CN102679910B - Rotary position detector and relevant method - Google Patents

Abstract

The invention discloses a rotary position detector, which comprises a shell with an inner space, wherein a reflection element is arranged in the inner space; a light source upwards emits light rays; a base supports a photodetector component with a first number of ringlike fan-shaped opto-sensors; the ringlike fan-shaped opto-sensors are arranged around the axis of a motor shaft in pairs; a detector element 'A' and a detector element 'B' are alternately arranged; a light interceptor rotates together with the shaft above the photodetector component and the light source and comprises a second number of transparent elements which are arranged around the axis and have the same surface area; the second number is half of the first number; a circuit is used for measuring signal which is from the detector A to the detector B and relevant with the quantity of light falling on the circuit; and the difference between the detector A signal and the detector B signal is relevant with the angular position of the motor shaft.

Description

Rotational position detection device and correlation technique

Technical field

The present invention relates to a kind of rotational position detection device being used for representing axle or other rotating element Angle Position.More specifically, the present invention relates to and be thisly used in motor and based on the position detector on galvanometric optical scanner.

Background technology

Rotational position detection device has many application, such as, detect the position of axle on motor so that electrical converter.Another kind of application is the position detecting regulating wheel in tape player or roll type printing machine, to keep constant-tension on band or paper.A more recent application of rotational position detection device is that induction uses motor as the position driving accelerator pedal (throttle) in the part of wheel or the automobile of whole device.

Be used to immovable input beam direction target area based on galvanometric optical scanner.This kind of scanner uses restricted rotational movement motor rotation to be delivered on the optical element of such as mirror.Usual mirror is directly installed on the output shaft of motor.Position detector is included in motor, near output shaft or be positioned in " afterwards " portion of motor.This position detector exports a curtage signal usually, and this signal is directly proportional to the relative angle of motor drive shaft, thus relevant relative to the angle of immovable input light beam with mirror.

Guide laser beam to be used for mark, cutting or display based on galvanometric optical scanner, this to positional accuracy and repeatability most important.Therefore, the degree of accuracy and the limiting factor of in repeatability are the performances of the position detector used together with optical scanner.

In theory, rotational position detection device should be only responsive to the anglec of rotation of scanner axis.Because mirror is directly connected in scanner axis, this is the anglec of rotation of the axle representing outlet beam direction.Axially-movable and radial motion generally can not affect the target location by specularly reflected jiong light beam, and because this is the target beam position important to scanning system, the output of position detector should represent target location and insensitive on the things not affecting target location, such as axis and radial motion.Axial axle motion can exist as the dynamic characteristic of scanner.Such as, if the magnetic texure of scanner is undesirable, when in fierce acceleration with between deceleration period, this axle during strong current pulse input scanner can outwards or inwardly be risen and fallen.The radial motion of scanner can exist as the result producing defect in " noise " or manufacture, and this result allows axle to have a small amount of radial motion.If rotor is not exclusively concentric with stator component, or attaches to inertia load (mirror and the support) incomplete equilibrium of output shaft, radial axle motion can also exist as dynamic effect.

One servo controller is connected between position detector and motor.If this position detector provides a certain output as axis or radial axle motion result, this indefinite output error is interpreted as the change of turned position by this servo controller, then cause the Wrong localization of whole system.Thus, the output that desirable rotational position detection device will provide as just rotating result, and the output as axis or radial motion result can not be provided.

Other good characteristics of rotational position detection device, the characteristic of the galvanometer scanner especially used together with analog servo system, comprises output voltage or electric current is the feature of linear relationship relative to the anglec of rotation.That is, the incremental change that axle rotates will produce equal incremental change in the output signal of position detector.Further, signal to noise ratio will be high as much as possible.

There is several mode and come the position of inductive axis in optical scanner.The position detector of two general class comprises capacitance positions detector and optical position detector.

Capacitance positions detector is used in that some are very original in galvanometric optical scanner.In a known detector, one rotates dielectric butterfly plate is connected in scanner axis, and check-out console is fixed.

Optical position detector has been formed as recently based on the selected position detector in galvanometric optical scanner field.Usually, optical position detector can be made very little, has low inertia, and can be manufactured at low cost with.These characteristics make optical position detector conform with the needs of the optical scanner adopted in commercial market and consumer market.

A kind of optical position detector is " projection " position detector, wherein attempts the comparatively large regions illuminating optical sensor material equably, and is incident upon on optical sensor by shadow by light blocker.Optical position detector can use photoelectric tube as optical sensor.These photoelectric tubes are the most general large area PIN type photodiodes, and for " photoelectricity " pattern, are amplified thus by photoelectric tube generation current by operational amplifier.When the light intensity on whole photoelectric tube region linearly increases, the numerical linear of electric current increases.As long as the illumination on whole region is constant, the numerical value of electric current also linearly increases illuminating when partial linear increases of photoelectric tube.That is, if the bright half optical sensor region of illumination, and light is stopped in another half optical sensor region, the half that the electric current of output will be the whole exposure of optical sensor, and forming position detector exports the linear relationship with photoelectric tube area illumination.

Kind regardless of use location detector is electric capacity or optics, and all known position detectors are all considered to have a common problem: they all export the signal representing and rotate relative to axle, but does not export the signal representing that absolute axle rotates.That is, concerning can not read-out position signal voltage or electric current and know the accurate mechanical angle of axle with absolute term servo controller.This is because the signal that the light produced to LED respectively from the output of photoelectric tube or capacitor board or oscillator produce is directly proportional.In optical position detector situation, if increased due to environmental change or component drift from the light of LED, the output produced by photoelectric tube will be increased pari passu.Deception servo-drive system is believed that axle has turned to larger mechanical angle by this relative growth.So this servo-drive system will manage compensate and produce mistake.

All known position detectors are attempted to revise this problem by automatic growth control as known in the art (AGC) circuit.When optical position detector, formation " total luminosity " signal voltage that the light that all photoelectric tubes receive is added up.This " total luminosity " voltage and reference voltage compare, and produce the rub-out signal of a driving LED.If sense that " total luminosity " increases, so make to deduct corresponding quantity by the light output of LED, thus manage the sensitiveness of holding position detector in time.But, use AGC to be just enough to revise initial instruction issue.Due to second-order effects, all known location detectors have the position offset drifts change of " absolute zero " aspect, position of axle (position detector think) and position scale drift (change that position detector represents by the mode often spending voltage), the change of the feedback resistor such as, used in the drift of reference voltage itself or operation amplifier circuit.These changes exist with time and temperature simultaneously.

In the past, attempt for rotational position detection device provides other signals representing some absolute position.To select or automatic algorithms, servo-drive system can use galvanometer scanner to find other signals, thus finds absolute position scale and the position skew of position detector.When being used in capacitance positions detector, this technology has several accessory problem.The first, the shape of capacitance positions detector to panel element is very sensitive.Due to the edge effect that outstanding or groove produce, will have linearly affected with plate that is outstanding or groove.If use other capacitor board, edge effect also can affect linearly.And no matter whether this technology uses together with optical position detector or capacitance positions detector, and the mobile butterfly plate of given shape manufactures costly.

The PID servo-drive system (analog servo system) be made up of analog element completely for controlling based on the main servo-drive system of galvanometric optical scanner.Because relatively cheap and relatively simple, analog servo system is brought into use, and all can not obtain required high-resolution and high sampling rate use fast electric flowmeter scanner due to digital servosystem up to now.The fast electric flowmeter scanner sold to support Vehicles Collected from Market, and within the working time less than 100 microsecond range completing steps, the sample rate of 200kHz and the sampling resolution of 16bits must be used.And due to the multiple internal calculation step of needs, Floating-point Computation caters to the need very much.Up to date, the servo controller realizing having high sampling rate and resolution ratio is in digital form all high cost.But, along with the steady progress occurred inevitable in technical field, digital signal processor (DSPs) and the analog-digital converter with enough speed and reasonable cost become available at present, this by contribute to produce for galvanometer scanner, from analog servo system to the conversion of the servo-drive system based on DSP.

Analog servo system has potentiometer that is relatively a large amount of, that be used for " adjustment " servo-drive system optimum performance usually.These potentiometers adjust a large amount of servo parameter, comprise servo-drive system gain, damping, notch filter frequency, the notch filter degree of depth, input gain, input offset etc.Usually two additional potentiometers are also had to adjust position scale and the position skew of position detector.Although latter two says it is not servo parameter from the strict sense, they affect servo-drive system performance and precision really.All these potentiometers must be manually adjustment or by people " adjustment ".Usual this adjustment is carried out in factory, but sometimes needs to regulate further at the scene.Because engineer is not the system end user with galvanometer scanner, the non-factory of any one regulates and all may cause time good speed row.

To avoid using all these adjustment potentiometers, because the servo parameter of such as servo-drive system gain, damping, notch filter frequency etc. all will be set by algorithm constant to the servo-drive system conversion based on DSP.These algorithm constants by people with carry out potentiometer and adjust identical mode and carry out manually " adjustment ", only use user interface to adjust, or alternatively, these algorithm constants regulate automatically by some Intelligent adjustment algorithms.Because about nearly all information of scanning system is only by utilization scanner and what observation place signal there occurs collects, this is possible.Such as, the torque constant of scanner obtains by the counter electromotive force observing scanner.KT=KE is expressed as in mechanical engineering.That is, the dynes per centimeter torque of every ampere is directly proportional to counter electromotive force of often spending voltage per second.Therefore, if servo-drive system causes scanner movements and can measure " degree/second " and motor back emf, so this servo-drive system can obtain the precision torque constant (KT) of scanner.

Once KT is known, next this servo-drive system can apply current known pulse the short time and measure the angular acceleration produced, be multiplied by acceleration because power equals quality, thus this servo-drive system can collect the system inertia (J) of rotor, mirror and position detector.Therefore, inertia equals KT divided by acceleration.

Next, this servo-drive system will be placed the ring of light and make Bode diagram around scanner, therefore show systematic resonance.According to this information, servo-drive system can set all pole and zero constants of notch biquadratic filter.

Once torque constant, system inertia and system resonance are all known, all servo parameters all available digital are accurate to the mode of second and set smoothly, obtain the absolute maximum performance from scanner and servo-drive system.But in order to make all these occur, this servo-drive system needs a basic information unit (BIU).This servo-drive system must be known " position scale ".That is, first this servo-drive system must know the often degree voltage from position detector.

As mentioned above, for previously known position detector, servo-drive system can not know the position scale definitely determined; Therefore the digital servosystem of full-automatic regulation can not have been formed.Up to now, scanner manufacturer solves this problem by little memory chip is put into side in scanner.Digital servosystem can read this memory chip, and this memory chip, in factory pre-programmed, comprises information and other information relevant with scanner that torque constant, position scale and position offset.The problem adopting the method is that these parameters can change along with the time.The torque constant of scanner depends on the magnetic of rotor (or other scanner element), and this magnetic varies with temperature definitely, and if this scanner abuse or overheatedly also to change in time.Due to component drift and due to temperature and other ambient influnences, position detector element also changes in time.

Therefore, it is beneficial that provide a kind of there is the rotational position detection device of the signal to noise ratio of improvement and absolute positional accuracy is provided.

Summary of the invention

The present invention refers to a kind of low inertia that provides and operates the optical position detector that also can use together with compact optical scanner.In addition, the invention provides the signal to noise ratio of improvement and optionally can provide absolute positional accuracy.

There is provided a kind of rotational position detection device at this, comprise the housing with the inner space limited by inwall, at least on a part of inwall, there is reflecting surface.Light source is set and injects the inner space of housing to make light from housing bottom.Base is located in enclosure interior space;

Optical detector components is arranged in the inner space of this housing and comprises the substantially fan-shaped in the form of a ring optical sensor of the first quantity, and this optical sensor is located on base and around the axis of motor drive shaft and arranges in pairs.Often comprise " A " detector element and " B " detector element for a pair.Often pair is all arranged to make each " A " detector to be circumferentially arranged between two " B " detectors and each " B " detector is located between two " A " detectors.Term " optical sensor " is used for representing the region of the light-sensitive material substantially with described shape at this; Such as, can provide and " modification " difform optical sensor material to provide described optical sensor.

Light blocker to be fixed in the inner space of housing in case be positioned at optical detector components and rotate together with the motor drive shaft above light source.This light blocker comprises the second quantity, that arrange around the axis of motor drive shaft, opaque, the element with equal surface area substantially.Second quantity equals the half of the first quantity.Therefore light that send from light source, that arrive reflecting surface reflects at optical detector components, and is stopped that the light that can not arrive reflecting surface is not received by optical detector components by light blocker.

Signal connector is located between light detector elements and a circuit, this circuit for measure with the light quantity dropped on wherein about, from " A " detector to the signal of " B " detector.Difference between " A " detector signal and " B " detector signal is relevant with the Angle Position of motor drive shaft.

By reference to the accompanying drawings, the feature characterizing structure of the present invention and method of operating can be understood better according to ensuing description, and its further object and advantage.Can be expressly understood that accompanying drawing does not intend to limit the invention for the object illustrated and illustrate.When reading ensuing description by reference to the accompanying drawings, these and other object realized by the present invention and advantage provided by the invention will become more clear.

Accompanying drawing explanation

Fig. 1 is the side perspective view of an embodiment of optical position detector of the present invention, the housing with cross-sectional view.

Fig. 2 is the side perspective view of optical position detector in Fig. 1, illustrate the light path of light when there is not light blocker, again the housing with cross-sectional view.

Fig. 3 is the top/side perspective view of position sensor of the present invention, removes housing and be illustrated as axle to rotate counterclockwise.

Fig. 4 comprises circuit board, the position sensor of optical sensor and the top plan of light blocker, illustrates the light blocker more much smaller than the external diameter of optical sensor.

Fig. 5 A, 5B illustrate top/side (Fig. 5 A) and bottom (Fig. 5 B) perspective view of the alternative of cup-shaped light blocker.

Fig. 5 C, 5D illustrate top/side (Fig. 5 C) and bottom (Fig. 5 D) perspective view of the alternative of the light blocker with " carnival hat " shape.

Fig. 5 E illustrates the top/side perspective view of another embodiment of the light blocker with the end face that a part is cut away.

Fig. 6 illustrates the embodiment connecting and be used to provide the optical sensor of output signal, and the optical sensor that wherein diametric(al) is relative is connected and only provides two outputs.

Fig. 7 illustrates another embodiment connecting and be used to provide the optical sensor of output signal, and wherein the output of each optical sensor is used directly and is not connected with other optical sensors.

Fig. 8 gives the top plan of relation between light blocker element and optical sensor.Dotted line represents that each optical sensor components is relative with light blocker.

Fig. 9 is the curve exported the output signal of optical sensor and synthesis " A-B " from " A " and " B ", wherein illustrate synthesis export be linear until " A " to or " B " optical sensor is exposed completely; After that, position detector still provides output, but is that the rate of change reduced provides.

Figure 10 is the side perspective view of another embodiment of optical position detector of the present invention, and it has the speculum be located at in the housing of cross-sectional view.

Figure 11 is the side perspective view of another embodiment of optical position detector of the present invention, wherein light blocker is formed by the bottom of motor drive shaft, the housing with cross-sectional view.

Detailed description of the invention

To describe the present invention more up hill and dale according to Fig. 1-11 hereinafter now, which show the preferred embodiments of the present invention.Unless otherwise defined, all science and technology used here and scientific terminology all have the identical implication usually understood with the technical field of the invention those of ordinary skill.Although with similar or equivalent method and material are described for practical application or experiment of the present invention at this, suitable method and material as described below.Here all publications mentioned, patent application, patent or other bibliography are all incorporated to by reference and all.When contradiction, this description comprising any definition will be examined.In addition, the material provided, method and embodiment be only in essence exemplary and be not intended to restriction.Therefore, the present invention can adopt multitude of different ways show and should not regard as and be restricted to illustrated embodiment set forth herein.It would be better to say that, provide these illustrated embodiment thoroughly complete with the content that exposes, and scope of the present invention is conveyed to those of ordinary skill in the art completely.According to ensuing detailed description, other Characteristics and advantages of the present invention will become clear.

Optical position detector of the present invention uses " projection " technology.Improve each element of this position detector when compared with other known optical position detector, obtain the improvement result of positional precision and signal to noise ratio aspect.In addition, some embodiment of this position detector allows to determine that absolute position represents that it has arrived a certain horn shape state according to position detector ability.

The preferred embodiments of the present invention can be seen in FIG, and are described in the scope that it is used in motor or galvanometer scanner, but are not intended as restriction.In the position detector of Fig. 1, light source 4 is located in the inner space 21 of housing 6.Housing 6 is suitable for accommodated position sensing system element and absorbs unwanted light from environment, and these elements is connected to the axle 10 of motor in a particular embodiment.Housing 6 comprises such as injection plastic or machined metal, but this is not intended as restriction.

Light source 4 preferably produces the uniform light field substantially circumferentially distributed, by the inwall 20 of light 5 guide housings 6.The inwall 20 of housing 6 comprises mirror reflection surface 11, and light 5 is pointed to multiple optical sensor 7A, 7B, 8A, 8B of such as comprising annular sector element by this reflecting surface again.Optical sensor 7A, 7B, 8A, 8B can manufacture on photodetector chip 7,8 and be arranged on comprise circuit board 2 base on, and on the side identical with light source 4 of motor.

The light blocker 12 with multiple protuberance of pie substantially 90 and 92 periodically stops the light 5 arriving housing 6 inner surface, therefore also periodically stops by cast shadow thereon the light arriving some region of optical sensor 7A, 7B, 8A, 8B.

Light blocker 12 in this structure is operably connected on motor drive shaft 10, and this axle extends through the hole 60 in the top 70 of housing 6.The rotation of the motor drive shaft 10 driven by motor makes light blocker 12 rotate.When the illuminated area of some optical sensor 7A, 8A, 7B, 8B increases (when being positioned under shade when less optical sensor region), increase from the output signal of optical sensor 7A, 8A, 7B, 8B simultaneously.When other optical sensors 7A, 8A, 7B, 8B field of illumination simultaneously and when reducing with same quantity (when being positioned under shade when more optical sensor regions), the output signal from these optical sensors 7A, 8A, 7B, 8B reduces.

According to Fig. 1 and 2, position sensor light source and inner shell are described now.Light source 4 preferably includes the single LED be arranged on photodetector chip 7 and 8 on same circuit board 2.Fig. 1 and 2 shows the LED be arranged on photodetector chip 7 and 8 on the opposite side of circuit board, and is directed to the through hole 3 in circuit board 2 from the light of light source 4.This is desirable, because the arbitrary light launched with landscape mode will to end on circuit board 2 material and can not directly impinge upon on photodetector chip 7 and 8.But as long as light source is suitable and arrange between two parties substantially, other embodiments are also possible.Such as, single led chip can be arranged on the same side of circuit board with photodetector 7 and 8, is even directly installed on photodetector matrix.

Light 5 penetrates and the inwall 20 of directive housing 6 along the direction away from photodetector chip 7 and 8 from light source 4.The inwall 20 of housing 6 comprises mirror reflection surface 11, and light 5 is reflected back into photodetector chip 7 and 8 by this reflecting surface.

This mirror reflection surface 11 can be as shown in the figure bending, such as, become parabola or elliptical shape, therefore makes light more parallel and is that light is concentrated in the general areas of photodetector 7A, 7B, 8A, 8B.But this mirror reflection surface 11 also can show as other shapes, such as taper and even flat ring 61, as long as allow not stopped by light blocker 12, arrive photodetector 7A, 7B, 8A, 8B from the light 5 of light source 4.

In addition, Fig. 1 and 2 shows the inwall 20 of the housing 6 with mirror reflection surface 11, but it is contemplated that, there is an embodiment, adopts the individual component be held in place by housing 6 to provide mirror reflection surface 11 thus.

Although position detector light source 4 is described as LED, light source can also be expressed as phosphor dot or edge needs direction to produce any other source of suitable light cone.Should be understood that position detector light source can be optical fiber supply.That is, actual light source can be arranged at a distance, such as, to be located on servo-drive system drive plate and to utilize optical fiber to be supplied to galvanometer scanner.This may be used in Military Application, and in this application, scanner will at high temperature work, and this is that direct LED operation forbidden.In addition, when being supplied by optical fiber, laser can be used as the light-emitting device of light source.

The embodiment of optical detector components and light blocker is such as discussed according to Fig. 3 and 4 now, and its location as shown in Figure 1.Optical detector components is positioned at the inner space 21 of housing 6.In the exemplary detectors assembly of Fig. 3 and 4, optical sensor comprises the first quantity (being 4 here) fan-shaped in the form of a ring, that have substantially equal surface area optical sensor 7A, 7B, 8A, 8B substantially, these optical sensors are arranged in pairs on the photodetector chip 7,8 around light source 4, and install on the circuit board 2.Often all comprise " A " detector element 7A, a 8A and " B " detector element 7B, 8B for a pair.Often pair is all arranged to make each " A " detector 7A, 8A to be circumferentially arranged between two " B " detectors 7B, 8B and each " B " detector 7B, 8B are located between two " A " detectors 7A, 8A.

The structure of this sensor construction major decision light blocker 12 and blade 90,92 thereof.Light blocker 12 comprises around axis 10 that the second quantity (being 2 here) is arranged in motor drive shaft, to have substantially equal surface area opaque element 90,92.Should be understood that the second quantity (such as 2) equals the half of the first quantity (such as 4).

With reference to figure 8, wherein light blocker exposes " B " completely to optical sensor, and it is right not cover " A " completely, the angle of chord (being 5 degree here) that the angle of chord (being 60 degree here) of each open area of light blocker can be more different than the angle of chord of detector element 7A, 7B, 8A, 8B (being 55 degree here).Due to this, the clockwise direction increased further rotates can not cause any increment in " B " the output side signal face to optical sensor, but causes a large amount of minimizing at " A " to output side signal face.When the angle of chord of light blocker opening be greater than light detector elements 7A, 7B, 8A, 8B the angle of chord time, sensor to be no more than light detector elements 7A, 7B, 8A, 8B angle of chord angle change linear convergent rate is provided, then to exceed this point angle change nonlinear object is provided.

The radial elongation of each light blocker element 90,92 can be less than the radial elongation of light detector elements 7A, 7B, 8A, 8B, and is not more than the radial elongation of inner edge 71 of light detector elements 7A, 7B, 8A, 8B.In some cases, depend on the elongation of the reflecting part 11 of cone angle and the inwall 20 comprising light source 4, the radial elongation of light blocker element 90,92 can be obviously less.This is favourable compared with the sensor of prior art time, and in prior art, the radial elongation of light blocker must be greater than the radial elongation of the external diameter of photodetector 7A, 7B, 8A, 8B.Less radial elongation essentially reduces inertia, thus improves systematic function simultaneously.

Light blocker 12 can be configured to when axle 10 rotates along " just " to 85 (shifting to the structure shown in Fig. 3 from the structure shown in Fig. 1), and major part " A " optical sensor region is illuminated by light source 4, and major part is under " B " optical sensor region is in shade.Therefore, when light blocker 12 rotates, once expose " A " optical sensor 7A, 8A completely, in fact can stop that light arrives the rotation that takes a step forward of " B " optical sensor 7B, 8B completely at it.This makes servo-drive system accurately detect when " A " and " B " sensor is covered completely, thus accurately detects the exterior angle of position sensor with absolute term.But some application does not need this absolute position to determine, and its opening can be used to have the light blocker of the angle of chord identical with sensor element 7A, 7B, 8A, 8B.

Although drawings show four photodetectors 7A, 7B, 8A, 8B and the light blocker with two outstanding elements 90,92, should be appreciated that, few to four photodetectors and two light blocker protuberances, or as many as eight photodetectors and four light blocker protuberances, or more is all possible, and still falls within the scope of the invention.

The device that discrete optical sensor can comprise optical sensor material or operate on principle, the linear increase of per unit area glazing makes to produce linear increase in the output signal thus.As non-limiting example, silicon photoelectric diode, PIN type photodiode, avalanche photodide and cadmium sulphide cell can be used as the optical sensor in the present invention.These are commonly referred to as " photocell ".

It is known that arrange discrete optical sensor pair on single " photocell " matrix being rectangle as Figure 1-4.But discrete optical sensor can be assembled by any way, as long as it is just passable to meet above-mentioned linear and shape restriction.Further, optical sensor can have the area larger than diagram, such as, can comprise the chip of arbitrary shape respectively, and be provided with decoration element thereon, wishes the fan-shaped of use to be formed.

The light that this light blocker is designed to prevent from being given out by light source 4 arrives on each several part of the specular reflection film 11 in inner walls 20, thus prevents light from arriving each several part of optical sensor 7A, 7B, 8A, 8B.The light blocker 12 comprising pie blade 90,92 utilizes epoxy resin or other attachment arrangements to be operably connected on turning cylinder 10.

Because light blocker only need prevent light from arriving optical sensor, therefore it can be made up of various material.Such as, can stop that the suitable material of light is made by pottery, glass fibre/epoxy resin, sheet metal, glass, plastics or any one.Manufacturing processes customary can be used to manufacture light blocker, such as injection moulding, laser cutting, punching press, photoengraving or Standard Machine processing technology.

Light blocker is made into consistent with the shape shown in Fig. 1-4, or is made up of transparent plate, realizes barrier functionality thus by the opaque material be deposited on transparent plate.In addition, other embodiment is also possible.Fig. 5 A, 5B show the alternative of light blocker 30, and wherein cup-shaped light blocker is formed with axial protuberance.That is, the end face 31 of light blocker 30 has two elements 32 substantially in pie be arranged in around central disc 33.What hang down from end face 31 is the sidewall 34 of forming section cylinder, and this cylinder has the top 35 extended on an equal basis with the outward flange 36 of end face 31.

Fig. 5 C, 5D show another embodiment that interior section has the light blocker 40 of the shape similar with above-mentioned smooth blocker 30.But at this, two base member 41 stretch out from sidewall 42, form a pair annular sector flange, the inner edge 43 of this flange at its bottom margin 44 place in conjunction with sidewall 42.Therefore this light blocker 40 has one " carnival hat " shape.

Fig. 5 E illustrates the another embodiment of light blocker 50, comprises cylindrical circular element substantially, has the inner space 57 that limited by sidewall 54 and is set to receive the light from light source 4.In a particular embodiment this circle tube element have by its end face 51 and along central disc 53 diametrically opposed, substantially there is the relative opening 52 of a pair of equal areas.Opening 52 arrives reflecting surface 11 for allowing light to pass.

In another embodiment (Figure 11), light blocker 70 comprises the bottom 71 of motor drive shaft 10.Bottom comprises one and is roughly columnar part, has and is set to receive the inner space 72 from the light of light source 4.This cylindrical shape part 71 has two openings 73 that are relative, same size or " window ", such as in this embodiment, extend through, but this is not construed as limiting from its bottom margin 74.Opening 73 limits the parts of the cylindrical shape part 71 that can be used as light blocker element.In addition, wording " a pair " is not intended as restriction, can comprise as many as 8 and even more in some number of applications.Each opening 73 has to be enough to allow light to arrive the height 75 of reflecting surface 11 by it.

Should believe, light blocker 30,40,50,70 as above can improve projection shade on the photo-detector, if if particularly light source be not spot light and/or mirror reflection surface quality marginal or very poor time.

It is not strictly required for should be understood that alternative light blocker embodiment has rectangular characteristic.This cup can make conical part, can realize more easily manufacturing light blocker or better photo-resistance.In addition, light blocker itself can show as blade and even directly on motor drive shaft itself, carry out machined thus the keyway of realization resistance light function.

Different from previously known rotational position sensor, the opening of light blocker can have the angle of chord larger than discrete optical sensor.Several advantage is there is when completing this.An advantage is, because the angle of chord of light blocker opening is greater than the angle of chord of optical sensor, when rotating along " forward " direction 85, " A " optical sensor did not stop completely before " B " optical sensor is completely by stop.Further " forward " rotates still generation one from the detected output of " B " sensor, but can not produce the output from " A " sensor.Therefore this state exporting further change and another change further can be used to determine shaft angle exactly with absolute term.Another advantage is, subtract each other if A and B exports, as the exemplary process for this sensor, there is " linearly " part of the axle anglec of rotation corresponding with output signal, and there is " non-linear " part of the shaft angle corresponding with output signal in edge.Such as, in fig .9, the rate of change of output is expressed as the change more than 25 degree.

Preferably, generally speaking, light blocker opening has at least equally large with the optical sensor angle of chord angle of chord.But, one with ordinary skill in the art would appreciate that the angle of chord can be substantially identical with the angle of chord of optical sensor when not deviating from spirit of the present invention, even less.In certain embodiments, the angle of chord of light blocker opening can be made into the arbitrary desirable numerical value that can meet greatly the requirement of engineering of system than the angle of chord of optical sensor.But for optical scanner application, it usually can within the scope of 2-10 degree.

The number of light blocker opening includes as few as 2 as many as 8 or more, as long as each light blocker opening has 2 optical sensors (" A " and " B "), a large amount of light blocker openings decrease the operation angle of position detector.Position detector can export single ramp signal maximum angular (to spend calculating) from " master " output area equals 360 and deducts (the blade angle of chord deducts the optical sensor angle of chord) divided by lobe numbers.

When light blocker is by when complete light-absorbing material is made substantially, do not allow light through arriving mirror reflection surface and detector.For this embodiment, the black coating that light blocker comprises black plastic, black oxidation metal or is deposited on transparent plate or transparent pipe.As can be seen here, then all light sent from light source arrive photodetector from mirror face reflection coating reflection or are absorbed by each several part of light blocker.

Although it should be pointed out that light blocker described here has protuberance simultaneously, those of ordinary skill in the art should admit that they can not have protuberance to have region of being in the light.Such as, light blocker can comprise transparent plate or other light pipes with printing superincumbent barrier zones.

In alternate embodiment 63 (Figure 10), reflecting surface can comprise: be arranged in the bottom surface 62 of the annular reflex element 61 of the inner space 21 of housing at least partially, allows motor drive shaft 10 to pass through thus the hole 64 of rotating betwixt.In this embodiment 63, reflecting element 61 is fixed in the inner walls 20 that is positioned at above light blocker 12.As for the embodiment 1 in Fig. 1, do not arrived the reflection bottom face 62 of reflecting element 61 by the light 5 that light blocker 12 stops and reflex on optical sensor 7A, 7B, 8A, 8B.

Pass now the signal that rotational position detection device of the present invention produces through discussion.In one embodiment, discrete optical sensor is connected in parallel, and therefore minimum electric wire is sent to servo controller, as shown in Figure 6.The benefit of this connected mode resides in reduced the number of wires needed for link position detector and servo-drive system.But, the defect common with prior art Position Sensor is, if just do not produce the output signal amount the same with other discrete optical sensors for given light quantity, the discrete optical sensor that is connected in parallel, not so best to the insensitivity of radial direction and axially-movable.

As alternative connected mode, the output from discrete optical sensor can be used one by one, as shown in Figure 7.The advantage of this layout is that this servo-drive system can characterize the output from each optical sensor, then algorithmically increases linear and radial insensitivity.In this embodiment, form output by the pad 9 on circuit board 2 to connect.

When being connected to digital servosystem, position detector of the present invention is particularly useful, this digital servosystem can be used this scanner and is successfully arranged on by this point during " A " and " B " optical sensor rotates by the axle that stops completely, thus determines angle drift degree with absolute term.Thus, do not need AGC system, and light source carries out work with maximum output all the time, thus make signal to noise ratio maximum.

In the accompanying drawings and the description, disclosed representative preferred embodiment of the present invention, although have employed proprietary term, the term of use is only describing significance instead of in order to limit.Specifically very describe in detail the present invention with reference to these illustrated embodiment.But, it is evident that in the essence of the present invention and scope that describe at above-mentioned description and can carry out various distortion and change.

Claims (25)

1. a rotational position detection device, this rotational position detection device comprises:

Housing, has the inner space that limited by inwall and has the hole top that is positioned at described housing passed to allow motor drive shaft;

Base, is located in the inner space of described housing;

Light source, is set to make light upwards inject the inner space of described housing from the bottom of contiguous described housing;

Optical detector components, be arranged in the inner space of described housing, and comprise optical sensor that is fan-shaped in the form of a ring, the first quantity, these optical sensors to be arranged on described base and to arrange in pairs around the axis of described motor drive shaft and light source, every a pair optical sensor comprises " A " detector element and " B " detector element, and optical sensor arranged in pairs is arranged to make each " A " detector to be circumferentially arranged between two " B " detectors and each " B " detector is arranged between two " A " detectors;

Light blocker, be arranged in the inner space of described housing, and can rotate together with the described motor drive shaft above described light source with being positioned at described optical detector components, described smooth blocker comprises the second quantity, that arrange around the axis of described motor drive shaft, have equal surface area, opaque element, described second quantity equals the half of described first quantity, wherein, the radial elongation of each element of described smooth blocker is less than the radial elongation of described optical sensor;

Reflecting surface, be arranged in the inner space of the described housing above described smooth blocker, wherein, light that send from light source, that arrive described reflecting surface is reflected downwards, make some light in light arrive described optical detector components, and the light that can not be arrived described reflecting surface by described smooth blocker stop is not received by described optical detector components; And

Signal connector, be positioned at described light detector elements and for measuring between the circuit from the signal relevant with the light quantity be irradiated on it of described " A " detector and described " B " detector, the difference between the signal from " A " detector and the signal from " B " detector is relevant with the Angle Position of described motor drive shaft.

2. rotational position detection device according to claim 1, is characterized in that, the radial elongation of each element of described smooth blocker is not more than the radial elongation of the inner edge of described optical sensor.

3. rotational position detection device according to claim 1, it is characterized in that, described smooth blocker has multiple opening, each opening is between the adjacent elements of described smooth blocker, and the angle of chord of each opening in multiple openings of wherein said smooth blocker is at least equally large with the angle of chord of described optical sensor.

4. rotational position detection device according to claim 1, is characterized in that, described light source comprises the single light source aimed at the axis of described motor drive shaft.

5. rotational position detection device according to claim 1, is characterized in that, the optical sensor of described first quantity comprises four optical sensors.

6. rotational position detection device according to claim 1, it is characterized in that, described optical sensor comprises photosensitive optical sensor material, and wherein, the linear increase being radiated at the per unit area glazing on described optical sensor makes output signal linearity increase.

7. rotational position detection device according to claim 1, is characterized in that, each element of described smooth blocker comprises blade.

8. rotational position detection device according to claim 1, is characterized in that, described smooth blocker comprises transparent dish, and described opaque element has been applied on this dish.

9. rotational position detection device according to claim 1, is characterized in that, described reflecting surface comprises a part for the inwall of described housing.

10. rotational position detection device according to claim 1, it is characterized in that, described reflecting surface comprises the element of the inner space being arranged in described housing, this element has bottom surface, described bottom surface be reflective at least partially, and this element also has the hole being enough to allow described motor drive shaft to pass.

11. rotational position detection devices according to claim 1, is characterized in that, each element in each element of described smooth blocker also comprises the sidewall dangled by this element downwards, thus form cup-shaped light blocker.

12. rotational position detection devices according to claim 11, is characterized in that, each element in each element of described smooth blocker also comprises from the outward extending annular sector flange of the bottom margin of described sidewall.

13. rotational position detection devices according to claim 1, it is characterized in that, described smooth blocker comprises cylindrical circular element, this columnar element has and to be limited by sidewall and to be set to receive the inner space from the light of described light source, this circle tube element have a pair spaced, that there is equal areas, by the opening of its end face, pass to allow light and arrive described reflecting surface.

14. rotational position detection devices according to claim 13, is characterized in that, the angle of chord of described opening is at least equally large with the angle of chord of described optical sensor.

15. rotational position detection devices according to claim 1, it is characterized in that, described smooth blocker comprises the bottom of described motor drive shaft, the cylindrical circular part with inner space is comprised bottom this, this inner space is set to receive the light from light source, each element of described smooth blocker comprises the parts of the cylindrical shape part separated by that extend from its bottom margin, spaced opening, and this opening has to be enough to allow light through the height arriving described reflecting surface.

16. rotational position detection devices according to claim 15, is characterized in that, the angle of chord of described opening is at least equally large with the angle of chord of described optical sensor.

17. 1 kinds of methods detecting the turned position of motor drive shaft, the method comprises:

Light is upwards irradiated in the inner space of housing, and this housing has the hole being positioned at its top, passes to allow described motor drive shaft;

Downward reflection at least some light;

Optical detector components is utilized to detect at least some reverberation, this optical detector components to be arranged in the inner space of described housing and to comprise fan-shaped in the form of a ring, the optical sensor of the first quantity, these optical sensors are arranged on base and axis around described motor drive shaft is arranged in pairs, every a pair optical sensor comprises " A " detector element and " B " detector element, the optical sensor of paired setting is arranged such that each " A " detector is circumferentially arranged between two " B " detectors and each " B " detector is arranged between two " A " detectors,

Utilize the inner space being arranged in described housing, the light blocker rotated together with described motor drive shaft stops the light that a part is upwards irradiated, described smooth blocker comprise the second quantity, arrange around the axis of described motor drive shaft, the opaque element with equal surface area, described second quantity equals the half of described first quantity, can not be arrived described optical sensor by the light part stopped thus, wherein the radial elongation of each element is less than the radial elongation of described optical sensor; And

Receive with process from " A " detector and " B " detector, relevant with the light quantity be irradiated on it signal, the difference between the signal from " A " detector and the signal from " B " detector is relevant with the Angle Position of described motor drive shaft.

18. methods according to claim 17, is characterized in that, the radial elongation of each element of described smooth blocker is not more than the radial elongation of the inner edge of described optical sensor.

19. methods according to claim 17, is characterized in that, the single light source that the light irradiating step be upwards irradiated in the inner space of housing is comprised by aiming at the axis of described motor drive shaft irradiates light.

20. methods according to claim 17, is characterized in that, the optical sensor of described first quantity comprises four optical sensors.

21. methods according to claim 17, is characterized in that, described optical sensor comprises photosensitive optical sensor material, and wherein, the linear increase being radiated at the per unit area glazing on described optical sensor makes output signal linearity increase.

22. methods according to claim 17, is characterized in that, each element of described smooth blocker comprises blade.

23. methods according to claim 17, is characterized in that, described smooth blocker comprises transparent dish, and described opaque element has been applied on this dish.

24. methods according to claim 17, is characterized in that, downwards the reflection steps of reflection at least some light comprises and reflects described at least some light by the reflecting part of the inwall of described housing.

25. methods according to claim 17, it is characterized in that, the reflection steps of downward reflection at least some light comprises by least some light described in the element reflects of the inner space being arranged in described housing, this element has bottom surface, this bottom surface be reflective at least partially, and this element also has the hole being enough to allow described motor drive shaft to pass.