SU1411790A1 - Device for input of handwritten data - Google Patents

Abstract

The invention relates to the field of automation and computer technology and can be used for input & in the computer handwritten information. The purpose of the invention is to improve the noise immunity and reliability of the input information. Six differential amplifiers are introduced into the device containing a pen made in the form of a hollow body inside which the writing element, the pressure sensor and the acceleration sensor associated with the inertial element are located. The pressure and acceleration sensors are made in the form of two strain gauges, each of which contains four mutually orthogonal plates. On each plate there are two strain gage resistors, with strain gages placed on opposite plates of the corresponding sensor included in DC bridge circuits whose diagonal points are connected to the inputs of the corresponding differential amplifiers. 4 il. o (l

Description

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The invention relates to automation and computing and can be used to enter hand-written information into a computer.

The purpose of the invention is to increase the noise immunity and reliability of the input information,

FIG. Figure 1 shows the construction of an inventive pen used in the device; FIG. 2 shows section A-A in FIG. 1, in FIG. 3 shows a section BB in FIG. 1, in FIG. 4 - electrical circuit of the device.

The pen of the device contains (Fig. 1) an inertial element 1, a hollow body 2, inside of which acceleration and pressure sensors are located.

The acceleration sensor is made in the form of a strain gauge and is formed by plates 3 and wire strain gauges 4. The pressure sensor is made in the shape of a strain gauge and is formed by plates 5 and wire strain gauges 6. The writing element 7 is located on the central axis of the pen.

Strain gages 4 sensors are denoted, R, -R.

The strain gauges 6 of the pressure sensor are designated Ry-R, Rj-Rg,

Strain gages R ,, Rg and R ,, Rj,. located along the x axis, are included in the electric, x1 direct current bridge (Fig. 2).

Strain gages Rj, R, and Rj, R. located along the y-axis, are included in the DC electric bridge

Y1Analogously in the bridges x2 and y2 included the resistance strain gages R, R, Rj, R and R Rg Ry Rg.

The device also contains differential amplifiers 8 (DA1), 9 (DA2 10 (DA3), 11 (DA4), 12 (DA5) and 13 (DA6).

The device works as follows.

In the normal state, the mutually perpendicular plates 3 and 5 of pressure and acceleration sensors located in the lower and upper parts of the pen, respectively, are not deformed, the strain resistors have the same resistance, and the DC electric bridges are balanced. The electrical signals at the x and y outputs of differential amplifiers 12 and 13 are zero.

Q

0 5

Q

, five

five

When writing handwritten characters (touching, pressing and moving) with a writing element 7 on a solid surface, for example paper, the pressure sensor plates 5 deform, which leads to a change in resistance of the resistance strain gages R.-Rj and Rj-R (Fig. 1) and the imbalance of bridges x2 and y2. The electrical signal of the unbalance of the bridges is amplified by differential amplifiers VAZ, DA4, DA5, DA6 (Fig. 2).

When writing characters, the upper end of the pen describes in space the trajectory of the character written by the lower end, writing element, but rotated by 180. Due to the inertia of the mass of the inertial element 1, the plates 3 of the acceleration sensor are deformed. The deformation of the plates leads to a change in the resistance of the strain gauges and to the imbalance of the bridges x1 and y1. The imbalance signal is amplified by amplifiers DA1, DA2, DA5, DA6.

Consider the job of the pen to enter handwritten information in more detail. When the pen is in a vertical position and the writing element moves along the paper along the X axis, for example, plates 3, located along the x axis (Fig. 1), are deformed from left to right. Due to the resistance of the paper, the plates of the pressure sensor 3 with the resistance strain gages RJ and R are compressed, and with the resistance strain gages Rg and Rg are expanded. The resistance of the resistance strain gages R j and R increases, and the Rg and R decrease.

At the same time, the acceleration sensor plates 5 are also subjected to deformation due to the inertia of the inertial element 1, the plate with strain gauges R and R is stretched and compressed with resistance strain gauges R and Rg. The resistance of the strain gauges R and Rg increases, and R and Rg decreases.

Since the resistances of the strain gauges connected to the x1 and x2 bridges change, their imbalance occurs. At the inverting input of D | If the amplifier DA1 appears, the signal of the x1 unbalance of the positive polarity appears on the inverting input of the DA3 amplifier bridge imbalance x2 negative polarity.

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Y ,, strong signals of different polarities are fed to the differential amplifier DA5, the signal of negative polarity is fed to the non-inverting input, the positive - to the inverting input. Thus, at output x, a negative polarity signal appears.

The plates located along the y axis, JQ, are deformed slightly and in a plane, in which there is no change in the resistance of the strain gauges wound on these plates. There is no signal at the output.

In the direction of movement along the x axis from right to left, the same plates are deformed, but the deformation occurs in

and RJ are compressed. Resistance RJ and R,

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{increases

opposite direction. The resistance of the strain gauges is changed, the 20 + b decreases. The strain gauges Rf and Rj of the pressure sensor occur increase their resistance, and Rj and Rg decrease. Accordingly, for the acceleration sensor, the resistance unbalance of the bridge y1. The negative polarity of the unbalance of the bridge flow to the inverting input of the differential amplifier DA2. A positive polarity signal appears at the amplifier output, i.e. Signal of the pen tilt comp. Thus, at the output, there is a signal corresponding to the movement of the pen with a tilt compaction. There is no signal at output x.

niya

it comes to

strain gages

R. and R, j increase

R

and R decreases. About

will change the polarity of the imbalance of the bridges x1 and x2 to the opposite, which causes a polarity change at the output x.

There is no signal at the output for the reason indicated.

Similarly, the pen works when moving along the y axis. Tension resisters R, Rg and R, Rg of the pressure sensor and Rj, R and Rj, R of the acceleration sensor work. There is an imbalance of bridges y1 and y2. The imbalance signals are amplified by the differential amplifiers DA2, DA4, DA6. A signal of the corresponding polarity appears at the output y, depending on the direction up and down, while at the output x there is no signal. The edges along the X axis do not cause a change in resistance of the strain gauges.

The error compensation in the position of the pen differs from the vertical position, and the decrease in error from the angle of inclination of the pen is as follows. For example, - the angle of inclination lies in the plane of the ribs with the tensor by the resistors R, Rg and Rg, R of the pressure sensor and Rj, R and R4. RS Acceleration Sensor, i.e. in the plane of the y axis. Pressing the pen stretches the plates with strain gauges Rg and compresses with Rg and R. Co-vs

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perception

strain gauges R and R increase, Rg

and R 8

decreases. Pro90

There is a slaughter. Hans of the bridge is Y2, and moreover, it is negative. The league is fed to the inverting input) - a potential amplifier 1) A4, the output signal of a positive polarity is fed to the inverting input di (} 1 () e- of the secondary amplifier VAB. A positive signal from the amplifier DA2 is fed to the non-inverting input of this amplifier the lean angle of the pen. This signal is formed as follows. As the pen is tilted, the accelerator sensor plates are deformed due to the weight of the inertial element. R, / 1 R strain gauge plates

and R are expanded.

and RJ are compressed. Tension resistance - RJ and R,

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{increases.

  + b decreases. Going on

0 + b decreases. Going on

five

0

0

five

0

five

unbalance of the bridge y1. The negative polarity of the unbalance of the bridge is fed to the inverting input of the differential amplifier DA2. A positive polarity signal appears at the output of the amplifier, i.e. Signal tilt compensation pen. Thus, at the output, there is a signal corresponding to the movement of the pen with tilt compensation. There is no signal at output x.

Similarly, the pen works with an arbitrary angle of inclination. In this case, all plates are deformed, all strain gauges and differential amplifiers work. As a result, the ratio of electrical signals at the x and y outputs clearly corresponds to the written symbol with the pen tilt compensation parameter.

The proposed pressure transducer, which optically separates the pressure and direction of movement of the pen, makes it possible to increase the reliability of the reproduction of handwritten characters in comparison with the known one. The acceleration sensor in conjunction with differential amplifiers allows to increase the noise immunity from variations in pen tilt. In addition, the signal obtained after amplification can be immediately used, for example, as an input signal of the ADC. In a known sensor, the output signal requires amplification.

The proposed pen has high operational characteristics: it is not afraid of mechanical and climatic influences, durability - the parameters are stable in time, technologically effective in production, has low cost.

Claims (1)

Invention Formula A device for inputting handwritten information, comprising a pen made in the form of a hollow body, inside which a pressure sensor and an acceleration sensor are located, which is connected to an inertial element, characterized in that, in order to increase the noise immunity and reliability of the entered information, it contains six differential amplifiers, and the pressure and acceleration sensors of the pen are made in the form of two strain gauges, each of which contains four mutually orthogonal plates, each of which contains two a resistor, where the strain gauges located on opposite plates of the corresponding sensor are included in DC bridge circuits, the diagonal points of the bridge bridge of the first load cell are connected to the inputs of the first and second differential amplifiers, the diagonal points of the bridge bridge of the second load cell are connected to the inputs of the third and fourth differential amplifiers, the outputs of the first and third differential amplifiers are connected to the inputs of the fifth differential y ilitel whose output is the first output device, the second output of which is the output of the sixth differential amplifier whose inputs are connected to outputs of the second and fourth differential amplifiers. Phi 1 FiaZ FiveM