US3482255A

US3482255A - Compensation control system for cathode-ray recording tube

Info

Publication number: US3482255A
Application number: US688413A
Authority: US
Inventors: Arthur Y Baker Jr; Lonnie K Lindsay
Original assignee: Century Geophysical Corp
Current assignee: Century Geophysical Corp
Priority date: 1967-12-06
Filing date: 1967-12-06
Publication date: 1969-12-02
Anticipated expiration: 1986-12-02

Description

Dec. 2, 1969 A Y BAKER, JR., ET AL 3,482,255

COMPENSATION CONTROL SYSTEM FOR CATHODE-RAY RECORDING TUBE Filed Dec. 6, 1967.

5 Sheets-Sheet l De.2,19e9 M. BAKER, J'R, Em. 3,482,255

COMPENSATION CONTROL SYSTEM FOR CATHODE-RAY RECORDING TUBE Filed nec. 6. 19e? 5 Sheets-Sheet 2 Dec. 2. 1969 A. Y. BAKER, JR., ET AL 3,482,255

COMPENSATION CONTROL SYSTEM FOR CATHODE'RAY RECORDING TUBE Filed Dec. 6. 1967 5 Sheets-Sheet 5 Dec. 2, 1969 A. Y. BAKER, JR., ETAL COMPENSATION CONTROL SYSTEM FORy OATHODE-RAY RECORDING TUBE Filed Dec. 6. 1967 5 Sheets-Sheet 4 @L www N v .Ewhww W .n NEW m.. N QN EN@ N NNN ENW E ENTR .m EN Eq Q NN A A s. .NIMM NWMW QN* NN\\AM WNWMNM-WV QQ* H1 IN .mv m EN -REQNRNEQ Nag.

' De@ 2, 1969 A. Y. BAKER, JR., ET AL 3,482,255

COMPENSATION CONTROL SYSTEM FOR cATHoDE-RAY RECORDING TUBE Filed Dec. 6, 1967 5 Sheets--Sheexl 5 United States Patent O 3,482,255 COMPENSATION CONTROL SYSTEM FOR CATHODE-RAY RECORDING TUBE Arthur Y. Baker, Jr., Encino, Calif., and Lonnie K. Lindsay, Tulsa, Okla., assignors to Century Geophysical Corporation, Tulsa, Okla., a corporation of Oklahoma Filed Dec. 6, 1967, Ser. No. 688,413 Int. Cl. G01d 9/42 U.S. Cl. 346-110 4 Claims ABSTRACT F THE DISCLOSURE An improved cathode-ray display and recording instrument is described which is capable of responding to electrical input signals to display and record numeric or other characters represented thereby; and which incorporates a compensation control system for permitting high speed operation of the instrument without over-printing of successive lines, or other reproduction defects.

BACKGROUND OF THE INVENTION United States Patent 3,289,196-Hull discloses a cathode-ray type of display and recording system and instrument in which an electron beam in a cathode-ray tube iS caused to respond to applied electrical signals to trace out numeric or other characters on the display screen of the tube.

The mechanical details of the aforesaid instrument are described in detail in United States Patent 3,121,604- Hull. As'described in the latter patent, a light-sensitive paper is drawn across the face of the cathode-ray display tube to be exposed to the characters displayed thereon. A permanent record of the displayed characters is, thereby, provided on the sensitized paper. The characters themselves are sequentially displayed in a line across the face of the cathode-ray tube, and the sensitized paper is moved in a transverse direction with respect to the line, so that each subsequent line of characters displayed on the cathode-ray tube appears in a displaced position with respect to the preceding line on the paper.

A limiting factor in the speed at which the displayed characters can be recorded on the sensitized paper in the aforesaid system and instrument is the time required t0 move the sensitized paper from one line to the next. For example, it is' possible in the system sequentially to generate a line of characters across the face of the cathode-ray tube in a few microseconds. However, it requires a few thousand microseconds to draw the sensitized paper from one line to the next.

In an attempt to speed up the operation in the prior art systems, and prior to the advent of the present invention, it has been the practice to record each line of characters while the paper was in motion. This results, however, in a skewing of the successive lines of information on the sensitized paper; and it also results in a tendency to `overprint the rst two lines of information, each time the paper is moved. For continuous printing, the overprinting problem occurs only on the rst few lines. However, when the printing is not continuous, the overprinting will occur throughout the text. The line skew, which is undesirable from a comprehension standpoint, occurs at all times.

The compensating system of the present invention is constructed to correct the skew eifects, so that even though the paper may be in motion when a portion of a line of information is printed, the information at all times is recorded in a straight line extending across the paper without skew and Without any tendency to overprint other lines.

The line compensation control system of the invention "ice across the paper in a straight line, without skew, may be realized.

BRIEF DESCRIPTION OF THE DRAWINGS FIGURE 1 is a simplified block diagram of a display and recording system in which the line compensation control system of the present invention may be incorporated;

FIGURE 2 is a plan view of an instrument embodying the compensation system and apparatus of the present invention in one of its embodiments;

FIGURE 3 is a schematic perspective representation, partly in block form, of the control system of the invention;

FIGURE 4 is a circuit diagram of a photocell amplier which may be included in the system of FIGURE 3;

FIGURE 5 is a logic block diagram of a four-bit counter which may be included in the system of FIG- URE 3; and

FIGURE 6 is a circuit diagram of a digital-analog converter which also may be included in the control system of FIGURE 3.

DESCRIPTION OF THE ILLUSTRATED EMBODIMENT The system shown in FIGURE 1 is similar to the display and recording system disclosed in the Patent 3,289,- 196 referred to above. The simplified block diagram of FIGURE l includes a source 10 of binary coded data. This source, as explained in the said patent, may be a counter positioned in a receiving station of a telemetering system, it may be an electronic digital computer, or it may be any other appropriate source of binary coded data.

The source 10 introduced the binary coded data to a blanking signal generator 12. This generator, as also explained in the said patent, transforms the coded input signals into appropriate blanking signals. The blanking signals from the generator 12 are applied to a blanking circuit 14. The blanking circuit 14 is connected to the input electrode of a cathode-ray tube 18. The cathode-ray tube may include the usual beam-forming electrodes and deection plates. An electron beam is formed in the tube, and the electron beam is blanked at proper intervals by blanking signals applied to the input electrodes by the blanking circuit 14.

The electron beam in the tube 18 is deflected horizontally and vertically across the face of the tube. A liber optic system 22 is mounted on the face of the tube 18. As the electron beam of the cathode-ray tube 18 is deilected across the screen of the tube, the resulting light produced by the screen is projected by the optical system 22 onto a light sensitive paper 26, as the paper is drawn across the face of the tube. It will be appreciated that the tube 18 is controlled so that a sequence of characters is inscribed on its screen in a line extending across the screen, which line is recorded on the paper 26. The process is then repeated, and another sequence of characters is formed in a line across the screen of the tube 18. The sensitized paper is moved so that each line of characters is recorded unit 28, A clock input from a suitable clock source 27 is applied to the logic unit 28. A printcommand is also applied to the unit 28, and the display and recording of each separate character by the tube 18 and sensitized paper 26 is initiated upon the receipt of the print command from, for example, the computer or other source of binary coded data.

As each character is displayed by the system of FIG- URE l, an end of character command is formed, and the latter command is returned to the source of binary coded datato indicate that the system is ready for the next character.

The clocking unit 28 is coupled to a deflection signal forming generator 30 which applies synchronizing signals `to the blanking generator 12, as described in the Patent 3,289,196. The generator 30 also forms the appropriate deflection signals which are amplified in a line, or horizontal deflection amplifier 32, and in ,a field or vertical deflection amplifier 33. The horizontal deflection signal amplifier 32 and vertical deflection signal amplifier 33 apply appropriate deflection signals respectively to the line (or horizontal), and to the field (or vertical) deflection plates of the cathode-ray tube 18.

As fully described in the Patent 3,289,196, the system of FIGURE l controls the cathode-ray tube 18 so that the series of characters appears in a line across the screen of the reproducing tube 18. As mentioned previously herein, each such line of information normally will skew, whenever the paper is in motion as the beam is scanned in the line direction. As also pointed out previously, this skewing effect in some instances also has tendency to cause one line to be printed over a preceding line on the paper as the paper is moved.

The line compensation control of the present invention senses the motion of the paper across the face of the cathode-ray tube 18, and produces an analog signal which is used to compensate for the aforesaid skewing effect.

In the plan view of FIGURE 2, the cathode-ray tube 18,\for example, is shown supported on one side of a housing 100, the housing serving to encase the various components which go to make up the display and recording instrument. In the instrument of FIGURE 2, the sensitized paper 26 is drawn from a reel (not shown) by a roller 102 around a guide roller 103 and across the face of the cathode-ray tube 18. The actual drive of the paper, and the other mechanical components of the instrument, may be equivalent to those shown and described in the Patent 3,121,604.

`In the instrument of FIGURE 2, the drive roller 102 is driven by a motor 104 whose shaft is directly coupled to the roller 102. The drive motor 104 may, for example, be a stepping type of motor. For example, in a constructed embodiment the motor stepped in each activation through an arc of and served during the stepping motion to move the paper 26 yfrom one line to the next across the face of the cathode-ray tube 18. That is, ideally between the printing on the paper 26 of each line of information displayed on the face of the cathode-ray tube, the motor 104 is actuated, so as to step through an angular distance of 15, to present the next line of the paper to the screen of the cathode-ray tube. However, as explained, in order to speed up the recording by the instrument, the recording of each line on the paper is started before the paper has actually been moved to the next line and while it is still in motion.

In carrying out the concepts of the invention, an optical disc 106 is attached to the shaft of the drive motor 104, on the side of the drive motor opposite to the drive roller 102. A light source 108 is provided in a bracket 110, and light from the light source is focused by a lens 112 on the optical disc 106. A photocell 113 is mounted in tite6 bracket 110 on the opposite side of the optical disc By constructing the optical disc in accordance with known techniques, so as to have one opaque mark and one translucent mark for every degree of the disc, when the motor takes a single step of, for example, 15 as mentioned above, fifteen increments are generated by the optical disc, so that the photocell 113 generates fifteen pulses. It will be appreciated, therefore, that for every step the motor takes, fifteen pulses are generated by the photocell 113. The repetition frequency of the fifteen pulses, and the time interval during which the burst of fifteen pulses is generated, depends upon the speed at which the motor turns during its particular step.

As clearly shown in FIGURE 6, the pulses generated by the photocell 113 are amplified in a solid state photo amplifier 200, which will be described in detail subsequently in conjunction with lFIGURE 4. The amplified pulses from the photocell amplifier are fed to a four-bit binary counter 202, which will be described in conjunction with FIGURE 5. The complemented outputs from the counter 202 are fed to a simple resistive type of digital analog converter 204 which will be described in conjunction with FIGURE 6. The output of the converter is applied to the vertical deection plates of the cathode-ray tube 18 as a compensating voltage.

As mentioned above, in a particular constructed embodiment, the stepper motor 104 takes a 15 step for each line of advance of the sensitized paper 26. The resulting fteen pulses derived from the photocell amplifier 200 are fed to the four-bit binary counter 202, which is reset to zero each time the stepper motor is energized to advance the paper 26. Then, as the motor rotates through each of its 15 steps, the counter counts the pulses produced at the output of the photocell amplifier 200. When the motor completes its particular step, the counter will normally have counted to fifteen. The counter is controlled in a manner to prohibit it from counting beyond fifteen, so that motor hunting cannot advance the counter after the fifteen steps are completed.

The complemented outputs from the four-bit binary counter are fed to the digital-analog converter 204, and the converter generates a direct-current voltage which is proportional to the position of the paperV during each step. This voltage is mixed with the signals fed to the vertical deflection plate of the cathode-ray tube 18 to deflect the electron beam in the direction of movement of the sensitized paper 26, and this lserves to compensate the beam position for such movement of the sensitized paper.

For example, at the beginning of the paper advance cycle, the counter is set to zero, so that the complemented outputs from the counter cause the digital-analog converter 204 to produce a maximum output voltage. This maximum voltage causes the cathode-ray Ibeam of the tube 18 to be shifted in a vertical direction in the direction the paper is to be moved and by an amount, equivalent, for example, to the space between one line and the next on the paper. Therefore, in carrying out the compensation of the present invention, the cathode-ray tube 18 is immediately caused to print the characters on the next line even before the paper is moved. As soon as the motor starts responding to the motor step (MS) initiation pulse introduced to it, the counter 202 starts counting. As the counter accumlates its count, the amplitude of the analog output from the converter 204 decreases, and the electron beam in the cathode-ray tube 18 moves towards its normal position. This movement of the beam continues until the motor has actually moved through its 15 and drawn the paper to the next line, at which time the motor stops and compensation of the #beam ceases. This action causes the line of print to appear straight across the paper.

It will be appreciated, of course, that the stepper motor 104 is controlled, so as to step the paper from one line to the next as quickly as possible, at which position it Waits until the next initiation pulse causes it to repeat the operation for the `subsequent line. As noted above, printing begins (with Ibeam compensation) while the stepper motor is moving the paper to the next line position, and just as soon as the stepper motor reaches the next line position, the compensation voltagev is removed, and the line scanning can proceed directly across the paper since it is now at rest. However, as long as the paper is in motion, the compensation is generated, and effectively causes the electron beam to scan straight across the paper.

The circuit details for the photocell amplifier 200 are shown in FIGURE 4. As illustrated, the output from the photocell 113 is .applied to an input terminal 300 of the `amplifier which is coupled through a 300 micromicrofarad capacitor 302 to the base of a PNP transistor 304. The transistor 304 may be of the type presently designated 2N3906. The emitter of the transistor 304 is connected to the base of a similar transistor 306, the emitter of which is connected ot the positive terminal of a 12 volt direct voltage source. The input terminal 300 is also connected to the positive terminal through a `680 kilo-ohm resistor 308, whereas the rbase of the transistor 304 is connected to the positive terminal through a diode 310. The diode may be of the type presently designated 2N3906.

The collector of the transistor 306 and the collector of the transistor 304 are both connecteed to a grounded resistor 312 which may, for example, have a value of 2.2 kilo-ohms. The collectors are also connected through a l kilo-ohm resistor 314 to the base of an NPN transistor 316. The emitter of the latter transistor is grounded, and the collector is connected through a 1.2 kilo-ohm resistor 318 to the positive terminal of a 4.5 volt direct voltage source. The collector of the transistor 316 is also coupled back to the base of the transistor 304 through a 33 micromicrofarad capacitor 320. The collector is also connected to an output terminal 322.

The low amplitude input signals introduced to the input terminal 300 are amplified in the solid state transistor amplifier of FIGURE and appear in amplified form at the output terminal 322. The amplified pulses appearing at the output terminal 322 are applied to the four-bit counter 202 which is shown in some detail in FIGURE 5. The motor step pulses (MS) are applied to an input terminal -400 of the counter in FIGURE 5 to reset the counter to zero. The input terminal 400 is connected to an inverter 402 which, in turn, is connected to the reset input terminals C of a series of J--K fiip-fiops L1, L2, L4, L8 and L16. The ffip-fiops L1, L2, L4, L8 and L16 are interconnected through a series of and

gates

404, 406 and 408, and

corresponding inverters

410, 412 and 414, to form a usual binary counter. The complemented output terminals O of the various flip-flops are connected to

corresponding output terminals

416, 418, 420, 422 and 424 which represent, respectively, the binary values T72", E, L S and L.

The binary counter of FIGURE 5 is stepped from one counting condition to the next by the successive pulses derived from the amplifier 200 of FIGURE 4. Since the complemented output terminals of the counter are connected to the digital-analog converter of FIG- URE 6, a maximum amplitude analog output from the converter is derived when the counter is reset to Zero (-l-.L-ITS') at the beginning of each step by the pulse (MS), and the analog output is reduced to zero as the counter counts up to fifteen.

When the counter reaches the count of fifteen, the terms L1, L2, L4 and L8 enable an and gate 426. This, in turn, disables an and gate 42S which prevents the amplified pulses from the photocell amplifier 200 of FIGURE 4 from stepping the counter any further. Only so long as the an gate 428 is enabled are the amplified photocell pulses applied to the terminals (T) of the flip-flops through an inverter 430 to step the counter from one count to the next. The next motor step pulse (MS) subsequently resets `the counter to zero, so that the process may be repeated.

As mentioned above, the output from the four-bit counter 202 of FIGURE 5 is applied to the digital-analog converter 204 which is shown in some detail in FIG- URE 6. The converter of FIGURE 6 is a simple resistive ladder which provides an analog output signal corresponding in amplitude to the digital inputs derived from the counter. The digital inputs, as shown in FIG- URE 6, are applied to

respective input terminals

500, 502, 504, 506 and 508 of the converter which, in turn, are connected to

respective amplifiers

510, 512, 514, 516 and 518. The outputs of the amplifiers are connected to the positive terminal of a 12 volt direct voltage source through respective 1.2 kilo-ohm resistors designated R1, R2, R3, R4 and R5. These outputs are also connected through respective diodes C-Rl, CR2, CRS, CR4 and CRS to the positive terminal of a 7.5 volt direct voltage source. These diodes may be of the type designated 1N914.

The outputs from the

amplifiers

510, 512, S14, 516, 518 are also connected to a common lead 520 through precision resistors R9, R10, R11, R12 and R13. The resistor R9 has a resistance, for example, of 48 kiloohms; the resistor R10 has a resistance of 24 kilo-ohms; the resistor R11 has a resistance of 12 kilo-ohms; the resistor R12 has a resistance of 6 kilo-ohms; and the resistor R13 has a resistance of 3.01 kilo-ohms.

The common lead 520 is connected to the base of a grounded emitter PNP transistor Q1 which may be of the type designated 2N3906 or 2N2907a. The collector of the transistor Q1 is connected through a 2.2 kiloohm resistor R20 to the negative terminal of the 12 volt direct voltage source. The common lead 520 is also connected to that terminal through a 22 kilo-ohm resistor R18. The collector of the transistor Q1 is connected to the base of a PNP transistor Q3 which may be of the same type. The collector of the transistor Q3 is directly connected to the negative terminal of the 12 volt source; and its emitter is connected through a 5 kilo-ohm potentiometer R21 and through a one kilo-ohm resistor R19 to the common lead 520. The potentiometer R21 serves as a compensation gain control. A capacitor C1 having a capacity, for example, of micromicrofarads is shunted across the resistor R19 and potentiometer R21. A diode CR9, which may be of the type designated lNlOO, is shunted between the base and emitter of the transistor Q3.

The emitter of the transistor Q3 is connected through a 3.3 kilo-ohm resistor R27 to the base of a grounded emitter PNP transistor Q5. The transistor Q5 may be of the type designated 2N3904. The character-forming vertical deflection signals derived, for example, from the defiection signal forming generator 30 of FIGURE 1 are applied to the base of the transistor Q5 by way, for example, of an input terminal 511. The circuit of the transistor Q5, and the circuit of associated transistors Q6, Q11 and Q12 form the vertical deflection signal arnplifier 33 of FIGURE l.

The base of the transistor Q5 is also connected through a 3.3 kilo-ohm resistor R28 to a grounded capacitor C4, the capacitor having a value, for example, of .47 micromicrofarad. The junction of the resistor R28 and capacitor C4 is connected to the movable contact of a potentiometer R26. The potentiometer R26 has a resistance of 5 kilo-ohms, and is connected between the positive terminal of the 7.5 volt source and the negative terminal of the l2 volt source. The potentiometer R26 serves as a vertical position control for the system.

The collector of the transistor Q5 is also connected to the base of an NPN transistor Q6 which, likewise, may be of the type designated 2N3904. The collector of the transistor Q6 is directly connected to the positive terminal of a 24 volt direct voltage source. A resistor R31 having a resistance of 2.2 kilo-ohms is connected from that terminal to the base of the transistor Q6. A capacitor C3 having a capacity of 33 micromicrofarads is connected between the base and collector of the transistor Q5. A diode CR11 of the type designated 1N100 is connected between the base and the emitter ofthe transistor A vertical gain potentiometer R33 having a resistance of kilo-ohms, and a 1.5 kilo-ohm resistor R34 are c011- nected between the base of the transistor Q5 and the emitter of the transistor Q6.

The emitter of the transistor Q6 is connected through a 10 kilo-ohm resistor R37 to the base of a grounded emitter NPN transistor Q11 of the type designated 2N3904. The base of the transistor Q11 is connected to a resistor IR39. The resistor R39 may have a resistance of 6.8 kilo-ohms, and it is connected to the negative terminal of the l2 volt source. The collector of the transistor Q11 is connected to the base of an NPN transistor Q12 of the same type, and to a resistor R41. The resistor R41 may have a resistance of 2.2 kilo-ohms, and is connected to the positive terminal of the 24 volt direct voltage source. The collector of the transistor Q12 is also connected to that terminal. The emitter of the transistor Q12 is connected back to the base of the transistor Q11 through a 10 kilo-ohm resistor R43. A diode CR14 of the type designated INlOO is connected between the base and emitter of the transistor Q12. The emitter ofthe transistor Q12 is connected to the vertical deflection plates of the cathode-ray tube 18 of FIGURE 1.

The invention provides, therefore, a high speed display system in which any skew in the displayed characters is compensated and any tendency for the instrument to overprint the information is obviated. This is achieved, as described herein, by means of a simple compensation circuit and system.

What is claimed is:

1. In an instrument for displaying and recording data and which includes: a cathode-ray tube having a viewing screen and further having means for deflecting an electron beam across the viewing screan; means having its output coupled to said beam-deflecting means and producing dcection signals for deflecting the electron beam in a predetermined manner to enable a sequence of characters t0 be displayed in a line on the viewing screen; sensitized paper means positioned adjacent said viewing screen for recording the line of characters displayed on said viewing screen; and drive means including an electric stepping motor for moving said sensitized paper across said screen in a series of steps so as to enable the characters displayed in said line on said screen to be recorded in a series of successive lines on said paper; a line compensation control system including: a converter circuit responsive to an applied digital input signal for producing an analog output signal and having its output coupled to said be'am deflecting means to cause said electron beam to be deected in a direction transverse to the aforesaid line on the viewing screen thereof by an amount dependent on the amplitude of the analog output signal produced by the converter circuit; pulse generating means coupled to said stepping motor and producing a predetermined number of electrical pulses for each step of said motor; and control circuitry electrically coupled to said pulse generating means and responsive to the electrical pulse generated thereby for introducing digital signals to said converter circuit to cause the amplitude of the analog signal generated by said converter circuit to be a function of the displacement of said paper between one line and the next.

2. The combination defined in claim 1, in which said pulse generating means includes an optical disc mechanically coupled to said stepping motor to be rotated thereby, a light source positioned on one side of said disc, and a photo cell positioned on the other side of said disc.

3. The combination defined in claim 1, in -which said control circuitry includes binary counter means electrically coupled to said pulse generating means for producing a binary coded output in response to the pulse produced by said pulse generating means, and in which said con verter circuit includes a digital-analog converter for transforming said binary coded output from said binary counter means into an analog signal.

4. The combination dened in claim 1, in which said analog signal produced by said converter circuit has a maximum amplitude at the beginning of each step of said stepper motor and is reduced in amplitude during such step.

References Cited UNITED STATES PATENTS 2,525,891 10/ 1950 Garman et al 178--6.7 2,596,741 5/1952 Tyler et al. 346-110 X 2,736,770 2/ 1956 McNaney 178-15 3,137,768 6/ 1964 Mullin 178-6.6 3,313,883 4/1967 Huntley 178-15 JOSEPH W. HARTARY, Primary Examiner U.S. Cl. X.R. 178-6\.7, 15