aluminium).Contact site 51 is connected with it below light shielding part 35-1, contacts (contact) with light receiving surface 25 simultaneously.Therefore, wiring 47 is connected on the photodiode 23 by light shielding part 35-1 and contact site 51.In addition, in this embodiment, form contact site 51, but also can on insulation course 41, form film as light shielding part 35-1 the time with conductive plug, this film of in contact hole 49, packing into, with it as contact site.
The 2nd embodiment except have with the same effect of the 1st embodiment, also have following effect.When wiring 47 is not used light shielding part 35-1 with being connected of photodiode 23,, must on the light receiving surface 25 of the layer identical, form new conducting film with light shielding part 35 for this connects.This conducting film reduces effective light receiving area of light receiving surface 25.On the contrary, in the 2nd embodiment, the wiring 47 with used electric conductivity light shielding part 35-1 being connected of photodiode 23.Therefore, effective light receiving area that can prevent light receiving surface 25 reduces.
In addition, when not utilizing described light shielding part 35-1, on the section of Fig. 8, there is not contact site 51.Therefore, form the stray capacitance that has by the structure of light shielding part 35-1 and p type diffusion zone 39 clamping dielectric films 41.This is the reason that reduces the scrambler answer speed.Relative therewith, in the 2nd embodiment, light shielding part 35-1 is connected by contact site 51 with p type diffusion zone 39, so do not produce described stray capacitance.
The 3rd embodiment
Is that the center illustrates to the 3rd embodiment with the difference with the 1st embodiment.Fig. 9 is the planimetric map of photodiode array of schematically representing the light-receiving chip 15 of the 3rd embodiment observed from the optical lattice side.In the figure, omitted the diagram of demarcating grid.Figure 10 is the partial plan layout of the light-receiving chip 15 of the 3rd embodiment.The position relation that has shown light receiving surface 25 in the figure and demarcated the transmittance section 40 of grid.Grid in the light receiving element former configuration is called the demarcation grid.
As shown in Figure 9, light receiving surface 25 two dimensions of a plurality of PD23 be configured in (two dimensions) with optical lattice mutually towards the xy face on.In other words, a plurality of PD23 are disposed with array-like.Also can be described as a plurality of PD23 are disposed with array-like along x direction on the light-receiving chip 15 (promptly measuring direction of principal axis) and y direction (the axial direction of promptly vertical mensuration).On the light receiving surface 25 of the light signal of incident A phase, B phase, AA phase, BB phase, record " A ", " B ", " AA ", " BB " separately.This is in order to be presented at the light signal of the sort of phase place of which light receiving surface incident, not have these records on the light receiving surface 25 of reality.A mutually with, B mutually with, AA mutually with, BB mutually the light receiving surface 25 of usefulness periodically be configured in x direction and y direction.
As shown in figure 10, be arranged with the light receiving surface 25 that out of phase is used in the y direction.By the phase place of skew transmittance section 40, each PD23 can receive the light signal of corresponding phase place.Like this, on each light receiving surface 25, transmittance section 40 is positioned at and the position of the light signal correspondence of the phase place of distributing, and the light shielding part of demarcating grid is positioned at the position beyond it.That is, the former configuration at each PD23 has the demarcation grid.These demarcate grid mutually along measuring the side-play amount configuration of axle directions X with regulation, move along measuring axle X by making support 21, from the different a plurality of light signals of a plurality of PD23 output phases.The quantity of the transmittance section 40 of configuration is one on each light receiving surface 25, but also can be a plurality of.
As shown in Figure 9, be the y direction with measuring a direction of X quadrature, the interval P of the PD23 that disposes in the end 53 of array
1Interval P than the PD23 that disposes at central portion 55
2Little.Thus, (1) can improve the average effect with respect to intensity variation on the array end 52 of y direction, and (2) are on array central portion 55, because the interval of PD23 is bigger, increases so can suppress the quantity of PD23, prevents the increase of the total junction capacity of a plurality of PD23.
Size S with the direction (promptly, perpendicular to the y direction of measuring a directions X) of the mensuration axle X quadrature of the light receiving surface 25 of the PD23 of configuration on the array end 53
1Corresponding size S than the PD23 of configuration on central portion 55
2Littler.Therefore, according to the 1st embodiment explanation along a plurality of PD23 of measuring the configuration of axle directions X the time identical reason, to a plurality of PD23 along the configuration of y direction, can further improve the average effect with respect to intensity variation of end side 53, simultaneously, can suppress the increase of the total junction capacity of a plurality of PD23.
In addition, A mutually with, B mutually with, AA mutually with, BB mutually the light receiving surface 25 of usefulness dispose obliquely with respect to measuring an axle X separately.The vergence direction of measuring axle C dispose periodically A mutually with, B mutually with, AA use mutually, the BB light receiving surface 25 of usefulness mutually.Like this, the PD23 that receives the light signal of same phase disposes with respect to measuring axle X with being tilted, and simultaneously, the PD23 that receives the light signal of out of phase is configured in the vergence direction of measuring axle X periodically.Thus, can dispose each phase place PD23 equably, so can improve average effect.Disposing each phase place equably also can realize with PD23 by disposing each phase place brokenly with PD23.But, compare with such configuration, according to the 3rd embodiment, can realize the equalization of PD23 configuration simply.
The 4th embodiment
The 4th embodiment is the center explanation with the difference with the 1st embodiment.Figure 11 is the planimetric map of photodiode array of schematically representing the light-receiving chip 15 of the 4th embodiment, itself and Fig. 3 correspondence.
In group 27 at the pars intermedia 57 of the central portion 29 of array and the array between the end 31, the interval P of PD23
3Than interval P
1Greatly, than interval P
2Little.Equally, the width W of PD23
3Compare width W
1Compare width W greatly,
2Little.
The main effect of the 4th embodiment below is described.
(1) light intensity of each position of the array of the following curve display light-receiving chip 15 of the light-receiving chip 15 of Figure 11, it is corresponding with Fig. 6.The pars intermedia 57 of array is compared with the end 31 of array, and the variable quantity of light intensity (rate of curve) is little.Therefore, even pars intermedia 57 is close not as the interval of the PD23 of end 31, also can obtain sufficient average effect.On the other hand, the variable quantity of the light intensity of array pars intermedia 57 is bigger than the variable quantity of the light intensity of array central portion 29.Thus, when mate with the interval of the PD23 of central portion 28 at the interval of the PD23 that makes pars intermedia 57, can not obtain sufficient average effect.
Therefore, in the 4th embodiment,, change the interval of PD23 according to variation of light intensity.Thus, do not increase the quantity of PD23, in the group 27 of the group 27 of the group 27 of each central portion 29, pars intermedia 57, end 31, just can obtain with respect to the light intensity distributions on the face of array 29,31,57 is the sufficient average effect of variation of the light intensity of reason.In addition, this light intensity distributions for example produces because of light source.
Have, the curve of Figure 11 (light intensity distributions) can be made by the practical measurement value, also can be made by Gaussian distribution model values such as (Gaussian distribution) again.
(2) in the 4th embodiment, set the size X of mensuration axle directions X of the group 27 of pars intermedia 57 separately
3, end 31 the size X of mensuration axle directions X of group 27
1, so that the variation delta E of the light intensity on the group 27 of array pars intermedia 57
3This variation delta E with end 31
1Identical.Therefore, can make the group 27 of average effect with respect to the variable quantity of light intensity 31 group 27 and pars intermedia 57 identical in the end.Thus, the mensuration precision is improved.
In addition, in the 4th embodiment, the variable quantity of the light intensity on the group 27 of array central portion 29 is little more a lot of than this variable quantity of pars intermedia 57 or end 31.Therefore, the variable quantity of the light intensity of central portion 29 is identical with this variable quantity of pars intermedia 57 or end 31, and the size of the mensuration axle directions X of the group 27 of setting central portion 29 is difficult.Therefore, in the 4th embodiment, in the setting of the size of group 27 mensuration axle directions X, do not consider the group 27 of central portion 29.Wherein, when the variable quantity of the light intensity on the group 27 of central portion 29 is big, preferably also consider the group 27 of central portion 29.
The 5th embodiment
Figure 12 is the planimetric map as the light-receiving chip part of the comparison of the 5th embodiment.Figure 13 is the planimetric map of a part of the light-receiving chip of the 5th embodiment.In the 1st～the 4th embodiment, the interval P of PD23 is based on the variable quantity decision of light intensity.On the other hand, the position of the transmittance section 40 of demarcation grid 33 is based on the phase decision of light signal.Therefore, light receiving surface 25-1 as shown in figure 12, transmittance section 40-1 might not be positioned on the light receiving surface 25-1.
Therefore, in the 5th embodiment shown in Figure 13, about transmittance section 40-1, the front and back position skew transmittance section 40-1 at the light signal of incident same phase is positioned on the light receiving surface 25-1 transmittance section 40-1.
Specifically describe the 5th embodiment below.Figure 14 is the planimetric map of an example of the demarcation grid 33 of the 5th embodiment.Optical lattice 33 disposes along the x direction.This optical lattice 33 is configurable on the light-receiving chip 15 of Fig. 3.On the other hand, Figure 15 is another routine planimetric map of the demarcation grid 33 of the 5th embodiment.Optical lattice 33 promptly, disposes with the ranks shape along x direction and the configuration of y direction.This optical lattice 33 is configurable on the light-receiving chip 15 of Fig. 9.Have again, in Figure 15, along the position expression in the same manner in each phase of the transmittance section 40 of the demarcation grid 33 of y direction configuration.This is for fear of any confusion, and in fact phase differential is arranged.
The position of transmittance section 40 is according to the calculating decision of following explanation.At first, on light-receiving chip 15, at random determine the reference position RP of x direction.Usually, select the end face of the imagining center line of the light-receiving chip 15 that draw (1) (machine center line) or (2) light-receiving chip 15 as reference position RP on the plane of light-receiving chip 15.
If reference position RP to each phase place be Xa (k), Xb (k), Xaa (k), Xbb (k) with the distance of transmittance section 40.K is the sequence number of expression transmittance section 40 orders.For example, Xa (1) uses the transmittance section 40 of first configuration in the transmittance section 40 and the distance of reference position RP mutually at A.Xa (k), Xb (k), Xaa (k), Xbb (k) are set at the value that satisfies following formula.Thus, transmittance section 40 can be configured on the light-receiving chip 25.
MOD(Xa(k)，Pf)＝(0/4)×Pf+φ
MOD(Xb(k)，Pf)＝(1/4)×Pf+φ
MOD(Xaa(k)，Pf)＝(2/4)×Pf+φ
MOD(Xbb(k)，Pf)＝(3/4)×Pf+φ
At this, MOD (A, B) computing is to ask the computing of A divided by the remainder of B.In addition, φ is the value by reference position RP decision.φ is a value common in each phase place, and is irrelevant with phase differential.The wavelength of the shading graphic L1 that generates when as shown in Figure 1, Pf is phase optical lattice 11 irradiation from the light L of light source 3.The position of the transmittance section 40 of grid 33 is demarcated in decision by as described above, can make PD23 receive the light signal of corresponding phase place.
Have again, as Fig. 6 explanation, according to the position different light intensity degree difference of PD array.Therefore, when using the position of described formula decision transmittance section 40, A uses total light-receiving amount of PD23 inequality with total light-receiving amount, the BB of PD23 with total light-receiving amount, the AA of PD23 with total light-receiving amount, the B of PD23 mutually mutually mutually mutually, might form inhomogeneous.At this moment, number that can be by changing transmittance section 40 or size make each phase place with PD23 total light-receiving amount even.For example, at A mutually with total light-receiving amount of PD23 than total light-receiving amount of other PD23 hour, be adjusted at the number or the width of transmittance section 40 of demarcation grid that A uses the former configuration of PD23 mutually.
In addition, in the 1st～the 5th embodiment, use four different light signals (A phase, B phase, AA phase, BB phase) of phase place to measure addendum modification, but optical-electricity encoder of the present invention is not limited thereto.For example, the light signal that three phase places are different (light signal of 0 degree phase place, phase place are spent the light signal that phase deviation 240 is spent than light signal, the phase place of 0 degree phase deviation, 120 degree than 0) is also applicable to optical-electricity encoder of the present invention.
In addition, as shown in Figure 1, the optical-electricity encoder 1 of the 1st～the 5th embodiment is to use the type of carrying out the mensuration of addendum modification from the light L of the light emitting diode 3 of the optical lattice that sees through scale 5, the i.e. type of infiltration type.But,, when just the light L of the light emitting diode 3 of optical lattice 11 reflections of the next free scale 5 of use measures addendum modification, also can use the present invention in the type of reflection-type.
The optical-electricity encoder 1 of the 1st～the 5th embodiment is the type that is included on the scale 5 optical lattice 11 that is provided with, constitutes at two grid of the demarcation grid 33 of PD23 former configuration.But, on the basis of these grid, further have again in the type that three grid as the optical lattice of configuration between the light emitting diode 3 of light source and the scale 5 constitute, also can use the present invention.
As mentioned above, according to optical-electricity encoder of the present invention, the light intensity distributions that can improve with respect to light source is the average effect of the intensity variation of reason, can prevent the increase of the total junction capacity of a plurality of light receiving elements simultaneously.Thus, can realize the optical-electricity encoder of high precision and high-speed responsive.
Claims (3)
1, a kind of optical-electricity encoder is characterized in that, comprising: light source; Scale, it comprises by the light-struck optical lattice from described light source; Light-receiving chip, it is situated between by the rayed of described optical lattice quilt from described light source, simultaneously, can relatively move at described mensuration direction of principal axis by described relatively scale; A plurality of light receiving elements, it is configured to the two-dimensional array shape along the mensuration direction of principal axis on the described light-receiving chip and perpendicular to measuring axial direction; A plurality of demarcation grid, it is configured in described a plurality of light receiving element front separately; Described a plurality of demarcation grid disposes with specify offset along measuring direction of principal axis mutually, relatively moves by described, from the different a plurality of light signals of described a plurality of light receiving element output phases.
2, optical-electricity encoder as claimed in claim 1, it is characterized in that, the described light receiving element that receives the light signal of same phase disposes obliquely with respect to described mensuration axle, simultaneously, the described light receiving element that receives the light signal of out of phase periodically disposes at the described vergence direction of measuring axle.
3, optical-electricity encoder as claimed in claim 1 is characterized in that, and is with regard to regard to the axial size of mensuration, littler than the light receiving element that disposes at described array central portion at the light receiving element of the end of described array configuration.
Applications Claiming Priority (3)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP2003139062 | 2003-05-16 | ||
| JP139062/03 | 2003-05-16 | ||
| JP126994/04 | 2004-04-22 |
Related Parent Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CNB2004100432980A Division CN100351613C (en) | 2003-05-16 | 2004-05-17 | Photoelectric encoder |
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| Publication Number | Publication Date |
|---|---|
| CN101078637A true CN101078637A (en) | 2007-11-28 |
| CN100535605C CN100535605C (en) | 2009-09-02 |
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| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CNB2007101286595A Expired - Fee Related CN100535605C (en) | 2003-05-16 | 2004-05-17 | Photoelectric encoder |
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| JP (1) | JP4834141B2 (en) |
| CN (1) | CN100535605C (en) |
Families Citing this family (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP6087722B2 (en) * | 2013-05-16 | 2017-03-01 | 株式会社ミツトヨ | Origin signal generator and origin signal generation system |
| JP6271174B2 (en) * | 2013-07-12 | 2018-01-31 | 株式会社ミツトヨ | Detection head, optical encoder, and adjustment method of optical encoder |
| JP6487724B2 (en) * | 2014-03-14 | 2019-03-20 | キヤノンプレシジョン株式会社 | Encoder |
| EP3064903B1 (en) | 2015-03-06 | 2018-06-13 | Canon Precision Inc. | Encoder |
| US10168189B1 (en) * | 2017-06-29 | 2019-01-01 | Mitutoyo Corporation | Contamination and defect resistant optical encoder configuration for providing displacement signal having a plurality of spatial phase detectors arranged in a spatial phase sequence along a direction transverse to the measuring axis |
Family Cites Families (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| IT1160210B (en) * | 1983-09-30 | 1987-03-04 | Olivetti & Co Spa | OPTICAL TRANSDUCER TO DETECT THE POSITION OF A MOVING BODY COMPARED TO A FIXED STRUCTURE |
| JP2690680B2 (en) * | 1993-11-26 | 1997-12-10 | 株式会社ミツトヨ | Photoelectric encoder |
| US6635863B1 (en) * | 1999-08-06 | 2003-10-21 | Mitutoyo Corporation | Optical encoder |
| DE10020575A1 (en) * | 2000-04-28 | 2001-10-31 | Heidenhain Gmbh Dr Johannes | Scanning unit for an optical position measuring device |
| JP4350417B2 (en) * | 2003-05-13 | 2009-10-21 | 株式会社ミツトヨ | Photoelectric encoder |
-
2004
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| JP4834141B2 (en) | 2011-12-14 |
| CN100535605C (en) | 2009-09-02 |
| JP2010048833A (en) | 2010-03-04 |
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