CN100494912C - Optical encoder and electronic equipment using the same - Google Patents
Optical encoder and electronic equipment using the same Download PDFInfo
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- CN100494912C CN100494912C CNB2005100915302A CN200510091530A CN100494912C CN 100494912 C CN100494912 C CN 100494912C CN B2005100915302 A CNB2005100915302 A CN B2005100915302A CN 200510091530 A CN200510091530 A CN 200510091530A CN 100494912 C CN100494912 C CN 100494912C
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Abstract
Given n move information signals and m slits 22 (n and m: positive integers), the number of photodiodes associated with the m slits 22 is set to nxm<SUP>a </SUP>(a: a positive integer). By doing so, all of the (nxm<SUP>a</SUP>) photodiodes (23) can necessarily be positioned evenly in units of an equal number against the slits (22) and the move information signals. Also, the photodiodes can be subdivided more than in a conventional optical encoder having photodiodes counting a number represented by mxn, which is a common multiple of the number m of the slits 22 and the number n of move information signals. Thus, with light reception area of each photodiode reduced, shifts, distortions, variations and the like of the move information signals can be suppressed, resolution can be enhanced, and accurate move information signals can be obtained.
Description
Technical field
The present invention relates to the optical encoder of a kind of position that utilizes photocell and light receiving element to detect mobile unit, movement velocity, direction of motion etc., especially, a kind of optical encoder that is used for as printing device duplicating machine, the printer and the electronic equipment as FA (factory automation) equipment.
Background technology
Such optical encoder has been arranged, and it has as shown in Figure 4 mobile unit and the relation of the position between photodiode (referring to patent document 1 (JP2001-99684A)).This optical encoder is by a plurality of opening groups of being made up of three opening 2a, 2b, 2c, with a plurality of photo diode sets of forming by four photodiode 3a, 3b, 3c, 3d, wherein the modes of emplacement of four photodiode 3a-3d is that they face three opening 2a-2c that are formed on the mobile unit 1 successively, thereby reads four light modulating signals.
More particularly, a plurality of opening 2a, 2b, 2c are formed on the mobile unit 1 in the mode of punching, and its spread length is P.And the width of each among four photodiode 3a-3d is (1/2) P, and with the spacing location of (3/4) P (270 ° at electricity angle).So that adjacent photodiode 3a-3d is (1/4) P at interval.When mobile unit 1 during with respect to light radiating portion (not shown) and photodiode 3a-3d motion, photodiode 3a-3d receives the light that is sent and seen through opening 2a, 2b, 2c by the light radiating portion, export four independently light modulating signal (that is movement information signal) A+, B+, A-, B-from four photodiode 3a-3d.
In this case, in order to be read the movable information of mobile unit 1 by optical encoder, input to the light of photodiode 3a-3d from the light source of light radiating portion, in ideal conditions, its luminous flux is distributed in the optical receiving surface of photodiode 3a-3d equably.In this case, can only accurately read the movable information relevant, as light modulating signal with mobile unit 1.
Yet, in fact relate to multiple error component, comprise: the distribution bias of the luminous flux of light source itself, the deviation of the light flux distribution that the condenser lens of light source causes, the diffraction light that causes owing to mobile unit 1 or other similar reason, refract light and catoptrical existence, the variation of position relation, comprise the variation of mobile unit 1 and the collimation of the optical receiving surface of each photodiode 3a-3d, the variation of the size of opening 2a-2c, light source, mobile unit 1 and photodiode 3a-3d stain or variation that analogue causes, the variation of the susceptibility of the light-receiving relevant with the movement velocity change of mobile unit 1, or the like.As a result, a plurality of movement information signal that obtain from photodiode 3a-3d have changes in amplitude, the waveform distortion of dc voltage biasing, the signal of signal, the phase change of signal etc.This movable information that has caused being obtained coarse problem that becomes.
So, another kind of optical encoder has been proposed, in order to strengthen position, the movement velocity to the mobile unit 1 of patent document 1, the accuracy of detection of direction of motion, mobile unit that it had and the position of photodiode relation are as shown in Figure 5.
After this, each opening among the opening 2a-2c among Fig. 4 is collectively referred to as opening 2 in some cases.The light shield part 4a of mobile unit 1, each of 4b, 4c are collectively referred to as light shield part 4 in some cases.Photodiode 3a-3d is collectively referred to as photodiode 3 in some cases.And each opening among the opening 12a-12c among Fig. 5 is collectively referred to as opening 12 in some cases.The light shield part 14a of mobile unit 11, each of 14b, 14c are collectively referred to as light shield part 14 in some cases.Photodiode 13a1,13a2,13a3,13a4,13b1,13b2,13b3,13b4,13c1,13c2,13c3,13c4 are collectively referred to as photodiode 13 in some cases.
This optical encoder comprises k photodiode 13 is set, wherein each all comes from divides equally the photodiode in the patent document 13 by the digital x corresponding to k/n, the numerical value of k/n comes from the common multiple k of m and n is divided by n, wherein m (m is a natural number) is the opening number of mobile unit 12, and n (n is a natural number) is the number of movement information signal.Then, the connected mode of the output terminal of photodiode 13 is that the individual end of every x (x is a natural number) links to each other, thus k the individual independently movement information signal of photodiode 13 output n.
For example, if m=3, n=4, k=12, so, photodiode 3 is in the length of wide direction, and promptly the photodiode 3 of patent document 1 is divided equally by x along the length of the direction of motion of mobile unit, obtains x=3.So the light receiving part that comprises a plurality of photodiodes 13 is rearranged by 12 photodiodes 13, wherein each comes from comes five equilibrium to the photodiode 3 of patent document 1 by 3.Correspondingly, mobile unit 11 at the optical receiving surface of photodiode 13 be along the length of direction of motion patent document 1 photodiode 3 optical receiving surface 1/3rd.In addition, the output terminal of three photodiode 13a1,13b1,13c1 is connected in together, the output terminal of three photodiode 13a2,13b2,13c2 is connected in together, the output terminal of three photodiode 13a3,13b3,13c3 is connected in together, and the output terminal of three photodiode 13a4,13b4,13c4 is connected in together.By these connections, light receiving part output movement information signal A+, B+, A-, B-, they are light modulating signals of four pinpoint accuracy.
As implied above, optical encoder has as shown in Figure 5 been arranged, compare to the photodiode in the patent document 1, by each photodiode 3 is divided again, might reduce the light receiving area of each photodiode 13.Therefore, can suppress the deviation, waveform distortion, phase change of the movement information signal that obtains from light receiving part etc., improve resolution, thereby obtain accurate movement information.
Fig. 6 shows the measurement result of the lightsensitivity of the optical encoder that uses Fig. 5.According to Fig. 6,, improved differing and amplitude excursion with respect to the measurement result of the lightsensitivity of the optical encoder of use patent document 1 shown in Figure 7.
As mentioned, use optical encoder shown in Figure 5, might improve phase differential, amplitude excursion.Yet optical encoder shown in Figure 5 is not eliminated skew fully, and as shown in Figure 6, it does not have enough signal to noise ratio (S/N ratio) S/N yet.So, be necessary the more high-precision optical encoder of design.
In addition, because the bigger light source of light flux distribution deviation is used for optical encoder at a low price, naturally, in the deviation of light receiving part one side bigger deviation has taken place also.Thus, when the optical encoder of making small size, can't realize enough lens convergences, the reception that causes light is not a directional light.And when opening 12 broads of mobile unit 11, it is big that the diffraction of light becomes, and also causes realizing enough precision.So, the photodiode of unlimited adaptive faculty need be arranged deviation.
Summary of the invention
One of purpose of the present invention is, a kind of optical encoder is provided, and situations such as the skew of movement information signal that can be by suppressing to come from light receiving part, waveform distortion, phase variation obtain accurate movement information.
To achieve these goals, the invention provides a kind of optical encoder, comprising:
Mobile unit, wherein light transmission part and light shield are partly alternately arranged, and width is equal to each other, and are equal to each other at interval, the light transmission part is assigned to realize by light transmission part or photo-emission part, is divided between the phase region that forms 360 degree by described light transmission part and described light shield;
The light radiating portion is used for to mobile unit emission light;
Light receiving part is used for receiving the light that the light radiating portion is partly launched by the light transmission of mobile unit; With
The movement information signal generating portion, be used for, generate and export four movable informations of represent mobile unit and phase place based on the variable quantity of light and have 90 phase differential of spending successively with respect to mobile unit, the variable quantity of described light responds the motion of mobile unit and changes, and received by light receiving part, wherein
Light receiving part is by 4 * 3
nIndividual photodiode is formed, and wherein, n is the integer more than 2,
Described 4 * 3
nIndividual photodiode constitutes three photo diode sets, and each photo diode sets is by 4 * 3
(n-1)Individual adjacent described photodiode is formed,
Described 4 * 3
nIndividual photodiode is by described each movement information signal, with 180 degree/3
nThe phase place interval width and phase place differ successively 180 the degree/3
nMode, being divided into what described mobile unit was detected respectively is 3
nIndividual described photodiode,
Be used to generate described four movement information signal each described 3
nIndividual described photodiode is configured in described three photo diode sets with impartial quantity,
Described movement information signal generating portion is by above-mentioned each movement information signal, with dispose in described three photo diode sets described 3
nIndividual photodiode output signals addition is as described four movement information signal.
This structure has been arranged, the photodiode that is provided with corresponding to the given number of the light transmission part that constitutes light receiving part, provided according to the number of expressing by the product of two numbers, the number of one of them movement information signal, representative provides the movable information of the mobile unit of light transmission part thereon, and another is the exponential depth of the number of corresponding light transmission part.Correspondingly, the number of a plurality of photodiodes just becomes inevitably that number by movement information signal can divide, and therefore, can be unit with the number that equates with single movement information signal, distributes all photodiodes equably.Further, can divide, can distribute all photodiodes equably to be unit with number that single light transmission partly equates because the number of a plurality of photodiodes is numbers by corresponding light transmission part.
In addition, the photodiode of forming light receiving part further divides again than optical encoder shown in Figure 5 again, and in Fig. 5, the number of photodiode is expressed by the common multiple of two numbers, one of them number is the number of corresponding light transmission part, and another number is the number of movement information signal.Photodiode can distribute with respect to single zone and arrange more equably.So the skew of movement information signal, waveform distortion, phase variation etc. are suppressed, resolution is strengthened, thereby obtains accurate information signal.
In one embodiment, in described three photo diode sets, the photodiode that is used to generate described four movement information signal is arranged with same sequence.
According to this embodiment, because the movement information signal of given number based on a plurality of movement information signal groups, obtains more accurate movement information respectively from a plurality of photo diode sets outputs.
According to this embodiment, can obtain more accurate movement information.
In one embodiment, the front end of light transmission from mobile unit part is a unit distance to the front end of adjacent light transmission portion at interval,
In the photodiode that belongs to two described photo diode sets that adjoin each other, interval between the photodiode of the most contiguous another photo diode sets in photo diode sets and the photodiode of the most contiguous previous photo diode sets in another photo diode sets, and belong to interval between two adjacent photodiodes of same photo diode sets, be the numerical value that obtains with the product of the power of the number 3 of described photo diode sets divided by the number 4 of separate movement information signal with described unit distance.
According to this embodiment, photo diode sets is respectively to be provided with equably with the photodiode that belongs to a photo diode sets, and its interval separately is inversely proportional to the power of the number of corresponding light transmission part.So the photodiode of forming light receiving part is more equably with respect to each areal distribution, thereby can obtain more accurate movement information.
In one embodiment, the number of movement information signal is 4,
The number of photo diode sets is 3,
Described power is square,
The width of each photodiode is (1/18) unit distance,
In the photodiode that belongs to two described photo diode sets that adjoin each other, between the photodiode of the most contiguous another photo diode sets in photo diode sets and the photodiode of the most contiguous previous photo diode sets in another photo diode sets is (1/12) unit distance at interval; And
Belong between two adjacent photodiodes of same photo diode sets is (1/36) unit distance at interval.
According to this embodiment, each receiving unit has the individual photodiode in 36 (=4 * 32), be used for four movement information signal and corresponding three light transmission parts, photo diode sets is provided with the interval of (1/12) unit distance, belongs to the interval setting of the photodiode of same photo diode sets with (1/36) unit distance.So, 36 photodiodes are arranged and are distributed into the impartial unit of 12 photodiodes corresponding to single zone, each zone is grouped into by a light transmission part and a light shield, wherein said light transmission partly is in the middle of corresponding 3 optical communication means, and described light shield part is adjacent with the light transmission part in the back along the direction of motion of mobile unit.
In one embodiment, the number of movement information signal is 4,
The number of photo diode sets is 3,
Described power is cube,
The width of each photodiode is (1/54) unit distance,
In the photodiode that belongs to two described photo diode sets that adjoin each other, between the photodiode of the most contiguous another photo diode sets in photo diode sets and the photodiode of the most contiguous previous photo diode sets in another photo diode sets is (1/36) unit distance at interval; And
Belong between two adjacent photodiodes of same photo diode sets is (1/108) unit distance at interval.
According to this embodiment, each receiving unit has the individual photodiode in 108 (=4 * 33), be used for four movement information signal and corresponding three light transmission parts, photo diode sets is provided with the interval of (1/36) unit distance, belongs to the interval setting of the photodiode of same photo diode sets with (1/108) unit distance.So, 108 photodiodes are arranged and are distributed into the impartial unit of 36 photodiodes corresponding to single zone, each zone is grouped into by a light transmission part and a light shield, wherein said light transmission partly is in the middle of corresponding 3 optical communication means, and described light shield part is adjacent with the light transmission part in the back along the direction of motion of mobile unit.
Further, compare, realized further dividing again again photodiode with the situation that exponential depth is square.Correspondingly, all photodiodes are distributed to movement information signal and light transmission part more equably than the situation of square exponential depth.So the skew of movement information signal, waveform distortion, phase variation etc. are suppressed, resolution is strengthened, thereby obtains the accurate movement information signal.
In one embodiment, light transmission in mobile unit part be a unit distance at interval,
And at a plurality of photodiodes that belong to each photo diode sets,
From a terminal number of described photo diode sets, the photodiode that is positioned at the odd number position is first photodiode, and the photodiode that is positioned at the even number position is second photodiode,
And,
In first photodiode, being arranged in apart from the photodiode of a described end (1/2) unit distance is an A photodiode, be called as a B photodiode and be arranged in apart from the photodiode of other end rear side (1/2) unit distance opposite with a described end
And, in second photodiode, being arranged in apart from the photodiode of a described end (1/4) unit distance is the 2nd A photodiode with the photodiode that is arranged in apart from the described other end (1/4) unit distance, and the photodiode that is arranged in (1/2) unit distance in the middle of a described end (1/4) unit distance of distance and the distance described other end (1/4) unit distance is the 2nd B photodiode
So, the movement information signal generating portion, come from four types photodiode, the i.e. signal of the variable quantity of the reception luminous flux of an A photodiode, a B photodiode, the 2nd A photodiode and the 2nd B photodiode based on representative, generate and export four movement information signal independently of one another, as to represent the movable information of mobile unit.
According to this embodiment, the generation of four movement information signal independent of each other is by in each photo diode sets, come from all from the front numerical digit in the odd number position, the output that is arranged in an A photodiode of front side (1/2) unit distance adds up, come from all from the front numerical digit in the odd number position, the output that is arranged in a B photodiode of rear side (1/2) unit distance adds up, come from all from the front numerical digit in the even number position, the output that is arranged in the 2nd A photodiode of front side (1/4) unit distance and rear side (1/4) unit distance adds up, come from all from the front numerical digit in the even number position, the output that is arranged in the 2nd B photodiode of (1/2) unit distance between front side (1/4) unit distance and rear side (1/4) unit distance adds up.
The electronic equipment of an embodiment comprises optical encoder as defined above.
According to above-mentioned structure, can obtain the accurate movement information signal of representing the movable information of the mobile unit that is arranged on the motion place.
Can clearly be seen that from above description, in optical encoder of the present invention, the setting of a plurality of photodiodes is corresponding to being provided on the mobile unit, light transmission part with given number, formed light receiving part, the number that provides of described photodiode is represented with the operation result of the power of the number of the light transmission part that will answer by the number of movement information signal, described movement information signal is represented the movable information of mobile unit, so the number of a plurality of photodiodes can come whole branch by the number of movement information signal and the number of corresponding light transmission part necessarily.Therefore, can be that unit arranges equably and distributes all photodiodes with the number that equates with single zone, described single zone partly is made of light transmission part and light shield, described light transmission partly is in the corresponding light transmission part of given number, and described light shield part is adjacent with the light transmission part in the back along the direction of motion of mobile unit.In addition, can be that unit distributes photodiode equably with the number that equates with movement information signal.
Further, with number as shown in Figure 5, photodiode is that corresponding light transmission number is partly compared with the situation of the common multiple of movement information signal number, the photodiode that constitutes light receiving part further divides again again, makes photodiode be assigned with and arrange more evenly with respect to single zone.In addition, along with reducing of the light receiving area of photodiode, the skew of movement information signal, waveform distortion, phase variation etc. are suppressed, and resolution is strengthened, thereby obtain the accurate movement information signal.
Further again, comprised the electronic equipment of the present invention of above-mentioned optical encoder, can obtain accurately to represent the movement information signal of the movable information of the mobile unit that is arranged on the motion place.
Description of drawings
By the explanation of doing below in conjunction with accompanying drawing, the present invention can be understood more completely, and accompanying drawing only is used for example, is not construed as limiting the invention.
Fig. 1 shows mobile unit and the relation of the position between photodiode in the optical encoder of the present invention;
Fig. 2 is the schematic block diagram of the light-receiving side of the light-receiving lateral circuit in the optical encoder shown in Figure 1;
Fig. 3 is the synoptic diagram that is different from mobile unit in the optical encoder shown in Figure 1 and the relation of the position between photodiode;
Fig. 4 shows mobile unit and the relation of the position between photodiode in the optical encoder of the prior art;
Fig. 5 is the synoptic diagram that is different from mobile unit in the optical encoder shown in Figure 4 and the relation of the position between photodiode in the prior art;
Fig. 6 is the synoptic diagram that adopts the lightsensitivity of optical encoder shown in Figure 5; And
Fig. 7 is the synoptic diagram that adopts the lightsensitivity of optical encoder shown in Figure 4.
Embodiment
Embodiment below in conjunction with shown in the accompanying drawing is described in detail the present invention.Fig. 1 shows mobile unit and the relation of the position between photodiode in the optical encoder of this enforcement.
This optical encoder comprises: mobile unit 21, and wherein opening 22a, 22b, 22c and light shield part 24a, 24b, the 24c as light transmission example partly alternately arranges, and its width equates that interval each other equates; Light radiating portion 100 is used for to mobile unit 21 emission light; Photodiode 23a1,23a2,23a3 ... 23a12,23b1,23b2,23b3 ... 23b12,23c1,23c2,23c3 ... 23c12 as the example of light receiving part, is used for receiving from the next light of light radiating portion 100 emissions by opening 22a, 22b, the 22c of mobile unit 21; Movement information signal generating portion 200, be used for variation based on luminous flux, generate and export movable information and a plurality of movement information signal independent of each other of representing mobile unit 21, the variation of described luminous flux changes in response to the motion of mobile unit 21, and by photodiode 23a1,23a2,23a3 ... 23a12,23b1,23b2,23b3 ... 23b12,23c1,23c2,23c3 ... 23c12 receives.
Below, opening 22a, 22b, 22c are collectively referred to as opening 22 in some cases.Light shield part 24a, 24b, 24c are collectively referred to as light shield part 24 in some cases.Photodiode 23a1,23a2,23a3 ... 23a12,23b1,23b2,23b3 ... 23b12,23c1,23c2,23c3 ... 23c12 is collectively referred to as photodiode 23 in some cases.
Simultaneously, as the situation of optical encoder of the prior art shown in Figure 5,, can improve the performance of scrambler by divide the photodiode 3 of the patent document 1 shown in Fig. 4 again with the number of movable information and common multiple 12 as the number of openings of light transmission part.And, under the situation that the photodiode that divides again is set, by handle photodiode 13a1,13a2,13a3, the 13a4 related with opening 12a-12c; 13b1,13b2,13b3,13b4; Form respectively three groups of 13c1,13c2,13c3,13c4 13a, 13b, 13c are arranged to uniformly-spaced, and by each photodiode 13a1,13a2,13a3, the 13a4 that belong to identical photo diode sets 13a, 13b, 13c respectively; 13b1,13b2,13b3,13b4; 13c1,13c2,13c3,13c4 are arranged to uniformly-spaced, can reduce multiple deviation.
Based on this contact, can suitably be subdivided into bigger number to the single photodiode 3 in the patent document 1, that is, and the exponential depth of the number that is arranged on the opening 22 in the mobile unit 21 as shown in Figure 1.For example, if the number of movement information signal is 4, by A+, B+, A-, B-representative, and if the number of opening 22 are " 3 ", then the number of photodiode 23 that will be related with three openings 22 is made as:
4 * 3
2=36 (individual), 4 * 3
3=108 (individual), 4 * 3
4=324 (individual),
The reason of doing like this is, be located at " 3 " regularly owing to face the number of the opening 22 of photodiode 23, if the number of photodiode 23 can be by numeral 3 whole branches, they just can be necessarily given each opening 22 with equal number etc. so.
Further, as mentioned above, by the sum of photodiode 23 being set as the multiple of movement information signal A+, B+, A-, B-, the number of photodiode 23 can passive movement information signal A+, the whole branch of number " 4 " of B+, A-, B-, thereby photodiode 23 can be necessarily given each movement information signal A+, B+, A-, B-with the number that equates etc.
Further again, in order to divide photodiode again, be necessary to make the number of the number of opening 22 and movement information signal A+, B+, A-, B-not have common denominator.Its reason is, for example, if the number of opening 22 is " 2 ", the number of movement information signal is " 4 ", that is, if these numerals have common denominator " 2 ", so, the number of movement information signal is that " 4 " can be " 2 " whole branches by the number of opening 22 just.So even photodiode is divided again, they need not be rearranged in order to be associated with " 2 " individual opening 22 yet, more directly say, same position before they can be in and be divided, the interval of the photodiode that is divided does not again reduce.In contrast, for example, if the number of opening 22 is " 2 ", the number of movement information signal is " 3 ", that is, if they are the prime numbers that differ from one another, so, the number of movement information signal is that " 3 " cannot be " 2 " whole branches by the number of opening 22 just.Like this, in order to halve equably corresponding to three photodiodes of the number " 3 " of movement information signal by handle, thereby be divided into six photodiodes altogether, be necessary photodiode is rearranged into two groups, every group of 3 photodiodes make " 6 " individual photodiode be associated with " 2 " individual opening 22.Correspondingly, when rearranging, the interval of the photodiode that is divided again can reduce.
By the photodiode in the patent document 1 being carried out above-mentioned branch again, obtain a plurality of photo diode sets, and they are configured to row and column, can when the light-receiving susceptibility is low, realize the effect that adds up, and this situations such as deviation that add up for bigger luminous flux are effective.
In order to arrange the photodiode 22 that is divided again, use the layout that is equal to, the photodiode 23 of similar number is distributed in a plurality of openings 22 each.For example, referring to Fig. 1, three photo diode sets 23 are used to movement information signal A+, B+, A-, B-, that is, 12 photodiodes are assigned to by an opening 22 and the unit distance P that light shield part 24 is formed altogether.In other words, three groups of photodiodes 22 are made up of 12 photodiodes 23 for every group, are arranged to related with three opening 22a, 22b, 22c.Be noted that in one group of photodiode 23 at the number of the photodiode of same movement information signal and need set according to deviation condition of luminous flux etc.
In addition, each photo diode sets 23a, 23b, 23c comprise a plurality of photodiodes that divided again 23, the same, identical with a light shield part (being light tight regional 24) with respect to opening 22 position of photodiode 3a, 3b, 3c that they have as shown in Figure 4 concerns, under this condition, the output signal of the photodiode 23 by add up photo diode sets 23a, 23b, 23c, can obtain with divide again before same movement information signal A+, B+, A-, the B-of movement information signal A+, B+, A-, B-of patent document as shown in Figure 41.For example, in Fig. 1, the surface of position that photodiode 23a4,23a6,23a8 are set up is to the part of opening 22a and the part of lightproof part 24a, part and light tight regional 24 positions of being faced just as the opening 2c that in patent document 1, is faced corresponding to the photodiode 3d of movement information signal B-, by the output signal of photodiode 23a4,23a6,23a8 is added up, can obtain with patent document 1 (as shown in Figure 4) in the same movement information signal B-.
Now, about facing " 3 " individual opening 22a-22c of a plurality of photodiode 23a1-23c12 that form light receiving part, the photo diode sets of being made up of a plurality of photodiode 23a1-23a12 is arranged and distributes to a zone, this zone is made up of an opening 22a and a light tight regional 24a, and described light tight regional 24a is positioned at the position of the rear adjacent of opening 22a along the direction of motion of mobile unit 21.So, about the interval of photo diode sets 23a, 23b, 23c, come photodiode 23 is divided again with the number of the power of the number of a light opening 22 of bringing up to the opposite, can satisfy equally spaced setting.Be noted that photo diode sets 23a, 23b, 23c at interval as giving a definition.For example, two photo diode sets 23a, 23b's adjacent one another are is interval between photodiode 23a12 and the photodiode 23b1 at interval, wherein photodiode 23a12 is the most close another photo diode sets 23b among the photo diode sets 23a, and photodiode 23b1 is the most close photo diode sets 23a among another photo diode sets 23b.For example, arrangement pitch at hypothesis opening 2 is 1P (Pitch, i.e. unit distance) under the situation, in view of the photodiode of the optical encoder of patent document shown in Figure 41 is (1/4) P at interval, that the photo diode sets 13a in the optical encoder of prior art shown in Figure 5,13b, 13c is (1/4) P at interval, the interval of the interval of the photodiode 23 of optical encoder shown in Figure 1 and photo diode sets 23a, 23b, 23c is respectively P/36 and P/12, and its expression formula is 1/ (4 * 3 powers) P.
In conventional art, photodiode and late-class circuit thereof are to construct like this.Under the situation of patent document shown in Figure 11, at movement information signal A+, B+, A-, the B-of output from four photodiode 3a-3d, movement information signal A+ and movement information signal A-are compared to each other, and amplify by amplifier shown in Figure 2 25, and movement information signal B+ and movement information signal B-are compared to each other, and are amplified by amplifier 26.Thereby Ach signal and Bch signal that the phase phasic difference is 90 ° are extracted out.
In this embodiment that has used the photodiode 23 that divides again, photodiode 23, movement information signal generative circuit, promptly the make of late-class circuit 200 basically with background technology in similar.That is, exported the photodiode 23 of cycle, and exported the photodiode 23 that phase place lags behind 90 ° of the Bch movement information signal of Ach movement information signal and be arranged alternately corresponding to the Ach movement information signal of the spread length P of opening 22.
Then, suppose mobile unit 21 motion towards direction be the front side, begin number from the most preceding point, Ach special photoelectric diode 23 is positioned at the position of odd number, in these photodiodes 23, photodiode 23a1, the 23a3, the 23a5 that are arranged in front side (1/2) P are designated as the photodiode that is used for movement information signal A+, and simultaneously, photodiode 23a7, the 23a9, the 23a11 that are arranged in rear side (1/2) P are designated as the photodiode that is used for movement information signal A-.And, begin number from the most preceding point, Bch special photoelectric diode 23 is positioned at the position of even number, in these photodiodes 23, photodiode 23a2, the 23a10, the 23a12 that are arranged in front side (1/4) P and rear side (1/4) P are designated as the photodiode that is used for movement information signal B+, simultaneously, photodiode 23a4,23a6, the 23a8 that is arranged in (1/2) P in the middle of front side (1/4) P and rear side (1/4) P is designated as the photodiode that is used for movement information signal B-.
Be used for photodiode 23a1, the 23a3 of movement information signal A+, the output of 23a5 is added up, and input to amplifier shown in Figure 2 25 "+" end.Simultaneously, be used for photodiode 23a7, the 23a9 of movement information signal A-, the output of 23a11 is added up, and input to "-" end of amplifier 25.Similarly, be used for photodiode 23a2, the 23a10 of movement information signal B+, the output of 23a12 is added up, and input to "+" end of amplifier 26.Simultaneously, be used for photodiode 23a4, the 23a6 of movement information signal B-, the output of 23a8 is added up, and input to "-" end of amplifier 26. Amplifier 25 and 26 is included in the movement information signal generative circuit 200.
So phase place differs 90 ° Ach signal and Bch each other by output from amplifier 25 and amplifier 26 respectively.In this case, by dividing the signal of a plurality of (being 3 in Fig. 1) photodiode 23 to add up again, obtain movement information signal A+, B+, A-, B-coming from.Thereby the less output signal of acquisition phase shift variations.
Situation shown in Figure 1 has provided the explanation of a concrete example.Referring to Fig. 1, as mentioned above, be provided with four groups of photodiodes 23, come from four photodiodes 3,3 in the patent document 1, it is individual that each of 3,3 is divided into " 9 " again, just the number of opening 22 " 3 " square.That is, the number of the photodiode 23 of setting is " 36 ", just, the number " 3 " of the number of movement information signal " 4 " and opening 22 square product.The mode of She Zhiing is given by following condition in the case: the width of each photodiode 23 is (1/18) * P, photodiode 23 be (1/36) * P at interval, that photo diode sets 23a, 23b, 23c is (1/12) * P at interval.In addition, at movement information signal, each among three photo diode sets 23a, 23b, the 23c is formed by 12 photodiodes 23, and the order of its arrangement is A+, B+, A+, B-, A+, B-, A-, B-, A-, B+, A-, B+.Then, the signal of same channel, same symbol is added up, and compares operation by amplifier shown in Figure 2 25 and amplifier 26.Thus, obtained to have the optical encoder of continuity and enough S/N (signal noise) ratios.
In addition, in the middle of actual, using the photodiode that obtains by the photodiode in the patent document 13 is further divided again to become possibility, as shown in Figure 3 with the situation of the thinner photodiode of semiconductor technology making.
Optical encoder shown in Figure 3 comprises: mobile unit 31, and wherein opening 32a, 32b, 32c and light shield part 34a, 34b, the 34c as light transmission example partly alternately arranges, and its width equates that interval each other equates; Be used for to mobile unit 31 radiative smooth radiating portions 100; Photodiode 33a1,33a2,33a3 ... 33a36,33b1,33b2,33b3 ... 33b36,33c1,33c2,33c3 ... 33c36 as the example of light receiving part, is used for receiving from the next light of light radiating portion 100 emissions by opening 32a, 32b, the 32c of mobile unit 31; Movement information signal generating portion 300, be used for variation based on luminous flux, generate and export movable information and a plurality of movement information signal independent of each other of representing mobile unit 31, the variation of described luminous flux changes in response to the motion of mobile unit 31, and by photodiode 33a1,33a2,33a3 ... 33a36,33b1,33b2,33b3 ... 33b36,33c1,33c2,33c3 ... 33c36 receives.
Below, opening 32a, 32b, 32c are collectively referred to as opening 32 in some cases.Light shield part 34a, 34b, 34c are collectively referred to as light shield part 34 in some cases.Photodiode 33a1,33a2,33a3 ... 33a36,33b1,33b2,33b3 ... 33b36,33c1,33c2,33c3 ... 33c36 is collectively referred to as photodiode 33 in some cases.
Referring to Fig. 3, be provided with four groups of photodiodes 33, come from that each of four photodiodes 3 in the patent document 1 is divided into " 27 " again is individual, just the number of opening 32 " 3 " cube.That is, the number of the photodiode 33 of setting is " 108 ", promptly the number " 3 " of the number of movement information signal " 4 " and opening 32 cube product.The mode of She Zhiing is given by following condition in this case: the width of each photodiode 33 is (1/54) * P, photodiode 33 be (1/108) * P at interval, that photo diode sets 33a, 33b, 33c is (1/36) * P at interval.In addition, at movement information signal, among three photo diode sets 33a, 33b, the 33c each is formed by 36 photodiodes 33, and the order of its arrangement is A+, B+, A+, B+, A+, B+, A+, B+, A+, B-, A+, B-, A+, B-, A+, B-, A+, B-, A-, B-, A-, B-, A-, B-, A-, B-, A-, B+, A-, B+, A-, B+, A-, B+, A-, B+.Then, the signal of same channel, same symbol is added up, and compares operation by amplifier shown in Figure 2 25 and amplifier 26.Thus, obtained to have the optical encoder of continuity and enough S/N (signal noise) ratios.In addition, amplifier 25 and 26 is included in the movement information signal generative circuit 300.As mentioned above, in this embodiment, setting is by dividing the photodiode 23 or 33 of acquisition each of the photodiode in the patent document 13 again, the number that is divided into is again expressed by the power in the face of the number of the opening 22 of light receiving part (being photodiode 23 or 33) or 32, and photodiode 23 or 33 number are by the product representation of the power of the number of the number of A+, the B+ of movement information signal, A-, B-and opening 22 or 32.Because by the photodiode shown in Fig. 43 is divided again, shortened the distance between adjacent photodiode 23 or 33, might realize photodiode 23 or 33 at single zone and at the equilibrium setting of single movement information signal A+, B+, A-, B-, described single zone by opening 22 or 32 and light shield part (being lightproof part 24 or 34) form.
In addition, photodiode 23 or 33 number are can be according to the whole branch of number of the number of movement information signal A+, B+, A-, B-and opening 22 or 32.So all photodiodes 23 or 33 can distribute equably and are provided with the number that equates with respect to movement information signal A+, B+, A-, B-and opening 22 or 32.
And, be assigned to by opening 22 or 32 and the interval of the photo diode sets in the single zone formed of lightproof part 24 or 34, and the interval that belongs to the photodiode of same photo diode sets, be configured to the spread length P of opening 22 or 32 divided by the product of the exponential depth of the number of the number of movement information signal A+, B+, A-, B-and opening 22 or 32 and the numerical value that obtains.So photo diode sets can be provided with equably with the photodiode 23 or 33 that belongs to a photo diode sets, the inverse ratio that it becomes with the number of opening 22 or 32 at interval.
Can find out significantly from above description, photodiode 23 or 33 setting, the interval of photo diode sets and photodiode 23 or 33, and at the photodiode 23 of single movement information signal A+, B+, A-, B-or 33 setting, can be uniform.So the skew of movement information signal A+, B+, A-, B-, waveform distortion, phase variation etc. all can be suppressed, resolution is strengthened, thereby can obtain accurate movement information signal A+, B+, A-, B-.
Optical encoder in the foregoing embodiments is suitable for use as the optical sensor in printing device and FA (factory automation) equipment.
In the above-described embodiments, opening 22 or 32 orientation are not limit.For example, opening can be arranged in circular arc, round the mobile unit with disc-shape, perhaps can have the shape that is arranged in a straight line on the mobile unit of straight plate shape.
The foregoing description has provided light-transmission type as an example, wherein, the light that sends from the light radiating portion 100 of the side that is positioned at mobile unit 21 or 31, by opening 22 or 32 transmission, incide then on the photodiode 23 or 33 of the opposite side that is arranged at mobile unit 21 or 31 as light transparent member., the present invention is not limited thereto, but can also be used for the reflection-type (not shown), wherein, light from the light radiating portion of the side that is positioned at mobile unit sends by light tight regional reflex, incides on the photodiode of the opposite side that is arranged at mobile unit then.In this case, opening is as the light shield part.
In addition, the present invention can also be used for reflection-type, wherein, the light transmission part is realized by the light reflecting member that has replaced opening 22,32, the light that sends from the light radiating portion of the side that is positioned at mobile unit, reflected by light-reflecting components, incide then on the photodiode of the same side that is arranged at mobile unit.Under this situation, needn't give unnecessary details, the interval between the light-reflecting components in the mobile unit is as light shielding member.Still in this situation, for example, nickel-plated sheet is used as light-reflecting components, copper, for melanism oxidized further roughening is carried out on the surface after, be used as light shielding member.As method for making, copper is coated on the nickel-plated sheet, remove the nickel-plated sheet of specific region by etching, form light reflecting member zone and light shielding member zone thus.
In addition, no matter light-transmission type or reflection-type, mobile unit can be a light shielding plate, through hole as opening wherein is provided, maybe can be transparent panel, the optical screen film with light shielding member wherein is provided, and its part as opening comes out as photic zone.
Embodiments of the invention have more than been described, obviously, it can do multiple variation, and these variations can not be considered to depart from the spirit and scope of the invention, for the person of ordinary skill of the art, these modifications clearly can comprise within the scope of the appended claims.
Claims (7)
1, a kind of optical encoder comprises:
Mobile unit, wherein light transmission part and light shield are partly alternately arranged, and width is equal to each other, and are equal to each other at interval, the light transmission part is assigned to realize by light transmission part or photo-emission part, is divided between the phase region that forms 360 degree by described light transmission part and described light shield;
The light radiating portion is used for to mobile unit emission light;
Light receiving part is used for receiving the light that the light radiating portion is partly launched by the light transmission of mobile unit; With
The movement information signal generating portion, be used for, on behalf of the movable information of mobile unit and phase place, generate and export four based on the variable quantity of light have the movement information signal of 90 phase differential of spending successively with respect to mobile unit, the variable quantity of described light responds the motion of mobile unit and changes, and received by light receiving part, wherein
Light receiving part is by 4 * 3
nIndividual photodiode is formed, and wherein, n is the integer more than 2,
Described 4 * 3
nIndividual photodiode constitutes three photo diode sets, and each photo diode sets is by 4 * 3
(n-1)Individual adjacent described photodiode is formed,
Described 4 * 3
nIndividual photodiode is by described each movement information signal, with 180 degree/3
nThe phase place interval width and phase place differ successively 180 the degree/3
nMode, being divided into what described mobile unit was detected respectively is 3
nIndividual described photodiode,
Be used to generate described four movement information signal each described 3
nIndividual described photodiode is configured in described three photo diode sets with impartial quantity,
Described movement information signal generating portion is by above-mentioned each movement information signal, with dispose in described three photo diode sets described 3
nIndividual photodiode output signals addition is as described four movement information signal.
2, optical encoder as claimed in claim 1 is characterized in that,
In described three photo diode sets, the photodiode that is used to generate described four movement information signal is arranged with same sequence.
3, optical encoder as claimed in claim 1 is characterized in that,
The front end of light transmission from mobile unit part is a unit distance to the front end of adjacent light transmission portion at interval,
In the photodiode that belongs to two described photo diode sets that adjoin each other, the photodiode of the most contiguous another photo diode sets in photo diode sets, and another photo diode sets in the photodiode of the most contiguous previous photo diode sets between the interval, and belong to interval between two adjacent photodiodes of same photo diode sets, be the numerical value that obtains with the product of the power of the number 3 of described photo diode sets divided by the number 4 of separate movement information signal with described unit distance.
4, optical encoder as claimed in claim 3 is characterized in that,
The number of movement information signal is 4,
The number of photo diode sets is 3,
Described power is square,
The width of each photodiode is 1/18 unit distance,
In the photodiode that belongs to two described photo diode sets that adjoin each other, the photodiode of the most contiguous another photo diode sets in photo diode sets, and another photo diode sets in the photodiode of the most contiguous previous photo diode sets between be 1/12 unit distance at interval; And
Belong between two adjacent photodiodes of same photo diode sets is 1/36 unit distance at interval.
5, optical encoder as claimed in claim 3 is characterized in that,
The number of movement information signal is 4,
The number of photo diode sets is 3,
Described power is cube,
The width of each photodiode is 1/54 unit distance,
In the photodiode that belongs to two described photo diode sets that adjoin each other, the photodiode of the most contiguous another photo diode sets in photo diode sets, and another photo diode sets in the photodiode of the most contiguous previous photo diode sets between be 1/36 unit distance at interval; And
Belong between two adjacent photodiodes of same photo diode sets is 1/108 unit distance at interval.
6, as the described optical encoder of claim 4 or 5, it is characterized in that,
The front end of light transmission from mobile unit part is a unit distance to the front end of adjacent light transmission portion at interval,
And at a plurality of photodiodes that belong to each photo diode sets,
From a terminal number of described photo diode sets, the photodiode that is positioned at the odd number position is first photodiode, and the photodiode that is positioned at the even number position is second photodiode,
And,
In first photodiode, being arranged in apart from the photodiode of a described end 1/2 unit distance is an A photodiode, is called as a B photodiode and be arranged in apart from the photodiode of the other end 1/2 unit distance opposite with a described end,
And,
In second photodiode, being arranged in apart from the photodiode of a described end 1/4 unit distance is the 2nd A photodiode with the photodiode that is arranged in apart from the described other end 1/4 unit distance, and the photodiode that is arranged in 1/2 unit distance in the middle of a described end 1/4 unit distance of distance and the described other end 1/4 unit distance of distance is the 2nd B photodiode
So, the movement information signal generating portion, come from four types photodiode, the i.e. signal of the variable quantity of the reception luminous flux of an A photodiode, a B photodiode, the 2nd A photodiode and the 2nd B photodiode based on representative, generate and export four movement information signal independently of one another, as to represent the movable information of mobile unit.
7, a kind of electronic equipment comprises each the described optical encoder as claim 1～5.
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| JP2004240872 | 2004-08-20 | ||
| JP2004240872 | 2004-08-20 | ||
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