US3752069A

US3752069A - Back printer print line visibility control

Info

Publication number: US3752069A
Application number: US00158839A
Authority: US
Inventors: D Stiles
Original assignee: International Business Machines Corp
Current assignee: International Business Machines Corp
Priority date: 1971-07-01
Filing date: 1971-07-01
Publication date: 1973-08-14
Anticipated expiration: 1990-08-14
Also published as: DE2224951A1; CA951573A; GB1327358A; IT955532B; DE2224951C3; DE2224951B2; FR2144440A5; JPS5217767B1

Abstract

In a back printer print hammers impact the document against type characters formed on upwardly projecting fingers of a steel band. The fingers are backed by a platen which is removable from the print position to permit inspection of the printed information through spaces between the fingers as the band moves along the print line.

Description

United States Patent 1191 Stiles "Aug. 14, 1973 BACK PRINTER PRINT LINE VISIBILITY 3,241,480 3/1966 Cunningham 101/93 c CONTROL 3 3,416,442 12/1968 Brown 61111 mm c 3,451,335 6/1969 Cunningham.... l0l/93 C [75] Inventor: Donal J- St les, d e NY 3,467,234 9/1'969 Potter 101/93 c 3,552,309 1,7197! Stantchev l0l/96 [73] Assgnee' memthm] Business Mums 3,576,164 ,4/1971 Drejza 101/93 c Ammk, 3,583,315 6/1971 Hebert 101/96 [22] Filed: July 1, 1971 21 A L N 158 839 Primary Examiner--Willia1n B. Penn 1 pp 0 Attorney-Francis V. Giolma et al.

[52] US. Cl. 101/93 C, lOI/lll 51 Int. Cl 841,] 1/20, 1341; 9/02 ABSTRACT of Search C, R, In a printer p i hammers impact the document 197/114 6 against type characters formed on upwardly projecting fingers of a steel band. The fingers are backed by a [56] References Cited platen which is removable from the print position to UN TED S S PATENTS permit inspection of the printed information through 2,800,854 7/1957 Werner et a1. 101/93 R spaces between the fingers as the band moves along the 2,936,704 5/1960 Hense l0l/93 C print line. 2,976,800 3/l96l Gross et al. l0l/93 R 3,224,366 12 1965 Cunningham 101/93 c 10 Claims, 5 Drawing Figures BACK PRINTER PRINT LINE VISIBILITY CONTROL FIELD OF THE INVENTION DESCRIPTION OF THE DRAWING In the drawing: FIG. 1 is a partial schematic plan view of a printer The invention relates generally to printers and it has mechanism embodying the invention in one of its reference in particular to back printers and a movable platen therefor.

DESCRIPTION OF THE PRIOR ART Movable platens have been used heretofore with print wheels which are first set, whereupon the platen is moved to impact the document against the print wheels for printing, as in U. 8. Pat. No. 3,540,373, which issued Nov. 17, l970, to Paul Dubs et al.

SUMMARY OF THE INVENTION Generally stated, it is an object of the invention to provide better visibility of the printed information in a back printer.

More specifically, it is an object of the invention to provide for using a type carrying element having type characters on spaced apartfingers which are backed up by a platen during printing, with the platen being removable from the print line to permit viewing the printed information through the spaces between the fingers as they move along the print line.

Another object of the invention is to provide for pivotally mounting a platen behind a type chain having spaced apart type carrying fingers so that the platen may be pivoted out of its operating position behind the fingers to permit viewing typed information through the spaces between the fingers as they move along the print line.

Yet another object of the invention is to provide for so controlling the operation of a movable platen used with a flexible type carrying band that it may be removed from its operating position behind a plurality of spaced apart type fingers carried by the band and moving along the print line, when the operator interrupts keying of information, so as to permit the operator to view what has been printed.

It is also an object of the invention to provide for utilizing the natural persistence of vision of the human eye to view typed characters on a document through the spaces between successive type carrying fingers as they pass along the print line.

Yet another important object of the invention is to provide for operating a movable platen in a back printer so as to position the platen behind a flexible metal type finger character bearing type element during printing when a print hammer impacts a document against the type finger, and removes it from behind the type finger after printing, so that the printed character can be seen.

It is also an important object to provide for removing a platen from an operating position behind a type finger character bearing element after a key has been operated to cause a character to be printed, and to restore the platen to its operating position when another key is operated to print another character.

The foregoing and other objects, features and advantages of the invention will be apparent from the following more particular description of a preferred embodiment of the invention, as illustrated in the accompanying drawing.

forms;

FIG. 2 is a partial schematic side elevational view of the printer mechanism of FIG. 1;

FIG. 3 is an enlarged partial front elevational view of the flexible type carrier of FIGS. 1 and 2;

FIG. 4 is a sectional view of the type carrier of FIG. 3 along the line 4--4; and

FIGS is a schematic circuit diagram showing a control circuit for the printer platen mechanism of FIGS. 1 and 2.

DESCRIPTION OF A PREFERRED EMBODIMENT FIGS. 1 and 2 show a printer apparatus of one type with which the present invention may be used. As shown, the printer apparatus comprises generally a flexible Type Carrier 10 having a straight line path between Impact Means 11 and a Platen 12 for moving a plurality of type characters along a print line of a Document 14 for performing a printing operation thereon.

The Impact Means 11 may, as shown in FIGS. 1 and 2, comprise a plurality of Print Hammers 16, which are arranged in side-by-side relation along the print line on the side of the Document 14 away from the Type Carrier 10. The Print Hammers 16 are pivotally mounted on a Shaft 18 and have an Armature Portion l9 positioned in operating relation with a stationary Magnetic Core Member 20. The Magnetic Core Member 20 has an Operating Winding 22 thereon, which may be energized for actuating the Armature 19 to impact the Print Hammer 16 against the Document 14.

The Type Carrier 10 may comprise a flexible Band 24 of metal such as stainless steel or the like having a plurality of spaced apart upstanding Fingers 26, as shown in FIGS. 3 and 4. The Fingers 26 carry raised Type Characters 28, and raised Projections 32 of magnetic material may be spaced apart along the body of the Band 24 and used in conjunction with a magnetic Transducer 33 to produce emitter signals for keeping track of the locations of the different type characters on the Type Carrier 10, so as to compare the characters on the Carrier 10 with characters to be printed either from data input from a keyboard or the like or from a computer processing unit for effecting timed operation of the Print Hammers 16 in relation to passage of the Type Characters 28 past print positions along the print line of the Document 14 in a well-known manner such as shown in the F. M. Demer et al. U.S. Pat. No. 2,993,437 which issued on July 25, 1961 or the E. M. Bloom, Jr., et al. U.S. Pat. No. 3,349,695 which issued on Oct. 31, I967. The Fingers 26 are spacedapart so as to provide Spaces 29 therebetween. The flexible Band 24 may extend between a pair of spaced apart wheels represented by the Wheel 34, which is rotatably The platen may comprise a T-shaped member having a flat Bar Portion 40 forming the head of the T extending along the print line in spaced relation with the Print Hammers 16. The Leg 42 of the Platen 12 extends away from the print line and is provided with a Pivot Shaft 44 for pivotally supporting the Platen on spaced apart supports represented by the Support 46, which is secured by means of Screws 47, to a Base 50. An Adjustable Stop 52 having a layer of Elastic Material 53 to cushion the movement of the Platen 12 is threadably secured in the Base 50 to provide an adjustable stop for positioning the Platen 12. A Spring 54 secured by means of a Screw 55 to the end of the Leg 42 and attached to the Base 50 biases the Platen to its operating position.

As shown in FIG. 2, the Platen 12 shown in solid outline in the printing position interferes with a line of sight designated by the dot-dash line 58 in the direction of the arrow thereon along which an operator would otherwise be able to view characters printed on the Document 14 on the left side or the side facing the operator through the Spaces 29 as the Band 24 moves along the print line during printing. By pivotally supporting the Platen 12 on a Pivot Shaft 44 and utilizing operating means such as a Solenoid or the like, as shown in FIG. 5, for actuating a Pull Rod 56 attached to the Platen 12 by means of a Pivot Shaft 57, the Platen 12 may be removed from the line of sight. The Platen may, for example, be rotated in a clockwise direction about the Pivot Shaft 44 to the dotted position 12 shown, in which it is clear of the line of sight 58, so that an operator may view characters printed on the Document 14 through the Spaces 29 between the upstanding Fingers 26 of the Type Carrier as it moves along the print line. Because of the persistence of vision phenomena the entire print line may be viewed as the Type Characters 26 pass therealong, even though the printed type characters themselves are at times obscured by the passing Fingers 26, so that an operator who is printing data by operating a keyboard may readily see what he has printed.

Referring to FIG. 5, the reference numeral 60 represents a Solenoid connected to operate the Pull Rod 56 for removing the Platen 12 from the line of sight 58. A Platen Drive Latch 62 is connected to effect energization of the Solenoid 60. Operation of the Latch 62 is effected by connecting the set terminal s of the Latch 62 to a source of electrical energy through each of the keys on the keyboard represented by the single Key 64. This connection is effected through a Single Shot 66 and an Inverter 68 with the Single Shot having a 1.2 second pulse so as to provide a 1.2 second delay for setting the Latch 62 after the Key 64-is depressed to type a character. The Key 64 is also connected to the Reset Terminal R of the Latch 62 for resetting the Latch when a Key 64 is depressed. The On output of the Latch 62 is connected to set a Print Control Latch 70 to provide a Print Inhibit signal at the On terminal N. The Off terminal 0 of the Latch 70 is connected to provide a Print signal to a Printer Control and Hammer Select Circuit 72, which controls the energization of the Operating Winding 22 of a selected Print Hammer 16 in a manner similar to that described in the Demer et al., and Bloom, Jr. et al. patents in accordance with ei- 6 for keeping track of and comparing characters on the Type Carrier 10 with Input Data or Keyboard Data as described in the referenced patents for effecting operation of seiect Print Hammers 16 by effecting energization of their associated Operating windings 22. The Latch is reset by the Off output of the Latch 62 through a Single Shot 74 and Inverter 75. The Single Shot 74 has a pulse duration signal on the order of 20 milliseconds so as to allow the platen to settle in the operating position before the Print Hammer is operated. The 1.2 second delay time of the Single Shot 66 and Inverter 68 provides for maintaining the Platen 12 in the operating position so long as the operator continues to key at a more or less normal rate on the order of 3 to 5 characters per second. Should the time between operating successive keys exceed the 1.2 second delay time, this indicates that the operator is hesitating and wants to see what he is printing so permits the Platen to be pulled down.

With the equipment in a rest position and the keys represented by the Key 64 in the non-operated position, the output of the Inverter 68 will be up and the Latch 62 will be set so that the Solenoid 60 is energized to operate the Pull Rod 56 and pull the Platen 12 down to clear the sight line. When the Key 64 is operated, the Single Shot 66 will be energized to provide a timed output pulse. The Inverter 68 output does not rise until the fall of the output signal of the Signal Shot 66. When the Key 64 is depressed, the reset input R of the Latch 62 is energized directly and the Latch 62 is reset, turning off the On output and de-energizing the Solenoid 60 so that the Platen 12 is restored to the operating position by the Restore Spring 54. The Off output of the Latch 62 is connected to reset the Latch 70 through the Single Shot 74 and the Inverter 75. Since the Single Shot has a pulse duration on the order of 20 milliseconds, the Latch 70 will be reset after a 20 millisecond delay, thus removing the print inhibit signal at the On output and producing the print signal at the Off output to effect operation of a print hammer by energizing its Operating Winding 22 through the Printer Control & Hammer Select Circuit 72.

From the above description and the accompanying drawing it will be seen that there is provided a simple and effective control for the platen of a back printer, which enables the operator to see what he is printing. By using a relatively long delay in operating the platen solenoid, continuous entry of data may be made by successively depressing different Keys 64 to key different characters without causing the Platen 12 to depress. However, should the operator desire to view what he has printed, he merely delays pressing the next Key 64 for a sufficient length of time and the Platen 12 will be depressed so that he can see what he has printed through the spaces between the type characters even though the Type Carrier 10 continues to move the Fingers 26 along the print line.

While the invention has been particularly shown and described with reference to a preferred embodiment thereof, it will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the invention.

What is claimed is:

1. Ina printer,

a type carrier comprising an endless band mounted on spaced apart pulleys and having type characters on upwardly projecting fingers which have spaces therebetween and are movable along a print line on one side of a document on which a printing operation is to be performed,

means for rotating one of said pulleys to move said carrier along said print line,

print hammer means on the other side of said document selectively operable to impact said document against said type characters for printing characters thereon, and

a movable platen positioned on the other side of said type carrier from said document and extending along the print line to provide a backing for said fingers, said platen being normally aligned in an operating position behind said characters on said fingers and blocking said spaces between said fingers, and having operating means for moving said platen away from said print line and out of blocking relation with with said spaces so that characters printed on said document can be observed through the spaces between said fingers.

2. The invention as defined in claim 1 characterized by said type carrier comprising a flexible endless metal band.

3. The invention as defined in claim 2 characterized by the type characters being spaced apart with at least one character space between.-

4. The invention as defined in claim 3 characterized by said movable platen being pivotally supported by a substantially horizontal pivot shaft adjacent the side away from said fingers.

5. The invention as defined in claim 1 characterized by stop means positioned to engage said platen in the operating position and spring means normally biasing said platen against said stop means.

6. The invention as defined in claim 5 characterized by said operating means comprising solenoid means having an armature connected to said platen operable to retract it from its operating position against the force of said spring means.

7. The invention as defined in claim 6 characterized by one or more operating keys so connected as to be operable to selectively energize different ones of said hammer means for printing, and circuit means including switch means connected in circuit with said solenoid means actuated by said operating keys to effect energization of said solenoid means between printing operations.

8. The invention as defined in claim 7 characterized by said circuit means including delay means controlled by said operating keys connected in circuit relation with said switch means to delay energization of said solenoid means for a predetermined interval after a printing operation.

9. The invention as defined in claim 8 characterized by said delay means including a resettable single shot and an inventor so connected in circuit relation with said operating keys and said switch means that repeated operations of said operating keys continue to' extend said predetermined interval from the last operating key operation.

10. The invention as defined in claim 8 characterized by said circuit means including a first latch so connected as to be reset by said operating key and set by said delay means, and a second latch so connected to said first latch as to be set when said first latch is set and so connected by delay means as to be reset a predetermined time after said first latch is set to effect energization of said print hammer means.

Claims

1. In a printer, a type carrier comprising an endless band mounted on spaced apart pulleys and having type characters on upwardly projecting fingers which have spaces therebetween and are movable along a print line on one side of a document on which a printing operation is to be performed, means for rotating one of said pulleys to move said carrier along said print line, print hammer means on the other side of said document selectively operable to impact said document against said type characters for printing characters thereon, and a movable platen positioned on the other side of said type carrier from said document and extending along the print line to provide a backing for said fingers, said platen being normally aligned in an operating position behind said characters on said fingers and blocking said spaces between said fingers, and having operating means for moving said platen away from said print line and out of blocking relation with with said spaces so that characters printed on said document can be observed through the spaces between said fingers.

3. The invention as defined in claim 2 characterized by the type characters being spaced apart with at least one character space between.

9. The invention as defined in claim 8 characterized by said delay means including a resettable single shot and an inventor so connected in circuit relation with said operating keys and said switch means that repeated operations of said operating keys continue to extend said predetermined interval from the last operating key operation.