TWI557396B - Capacitance sensation unit of plane position measurement device - Google Patents

Description

Capacitive sensing unit of planar position measuring device

The present invention relates to position measurement techniques, and more particularly to a capacitive sensing unit for a planar position measuring device.

The specific technical content of the planar stepping motor disclosed in the invention patent No. RE27436 is mainly based on a flat plate steel plate and a mover moving on the surface of the steel plate to form the basic structure of the planar motor. The mover is allowed to interact with a magnetic field formed by a plurality of stator teeth arranged in a two-dimensional lattice on the surface of the steel sheet, so that the mover can be quickly and accurately operated on the surface of the steel plate, but The technology of position measurement with laser jammers is limited by the high price and complexity, which greatly limits the specific application of planar stepper motors.

In the prior art, in order to provide a specific technique suitable for sensing and measuring the position of a mover of a planar motor, different sensing means are disclosed and applied, which are specifically as follows: US Pat. No. 6,476,601 In the previous case, the compensation magnetic sensor provided on the basis of Hall sensing, but it is too sensitive to the residual magnetization of the stator teeth, which is a limitation of its specific application.

In the US patent No. 6175169, the improved electromagnetic sensor is integrated. On the mover, and has sub-micron sensing capability, but its accuracy decreases with the cross-modulation effect, the influence of the magnetic flux of the mover, and the stator tooth defects caused by the small sensing size. Still not perfect.

In the case of the US Patent No. 5180039, based on optical sensing technology Basically, through the fluorescence to sense the change of position, but because it is too large to be integrated into the mover component, it limits its application in the field of planar motor technology, and at the same time, because it is difficult to provide a uniform dye concentration It is also impossible to remove the noise in the position signal, and it is difficult to provide accurate position measurement results.

The different sensing techniques mentioned above have their technical limitations. The best technical means for measuring the position of the planar motor, and benefiting from the development of the planar motor manufacturing technology, the air gap of the planar motor is stabilized, and the stable air gap is the basis of the capacitive measuring technology. The capacitance measurement technique with nanometer resolution accuracy and insensitivity to magnetic flux is used for the measurement of the planar position for the prior art application.

In this connection, there is a pre-report of the invention patent No. 642911 of the United States, which discloses a base. The sensor for rotating and linear capacitance regulates the position through the special type of electrode, but it cannot be applied to the motor with planar linear displacement because of its special type.

In addition, the US Patent No. 4,893,071 discloses that the use of stator teeth is The capacitive sensing technology of the reference is used, but the harmonic distortion of the position sensing signal greatly reduces its accuracy. At the same time, because the technique of correcting and adjusting the sensor relative to the moving position is too complicated, it is difficult to be Integrated into a mover armature.

Therefore, the main object of the present invention is to provide a planar position measuring device The capacitive sensing unit is capable of measuring high-accuracy and high-resolution single-axis, multi-axis or rotational position angles.

Therefore, in order to achieve the above object, the present invention provides a planar position measuring device The capacitive sensing unit comprises a movable base body; a sensing portion is configured to sense one dimension of the virtual one sensing axis, and has a plurality of long strips of sensing electrodes. The longitudinal axis is perpendicular to the sensing axis and spaced apart from each other and spaced apart from each other, and is disposed on one side plane of the substrate, and the respective long axes of the sensing electrodes are separated from each other by a distance equal to 180. The angle between the angles.

Wherein, the angles at which the ends of the long axes of the respective sensing electrodes are spaced apart from each other, It is preferable to use an angle of an obtuse angle, and the shape thereof is set to have an inclined shape of a substantially meandering shape.

Wherein, each of the sensing electrodes is of equal width and spaced apart from each other at equal distances.

In order to improve the accuracy of the measurement, the number of the sensing portions may be increased, and is disposed on one side surface of the substrate.

Wherein, each of the sensing portions can be arranged in the axial direction of the linear arrangement, or can be arranged along a non-single arrangement axial direction of the Z-shape, that is, the specific arrangement can be adapted to different sensing needs. The range of the resulting sensing is expanded as much as possible under specific rules to improve the accuracy of sensing.

Wherein, when the sensing axes sensed by the sensing portions are parallel to the alignment axis, the direction in which the sensing is performed is the same axial direction, and becomes a single-dimensional sensing component.

Further, in order to increase the number and range of sampling, each of the sensing portions may be sequentially staggered along the alignment axis.

In addition, when the sensing axes sensed by the adjacent two sensing portions are perpendicular to each other At the same time, it is possible to perform position sensing in at least two-dimensional directions.

Furthermore, in order to improve the accuracy of the rotation angle measurement, a sensing portion of at least two may be symmetrically disposed on one side plane of the substrate with respect to a geometric center.

The tilting direction of the sensing electrodes of each of the sensing portions is reversed.

Wherein, the two sensing portions respectively make one of the sensing electrodes at the end of the oblique direction corresponding to the position of the geometric center.

(1’)(1a”)(1b”)(1c”)‧‧‧One-dimensional sensing composition

(10)(10')(10''')‧‧‧ Capacitance sensing unit

(20) (20’) (20''') ‧ ‧ base

(21’)‧‧‧Connected lines

(22’)‧‧‧Connecting holes

(23’) ‧ ‧ square side length

(30)(30’)(30”)(30''')‧‧‧ Sensing Department

(31) (32) (33) (34) (31') (32') (33') (34') (31''') ‧ ‧ sensing electrodes

(35) ‧‧‧electrode cycle

(36) ‧‧‧ separation distance

(37) ‧‧‧Sensing electrode thickness

(40)‧‧‧ Planar motor

(41)‧‧‧ Stator

(411) (411') ‧‧‧ Stator teeth

(412)‧‧‧ Backlash

(42)(42’)(42”)‧‧‧ Stator tooth cycle

(43) ‧‧‧Standard tooth height

(50’) ‧‧‧Processing Circuit

(51’) (52’) ‧‧ ‧bridge

(511') (512') (521') (522') ‧ ‧ resistance

(53’)‧‧‧Oscillator

(54’)(55’)‧‧‧Amplifier

(a)(a’)(a”)(a''') ‧‧‧ Sense axis

(b’)(b”)‧‧‧ Alignment of the axial direction

(C1)(C2)(C3)(C4)‧‧‧ Capacitance

(α)‧‧‧ angle

The first figure is a schematic plan view of a first preferred embodiment of the present invention.

The second drawing is a schematic view of the use of the first preferred embodiment of the present invention.

The third drawing is a cross-sectional view of a first preferred embodiment of the present invention.

Figure 4 is a plan view showing a second preferred embodiment of the present invention.

The fifth drawing is a bottom view of a second preferred embodiment of the present invention.

Figure 6 is a top plan view of a second preferred embodiment of the present invention.

Figure 7 is a schematic diagram showing the combination of a second preferred embodiment of the present invention and a processing circuit.

Figure 8 is a sine wave diagram of the output of the processing circuit of the second preferred embodiment of the present invention.

Figure 9 is a perspective view of a third preferred embodiment of the present invention.

Figure 11 is a plan view showing a third preferred embodiment of the present invention.

Figure 11 is a plan view showing a fourth preferred embodiment of the present invention.

First, referring to the first figure, the capacitance sensing unit (10) of the planar position measuring device provided in the first preferred embodiment of the present invention mainly includes a base body (20). And a sensing unit (30).

The base body (20) is a suitably sized circuit board provided for the sensing portion (30) and has a connection line for externally electrically connecting the sensing portion (30).

The sensing portion (30) has four strip-shaped equal-width sensing electrodes (31) (32) (33) (34) disposed in parallel with each other and equally spaced apart from the substrate (20). One side of the plate surface, and the ends of the individual major axes of the sensing electrodes (31) (32) (33) (34) are separated by an obtuse angle (α), and the center of the long axis is A bilaterally oblique shape that extends obliquely.

Accordingly, the planar position measuring device having the capacitive sensing unit (10) is integrated into a mover (not shown) of a planar motor (40) as shown in the second and third figures. For sensing the displacement position of the mover relative to a flat stator (41), wherein: The planar motor (40) is a conventional technique in which the stator (41) has a flat shape and has a plurality of conductive stator teeth (411) arranged in a checkerboard shape, and at the same time, the surface of the stator (41) is flattened and Appropriate protection is provided for each of the stator teeth (411), and is filled with an insulating encapsulating material such as epoxy resin in the backlash (412) between the stator teeth (411), thereby making the stator (41) The surface is flat, and the size of the air gap formed between the mover and the mover is stabilized.

The capacitive sensing unit (10) is directly fixed to the mover by the base body (20), and the sensing portion (30) is located on the side of the mover facing the stator (41). On the end face, according to this, each of the sensing electrodes (31) and the corresponding conductive stator teeth (411) are separated by the air gap to form corresponding capacitors (C), respectively, and then by trigger circuit, measurement The processing circuit composed of a conventional technique such as a circuit and a digital interpolator performs the processing of the sensing signal, but the processing technique of the equal signal is not the main technical feature of the present invention, and thus is not redundant.

However, the individual should be described separately, each of the sensing electrodes (31) (32) (33) (34) and The dimensions of the stator teeth (411) are mutually corresponding to each other in the present embodiment, and specifically, the sum of the stator teeth (411) and the adjacent backlash (412). The value is a certain sub-tooth period (42), and the sum of the widths of a sensing electrode and its spacing from the adjacent sensing electrodes is one electrode period (35), and the electrode period is (35) This corresponds to three-quarters of the stator tooth period (42) such that the sensing portion (30) accurately spans three stator tooth periods (42).

At the same time, the thickness (37) of each of the sensing electrodes (31) is minimized to provide a smooth surface and reduce stray capacitance, and, as shown in the second figure, each of the sensing electrodes (31) ( 32) In each of the capacitors (C1)(C2)(C3)(C4) formed by (33)(34), the first capacitor (C1) has the largest value, and the third capacitor (C3) has the largest value. Has the smallest value.

In addition, each of the sensing electrodes (31) (32) (33) (34) has a meandering inclined shape, which helps to reduce harmonic distortion to maintain its linear state, compared with the prior art. The particular shape provided by the present invention helps to improve the accuracy and sensitivity of position sensing.

Thereby, when the capacitance sensing unit (10) of the planar position measuring device is integrated into the mover and then displaced relative to the stator (41), the sensing portion (30) can be in a virtual state. Sensing of the one-dimensional direction in the direction of the sensing axis (a), specifically, the sensing axis (a) and the center point of the long axis of each of the sensing electrodes (31) (32) (33) (34) The connection is in a parallel state, that is, if the presence of the included angle (α) is ignored, the sensing axis (a) is the length of each of the sensing electrodes (31) (32) (33) (34). The axes correspond vertically.

Continuing to refer to the fourth figure, it is inevitable that a large number of the stator teeth (411') are susceptible to damage or distortion, thereby affecting the stability of the air gap size and forming spatial noise. Therefore, once the configuration of the stator teeth (411') is deformed, cornered or otherwise damaged, it also affects its reference as a measuring scale, and greatly reduces the capacitance measured by the sensing portion (30'). The accuracy of the position, and in order to reduce the influence of the deformation of the stator teeth on the sensing accuracy, in the second preferred embodiment of the present invention, the number of the capacitive sensing unit (10') is five. A linearly extending alignment axis (b') is sequentially arranged, and the sensing axes (a') of the respective sensing portions (30') are parallel to the alignment axis (b'), and along The arrangement is axially staggered, and accordingly, the number of measurement points transmitted through the sensing axis (a') and the sensing range extended to both sides after the step is misaligned, and the number of sensing samples is large. In the case of an increase, the influence of the aforementioned deformation on the sensing accuracy can be reduced.

Thereby, the sensing axis (a') of the plurality of sensing units (10') is parallel to each other in this embodiment. Corresponding to the single-dimensional sensing composition (1'), the electronic signal generated by the single-dimensional sensing component is processed by a processing circuit (50'), as shown in the seventh figure. The position sensing performed is not to directly measure each of the capacitance values, but is based on the corresponding voltage, specifically, the sensing electrodes (31') of the sensing portions (30'). (32')(33')(34') is electrically connected to each of the two bridges (51') (52') (511') (512') (521') (522') The lower point of each of the bridges (51') (52') is the surface of the stator (41') that is grounded, and the high point is the high frequency generated by an oscillator (53'). The trigger signals are connected, and the voltage balance at the branches of each of the bridges (51') (52') is measured by an amplifier (54') (55').

When the single-dimensional sensing composition is displaced by the action of the mover, each of the corresponding components The capacitance is also changed accordingly, according to which the voltage balance of each of the bridges (51') (52') is changed, and after the signal is processed, the sine wave signal as shown in the eighth figure is generated as the position. The basis of calculation of measurement.

Referring again to the ninth and tenth drawings, in the third preferred embodiment of the present invention The majority of the single-dimensional sensing composition (1") provided in the second preferred embodiment is sensed in a three-dimensional direction by appropriate composition, and is used to measure the position on the plane. Rotating angle.

Specifically, the embodiment is composed of the single-dimensional sensing of each of the number three. (1a") (1b") (1c"), sequentially arranged along the alignment axis (b"), and causing the sensing axis (a" of the first single-dimensional sensing component (1a" located at the center a sensing axis parallel to the alignment axis (b") and having a second single-dimensional sensing composition (1b") and a third single-dimensional sensing component (1c") ") are parallel to each other and perpendicular to the alignment axis (b").

Thereby, the composition disclosed in this embodiment is transmitted through each of the single-dimensional sensing groups. Form (1") to perform position measurement in different directions, wherein the embodiment can be avoided by the low sensitivity of each of the sensing portions (30") in the vertical direction of the sensing axis (a") The interaction between the single-dimensional sensing components that are vertically corresponding to each other enables accurate position sensing.

In addition, in addition to the composition method disclosed in the foregoing third preferred embodiment, in order to obtain more The high rotation measurement accuracy is the same as the capacitance sensing unit (10''') of the fourth preferred embodiment of the present invention shown in FIG. 11 by the first preferred embodiment. Based on the disclosed technology, the number of the sensing portions (30''') is increased to two, and each of the sensing portions (30''') is parallel to each other with the sensing axis (a'''). Measuring in the opposite direction, with a geometric center as an axis, symmetrically disposed on one side of the substrate (20'''), and having the first sensing electrode of each of the sensing portions (30''') (31''') is located on either side of the geometric center and measures the same stator tooth period (42''').

(10)‧‧‧Capacitance sensing unit

(20) ‧ ‧ base

(30) ‧‧‧Sensing Department

(31)‧‧‧Sensing electrodes

(a) ‧‧‧Sensing axis

Claims (12)

A capacitive sensing unit for a planar position measuring device, comprising: a movable base body capable of generating displacement relative to a planar device; and a sensing portion configured to one dimensional direction of the virtual one sensing axis Sensing, having a plurality of sensing electrodes having a meandering shape, is disposed on a side plane of the substrate with the long axis perpendicular to the sensing axis and spaced apart from each other, and each of the sensing The ends of the long axes of the electrodes are separated from each other by an angle not equal to 180 degrees; and the external device determines the displacement of the substrate relative to the planar device by the capacitance value sensed by the sensing electrodes. The capacitive position measuring device according to claim 1, wherein each of the longitudinal ends of each of the sensing electrodes is separated from each other by an obtuse angle. The capacitive position measuring device according to claim 1 or 2, wherein each of the sensing electrodes is of equal width and spaced apart from each other. The capacitive position measuring device according to claim 1 or 2, wherein the sensing portion is plural in number and is disposed on one side surface of the substrate. The capacitive position measuring device according to claim 4, wherein each of the sensing portions is sequentially disposed on one side surface of the substrate along an alignment axis. The capacitive position measuring device according to the fourth aspect of the invention, wherein the sensing axis sensed by each of the sensing portions is parallel to the alignment axis. The capacitive position measuring device for capacitive sensing according to claim 6 , wherein each of the sensing portions is sequentially staggered along the alignment axis. a position measuring device for capacitive sensing according to item 4 of the patent application scope, wherein The sensing shafts sensed by the adjacent two sensing portions are perpendicular to each other. The capacitive position measuring device according to claim 8 is characterized in that the number of the sensing portions is three. The capacitive position measuring device according to claim 1 or 2, wherein the number of the sensing portions is two, which is symmetric with respect to a geometric center, on one side plane of the substrate. The capacitive position measuring device according to claim 10, wherein the sensing electrodes of the sensing portions are inclined in a reverse direction. The capacitive position measuring device for capacitance sensing according to claim 11, wherein the two sensing portions respectively cause one of the sensing electrodes at the end of the oblique direction to correspond to the position of the geometric center.