CN2072210U

CN2072210U - Sensor

Info

Publication number: CN2072210U
Application number: CN 90207148
Authority: CN
Inventors: 吴小凡
Original assignee: Individual
Current assignee: Individual
Priority date: 1990-04-18
Filing date: 1990-04-18
Publication date: 1991-02-27

Abstract

The utility model provides an improved capacitor displacement sensor used for precisely measuring displacement. The utility model is characterized in that an emitter in the prior art is changed into a figure of a brick wall shape to make the pitch P/2 of the emitter become three times larger than the original pitch. In addition, a receiving pole a and an earthed pole b on a scale is made into electric poles with the same interval and the same shape. Under the condition of the same measurement request and the same electronic circuit, the capacitor of the sensor can be wide and the isolating gap between the electric poles has small effect on the precision of measurement. Therefore, the utility model is easy to manufacture and can easily replace the existing capacitor displacement sensor to be used in measuring appliances, such as a digital displayed caliper, etc.

Description

Sensor

The utility model relates to a kind of improved capacitive displacement transducer.More precisely, it relates to the sensor that a kind of improved electric capacitance change of utilizing the capacitance group that the palisade parallel pole forms is measured relative shift between parallel pole.

Existing capacitive displacement transducer is applied in digital display calliper equal length measuring equipment.Fig. 1 has shown the example of a used capacitive displacement transducer of digital display calliper.Sensor is made up of two plate electrodes, and the pitch that being fixed on scale 1 surface distributed on the slide calliper rule blade has strictness to equate is that the electrode a of P/2 is called receiving pole, and the earthing pole b with same pitch between receiving pole separates; The electrode c that being fixed on moving chi 2 surface distributed on the slide calliper rule chi frame has many groups to equate at interval is called emitter, and 8 every group at emitter is respectively c ₁, c ₂, c ₃, c ₄, c ₅, c ₆, c ₇, c ₈, resultant pitch is P, each is organized emitter of the same name and is bound up; Also be provided with an extraction pole d on the moving chi 2.The parallel installation in ground, electrode surface opposite of scale 1 and moving chi 2 constitutes capacitance group, and can carry out relative displacement.Utilize electronic circuit to 8 emitter c ₁～c ₈Apply the same waveform alternation driving voltage of phase place mutual deviation π/4 respectively, make receiving pole a go up the alternation composite signal that produces a modulation by the capacitance group between emitter c and receiving pole a.Along with scale 1 and 2 of moving chis are subjected to displacement, the corresponding variation takes place in the electric capacity of each electric capacity in the capacitance group between emitter c and receiving pole a, and the phase place of composite signal also will take place by corresponding the variation.Electronic circuit is drawn and be coupled to composite signal by the electric capacity between receiving pole a and extraction pole d, and electronic circuit is differentiated its phase shift and converted relative shift digital signal corresponding with scale 1 and moving chi 2 to, thereby finishes the measurement to displacement.

Therefore, in order accurately to measure displacement, under the available circuit condition, the pitch of receiving pole and emitter must be done very for a short time, for example the capacitive displacement transducer of digital display calliper cooperates existing electronic circuit for accomplishing that resolution is 0.01mm, and the pitch that must accomplish emitter is P/8=0.635mm, cause the difficulty of making, also must cause increasing the cost of product.In addition, also must separate with the gap between each emitter, external series gap just must be littler, and the external series gap of the sensor can only be 0.10～0.15mm.Because sensor generally has two emitter capacities to change when displacement, and at the receiving pole edge when the emitter external series gap, have only an emitter capacity to change, even external series gap is so little, at this moment the phase shift of composite signal also can produce 3 ‰ linear error, this error is the measuring error that the measurement of slide calliper rule has brought 0.015mm, and the total error of slide calliper rule only allows 0.03mm, and this has just increased the difficulty that slide calliper rule are made.In addition, be grounded for each earthing pole is associated in together, existing scale 1 connects earthing pole at chi face one end or two ends, and figure just can not be a simple straight palisade and will make battlement shape or I-shaped, also causes to make and goes up certain difficulty.

The purpose of this utility model is to provide a kind of distribution of electrodes form improved capacitive displacement transducer.Its emitter pitch of this improved sensor can be loosened to original 4 times; It is so unimportant that the width of the external series gap between emitter becomes, and promptly the error of bringing to whole measuring system in sizable interstice coverage is so not serious; Simultaneously receiving pole is made the simplest straight palisade.

In order to achieve the above object, the measure that the utility model is taked is that emitter is made into brick wall shape figure, and Fig. 2 has represented the figure of emitter c.Like this, it highly all is 4 rows of h that emitter c lines up, and the pitch of each emitter is P/2, first row's distribution emitter c ₁, c ₅, second row's distribution c ₂, c ₆, the 3rd row's distribution c ₃, c ₇, the 4th row's distribution c ₄, c ₈, the positions of external series gap of the adjacent two row's emitters P/8 that staggers.

The emitter pitch of redistribution is P/2, is original four times, and it is just comparatively convenient to manufacture, and seems easier especially when using the manufacturing of printed-wiring board (PWB) technology to move chi.

The composition of receiving pole composite signal had had change when the emitter of redistribution made displacement, and Fig. 4 has shown that composite signal has corresponding phase shift when sensor is displaced to diverse location with the synthetic composite signal of the first-harmonic vector of driving voltage on the emitter.As seen the capacitive displacement transducer after improving still can be worked with original sensor the samely.

The emitter of redistribution can make sensor general 8 emitter capacities when displacement takes place all change, and still has 7 emitter capacities to change when receiving pole edge process emitter external series gap.First-harmonic with driving voltage on the emitter is analyzed, and external series gap is in the very wide scope of 0.2～0.4mm, and the linear error of composite signal phase shift only is 1 ‰.The capacitive displacement transducer after application enhancements on the digital display calliper for example, the error of bringing to measuring system only is 0.005mm.

Another measure that the utility model is taked is the receiving pole a on the scale and earthing pole b to be made have the identical shaped electrode of equal intervals, promptly makes the simplest straight palisade.Fig. 3 has represented the figure of receiving pole a and earthing pole b.All earthing poles are attached to metal pore-formed hole on the conductive layer at the back side to obtain reliable ground connection.The figure of this simplification is easy to make of printed-wiring board (PWB) technology, is applicable to again with precision ruling technology and makes.If cooperate the above-mentioned emitter pattern that has improved, the width of palisade external series gap does not equally resemble the strict demand the existing sensor yet.

Fig. 1 is the distribution of electrodes figure of the capacitive displacement transducer that uses of measurer such as explanation existing digital display calliper etc.

Fig. 2 is emitter and an extraction pole distribution pattern on the improved moving chi of explanation the utility model.

Fig. 3 is receiving pole and an earthing pole distribution pattern on the improved scale of explanation the utility model.

Fig. 4 is the phase shift of the capacitive displacement transducer composite signal after explanation the utility model improves and the corresponding relation of displacement.

Because the utility model has only improved the distribution of electrodes of original capacitive displacement transducer, this distribution does not also rely on the electrode size of sensor and the shape and the overall dimensions of scale, moving chi, and do not change sensor working and adaptive electronic circuit, therefore can substitute original capacitive displacement transducer fully and in all kinds of measuring equipments such as digital display calliper, implement.

Even do not change the figure of original capacitive displacement transducer scale, the moving chi figure that the utility model has improved also can cooperate the former scale to implement in various measuring equipments.

The capacitive displacement transducer that the utility model provides is made the round sealed shape and be can be used as angle displacement measurement and implemented.

If adopt the precision ruling technology when making fine pith appearance grid are had no problem, the utility model can be used as the scheme that improves Measurement Resolution and is implemented.For example use original adaptive electronic circuit, the pitch P of capacitive displacement transducer is designed to 1.016mm, promptly emitter pitch and receiving pole pitch all are 0.508mm, can realize that then resolution is the high-acruracy survey of 0.001mm.

Claims

1, a kind of capacitive displacement transducer that is used for Displacement Measurement, but it is characterized in that having the electrode group of two parallel installations and relative displacement to constitute a capacitor system,

One of them electrode group be distributed with along sense of displacement several etc. the receiving pole of pitch P/2, the earthing pole with same pitch between receiving pole separates, each earthing pole is linked together and ground connection;

Another electrode group is distributed with many groups emitter of brick wall shape figure along sense of displacement, 8 every group, is followed successively by C ₁, C ₂, C ₃, C ₄, C ₅, C ₆, C ₇, C ₈, every pitch is that P/2 lines up 4 contour rows, first row is C ₁, C ₅, second row is C ₂, C ₆, the 3rd row is C ₃, C ₇, the 4th row is C ₄, C ₈, the external series gap position of the adjacent row's emitter P/8 that staggers mutually, emitter of the same name is linked together, and also is distributed with extraction pole in this electrode group;

On 8 emitters, apply the same waveform alternation driving voltage of phase place mutual deviation π/4 during working sensor respectively, at extraction pole output composite signal.

2, capacitive displacement transducer according to claim 1 is characterized in that receiving pole and earthing pole figure are in full accord, separates with straight palisade external series gap, and all earthing pole causes backside conductive layer to be linked together reliable ground with metal pore-formed hole.

3, capacitive displacement transducer according to claim 1 is characterized in that two electrode groups are made closed circle, is used to carry out angle displacement measurement.