US3719139A - High-speed printer with selectively operable print hammer - Google Patents

Abstract

A high-speed printer wherein the type-carrying member is provided with staggered rows of projections on the reverse side of each type character, and wherein a plurality of hammers operating at a print position selectively cooperate with the projections of a respective row.

Description

[ 1 March 6, 1973 United States Patent 11 1 Niccolai HIGH-SPEED PRINTER WITH 3,128,693 4/1964 Thiemann...........................

SELECTIVELY OPERABLE PRINT I? gy s--- en urg et a HAMMER 3,220,343 I I/1965 Wasserman..... [75] Inventor: Adrlano Nlccolai, Cornaredo 3,331,316 7 7 BrettimWMm (Milan), 1ta1y 3,371,766 3/1968 Sta11er............ 3,490,366 1/1970 Benson et a1. [73] Assignee: Honeywell lnformatmn Systems 3,542,182 11/1970 Lagenbergerm -p- Turm, Italy 3,575,107 4/1971 McDowell July 14, 1970 Primary Examiner-William B. Penn 22 Filed:

211 App]. 190.; 54,814

AttorneyGeorge V. Eltgroth, Lewis P. Elbinger, Frank L. Neuhauser, Oscar B. Waddell and Joseph B. Forman Foreign Application Priority Data July 7, 1969 ltaly.............,.............l9699A/69 T C A R T S B A 7 5 4 11 MW mu. I4 w 0 we 91 .1 Lu C4 3 9 4 0 1m C Sh um 11 21 55 A high-speed printer wherein the type-carrying [58] Field of Search member is provided with staggered rows of projections on the reverse side of each type character, and wherein a plurality of hammers operating at a print References Cited UNITED STATES PATENTS 5/1960 l-lense..... 12/ 196 l position selectively cooperate with the projections of a respective row.

...l0l/93 C Amada C 4 Claims, 6 Drawing Figures PATENTEUMR 6 3,719,139

' SHEET 10F 3 Adriano N/CCOLAI I X VE NTOR.

PATENTED 5 I975 SHEET 3 or 3 Adriana N CCOLAI IN"[ 10R HIGH-SPEED PRINTER WITH SELECTIVELY OPERABLE PRINT HAMMER BACKGROUND OF THE INVENTION The present invention relates to highspeed impact printers used in data processing systems, and more particularly to printers of this type which are known as platen printers; i.e., printers which print by means of the impact of one or more printing members, or hammers, against a fixed printing surface, or platen.

In such printers, a type-carrying member consisting, for example, of a plurality of flexible type-carrying elements supported from a belt, is interposed between hammer platen and is driven so that all of the characters forming the set of characters carried by the typecarrying member are positioned in sequence in front of each print position.

One of the most serious problems encountered in these printers is that of interference between print hammer and type-carrying member, which may result in jamming and breaking of the interfering members. This danger is lessened if the type-carrying elements are suitably spaced apart along the direction of motion, although such arrangement causes a substantial reduction in the printing speed inasmuch as the velocity at which the type-carrying member can be driven is limited. I

Another partial solution to the problem, often employed, is that of suitably beveling the comers of the print hammer and the type-carrying elements to reduce the width of the striking surface in the direction of motion of the type-carrying elements.

Moreover, in some synchronous printers, the print hammer must have a width sufficient to span two adjacent print positions, so that an even greater spacing of the type-carrying elements is required to prevent two characters being printed at a time in a single printing operation. Therefore the printing speed of this latter printing device is even further limited.

Therefore, it is the object of this invention to provide an improved printer which eliminates or greatly reduces some or all of the above-mentioned limitations.

SUMMARY OF THE INVENTION According to the present invention, printing is provided by means of a type-carrying member on which, at a single print position, at least two print hammers act alternatively or selectively according to the character to be printed.

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

FIG. 1 is a perspective view of a printer which employs the printing apparatus of the invention;

FIG. 2 is a cross-sectional view taken along a plane perpendicular to the printing plane of a prior art printer;

FIG. 3 is a cross-sectional view taken along a plane perpendicular to the printing plane of an embodiment of the invention;

FIG. 4 is a cross-sectional view taken along a plane perpendicular to the printing plane of another embodiment of the invention;

FIG. 5 is a perspective view of a serial synchronous printer employing the printing apparatus of the invention; and

FIG. 6 is a perspective view of an alternative printing apparatus according to the invention.

DESCRIPTION OF THE PREFERRED EMBODIMENT The printer of FIG. 1 is a parallel belt printer, of the platen type, employing the printing apparatus of the invention. However, the remarks made hereinafter relative to the invention are applicable to other printer types, such as serial or parallel printers, chain, bar or ribbon printers, synchronous or asynchronous printers, and printers provided with a printing head either stationary or moving along the print line. Only the elements of the printer needed for an understanding of the invention are shown, inasmuch as the basic structure of these printers are well-known to those skilled in the art.

The type-carrying member is formed by an endless flexible belt 1 provided with a set of elastic blades 2. Each one of blades 2 carries at its free end a graphic type character in relief, such as alphabetic letter, a numerical figure, or the like. The type-carrying member may be made of a flexible steel strap. It is provided with a set of holes 3 which are engaged by the teeth "of a driving wheel 4. Wheel 4 is rotated by a motor means The type-carrying member is positioned for a suitable length thereof a short distance away from a platen 6 against which a print-receiving member 7 is resting. By virtue of the rotation of driving wheel 4, the characters located at the ends of blades 2 move in proximity to print-receiving member 7 along a hypothetical line, which will hereinafter be termed the print line. Along this print line, and interposed between type-carrying blades 2 print-receiving member 7, is an inking ribbon 8, which for simplicity, is represented as a typewriter ribbon. Practically, however, inking ribbons having a width equal to the entire length of the print line, and which move in a direction perpendicular to the length of the print line, are usually employed in parallel printers.

The print line is divided into hypothetical print positions, each such print position having a width equal to thedistance between adjacent printed characters; i.e., usually one-tenth inch (2.54 mm.). Each print position is provided with a pair of print hammers 9 and 10, which face the print position and are arranged in two rows in two respective levels.

Type-carrying blades 2 move between the heads of print hammers 9 and 10 and inking ribbon 8. Blades 2 are provided, on their reverse sides, with projections 2a of suitable thickness, alternately arranged on two different levels. In FIG. 1 only four hammers, correspond ing to two adjacent print positions,are shown. By a technique well-known in the art, in order to permit the positioning of these hammers very close together, two of the four hammers are straight, and the other two are bent at right angles, thus permitting the alternate staggering of the electromagnets which actuate the hammers.

In the parallel printer, an entire bank of such hammers is mounted along the length of the print line, whereas in a serial printer only two hammers, such as hammers 9 and 10, are required. In the latter instance the hammers are mounted on a carriage movable along the print line, and apparatus is provided for shifting the hammers and the carriage along the print line through the various print positions. Composite techniques are adopted for serial-parallel printers.

The two rows of print hammers cooperate respectively with the two rows of projections 2a on the rear of the type-carrying blades. For each print position each hammer of the first row is adapted to print with half the set of characters located on alternate blades, and each hammer of the second row is adopted to print with the remaining half of the characters. As the electronic character identification equipment provided for these printers, well known to those skilled in the art, delivers information expressed in a binary code, the selective identification of the corresponding hammer to be energized to print a predetermined character in a predetermined print position requires only the testing of one digit in the binary code. For example, a widely used arrangement consists of using a generator of timing pulses, which delivers a pulse each time a character of the set is passing a print position. These pulses are applied to a counter, which responds to yield a sequence of binary signals, each representing a serial number or a character code. This number, or code, is even or odd according to the value of its least significant bit. The value of this bit may therefore control whether a hammer of the first or the second row is actuated.

Accordingly, the problem of possible interference between print hammers and type-carrying blades is solved, as explained in detail in FIGS. 2 and 3.

In the prior art printer of FIG. 2 is shown a print hammer 11 and a number of adjacent type-carrying blades 12, 13, 14, 15. For purposes of explanation, the set of type-carrying blades disposed along the print line will now be assumed to be a fixed reference system, and print-receiving member 16, inking ribbon 17 and platen 18, as well as print hammer 11, will be assumed to be moving in the sense of arrows I and II relative to the reference system; however, in reality, it is the typecarrying blades which are moving. This assumption permits of a better clarification of the interference action, by providing for a vector composition of the as sumed lateral displacement of the hammer and its real transverse motion when the hammer is driven against a type-carrying blade in the direction indicated by arrow III.

The dashed lines 19 and 20 represent the envelope of all regions occupied by the hammer cross-section during its forward and backward motion. From this envelope it is apparent that the left edge of blade 14 interferes with hammer 11, as does the right edge of blade 12. To obviate such problem, the prior art would provide for a greater distance between adjacent blades.

However, according to the instant invention, this greater spacing between type-carrying blades is not necessary, as is shown in FIG. 3, because the possibility of interference is eliminated by using blades provided with different projections on alternate rows. Thus, the printer of the instant invention comprises a set of typecarrying blades 21, 22, 23, 24, 25 and a print hammer 26. Blades 21, 23, 25 have upper projections 21a, 23a and 25a, through which the figure is sectioned, and blades 22 and 24 have lower projections 27 and 28.

When hammer 26 is driven against one of the blades with upper projections, for example blade 23, to effectuate the printing operation, no interference is possible with the adjacent blades because of the ample safety margin provided, inasmuch as such adjacent blades have no upper projection. When a character carried by a blade with a lower projection, such as blades 22 and 24 which are interposed between blades 21, 23, and 25, a second print hammer, located at a lower level (FIG. 1) is actuated. This second hammer acts on the lower row of projections provided on blades 22 and 24, shown by the solid lines 27 and 28.

It is evident that if a greater margin of safety against the danger of interference is desired, it is possible to use, in place of pairs of hammers and two rows of staggered projections, a greater number of hammers, for a print position for example three hammers, and a corresponding number of rows of staggered projections on the type-carrying blades.

The principle of the invention also offers a substantial advantage in the case of serial, and possibly parallel-serial, printers. In many printers of this type, the print hammer is moved along the print line at a uniform velocity, occupying the correct successive print positions only at predetermined moments. The printing usually occurs on-the-fly; i.e., at the time when the character to be printed is brought into the correct print position by virtue of the motion of the type-carrying member. However, this time usually does not coincide with the moment at which also the print hammer is in the correct print position; instead, the hammer may be offset to the right or left of the correct position. This offset distance in extreme conditions, may be equal to an entire pitch of a print position.

In these circumstances, printers use a print hammer having a width equal to the width of two print positions. Accordingly, the print characters and their related type-carrying members in prior art printers are correspondently spaced to avoid the printing of two adjacent characters at the same time. However, according to the instant invention as shown in FIG. 4, more closely spaced adjacent characters, are provided even though the width of the print hammer 52 is nearly equal to the width of two print positions. As illustrated in FIG. 4, this is accomplished by the use of a plurality of rows of staggered projections on the reverse sides of the type-carrying members. Accordingly, with the same velocity of the type-carrying member, relative to the print-receiving member, and with an equal number of characters, the printing speed is substantially doubled.

The preceding description and figures refer to a printer in which the type-carrying member is formed of a set of flexible blades carried by, or forming a part of a flexible belt. However, the instant invention is also applicable to printers having for type-carrying members a bar, a ribbon, or a chain, or even a star-shaped or a cup-shaped member. In particular, FIG. 5 shows the pertinent features of a platen-type serial synchronous printer, in which the type characters are distributed on a type-carrying star-shaped member, similar to the printer illustrated in copending U.S. Pat. application Ser. No. 50,659 filed June 29, 1970 in the name of Sergio Cattaneo and assigned to the assignee of the present invention. This star-shaped member is maintainedin rotation by a motor means M through a gear pair 31, a

rotating bar and a bevel gear 29. A 'worm screw 32, having a pitch equal to the print pitch, i.e., to the spacing between two adjacent print positions, is also maintained in rotation motor means M.

A drive nut 33 is engaged by worm screw 32 and forms a part of a carriage 34, on which bevel gear 29 and the type-carrying star-shaped member are mounted. Thus, for each turn of screw 32, carriage 34 advances by a print pitch, and, since bevel gear 29 has a l 1 ratio, the type-carrying star makes a complete revolution.

The printer is operated during the continuing motion of carriage 34, when the characters to be printed in sequence are in the correct print position. Electronic identification and timing apparatus, not shown, provide for actuating print hammers 36 and 37 individually and at the proper time.

The width of hammers 36 and 37 nearly spans two adjacent print positions, so that the desired character is printed in the correct position regardless of the position reached by the carriage between the correct print position and the next print position one. To provide for maintaining a close spacing between adjacent type characters, the reverse side of each type-carrying blade is provided with a projection of suitable thickness, such projections being alternately arranged in two different rows to cooperate, respectively with one or the other of hammers 36 and 37.

A variation of the invention, provides a printing device having a single hammer. The striking head of this single hammer, in addition to being moved in the printing direction, is movable so as to selectively strike one of the rows of projections of the type-carrying member. FIG. 6 illustrates such an embodiment.

The print hammer 38 is joumalled to an arm 39, which in turn is joumalled to a support. Under the combined action of an electromagnet 40 and a return spring 41, arm 39 selectively assumes one of two stable positions. Depending on the position of arm 39 the print hammer may be actuated to strike either the first or the second row of projections.

lclaim:

1. A high-speed printer of the platen type comprising a plurality of type characters, a type carrying member disposed adjacent the printer platen and having said type characters mounted thereon, said type carrying member being movable to present each type character in sequence in front of a print position on the platen, each of said type characters being provided with a single projection on its reverse side, said projections of all the type characters being distributed sequentially and repetitively over a plurality of projection rows and alternately arranged on different levels, a printing carriage movable along subsequent print positions, said carriage having a plurality of print hammers mounted thereon to provide at least one print hammer adjacent each of said projection rows, each of said hammers having a width substantially greater than the span of a single print position and no greater than the span of two adjacent print positions, each of said hammers being so disposed as to cooperate upon actuation thereof with a respective projection of a projection row to selectively strike the projection corresponding to a type character to fili g-inc: of claim 1 wherein each of said projections is disposed in two rows and wherein said plurality of print hammers comprises two print hammers, one disposed above the other in alignment transverse to said projection rows.

3. The printer of claim 1 wherein each of said hammers is of a width sufficient to span substantially two print positions.

4. The printer of claim 1 wherein each of said projections is disposed in two rows and wherein each of said hammers is of a width sufficient to span substantially two print positions, said plurality of print hammers comprising two print hammers one disposed above the other in alignment transverse to said projection rows.

Claims (4)

1. A high-speed printer of the platen type comprising a plurality of type characters, a type carrying member disposed adjacent the printer platen and having said type characters mounted thereon, said type carrying member being movable to present each type character in sequence in front of a print position on the platen, each of said type characters being provided with a single projection on its reverse side, said projections of all the type characters being distributed sequentially and repetitively over a plurality of projection rows and alternately arranged on different levels, a printing carriage movable along subsequent print positions, said carriage having a plurality of print hammers mounted thereon to provide at least one print hammer adjacent each of said projection rows, each of said hammers having a width substantially greater than the span of a single print position and no greater than the span of two adjacent print positions, each of said hammers being so disposed as to cooperate upon actuation thereof with a respective projection of a projection row to selectively strike the projection corresponding to a type character to be printed.

1. A high-speed printer of the platen type comprising a plurality of type characters, a type carrying member disposed adjacent the printer platen and having said type characters mounted thereon, said type carrying member being movable to present each type character in sequence in front of a print position on the platen, each of said type characters being provided with a single projection on its reverse side, said projections of all the type characters being distributed sequentially and repetitively over a plurality of projection rows and alternately arranged on different levels, a printing carriage movable along subsequent print positions, said carriage having a plurality of print hammers mounted thereon to provide at least one print hammer adjacent each of said projection rows, each of said hammers having a width substantially greater than the span of a single print position and no greater than the span of two adjacent print positions, each of said hammers being so disposed as to cooperate upon actuation thereof with a respective projection of a projection row to selectively strike the projection corresponding to a type character to be printed.

2. The printer of claim 1 wherein each of said projections is disposed in two rows and wherein said plurality of print hammers comprises two print hammers, one disposed above the other in alignment transverse to said projection rows.

3. The printer of claim 1 wherein each of said hammers is of a width sufficient to span substantially two print positions.

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