CN105843444B - A kind of signal coordinates processing method, circuit and electromagnetism apparatus for writing - Google Patents
A kind of signal coordinates processing method, circuit and electromagnetism apparatus for writing Download PDFInfo
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- CN105843444B CN105843444B CN201610157475.0A CN201610157475A CN105843444B CN 105843444 B CN105843444 B CN 105843444B CN 201610157475 A CN201610157475 A CN 201610157475A CN 105843444 B CN105843444 B CN 105843444B
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- G—PHYSICS
- G06—COMPUTING; CALCULATING OR COUNTING
- G06F—ELECTRIC DIGITAL DATA PROCESSING
- G06F3/00—Input arrangements for transferring data to be processed into a form capable of being handled by the computer; Output arrangements for transferring data from processing unit to output unit, e.g. interface arrangements
- G06F3/01—Input arrangements or combined input and output arrangements for interaction between user and computer
- G06F3/03—Arrangements for converting the position or the displacement of a member into a coded form
- G06F3/041—Digitisers, e.g. for touch screens or touch pads, characterised by the transducing means
- G06F3/0416—Control or interface arrangements specially adapted for digitisers
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- G—PHYSICS
- G06—COMPUTING; CALCULATING OR COUNTING
- G06F—ELECTRIC DIGITAL DATA PROCESSING
- G06F3/00—Input arrangements for transferring data to be processed into a form capable of being handled by the computer; Output arrangements for transferring data from processing unit to output unit, e.g. interface arrangements
- G06F3/01—Input arrangements or combined input and output arrangements for interaction between user and computer
- G06F3/03—Arrangements for converting the position or the displacement of a member into a coded form
- G06F3/033—Pointing devices displaced or positioned by the user, e.g. mice, trackballs, pens or joysticks; Accessories therefor
- G06F3/0354—Pointing devices displaced or positioned by the user, e.g. mice, trackballs, pens or joysticks; Accessories therefor with detection of 2D relative movements between the device, or an operating part thereof, and a plane or surface, e.g. 2D mice, trackballs, pens or pucks
- G06F3/03545—Pens or stylus
-
- G—PHYSICS
- G06—COMPUTING; CALCULATING OR COUNTING
- G06F—ELECTRIC DIGITAL DATA PROCESSING
- G06F3/00—Input arrangements for transferring data to be processed into a form capable of being handled by the computer; Output arrangements for transferring data from processing unit to output unit, e.g. interface arrangements
- G06F3/01—Input arrangements or combined input and output arrangements for interaction between user and computer
- G06F3/03—Arrangements for converting the position or the displacement of a member into a coded form
- G06F3/041—Digitisers, e.g. for touch screens or touch pads, characterised by the transducing means
- G06F3/046—Digitisers, e.g. for touch screens or touch pads, characterised by the transducing means by electromagnetic means
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- Engineering & Computer Science (AREA)
- General Engineering & Computer Science (AREA)
- Theoretical Computer Science (AREA)
- Physics & Mathematics (AREA)
- Human Computer Interaction (AREA)
- General Physics & Mathematics (AREA)
- Electromagnetism (AREA)
- Measurement Of Length, Angles, Or The Like Using Electric Or Magnetic Means (AREA)
Abstract
The invention discloses a kind of signal coordinates processing method, circuit and electromagnetism apparatus for writing, which includes：Electromagnetic signal receiving circuit receives the electromagnetic signal of time writer transmitting；Rotating Capacitor Filter controls Rotating Capacitor Filter using pwm signal identical with the frequency of the electromagnetic signal, is filtered to the electromagnetic signal, to filter out and the different invalid signals of the frequency of electromagnetic signal；Electromagnetic signal processing circuit handles filtered electromagnetic signal, obtains signal coordinates position.The present invention controls Rotating Capacitor Filter by pwm signal identical with the electromagnetic signal frequency emitted with time writer and is filtered come the electromagnetic signal received to electromagnetism apparatus for writing, Rotating Capacitor Filter under pwm signal control, its operational frequency bandwidth is relatively narrow, filtering is accurate, invalid signals can be effectively filtered out, accuracy of identification of the electromagnetic signal processing circuit to time writer writing process electromagnetic signal coordinate is improved.
Description
Technical field
The present invention relates to a kind of signal processing technology field more particularly to signal coordinates processing method, circuit and electromagnetism books
Write device.
Background technology
The technology of various time writers, either active either passive technology, can all be handled using filter circuit
Extraneous interference, to improve the identification for writing coordinate position to time writer, if not to the interference signal of interference time writer work
It is handled, then the identification that coordinate position can be write to time writer has an impact, can loss of function if serious.Electromagnetism book at present
There are commonly 3 kinds for the filtering mode write：1. software filtering, but the stronger processor that can support Fourier's series is needed,
The operating frequency range of time writer is 50HZ-1MHZ frequencies, usually supports the processor of 500HZ-1M Fourier's series all very
Expensive, this filtering mode is of high cost；2. ceramic filter, ceramic filter frequency is fixed, and supply environment is poor, frequency filtering selection
Property is poor；3. the active filter built with amplifier, including low-pass filter, high-pass filter, bandpass filter, these filters
Be required for periphery resistance, capacitance form a specific frequency filter, to resistance value, capacitance it is more demanding, be easy
The phenomenon that frequency of occurrences deviates, cannot effectively filter out specific frequency.The bad rear end that can influence is filtered to writing coordinate position
Identification reduces accuracy of identification.
Invention content
The purpose of the present invention is to provide a kind of signal coordinates processing method, circuit and electromagnetism apparatus for writing, can improve
Filter effect, to improve the coordinate accuracy of identification of electromagnetism writing process electromagnetic signal.
For this purpose, the present invention uses following technical scheme：
In a first aspect, a kind of signal coordinates processing method, including：
Receive the electromagnetic signal of time writer transmitting；
Rotating Capacitor Filter is controlled using pwm signal identical with the frequency of the electromagnetic signal, the electromagnetism is believed
It number is filtered, to filter out and the different invalid signals of the frequency of electromagnetic signal；
Filtered electromagnetic signal is handled, signal coordinates position is obtained.
Wherein, the electromagnetic signal for receiving time writer transmitting, including：
Detect the electromagnetic signal of time writer transmitting；
The electromagnetic signal is subjected to low level signal amplification, obtains amplified signal.
Wherein, further include the circular route for scanning electromagnetic writing plate before the electromagnetic signal for receiving time writer transmitting
Circle, obtains scanning result；
It is described that filtered electromagnetic signal is handled, signal coordinates position is obtained, including：
Exchange amplification is carried out to filtered electromagnetic signal, obtains exchange amplified signal；
Exchange amplified signal is switched into direct current signal；
The direct current signal is amplified, direct current amplified signal is obtained；
ADC samplings are carried out to the direct current amplified signal, obtain digital signal；
The digital signal and scanning result are handled, signal coordinates position is obtained.
Second aspect, a kind of signal coordinates processing circuit, including：
Electromagnetic signal receiving circuit receives the electromagnetic signal of time writer transmitting；
Rotating Capacitor Filter controls rotation capacitor filtering using pwm signal identical with the frequency of the electromagnetic signal
Device is filtered the electromagnetic signal, to filter out and the different invalid signals of the frequency of electromagnetic signal；
Electromagnetic signal processing circuit handles filtered electromagnetic signal, obtains signal coordinates position.
Wherein, the electromagnetic signal receiving circuit, including：
Electromagnetic signal detection circuit, the electromagnetic signal of detection time writer transmitting；
The electromagnetic signal is carried out low level signal amplification, obtains amplified signal by small signal amplification circuit.
Wherein, the signal coordinates processing circuit further includes scanning circuit, scans the cycle coil of electromagnetic writing plate, obtains
Scanning result；
The electromagnetic signal processing circuit includes：
AC amplifier carries out exchange amplification to filtered electromagnetic signal, obtains exchange amplified signal；
Exchange amplified signal is switched to direct current signal by rectification circuit；
Dc amplifier is amplified the direct current signal, obtains direct current amplified signal；
ADC sample circuits carry out ADC samplings to the direct current amplified signal, obtain digital signal；
CPU processor handles the digital signal and scanning result, obtains signal coordinates position.
Wherein, the CPU processor includes PWM controller, generates the pwm signal.
Wherein, the Rotating Capacitor Filter include transport and placing device U, two-way analog switch, resistance R1, R2, R3, capacitance C1,
C2, C3, one end ground connection of the model SGM3158, C1 of the two-way analog switch, the other end of C1 and one end of R1 connect,
The other end of R1 is connect with the positive input of transport and placing device U, and one end of C2 and one end of R2 connect, and the other end of C2 is that signal is defeated
Enter end, the other end of R2 is connect with 1 terminal of the reverse input end of transport and placing device U, two-way analog switch, the output end of transport and placing device U
It for signal output end, is connect with 4 terminals of two-way analog switch, 2 ends of one end of C3 and one end of R3, two-way analog switch
The 8 terminals connection of son, two-way analog switch, the other end of C3 and the other end of R3,5 terminals of two-way analog switch, two-way mould
The 11 terminals connection of quasi- switch, 3 terminals and 6 terminal grounds of two-way analog switch, 9 terminals and 12 terminals of two-way analog switch
It is connect with power Vcc, 10 terminals and 7 terminals of two-way analog switch are the input terminal of pwm signal, and pwm signal control is described double
The switch conduction direction of path analoging switch.
Wherein, the value of the C1 is 100PF, and the value of the C2 is 100PF, and the value of the C3 is 1000PF, the R1's
It is the value of 10K Ω, the R3 is 10K Ω that value, which is the value of 10K Ω, the R2,.
The third aspect, a kind of electromagnetism apparatus for writing with above-mentioned signal coordinates processing circuit.
A kind of signal coordinates processing method, circuit and electromagnetism apparatus for writing provided by the invention, the circuit include：Electromagnetism is believed
Number receiving circuit receives the electromagnetic signal of time writer transmitting；Rotating Capacitor Filter utilizes the frequency phase with the electromagnetic signal
Same pwm signal controls Rotating Capacitor Filter, is filtered to the electromagnetic signal, to filter out with the frequency of electromagnetic signal not
Identical invalid signals；Electromagnetic signal processing circuit handles filtered electromagnetic signal, obtains signal coordinates position.
The present invention controls Rotating Capacitor Filter come to electromagnetism by pwm signal identical with the electromagnetic signal frequency emitted with time writer
The electromagnetic signal that apparatus for writing receives is filtered, the Rotating Capacitor Filter under pwm signal control, work frequency
Rate narrower bandwidth, filtering is accurate, can effectively filter out invalid signals, improves electromagnetic signal processing circuit and was write to time writer
The accuracy of identification of journey electromagnetic signal coordinate.
Description of the drawings
Fig. 1 is a kind of method flow diagram of signal coordinates processing method provided in an embodiment of the present invention.
Fig. 2 is a kind of a kind of method flow of preferred embodiment of signal coordinates processing method provided in an embodiment of the present invention
Figure.
Fig. 3 is a kind of method flow of another preferred embodiment of signal coordinates processing method provided in an embodiment of the present invention
Figure.
Fig. 4 is a kind of block diagram of signal coordinates processing circuit provided in an embodiment of the present invention.
Fig. 5 is a kind of a kind of preferred embodiment block diagram of signal coordinates processing circuit provided in an embodiment of the present invention.
Fig. 6 is the circuit diagram of Rotating Capacitor Filter provided in an embodiment of the present invention.
Specific implementation mode
Technical solution to further illustrate the present invention below with reference to the accompanying drawings and specific embodiments.
As shown in Figure 1, a kind of signal coordinates processing method, includes the following steps：
S101, the electromagnetic signal for receiving time writer transmitting.
S102, Rotating Capacitor Filter is controlled using pwm signal identical with the frequency of the electromagnetic signal, to the electricity
Magnetic signal is filtered, to filter out and the different invalid signals of the frequency of electromagnetic signal.
S103, filtered electromagnetic signal is handled, obtains signal coordinates position.
It is received in the electromagnetic signal receiving circuit of time writer writing process, time writer transmission of electromagnetic signals, electromagnetic induction screen
It to after electromagnetic signal, needs to be filtered electromagnetic signal by filter, filtering is extremely important to the signal processing of rear end, filter
The bad identification that will have a direct impact on to signal coordinates position of wave.
The frequency of pwm signal is identical as the frequency of electromagnetic signal, and the operating frequency range of Rotating Capacitor Filter is electromagnetism
The frequency of signal, i.e., only identical as the frequency of the pwm signal under the control of the pwm signal, i.e., the described electromagnetic signal,
Can be by the Rotating Capacitor Filter, other invalid signals different from electromagnetic signal can be then actively filtered, filter
Wave is accurate, improves accuracy of identification of the rear end to electromagnetic signal coordinate.
Rotating Capacitor Filter is low to the tolerance of the electronic component of periphery, not will produce frequency drift, and filtering is accurate
Really, effect is good, and peripheral electronic component can be common specification.
Requirement of the Rotating Capacitor Filter to transport and placing device is also low, and common bandpass filter needs the increasing of the transport and placing device of selection
Beneficial bandwidth product is in 200M or more, and the gain bandwidth product for the transport and placing device that the Rotating Capacitor Filter of the present invention uses only needs 10M
Left and right, the cost of such transport and placing device is relatively low, to reduce the cost of Rotating Capacitor Filter.
Optionally, as shown in Fig. 2, step S101 includes：
The electromagnetic signal that S101a, detection time writer emit.
S101b, the electromagnetic signal is subjected to low level signal amplification, obtains amplified signal.
The electromagnetic signal receiving circuit of electromagnetic induction screen includes electromagnetic signal detection circuit and small signal amplification circuit, electromagnetism
Signal deteching circuit detects the input of electromagnetic signal, and small signal amplification circuit carries out low level signal amplification to the electromagnetic signal of input.
Optionally, further include the circular route for scanning electromagnetic writing plate before the electromagnetic signal for receiving time writer transmitting
Circle, obtains scanning result.
When the electromagnetic signal is output to the circuit of electromagnetic induction screen, the cycle coil of electromagnetic induction screen different location connects
The voltage magnitude of the electromagnetic signal received is different, and scanning circuit 400 finds electromagnetic signal by being scanned to cycle coil
Input, and obtain the substantially coordinate position of electromagnetic signal.
When the scanning of scanning circuit 400 is to when having electromagnetic signal input, control electromagnetic signal detection circuit 101 detects circular route
The electromagnetic signal received is enclosed, small signal amplification circuit 102 carries out the electromagnetic signal that electromagnetic signal detection circuit 101 detects
Low level signal amplification.
Optionally, as shown in figure 3, step S103, including：
S103a, exchange amplification is carried out to filtered electromagnetic signal, obtains exchange amplified signal.
The exchange of electromagnetic induction screen is amplified to carrying out exchange amplification to filtered electromagnetic signal.
S103b, exchange amplified signal is switched into direct current signal.
Rectification circuit switchs to direct current signal by amplified signal is exchanged.
S103c, the direct current signal is amplified, obtains direct current amplified signal.
DC amplification circuit is amplified the direct current signal.
S103d, ADC samplings are carried out to the direct current amplified signal, obtains digital signal.
Direct current amplified signal is switched to digital signal by ADC samplings.
S103e, the digital signal and scanning result are handled, obtains signal coordinates position.
The electromagnetic signal that the cycle coil of different location receives is after exchange amplification, rectification, direct current amplification and ADC samplings
Obtain different ADC values, i.e., different digital signals, scanning result and the ADC value of the last CPU processor by scanning circuit
Just the coordinate position of electromagnetic signal can be accurately determined.
Optionally, CPU processor includes PWM controller and coordinate processing circuit, coordinate processing circuit processes digital signal
And scanning result, obtain signal coordinates position；The pwm signal is generated by PWM controller, pwm signal not only frequency with it is described
The frequency of electromagnetic signal is identical, in phase and also synchronous with the electromagnetic signal, the then work of Rotating Capacitor Filter on the time
The bandwidth of working frequency is very narrow, can reach 1kHz-2kHz, and filter effect is very good, and filtering is very accurate.In addition, PWM is controlled
The frequency variation for the electromagnetic signal that the pwm signal that device generates can emit with time writer is adjusted, and changes frequency filtering, filtering
Frequency debugging is simple.
A kind of signal coordinates processing method provided by the invention, by identical with the electromagnetic signal frequency emitted with time writer
Pwm signal control Rotating Capacitor Filter be filtered come the electromagnetic signal received to electromagnetism apparatus for writing, in the PWM
Rotating Capacitor Filter under signal control, operational frequency bandwidth is relatively narrow, and filtering is accurate, can effectively filter out invalid letter
Number, improve accuracy of identification of the rear end to time writer writing process electromagnetic signal coordinate；And filter at low cost, debugging conveniently.
In order to realize the above method, the present invention provides a kind of signal coordinates processing circuits, as shown in figure 4, including：
Electromagnetic signal receiving circuit 100 receives the electromagnetic signal of time writer transmitting；
Rotating Capacitor Filter 200 controls rotation capacitance using pwm signal identical with the frequency of the electromagnetic signal and filters
Wave device is filtered the electromagnetic signal, to filter out and the different invalid signals of the frequency of electromagnetic signal；
Electromagnetic signal processing circuit 300 handles filtered electromagnetic signal, obtains signal coordinates position.
The frequency of pwm signal is identical as the frequency of electromagnetic signal, and the operating frequency range of Rotating Capacitor Filter is electromagnetism
The frequency of signal, i.e., only identical as the frequency of the pwm signal under the control of the pwm signal, i.e., the described electromagnetic signal,
Can be by the Rotating Capacitor Filter, other invalid signals different from electromagnetic signal can be then actively filtered, filter
Wave is accurate, improves accuracy of identification of the rear end to electromagnetic signal coordinate.
Optionally, as shown in figure 5, the electromagnetic signal receiving circuit 100, including：
Electromagnetic signal detection circuit 101, the electromagnetic signal of detection time writer transmitting；Small signal amplification circuit 102, will be described
Electromagnetic signal carries out low level signal amplification, obtains amplified signal.
The signal coordinates processing circuit further includes scanning circuit 400, scans the cycle coil of electromagnetic writing plate, is swept
Retouch result.
When the electromagnetic signal is output to the circuit of electromagnetic induction screen, the cycle coil of electromagnetic induction screen different location connects
The voltage magnitude of the electromagnetic signal received is different, and scanning circuit 400 finds electromagnetic signal by being scanned to cycle coil
Input, and obtain the substantially coordinate position of electromagnetic signal.
When the scanning of scanning circuit 400 is to when having electromagnetic signal input, control electromagnetic signal detection circuit 101 detects circular route
The electromagnetic signal received is enclosed, small signal amplification circuit 102 carries out the electromagnetic signal that electromagnetic signal detection circuit 101 detects
Low level signal amplification.
Electromagnetic signal processing circuit 300 includes：
AC amplifier 301 carries out exchange amplification to filtered electromagnetic signal, obtains exchange amplified signal；
Exchange amplified signal is switched to direct current signal by rectification circuit 302；
Dc amplifier 303 is amplified the direct current signal, obtains direct current amplified signal；
ADC sample circuits 304 carry out ADC samplings to the direct current amplified signal, obtain digital signal；
CPU processor 305 handles the digital signal and scanning result, obtains signal coordinates position.
AC amplifier 301 of the electromagnetic signal that the cycle coil of different location receives through rear end, rectification circuit 302,
Dc amplifier 303 and the processing of ADC sample circuits 304 obtain different ADC values, i.e., different digital signals, last CPU processor
The coordinate position of electromagnetic signal just can be accurately determined by the scanning result of scanning circuit and the ADC values.
Optionally, CPU processor 305 includes PWM controller and coordinate processing circuit, coordinate processing circuit processes number letter
Number and scanning result, obtain signal coordinates position；The pwm signal is generated by PWM controller, pwm signal not only frequency and institute
The frequency for stating electromagnetic signal is identical, in phase and also synchronous with the electromagnetic signal, then Rotating Capacitor Filter on the time
The bandwidth of working frequency is very narrow, can reach 1kHz-2kHz, and filter effect is very good, and filtering is very accurate.In addition, PWM is controlled
The frequency variation for the electromagnetic signal that the pwm signal that device processed generates can emit with time writer is adjusted, and changes frequency filtering, filter
Wave frequency rate debugging is simple.
Optionally, as shown in fig. 6, the Rotating Capacitor Filter 200 includes transport and placing device U, two-way analog switch, resistance
R1, R2, R3, capacitance C1, C2, C3, one end ground connection of the model SGM3158, C1 of the two-way analog switch, the other end of C1
It is connect with one end of R1, the other end of R1 is connect with the positive input of transport and placing device U, and one end of C2 and one end of R2 connect, C2
The other end be signal input part, the other end of R2 connect with 1 terminal of the reverse input end of transport and placing device U, two-way analog switch,
The output end of transport and placing device U is signal output end, is connect with 4 terminals of two-way analog switch, one end of C3 and one end of R3, two-way
The 8 terminals connection of 2 terminals of analog switch, two-way analog switch, the other end of C3 and the other end of R3, two-way analog switch
The 11 terminals connection of 5 terminals, two-way analog switch, 3 terminals and 6 terminal grounds of two-way analog switch, the 9 of two-way analog switch
Terminal and 12 terminals are connect with power Vcc, and 10 terminals and 7 terminals of two-way analog switch are the input terminal of pwm signal.
10 terminals and 7 terminals of two-way analog switch can input pwm signal respectively, can also link together while defeated
Enter the same pwm signal, pwm signal controls the switch conduction direction of the two-way analog switch.Such as the 10 of two-way analog switch
Terminal and the input of 7 terminals are pwm signal that the PWM controller generates, described double when the pwm signal is low level
1 terminal of path analoging switch is connect with 2 terminals, and 4 terminals are connect with 5 terminals, and sense of current is from the ends A to the ends B；When described
Pwm signal is high level, and 1 terminal of the two-way analog switch is connect with 11 terminals, and 4 terminals are connect with 8 terminals, the side of electric current
To the control for being the charging direction for from the ends B to the ends A realizing the RC circuits to being made of C3 and R3.
Wherein, the value of C1 is 100PF, and the value of C2 is 100PF, and the value of C3 is 1000PF, and the value of R1 is the value of 10K Ω, R2
Value for 10K Ω, R3 is that 10K Ω, Vcc are chosen as 3.3V.
Rotating Capacitor Filter 200 is low to the tolerance of the electronic component of periphery, not will produce frequency drift, filters
Accurately, effect is good, and peripheral electronic component can be common specification.
Requirement of the Rotating Capacitor Filter to transport and placing device is also low, and common bandpass filter needs the increasing of the transport and placing device of selection
Beneficial bandwidth product is in 200M or more, and the gain bandwidth product for the transport and placing device that the Rotating Capacitor Filter of the present invention uses only needs 10M
Left and right, the cost of such transport and placing device is relatively low, to reduce the cost of Rotating Capacitor Filter.
A kind of signal coordinates processing circuit provided by the invention, by identical with the electromagnetic signal frequency emitted with time writer
Pwm signal control Rotating Capacitor Filter be filtered come the electromagnetic signal received to electromagnetism apparatus for writing, filtering is accurate,
Improve accuracy of identification of the electromagnetic signal processing circuit to time writer writing process electromagnetic signal coordinate；And filter at low cost, tune
Examination is convenient.
The present invention also provides a kind of electromagnetism apparatus for writing, the electromagnetism apparatus for writing includes above-mentioned signal coordinates processing electricity
Road.
The technical principle of the present invention is described above in association with specific embodiment.These descriptions are intended merely to explain the present invention's
Principle, and it cannot be construed to limiting the scope of the invention in any way.Based on the explanation herein, the technology of this field
Personnel would not require any inventive effort the other specific implementation modes that can associate the present invention, these modes are fallen within
Within protection scope of the present invention.
Claims (8)
1. a kind of signal coordinates processing method, which is characterized in that including：
The cycle coil for scanning electromagnetic writing plate, obtains scanning result；
Receive the electromagnetic signal of time writer transmitting；
Using pwm signal identical with the frequency of the electromagnetic signal control Rotating Capacitor Filter, to the electromagnetic signal into
Row filtering, to filter out and the different invalid signals of the frequency of electromagnetic signal；
Exchange amplification is carried out to filtered electromagnetic signal, obtains exchange amplified signal；
Exchange amplified signal is switched into direct current signal；
The direct current signal is amplified, direct current amplified signal is obtained；
ADC samplings are carried out to the direct current amplified signal, obtain digital signal；
The digital signal and scanning result are handled, signal coordinates position is obtained.
2. signal coordinates processing method as described in claim 1, which is characterized in that the electromagnetism letter for receiving time writer transmitting
Number, including：
Detect the electromagnetic signal of time writer transmitting；
The electromagnetic signal is subjected to low level signal amplification, obtains amplified signal.
3. a kind of signal coordinates processing circuit, which is characterized in that including：
Scanning circuit scans the cycle coil of electromagnetic writing plate, obtains scanning result；
Electromagnetic signal receiving circuit receives the electromagnetic signal of time writer transmitting；
Rotating Capacitor Filter controls Rotating Capacitor Filter using pwm signal identical with the frequency of the electromagnetic signal, right
The electromagnetic signal is filtered, to filter out and the different invalid signals of the frequency of electromagnetic signal；
Electromagnetic signal processing circuit handles filtered electromagnetic signal, obtains signal coordinates position；
The electromagnetic signal processing circuit includes：
AC amplifier carries out exchange amplification to filtered electromagnetic signal, obtains exchange amplified signal；
Exchange amplified signal is switched to direct current signal by rectification circuit；
Dc amplifier is amplified the direct current signal, obtains direct current amplified signal；
ADC sample circuits carry out ADC samplings to the direct current amplified signal, obtain digital signal；
CPU processor handles the digital signal and scanning result, obtains signal coordinates position.
4. signal coordinates processing circuit as claimed in claim 3, which is characterized in that the electromagnetic signal receiving circuit, including：
Electromagnetic signal detection circuit, the electromagnetic signal of detection time writer transmitting；
The electromagnetic signal is carried out low level signal amplification, obtains amplified signal by small signal amplification circuit.
5. signal coordinates processing circuit as claimed in claim 3, which is characterized in that the CPU processor includes PWM controls
Device, PWM controller generate the pwm signal.
6. signal coordinates processing circuit as claimed in claim 3, which is characterized in that the Rotating Capacitor Filter includes amplifier
Device U, two-way analog switch, resistance R1, R2, R3, capacitance C1, C2, C3, the model SGM3158, C1 of the two-way analog switch
One end ground connection, one end of the other end of C1 and R1 connects, and the other end of R1 is connect with the positive input of transport and placing device U, C2's
One end and one end of R2 connect, and the other end of C2 is signal input part, the other end of R2 and the reverse input end of transport and placing device U, double
1 terminal of path analoging switch connects, and the output end of transport and placing device U is signal output end, and is connected with 4 terminals of two-way analog switch
It connects, the 8 terminals connection of one end of C3 and one end of R3,2 terminals of two-way analog switch, two-way analog switch, the other end of C3
It is connect with 11 terminals of the other end of R3,5 terminals of two-way analog switch, two-way analog switch, 3 terminals of two-way analog switch
With 6 terminal grounds, 9 terminals and 12 terminals of two-way analog switch are connect with power Vcc, 10 terminals of two-way analog switch and 7
Terminal is the input terminal of pwm signal, and pwm signal controls the switch conduction direction of the two-way analog switch.
7. signal coordinates processing circuit as claimed in claim 6, which is characterized in that the value of the C1 is 100PF, the C2's
Value is 100PF, and the value of the C3 is 1000PF, and the value of the R1 is that the value of 10K Ω, the R2 are 10K Ω, and the value of the R3 is
10KΩ。
8. a kind of electromagnetism apparatus for writing having such as claim 3-7 any one of them signal coordinates processing circuits.
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| Application Number | Priority Date | Filing Date | Title |
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| CN201610157475.0A CN105843444B (en) | 2016-03-18 | 2016-03-18 | A kind of signal coordinates processing method, circuit and electromagnetism apparatus for writing |
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| CN201610157475.0A CN105843444B (en) | 2016-03-18 | 2016-03-18 | A kind of signal coordinates processing method, circuit and electromagnetism apparatus for writing |
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| CN105843444B true CN105843444B (en) | 2018-11-09 |
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| WO2018170682A1 (en) * | 2017-03-20 | 2018-09-27 | 深圳市汇顶科技股份有限公司 | Signal processing method for active pen, active pen, and touch screen |
| CN110494828B (en) | 2019-07-02 | 2023-08-25 | 深圳市汇顶科技股份有限公司 | Signal processing system, chip and active pen |
Citations (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102929411A (en) * | 2012-10-15 | 2013-02-13 | 贺爱兰 | Electromagnetic touch device |
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| TWI416375B (en) * | 2011-01-21 | 2013-11-21 | Sunrex Technology Corp | Position detection device |
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102929411A (en) * | 2012-10-15 | 2013-02-13 | 贺爱兰 | Electromagnetic touch device |
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