US3636867A - Print timing and speed control circuit for high-speed printers - Google Patents

Abstract

A high-speed ''''on-the-fly'''' printer, wherein timing means is provided to identify the position of the print characters on a movable type-carrying member, to denote the instant for actuation of the print operation, and to control the speed of the motor driving the type-carrying member.

Description

United States Patent Bonzano 1 1 Jan. 25, 1972 1541 PRINT TIMING AND SPEED CONTROL 2,936,704 5/1960 Hense ..101/93 c T I 2,940,385 6/1960 House 101/93 C CIRCUI FOR H GH SPEED PRINTERS 3,049,990 8/1962 Brown et a1. 101/93 C [72] Inventor: Giorgio Bonzano, Caluso, Italy 3,1 17,514 1/ 1964 Doersam 101/93 C 3,356,921 12/1967 Bradford 6! a1 318/341 X [73] Assgnee' g'z sysems 3,399,753 9/1968 Revelle ..197 49 a 3,472,352 10/1969 Kondur 197/49 [22] Filed: June 25, 1970 3,559,017 1/1971 Dinger..... 318/341 X 3,560,827 2 1971 8 M1 ..318 341 211 Appl. 196.; 49,637 c er Primary Examiner-William B. Penn [3()] Foreign Application priority m AttorneyGeorge V. Eltgroth, Lewis P. Elbinger, Frank L.

Neuhauser, Oscar B. Waddell and Joseph B. Forman June 28, 1969 Italy ..18919 A/69 [57] ABSTRACT [52] US. Cl ..101/93, 197/16 51 1m.C1. ..B4lj ,13411 1100 A high-Speed y" Primer, wherein liming means 15 [58] Field 61 Search ..101/93 c; 197 1,49, 52, 16, Provided to identify the Position of the Print characters on a 97 7 23 5; |73/28, 32 3 3 movable type-carrying member, to denote the instant for ac- 318/34| tuation of the print operation, and to control the speed of the motor driving the type-carrying member. [56] References cued 10 Claims, 4 Drawing Figures UNlTED STATES PATENTS 2,915,966 12/1959 Jacoby ..101/93 C EEBNTING 85i? 9 4 5 5 1116 F5 I 11 1 1 1 1 I g I 1 I b 1 1 14 1 I C 22 1:121 I I 15 16 d 1 1 2i 7 1 POWER J REGULATINGV' CIROUI SUPPLY cmcun 5 PATENTED m2 I972 MI a of 2 3.636. 867

Giorgio BO/VZANO INVEN'I'OR.

PRINT TIMING AND SPEED CONTROL CIRCUIT FOR HIGH-SPEED PRINTERS BACKGROUND OF THE INVENTION The present invention relates to high-speed printers employed in digital data-processing systems, and more particularly to timing devices for use in such printers.

In the field of electronic data-processing devices, high printing speeds are obtained by the use of printers operating according to the principle termed on-the-fly" printing. Printers operating pursuant to such principle may assume various forms, including serial printers, serial-parallel printers, chain or drum printers, etc. Printers of this type employ impact printing or nonimpact printing, the latter including electrostatic and optical printing.

Briefly, because on-the-fly printers are well described in the prior art, these printers are characterized by a common element, i.e., a type-carrying member in continuous and uniform motion. The object of the type-carrying member is to bring all characters, of the character set carried by the member, sequentially into correspondence with one or more predetermined printing positions, whereupon, at the proper moments, the desired characters will be printed without halting the typecarrying member.

These on-the-fly printers present the requirement for identifying the characters and the position they occupy at each instant. Usually the problem is solved by providing a timing member, comprising a code-carrying device, moving integrally with the type-carrying member and bearing one or more readily recognizable reference and timing marks, located at positions corresponding to the positions of the different characters on the type-carrying member.

Various types of timing devices may be used for this purpose, such as those using photoelectric, magnetic, or capacitive pickup techniques. Difi'erent character-identifying techniques may be used, such as the direct comparison, of hinary codes or the stepping of codes through pulse counting.

An example of such techniques is provided in the Italian patent application N. 17,563 A/69 filed May 30, 1969 and the corresponding US. patent application Ser. No. 42,438, filed June 1, 1970, by F. Castoldi for SINGLE PICK-UP TIMING DEVICE FOR HIGH-SPEED PRINTER, both such applications being assigned to the assignee of the instant invention. A common characteristic of all of these techniques is to provide identifying timing pulses which recur uniformly so that not only can the characters to be printed be identified, but also so that the printing operating can be synchronized by means of these pulses, i.e., these pulses are employed to determine the times at which the printing member must be actuated to effect the printing operation.

If the logical operations of identifying a character and actuating the printing member required no time lapse, the timing pulses could be precisely concurrent with the times at which the various characters are in correspondence with a printing position. In such instance the speed with which the characters reached the printing position would not interfere with the proper printing operation. Practically, however, the timing pulses must be suitably advanced with respect to the times at which the characters to be printed are in correspondence with a printing position; for example, this lead time may be of the order of milliseconds.

As such lead time is obtained by appropriately offsetting the timing member with respect to the type-carrying member by a suitable angle, it is manifest that the speed of the type-carrying element must be maintained between precisely determined limits to ensure correct printing. The required speed control is generally obtained by the use of small-slip asynchronous motors. The synchronous speed of these motors depends, as is use in different countries (25 or 50 Hz., instead of the standard 60 Hz.) pose additional problems. Since the printers using these motors are also provided with electronic circuits, which require a direct current supply, it would be desirable to also use DC motors for driving the type and code-carrying members. However, the use of DC motors normally requires sophisticated speed regulation circuits, which comprise tachometric generators, difference amplifiers, and other devices.

Therefore, it is the object of this invention to eliminate these drawbacks by also using the timing and character-identifying devices for regulating the speed of the DC motors.

BRIEF DESCRIPTION OF THE DRAWING The invention will be described with reference to the accompanying drawing, wherein:

FIG. I is a schematic block diagram of a printer and the speed-regulating circuit of the invention; and

FIGS. 2 to 4 illustrate waveforms of voltages at different points in the speed-regulating circuit of FIG. 1.

DESCRIPTION OF THE PREFERRED EMBODIMENT In FIG. 1, a regulating circuit in accordance with the invention, is employed with a serial printer. For simplicity, only the essential parts of the printer are shown. Thus, the printer of FIG. 1 comprises a motor M which, through a shaft 1, drives a timing disk 2 and a type carrier 3 in continuous rotation. A pick up 4 reads out appropriate marks carried by timing disk 2.

A print hammer 5, located proximate to type carrier 3, is actuated by an electromagnet 6. A print-receiving member 7, usually of one or more paper sheets, and an inking ribbon 8 are interposed between type carrier 3 and print hammer 5.

Motor M, pick up 4, type carrier 3, timing disk 2, hammer 5, and electromagnet 6 are mounted on two movable carriages, not shown, which move together in a direction perpendicular to the plane of the figure.

The signals delivered by pickup 4, are suitably amplified by I an amplifier 9 and applied to a pulse-squaring circuit 10, which can be a simple univibrator. The output of circuit 10 is a succession of square timing pulses of precise duration and am- ,plitude, having a repetition rate depending on the number of marks located on timing disk 2 and on the rotational speed of the disk. Under normal operating conditions, i.e., at constant speeds, this pulse repetition rate is constant.

As described in the above-mentioned patent application, the uniform succession of timing pulses may be interrupted by a relatively long interval, due to the absence of a timing disk mark, or by two relatively short intervals, due to an additional interposed timing disk mark. This nonuniformity is provided to identify a predetermined angular position of the type carrier, such as an initial position, and occurs once each revolution of the type carrier. However, as will be explained hereinafter, despite these nonuniformities, the timing pulses provided by circuit 10 may be used to regulate the motor speed.

The output pulses of circuit 10 are applied to a logical counting and comparing circuit 1 which, through an amplifi- 'er 1?. controls the energizing of printing electromagnet 6 at known, on the supply frequency and the number of poles of the proper times.

In accordance with the invention, the output timing pulses of circuit 10 are also applied to a regulating circuit 25 for controlling and regulating the speed of motor M. In the preferred embodiment, circuit 25 comprises a pair of monostable univibrators l3 and 14, a pair of inverters l5 and I6 and a bistable circuit or flip-flop l7.

Univibrator 14 is preferably of the fast recovery type. Inverters l5 and 16 introduce an appropriate delay in the pulses applied to the inputs 22 and 23 of flip-flop 17. The output of flipflop 17 is applied to a controllable power supply circuit l8,

which is adapted to deliver to motor M a first or a second level of supply voltage, according to the signals received by flip-flop The operation of regulating circuit 25 will now be explained with reference to the waveforms of FIG. 2.

When motor M is started, a succession of timing pulses, having initially a very low repetition rate due to the low speed of the motor, is applied to the input of circuit 25, waveform a of FIG. 2.

The negative excursion of the first timing pulse 19 triggers the delivery of a positive pulse 20 by univibrator l3, waveform b of FIG. 2. Timing pulse 19 is also applied to the clock input 21 of flip-flop l7 and enables flip-flop 17 to assume a state corresponding to the signals applied to inputs 22 and 23 of the flipflop.

in its initial state, univibrator 14 is at rest. At the time when the first timing pulse 19 is applied to flip-flop 17, because of the delay introduced by inverters l and 16, the signals applied to inputs 22 and 23 continue to correspond to the initial state of univibrator 14, the output of flip-flop 17 does not change from its initial value, which is assumed to be at a relatively positive level. This positive level output of flip-flop 17 controls power supply circuit 18 to supply motor M with full voltage, which thereby delivering a torque sufficient for its acceleration.

Univibrator 14, upon being actuated by the output pulse of univibrator 13, generates a positive pulse of predetermined duration T waveform c of FIG. 2, duration T being the characteristic time" of univibrator 14. However, this pulse of univibrator 14 is applied to flip-flop 17 only after a predetermined delay relative to timing pulse 19, waveform d of FIG. 2, and therefore, in the absence of a pulse on input 21, the state of flip-flop 17 cannot change from its initial value, waveform e of FIG. 2.

When the second timing pulse 24 is applied to circuit 25, univibrators 13 and 14 and the output signals of inverters l5 and 16 have returned to their rest conditions. Accordingly, although the sequence of actuation of both univibrators is repeated as before, the state of flip-flop 17 remains unchanged.

In this condition motor M continues to accelerate. Finally, however, when the repetition period T of the timing pulses delivered by circuit becomes equal to the predetermined duration T, which occurs when the required motor speed is reached, fast recovery univibrator 14 is actuated before the termination of its preceding output pulse. Accordingly, when the next timing pulse is applied to flip-flop 17, the signals applied to its inputs 22 and 23 are inverted with respect to the rest condition of the circuit, waveform d of HG. 2. Flip-flop l7 thereupon transfers to its opposite state, wherein its logical output value is zero. This zero level controls power supply circuit 18 to supply motor M with a reduced voltage, and that the motor decelerates slightly. However, as soon as the repetition period T of the timing pulses again becomes slightly greater than predetermined duration T, the initial sequence of operations is repeated and motor M is again supplied with full voltage.

By this regulation technique, which can be termed an On- Off method, the actual operating speed of the motor is maintained very close to the nominal operating speed represented by the characteristic time T of univibrator 14.

Other regulating techniques, for example a proportional scheme, may be employed to attain a higher degree of regulating precision, without departing from the spirit and scope of the invention. The operation of a regulating circuit, such as the one disclosed, is not adversely affected by the presence of an additional timing pulse or by the absence of a timing pulse once each revolution of the timing disk, either occurrence being employed to identify a predetermined position of the type carrier, in accordance with the teachings of the aforementioned patent application. The waveforms of FIGS. 3 and 4 illustrate the operation of the circuit under such circumstances.

FIG. 3 demonstrates the case of the additional timing pulse, which is used for identifying the initial position of the type carrier. During deceleration of motor M the presence of an additional pulse has no effect, inasmuch as it further reduces the preceding pulse is less than characteristic time T, this condition is interpreted by regulating circuit 25 as the attainment of the nominal operating speed and, consequently, the motor supply voltage is reduced. If the interval T' by which the next successive timing pulse follows the additional pulse is less than characteristic time T, the control condition of reduced voltage is continued. However, the next successive timing pulse will occur following an interval T, which is greater than time T, so that the full supply voltage is restored. The disturbance of the regulating operation-is limited, therefore, to the span of two timing pulses, corresponding to two characters, and has no appreciable adverse influence on the actual operating speed of the motor.

Similar consideration also apply in the instance the absent timing pulse, although in this instance the nonuniformity participates during deceleration of motor M. Referring to FIG. 4, the absence of a timing pulse causes an interval T" between consecutive timing pulses greater than characteristic time T. This condition is interpreted by regulating circuit 25 as a decrease in operating speed and, consequently, at the next timing pulse full supply voltage is delivered to the motor. However, this condition occurs only in the interval between the next two timing pulses and is not of sufficient duration to sensibly accelerate the motor.

The failure of these nonuniformities to adversely influence operation of the circuit is because the repetition period of the timing pulses is between about 500 psec. and 2 psec, whereas the repetition period of the additional timing pulse, or missing timing pulse, depends on the number of the characters in the set of characters, and is of a duration 10 or more times the duration of the normal period.

Iclaim:

l. A high-speed printer of on-the-fly" type having symbols to be printed arranged on a type-carrying member, said member being maintained in motion relative to a printing position by suitable motor means operating at a predetermined speed, comprising in combination:

timing means for delivering a succession of pulses to denote the position of the characters to be printed and the time for actuation of the print operation;

first circuit means responsive to said pulses to control said printing operation; and

second circuit means responsive to said pulses to control the operating speed of said motor means, whereby both the timing of the printing operation and the regulation of the operating speed of said motor means are controlled by said pulses.

2. A high-speed printer as in claim 1, wherein said second circuit means comprises a fast recovery monostable univibra tor triggered in response to said pulses to provide an output signal, a bistable element enabled for triggering by said pulses and having set and reset inputs, said output signal being applied in direct and inverted form to said set and reset inputs respectively, said bistable element providing an output control signal to control the operating speed of said motor means.

3. High-speed printing apparatus comprising:

an image-bearing member adapted for movement past a printing position and bearing a plurality of different character images spaced apart on said member along said direction of movement,

a controllable driving member connected to drive said image-bearing member past said printing position to carry said character images successively past said printing position,

printing apparatus disposed proximate to said printing position and, when actuated by an energizing signal, for cooperating with the one of said character images at said printing position to make a copy of said one image,

a timing indicia bearing member integrally associated with said imageobearing member to move with said imagebearing member, said timing indicia bearing member comprising a timing indicium for each of said character images, each of said timing indicia being located on said timing indicia bearing member at a position corresponding to the position of the respective one of said character images,

sensing means disposed for sensing the timing indicia on said timing indicia bearing member as said timing indicia move past said sensing means and for delivering a timing signal when each ofsaid timing indicia is sensed,

circuit means responsive to each of said timing signals and enabled when a copy is to be made of the respective one of said character images to supply an energizing signal to said printing apparatus,

each one of said timing indicia being disposed on said timing indicia bearing member at a position to be sensed by said sensing means a characteristic duration before the respective one of said character images reaches said printing position when said driving member is operating at a predetermined speed, said characteristic duration corresponding to the interval between the time when said one timing indicium is sensed by said sensing means and the time when said printing apparatus is ready to make a copy of the respective character image, and control means responsive to said timing signals to control said driving member to maintain a substantially constant driving speed.

4. The apparatus of claim 3, wherein said control means responds to the rate of recurrence of said timing signals to control said driving member.

5. The apparatus of claim 4, wherein said control means responds to a relatively low rate of recurrence for accelerating said driving member and to a relatively high rate ofrecurrencc for decelerating said driving member.

6. The apparatus of claim 3, wherein said control means compares the intervals between successive ones of said timing signals with said characteristic duration to control said driving member.

7. The apparatus of claim 6, wherein when said intervals are less than said characteristic duration said control means decelerates said driving member and when said intervals are greater than said characteristic duration said control means accelerates said driving member.

8. High-speed printing apparatus comprising:

an image-bearing member adapted for movement past a printing position and bearing a plurality of different character images spaced apart on said member along said direction of movement,

a controllable driving member connected to drive said image-bearing member past said printing position to carry said character images successively past said printing position,

printing apparatus disposed proximate to said printing position and, when actuated by an energizing signal, for cooperating with the one of said character images at said printing position to make a copy of said one image,

a timing indicia bearing member integrally associated with said image-bearing member to move with said imagebearing member, said timing indicia bearing member comprising a timing indicium for each of said character images, each of said timing indicia being located on said timing indicia bearing member at a position corresponding to the position of the respective one of said character images,

sensing means disposed for sensing the timing indicia on said timing indicia bearing member as said timing indicia move past said sensing means and for delivering a timing signal when each of said timing indicia is sensed,

circuit means responsive to each of said timing signals and enabled when a copy is to be made of the respective of said character images to supply an energizing signal to said printing apparatus, and

contro means responsive to the rate of recurrence of said timing signals to control said driving member to maintain a substantially constant driving speed.

9. The apparatus of claim 8, wherein said control means compares the intervals between successive ones of said timing signals with a characteristic duration to control said driving member, said characteristic duration corresponding to the interval between the time when one of said timing indicia is sensed by said sensing means and the time when said printing apparatus is ready to make a copy of the respective character image.

10. The apparatus of claim 9, wherein said intervals are less than said characteristic duration said control means decelerates said driving member and when said intervals are greater than said characteristic duration said control means accelerates said driving member.

UNITED STATES PATENT OFFICE CETIFICATE OF CEQTE 3 36 a Dated Januaw 45; 1972 Patent No.

Inventor(s) Giorgio Bonzano It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

Column 6, line 27, after "respective" should read Signed and sealed this 24th day of October 1972.

(SEAL) Attest:

EDWARD M.FLETCHER,JR. ROBERT Commissioner of Patents Attesting Officer DRM Poqoso (10'69) USCOMM-DC 6O376-P6O u.s. GOVERNMENT FRINTING OFFICE: I969 0-566-334.

Claims (10)

1. A high-speed printer of ''''on-the-fly'''' type having symbols to be printed arranged on a type-carrying member, said member being maintained in motion relative to a printing position by suitable motor means operating at a predetermined speed, comprising in combination: timing means for delivering a succession of pulses to denote the position of the characters to be printed and the time for actuation of the print operation; first circuit means responsive to said pulses to control said printing operation; and second circuit means responsive to said pulses to control the operating speed of said motor means, whereby both the timing of the printing operation and the regulation of the operating speed of said motor means are controlled by said pulses.

2. A high-speed printer as in claim 1, wherein said second circuit means comprises a fast recovery monostable univibrator triggered in response to said pulses to provide an output signal, a bistable element enabled for triggering by said pulses and having set and reset inputs, said output signal being applied in direct and inverted form to said set and reset inputs respectively, said bistable element providing an output control signal to control the operating speed of said motor means.

3. High-speed printing apparatus comprising: an image-bearing member adapted for movement past a printing position and bearing a plurality of different character images spaced apart on said member along said direction of movement, a controllable driving member connected to drive said image-bearing member past said printing position to carry said character images successively past said printing position, printing apparatus disposed proximate to said printing position and, when actuated by an energizing signal, for cooperating with the one of said character images at said printing position to make a copy of said one image, a timing indicia bearing member integrally associated with said image-bearing member to move with said image-bearing member, said timing indicia bearing member comprising a timing indicium for each of said character images, each of said timing indicia being located on said timing indicia bearing member at a position corresponding to the position of the respective one of said character images, sensing means disposed for sensing the timing indicia on said timing indicia bearing member as said timing indicia move past said sensing means and for delivering a timing signal when each of said timing indicia is sensed, circuit means responsive to each of said timing signals and enabled when a copy is to be made of the respective one of said character images to supply an energizing signal to said printing apparatus, each one of said timing indicia being disposed on said timing indicia bearing member at a position to be sensed by said sensing means a characteristic duration before the respective one of said character images reaches said printing position when said driving member is operating at a predetermined speed, said characteristic duration corresponding to the interval between the time when said one timing indicium is sensed by said sensing means and the time when said printing apparatus is ready to make a copy of the respective character image, and control means responsive to said timing signals to control said driving member to maintain a substantially constant driving speed.

4. The apparatus of claim 3, wherein said control means responds to the rate of recurrence of said timing signals to control said driving member.

5. The apparatus of claim 4, wherein said control means responds to a relatively low rate of recurrence for accelerating said driving member and to a relatively high rate of recurrence for decelerating said driving member.

6. The apparatus of claim 3, wherein said control means compares the intervals between successive ones of said timing signals with said characteristic duration to control said driving member.

7. The apparatus of claim 6, wherein when said intervals are less than said characteristic duration said control means decelerates said driving member and when said intervals are greater than said characteristic duration said control means accelerates said driving member.

8. High-speed printing apparatus comprising: an image-bearing member adapted for movement past a printing position and bearing a plurality of different character images spaced apart on said member along said direction of movement, a controllable driving member connected to drive said image-bearing member past said printing position to carry said character images successively past said printing position, printing apparatus disposed proximate to said printing position and, when actuated by an energizing signal, for cooperating with the one of said character images at said printing position to make a copy of said one image, a timing indicia bearing member integrally associated with said image-bearing member to move with said image-bearing member, said timing indicia bearing member comprising a timing indicium for each of said character images, each of said timing indicia being located on said timing indicia bearing member at a position corresponding to the position of the respective one of said character images, sensing means disposed for sensing the timing indicia on said timing indicia bearing member as said timing indicia move past said sensing means and for delivering a timing signal when each of said timing indicia is sensed, circuit means responsive to each of said timing signals and enabled when a copy is to be made of the respective of said character images to supply an energizing signal to said printing apparatus, and control means responsive to the rate of recurrence of said timing signals to control said driving member to maintain a substantially constant driving speed.

9. The apparatus of claim 8, wherein said control means compares the intervals between successive ones of said timing signals with a characteristic duration to control said driving member, said characteristic duration corresponding to the interval between the time when one of said timing indicia is sensed by said sensing means and the time when said printing apparatus is ready to make a copy of the respective character image.

10. The apparatus of claim 9, wherein said intervals are less than said characteristic duration said control means decelerates said driving member and when said intervals are greater than said characteristic duration said control means accelerates said driving member.

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