US3408930A - High-speed printing with continuously moving carriage - Google Patents

Description

Nov. 5, 1968 L. DJCHAMNESS T' 3,408,930

HIGH-SPEED PRINTING WITH CONTINUOUSLY MOVING CARRIAGE Filed Oct. 2, 1967 2 Sheets-Sheet 1 m l G \25 r- 52b L. 1 2 IIJHE22 12 24' j, 2

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HIGH-SPEED PRINTING WITH CONTINUOUSLY MOVING CARRIAGE 2 Sheets-Sheet 2 Filed Oct. 2, 1967 SYNC. Cl QCUIT United States Patent 3,408,930 HIGH-SPEED PRINTING WITH CONTINUOUSLY MOVING CARRIAGE Leland D. Chamness, Castro Valley, and Andre F. Marion,

Berkeley, Calif., assignors to Friden, Inc., a corporation of Delaware Continuation-impart of application Ser. No. 553,961, May 31, 1966. This application Oct. 2, 1967, Ser. No. 672,137

9 Claims. (Cl. 101-93) ABSTRACT THE DISCLOSURE A high-speed serial printer having a single print hammer and a single continuously rotating endless character belt, both of which are mounted on a single carriage which moves continuously along the print line. The characterbelt rotates about an axis perpendicular to the direction of travel of the carriage.

This application is a continuation-in-part of our earlier filed application entitled High-Speed Printer, Ser. No. 553,961, filed May 31, 1966, now abandoned.

Background, field of invention This invention relates to high-speed serial printers, and in particular to a printer apparatus utilizing a continuously rotating endless character element.

Generally, printers incorporate means for carrying characters or symbols to be imprinted upon a record medium or paper, and a print hammer for striking selected characters. The character support may take the form of a drum or disk, a wire, chain or flexible belt, by way of example. In any case, it is highly desirable to achieve high printing speeds at the lowest cost, with optimum resolution and quality. In addition, the printer apparatus should have long life capability, with a minimum of maintenance during its operating life.

One method of increasing the speed of a printer is through the use of the on-the-fly printing principle. In an impact type printer using this principle, the type characters are formedson the circumference or periphery of a rotating element, for example, a wheel or a drum, and an inked ribbon and the paper are interposed between the character element and a print hammer. A character is printed on the paper by firing the hammer whenever a desired character passes in front of the hammer, thereby striking the paper against the continuously rotating character element.

In the past, such on-the-fly printers, in order to obtain great printing speed, have utilized a plurality of print hammers and actuating mechanisms, there being one print hammer for each print position or column in a row of printed characters. Such a printing mechanism, however, is obviously rather expensive. Accordingly, the cost cannot be justified for small systems, for example, dark-type calculators, wherein printing rates slower than those obtainable with a parallel print-out may be tolerated.

In order to reduce the cost of the 'on-the-fly printing mechanisms, printers which operate in a serial mode have been proposed and built. In such serial type printers, a single continuously rotating character element and a single hammer are moved in unison along the print line, either step by step or continuously, and the desired characters are printed out in sequence. Printers utilizing the former method of moving the hammer and print wheel along the print line suffer from problems of cost and maintenance due to the mechanical mechanism necessary to provide the step by step motion of the carriage, and/or a decrease of printing speed. Serial on-the-fly printers 3,408,930 Patented Nov. 5, 1968 using the continuous motion of the carriage along the print line, on the other hand, generally require that the characters on the character element be arranged in a complex geometrical pattern in order to compensate for the continuous movement.

Summary of invention The instant invention overcomes the problems of the prior art high-speed on-the-fly serial printers, byproviding a relatively simple printer of the continuous movement type having a minimum of movable parts and a relatively simple character arrangement on the character element. Y

Briefly, a high-speed serial printing apparatus, according to the invention, comprises a carriage, having mounted thereon an endless character element and a single print hammer, which is moved in a continuous-motion in the direction of a print line. The endless character element, i.e., a flexible belt, is mounted for rotation about an axis substantially perpendicular to the travel axis of the carriage along the print line so that all of the characters on the element are presented to each print position on the record medium. Preferably, the portion of the character element adjacent the hammer rotates in a direction opposite to the direction of movement of the carriage. Means are also provided for sensing the instantaneous position of the characters on the element, and for firing the hammer when a selected character passes a print position.

Brief description of drawings The invention will be described in greater detail with reference to the drawings in which:

FIG. 1 is a simplified plan view of the printer apparatus of this invention;

FIG. 2 is a sectional view taken along the plane indicated by the line 2-2 of FIG. 1;

FIG. 3 is an enlarged view of a number of characters in a line of print illustrating the dimensions between the various printed characters on the paper;

FIG. 4 is an enlarged view of a portion of a character element showing the dimensions between the various characters and character positions thereon;

FIG. 5 is a perspective view of the novel apparatus;

FGI. 6 is a top plan view of the printer apparatus illus trated in FIG. 5; and

FIG. 7 is a side elevational view taken along the planes indicated along the lines 7-7 of FIG. 6.

Description of preferred embodiments Similar numerals refer to similar elements throughout the drawings.

With reference to FIGS. 1 and 2 of the drawings, a high-speed printer apparatus in accordance with this invention comprises a carriage 10 on which is mounted an endless character element 12 and a print hammer assembly 14 for conjoint travel. The carriage 10 is moved by drive means 16 coupled to a rotary threaded shaft 18 on which the carriage rides in a well known manner. The character element 12, which as shown, is a flexible band or belt, e.g., a metal band, having embossed charracters 20 formed on the circumference or periphery thereof, is rotated by means of adriven pulley wheel 22 and an idler 24 about an axis substantially perpendicular to the travel axis of the carriage 10, i.e., perpendicular to the axis of shaft 18. The pulleys 22 and 24 are preferably provided with sprockets (not shown) which mate With correspondingly spaced holes or apertures in the character belt in order to prevent the belt from slipping when it is contacted by the hammer. The use of a flexible belt permits the hammer 14 to be placed within the loop formed by the belt, whereby all of the moving parts of the printer, i.e., hammer, belt and carriage may h juxtaposed only one surface of the paper. This has the advantage of providing a relatively simple, compact and inexpensive printer mechanism. Preferably, the character element 12 is rotated so that the portion of the element adjacent the hammer 14 moves in a direction opposite to that of the carriage 10. In the figures, wherein the direction of movement of the carriage is indicated as from left to right, the character element 12 is rotated in a counter-clockwise direction. This has the effect of reducing the relative velocity between the characters 20 and the paper or printing record medium 26, and thereby allows for higher velocities of the belt and higher printing speeds.

Although not shown in FIGS. 1 and 2, it is to be understood that the motion of the character element 12 must be synchronized with that of the rotary thread 18 in order that printing of the desired character may be accomplished at the proper print positions. The synchronism may be accomplished by any means Well known in the art, for example, by means of an external monitoring or synchronizing circuit, or by providing a positive mechanical drive connection, for example, a gear or a chain and sprocket drive, betweent he drive means for the carriage 10 and the drive pulley 22.

During operation of the apparatus, the carriage 10 is moved continuously in the direction of printing by the rotary thread 18. The carriage 10 may be engaged with the thread by means of a detent pin, by way of example, which is seated in the groove of the thread during the forward drive of the carriage in the print mode; and is disengaged from the thread when the carriage is being retracted to its starting or home position to enable the printing of a subsequent line of print. Retraction of the carriage at the end of each print cycle may be achieved in any known manner, e.g., by a resilient spring which is linked to the carriage and is progressively tensed as the carriage is moved during the print mode. A carriage drive of this type is disclosed in copending US. patent application Ser. No. 663,292, filed Aug. 25, 1967 which is a continuation-in-part of US. patent application Ser. No. 528,501, filed Feb. 18, 1966 now abandoned, in behalf of the same inventors and assigned to the same assignee as for this application.

To achieve printing on the record medium or paper 26, the belt 12 is disposed between the paper and hammer 14, and the paper is positioned between the belt 12 and a platen 28. A ribbon 30 carried by spools 32a and 32b is located between the belt 12 and paper 26; or alternatively, a self-inked paper may be employed. The printing of the desired characters is accomplished by firing the hammer to strike the selected character when the character arrives at print position. Such coincidence may be determined by means of timing marks 34, e.g., apertures or magnetic spots (FIG. 2) corresponding to each character and an index or reference mark (not shown), all formed at predetermined positions on the belt. The timing marks may be sensed optically or electrically, and counted successfully for each cycle of belt revolution, whereby the instantaneous position of each character or symbol may be established. Other well-known means for selecting the characters to be printed may be utilized. For example, the timing marks need not be located on the belt but may, if desired, be located on any other surface, e.g., the top of pulley 22, whichmoves in synchronism with the belt.

To determine the relationship of the various parameters of the printing system, let us assume that the counterclockwise rotational velocity of the belt 12 is V and that the carriage moves at a speed V in the forward or print direction. Therefore, the apparent velocity of any point on the character belt, as seen at the print position adjacent to the hammer, may be defined as V V If we wish to print R characters per second, then all the characters must traverse the print position in l/R seconds; and if we have N possible equally spaced character positions on the character element, each of which is to be scanned for each print position, the time interval between any two character positions is l/RN seconds. During such interval, the apparent displacement of a character on the belt is d=(V -V )1/RN and the displacement of the carriage 10 is s= V (l/RN) If, as shown in FIG. 3, eachcharacter on the paper occupies a space having a standard widthw, and the blank space between characters is designated as w, then w-l-w describes the distance P between print positions. Thus, for each revolution of the belt accomplished in l/R seconds, the carriage velocity is V =PI R inches per second; or the carriage displacement per character position movement past a print' position is s='P/N inches.

At this point, it should be noted that although theoretically all of the character positions on the character element or belt 12 may contain characters, and although such an arrangement is possible if the printing rate is very slow, in a practical application, the number of character positions on the character belt 12 must be greater than the number of characters in the group or sequence from which it is desired to select one character for printing in a particular print position. For example, if the group of characters on the character element represents the numeral 0 to 9, then the character element 12 should, for example, contain twenty equally spaced character positions. These additional character positions are required because of the finite time required to cock the hammer 14 between successive printing positions. It should be noted that in the above example, wherein it is stated that there are twenty character positions on the character element, that an additional sequence of characters may be placed in the remaining ten character positions. In such 'a case, in order to allow for cocking of the hammer, a space or unused print position on the paper would have to be provided whenever two successive characters were selected from different groups or sequences.

Returning now to the consideration of the parameters of the printer, it can easily be seen that the total displacement of the carriage measured between the first and last character of a group or sequence characters on the belt, wherein L represents the number of characters in the sequence, and all successive characters in the sequence are located in adjacent character positions, is equal to P XL In order for the hammer to be able to print any of the characters in any sequence at each print position, the hammer width It should be In order that the hammer not be able to hit two characters at the same time, the minimum spacing a (FIG. 4) between any two consecutive characters on the belt must equal the hammer width 11 plus some clearance K, e.g., .005 inch. This relationship may be expressed as Since the carriage is continually moving, it is necessary that after each complete revolution of the belt, the first character of the group must appear at the next print position or column. Therefore, as shown in FIG. 4, the distance between the last and first character positions on the belt must be increased by an amount equal to P (the distance between print positions) to achieve this alignment at each print position.

p In view of the above relationships, it may be determined that the belt length b is b=(w+ +K)N+P and the belt velocity is Q I I LP V w+ +K)N+P]R inches per second.

Turning now to the spacing of the timing marks 34, although any arrangement which will identify the various character positions may be used, preferably N equally spaced timingmarks are provided, there being one timing mark corresponding to each character position. The distance d between timing marks should therefore be equal to the belt length divided by the number of character positions or t 1 t 1 A particular embodiment of this invention is shown in FIGS. 5, 6 and 7, wherein the carriage 10 houses a drive motor 36 which is coupled to a drive wheel 38. The wheel 38, in turn, is coupled by a belt 40 to the driven pulley 22. The endless character belt 12 is looped around the pulley 22 and the idler 24, for counter-clockwise rotation, in juxtaposition to the print hammer 14 and the paper 26. Since, as illustrated, the drive link between the pulleys 22 and 38 is not of a positive nature, in order to provide synchronism between the rotation of the belt and the movement of the carriage, a synchronizing circuit 35 is shown. A spring 27 (partially shown) is provided to return the carriage 10 to its home position after the completion of a line of print.

In operation, a source of power 44 energizes the drive motor 36 thereby providing a rotational motion to the character belt 12. Simultaneously, the carriage drive 16 rotates the threaded shaft 18 whereby the carriage 10 is transported axially relative to the shaft and the platen 28 along a guide 25. A hammer actuator circuit'46 serves to fire the hammer at selected times so that predetermined characters are imprinted on the paper 26, in a manner well known in the printing art. The power source 44 and hammer actuator 46 are depicted as being connected to electrical wipers 48 that feed the energizing signals to the motor and hammer, respectively.

One embodiment of the novel printer of this invention employs twenty total characters, including ten numerals and ten symbols on the character belt. With a carriage velocity of three inches per second, and a spacing of approximately .135 inch between the type characters on the belt, a print speed of thirty characters per second is realized.

The scope of the invention is not limited to the particular parameters and values set forth above. For example, the belt may bear alphabetic or numerical characters, separately or in combination. Also, the velocities of the carriage and belt may be varied to satisfy the relationships set forth above.

It should be noted that although the serial printing arrangement specifically described is theoretically applicable to a character belt containing any number of characters, that as a practical matter if the number of characters is too large, the print rate may have to be reduced to an undesirable value. This is due to the fact that the print rate is limited by the necessity of the belt making a complete revolution per print position and the finite time required to strike and imprint a satisfactory character on the paper. Accordingly, in such cases, it is to be understood that the invention can equally well be applied to a more complex printing arrangement wherein a plurality of vertically displaced rows of characters are formed on the character belt. Of course, in such a printer, means capable of selectively shifting the character belt in a vertical plane during the time that the hammer is being cocked must be provided. Such means are, however, well known in the art, for example, see US. Patent 3,168,182, issued Feb. 2, 1965.

There has been described herein a novel high-speed printer, wherein an endless belt carries characters to be presented to a hammer at a print position, for selective printing on a paper. Both the belt and hammer are moved at a substantially constant speed relative to the paper by means of a common carriage. The apparatus affords a simple, inexpensive configuration with a minimum of parts, and is characterizedby low cost of manufacture andmaintenance.

It is to be understood that various changes and modifications of the preferred embodiment can be made without departing from the spirit of the invention. Accordingly, the invention is to be limited only as recited in the following claims.

What is claimed is:

1. A high-speed printer apparatus adapted for serially recording selected characters along a print line of a record medium comprising:

a carriage adapted for continuous travel along a predetermined print line;

an endless character element comprised of a flexible belt forming a closed loop, said belt being supported by said carriage and mounted for rotation about an axis substantially perpendicular to the travel axis of said carriage;

a single print hammer mounted on said carriage and disposed adjacent to a portion of said element for imprinting selected charatcers on said record medium;

means for moving said carriage conjointly with said element and said hammer, in a continuous motion in the direction of the print line;

means for moving the portion of said element adjacent to said hammer in a direction opposite to that of said carriage during line printing;

means for rotating said element in synchronism with the movement of said carriage along said print line so that all of the characters on the element are successively presented to each print position in said print 'line;

means for sensing the instantaneous position of the characters on said element; and

means for firing said hammer when a selected character is presented to a desired print position on said record medium.

2. A high-speed printer apparatus as in claim 1 wherein said hammer, said belt and said carriage are all disposed in juxtaposition to one surface of the record medium on which printing is effected, and wherein said hammer is positioned within the loop formed by said belt.

3. A high-speed printer apparatus as in claim 1 Wherein the periphery of said character element is subdivided into a plurality of character positions at least some of which contain characters, the spacing between adjacent character positions, other than the spacing between the last and first character positions being increased by a distance equal to the distance between adjacent print positions in a print line on said record medium.

4. A high-speed printer apparatus as in claim 3 wherein all of the characters in any sequence are located in adjacent character positions on said character elements, and wherein said hammer has a width equal to P is equal to the distance between adjacent print positions on said record medium, N is equal to the total number of character positions on said character element, and L is equal to the number of characters in any sequence which can be printed in one print position.

5. A high-speed printer apparatus as in claim 3 wherein said sensing means comprises a plurality of timing marks spaced at predetermined intervals for identifying the characters on said character element. 1

6. A high-speed printer apparatus as in claim 5 where in said timing marks are equally spaced about the circumference of said character element, there being one timing mark corresponding to each character position on said character element.

7. Ahigh-speed printer apparatus as in claim 6 Wherein the portion .of said character element adjacent to said hammer moves in a direction opposite to that of said carriage during line printing.

v 8. A high-speed printer apparatus as in claim 7 Wherein said hammer, said belt andsaid carriage are all disposed in juxtaposition to one surface of the record medium on which printing is effected, and wherein said hammer is positioned within the loop for-med by said belt.

9. A high-speed printer apparatus as in claim 4 Wherein said sensing means comprises a plurality of equally spaced timing marks for identifying the characters on said character element, there being one timing mark corresponding to each character position on said character element.

References Cited UNITED STATES PATENTS 2,831,424 4/1958 MacDonald e- 101-93 2,843,243 7/1958 Masterson 'l0l93' X 2,936,704 "5/1960' Hense 1- i 101 93 3,041,965 7/1962 Sasaki 101 111X 3,007,399 11/1961 Sasaki et al. 101 93 3,115,092 12/1963 Sasaki 101 93 3,164,084 1/1965- Paige 2 -101 93 ROBERT E. PULFREY, Primary Examiner.

E S. BURR, Assistant Examiner.

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 3,408,930 November 5, 1968 Leland D. Chamness et a1.

It is certified that error appears in the above identified patent and that said Letters Patent are hereby corrected as shown below:

Column 1, line 58, "dark-type" should read desk-type Column 2, line 21, after "riage" insert ,and is rotated in synchronism with the movement of the carriage line 44, FGI." should read FIG. Column 3, line 6, after "adjacent" insert to line 24, "betweent he" should read between the line 58, "successfully" should read successively Signed and sealed this 17th day of March 1970.

SEAL) IteSlZ iward M. Fletcher, Jr. E.

ttesting Officer Commissioner of Patents

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