Digitizer device with anti-noise and status display

• US 5,365,253 A
• Filed: 11/12/1992
• Issued: 11/15/1994
• Est. Priority Date: 11/12/1992
• Status: Expired due to Fees

• Current Assignee: Wintime Technology, Inc.
• Original Assignee: Wintime Technology, Inc.
• Inventors: Cheng, Robert, Chen, Robin, Horng, Chuen-Jing, Su, Michael
• Primary Examiner(s): Weldon, Ulysses
• Assistant Examiner(s): Mengistu, Amare
• Application Number:
  US07/974,881
• Time in Patent Office: 733 Days
• Field of Search: 340/706, 340/707, 340/712, 178/18, 178/19, 345/156, 345/157, 345/173
• US Class Current: 345/156
• CPC Class Codes: G06F 3/046 by electromagnetic means

Abstract

A digitizer device with anti-noise and status display having a hardware circuit controlled by a software program to eliminate outside noises. The system includes a cursor control mouse or stylus which emits an oscillating signal at several hundred KHz to induce a X-Y grid, an anti-noise circuit which eliminates outside noises from the induced signal, an ADC converter which converts the induced signal into a digital signal, a microcontroller unit which calculates the induced signal into corresponding X-Y axis coordinate value, and a display which shows the current status of the digitizer.

Claims

1. A digitizer device with an anti-noise circuit and a status display unit, comprising a digitizer having a microcontroller unit respectively connected to a host computer and a main clock, wherein the digitizer has a hardware circuit incorporated with a software program built in the microcontroller unit to protect against outside noise so as to ensure the stability of coordinate values, said status display unit being connected to said microcontroller unit in order to show the current status and operating mode of the digitizer, wherein:

the hardware circuit of said digitizer drives said microcontroller unit to provide a X, Y grid address to a Y grid selector, a X grid selector and a scanning sequence determining grid addresser and sends a secondary pulse signal to an LC oscillator through a frequency divider for use as a reference frequency for a mouse (or stylus), and then said microcontroller unit is controlled to send a start signal to reset a data counter and said frequency divider, thereby causing said data counter to start counting the value as the mouse (or stylus) projects a signal onto an X-Y grid of the digitizer, an induced signal from the digitizer being then sent to the anti-noise circuit through a Y grid selector and a X grid selector, thereby causing the anti-noise circuit to attenuate outside noises of frequency beyond the range of 15 KHz to 150 KHz, so as to eliminate the frequencies other than that emitted through the mouse (or stylus) and improve a signal-to-noise ratio, the signal from said anti-noise circuit being then sent with a synchronous signal from said frequency divider to a phase converter for phase separation and then to a low pass filter for low pass filtration so as to define a low frequency signal, the low frequency signal being then sent to a level recognizer and then converted into a digital pulse signal for controlling said data counter to stop from counting and simultaneously driving it to send counted data to said microcontroller unit for calculating accurate X-Y values for permitting said microcontroller unit to send the calculated result to said host computer and show the current status of the digitizer through said status display unit.

2. A digitizer device with an anti-noise circuit and a status display unit, comprising a digitizer having a microcontroller unit respectively connected to a host computer and a main clock, wherein the digitizer has a hardware circuit incorporated with a software program built in the microcontroller unit to protect against outside noise so as to ensure the stability of coordinate values, said status display unit being connected to said microcontroller unit in order to show the current status and operating mode of the digitizer, wherein:

said software program uses a convergence technique in calculating coordinate values and reducing the gain of outside noises in interfering with the digitizer by fixing the mouse (or stylus) on the X-Y grid and continuously scanning the X-Y grid for n times and then letting the scanned result be counted by said data counter for calculation, said convergence technique providing a weighted function to give a different weighted value to the function according to different convergence considerations so as to obtain an accurate and stable X-Y value, the function being;

##EQU3## wherein;

X0'"'"'=X0=0

Xn'"'"'=the convergence value of the n scanning

Xn=the value obtained from the n scanning

g(n)=the weighting for the convergence value at n-1

h(n)=the weighting for the n scanning n=1, 2, 3, . . .

such that;

when g(n)=1 and h(n)=1, ##EQU4## and an accurate X,Y value which is free from the interference of outside noises is obtained.

3. A digitizer device with an anti-noise circuit and a status display unit, comprising a digitizer having a microcontroller unit respectively connected to a host computer and a main clock, wherein the digitizer has a hardware circuit incorporated with a software program built in the microcontroller unit to protect against outside noise so as to ensure the stability of coordinate values, said status display unit being connected to said microcontroller unit in order to show the current status and operating mode of the digitizer, wherein:

said mouse (stylus) includes a signal emitting source using LC parallel resonance and wherein the relative relation between the cycling of the signal emitting source through LC parallel resonance and the time in scanning one line of the X-Y grid is;

space="preserve" listing-type="equation">t1=nt2, n>

2,

in which

t1=timing in scanning one line of the X-Y grid;

t2=cycling of the mouse (stylus); and

wherein the bigger the n value, the better the calculation result;

the value obtained from said data counter being adjusted by a multiplying power and then converted into a corresponding X-Y coordinate value of high stability and resolution.