High Speed Print Drum With Traveling Print Hammer

Abstract

A high speed serial printing device which employs a rotatable type drum having a plurality of adjacent c1rcumferential columns each containing a row of type characters extending over a sector of its associated column, the rows of characters of the odd and even numbered columns of the drum being alternately staggered and aligned in different sectors of the drum. A single hammer is moved in a direction parallel to the axis of the drum at such a substantially constant velocity as to cover two adjacent circumferential columns of the drum and the rows of type characters contained therein during each revolution of the drum.

Description

BACKGROUND OF THE INVENTION

This invention is directed to that field of art pertaining to high speed printing apparatus having a type bearing drum which is continuously rotated in an axially fixed position and with which is associated a single print hammer movable axially of the drum in close proximity to the periphery thereof. More particularly, the invention is directed to the layout of the type characters on the drum and the relative speed of the continuous movement of the print hammer across the columns of the characters on the moving periphery of the drum to effect a desired multiple printing of characters during each revolution of the drum.

One known high speed printer of this general character located all of the type characters in a given sector of the drum occupying approximately half the circumference thereof and provided continuous lateral movement of the printer hammer so as to cover one horizontal printing spacing during each revolution of the drum. In another form of such printer, the print characters were arranged in alternately staggered groups located individually in alternate columns of the drum's periphery with the result that there was provided between each pair of adjacent character bearing columns an interposing column devoid of type characters. A consequent result of this drum layout was the printing of characters in a nonconventional widely spaced apart relationship to one another. In a third form of related printer the group of characters were individually located in offset relation to one another in adjacent columns of the drum's periphery but employed one or more fixedly positioned print hammers each having a head dimension sufficient to span at least two columns of the drum.

SUMMARY OF THE INVENTION

Certain distinctive advantages result from the present invention. By virtue of a particular layout of the type characters on the drum and a particular relationship of the velocity of the print hammer to the drum's periphery speed, it is possible to increase the printer speed by enabling the print hammer to print two characters during each revolution of the drum. This is accomplished by dividing the type drum into four angular portions or sectors, two of which contain circumferential rows of characters and the remaining two of which are devoid of type characters and are interposed between the first two sectors. Moreover, the groups of type characters are alternately staggered with respect to one another so that the groups in the odd numbered columns of the drum are in one type containing sector thereof and the groups of characters in the even numbered columns of the drum are in the other type containing sector thereof. In coacting with this drum layout, the single print impacting member is caused to travel across the columns of the drum at constant relatively high velocity and so as to cover two adjacent annular columns of the drum during each revolution thereof with a result that the print impacting member is capable of printing two characters during each revolution of the drum. The drum sectors of this invention which are devoid of type characters are utilized for providing return of the print impacting member preparatory to performing another printing operation.

The above listed objects, advantages and other meritorious aspects of the invention will be fully explained in the following detailed description. For a more complete understanding of the invention reference may be had to the following detailed description in conjunction with the drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of a high speed printer embodying the invention and partly broken away to expose the drum's periphery; and

FIG. 2 is a surface development of the periphery of the drum illustrated in FIG. 1 and showing the layout of the type characters thereon and the helicoidal band-path of the printing impacting member with reference to the rotating drum and the character groups thereon as the impacting member is continuously moved across the circumferential columns of the rotating drum.

DESCRIPTION OF A PREFERRED EMBODIMENT OF THE INVENTION

With reference to FIG. 1, a high speed printer constructed in accordance with this invention includes a type drum 10 secured to a shaft 12 which is continuously rotated on a frame such as that generally indicated at 14 by means of a driving belt 16 extending to a power source which may be an electric motor (not shown). A print receiving medium, such as a paper strip or web 18, is fed to the device and partially around the print drum 10.

A sidewise movable carriage generally indicated at 20 is disposed adjacent to the drum's periphery and carries operating elements cooperating with the type characters on the drum for making a visible impression of the characters on the record medium 18. The general organization of the carriage and the operation of its parts is chosen for purpose of example to be like that described in U. S. Pat. No. 3,472,352 of common ownership herewith. Accordingly, the print impression means carried by the carriage includes an elongated body or interposer 22 mounted in the carriage axial for translational movement on spring wire elements 24 projecting from opposite sides of the body. The end of the interposer adjacent to the drum is reduced cross sectionally to form an extension 26 serving as a print impact member or head. Pivotally mounted on the outer portion of the carriage is a hammer 28 for applying a striking force on the interposer 22 to drive the same toward the drum in the manner described in the aforementioned patent. This action will cause the extension 26 to impact against an inking ribbon 30 and drive the latter and the recording medium 18 against a selected character of the rotating type drum, the ribbon and medium extending between the striker head 26 of the interposer and the drum for this purpose. As also disclosed in the aforesaid patent, the hammer 28 is operated in one direction by energization of a solenoid 52 carried 20 by the carriage and driven in the opposite direction by a spring means (not shown). The inking ribbon 30 may be mounted on a pair of spools 32--32 which in turn are supported by the carriage 20.

During a printing operation, the carriage 20 is bodily moved parallel to the axis of the drum and at a substantially constant speed. As disclosed in the aforesaid patent this is preferably accomplished by mounting the carraige for sliding movement on guide rods 33--33 and coupling the driving provisions of the carriage and drum by gearing which synchronizes the linear speed of travel of the carriage with the motion of the drum. The motion imparted to the carriage likewise conveys the single print impression member 26 and associated operating mechanism at the same speed relative to the drum. As will be later brought out hereinafter, the conjoint motion of the carriage and the print member 26 parallel to the drum's axis is related in a particular way with the peripheral speed of the drum and the array of type characters thereon to gain a certain printing advantage.

The hammer 28 is pivotally mounted on a post 35 of the carriage 20 and is biased to a retracted position by a spring (not shown) against a stop which may be adjustable as shown in the aforementioned patent to Kondur. Also mounted on a lateral extension 37 of the carriage 20 is the solenoid 31, the armature of which is attached to the end of the hammer 28 remote from the interposer 22 and which, when the solenoid is energized, will work the hammer in the direction to propel the impact head of the interposer against a selected type character on the drum. The carriage 20 is yieldingly biased by a tensioned coiled spring 39 for return movement on the guide rods 33--33 to a home position which would dispose the print impacting member 28 rightwardly of the first column of printing type on the drum 10 as described in the aforementioned patent.

For providing translational movement of the carriage 20 away from its home position and parallel to the print line of the drum 10, there is provided a continuously driven feed means in the form of an endless, internally toothed belt 41 and a cooperable toothed clutch device 43 carried by the carriage 20 which is normally biased to a disengaged position. The belt 41 is trained about pulleys 45 and 47, the former of which is affixed to a driven shaft 49 which is coupled as shown by a worm gear connection 51 to the continuously rotating print drum shaft 12. The gear ratio is such as to synchronize the rotation of the print drum with the linear speed of travel of the hammer carriage 20 such that for each revolution of the drum the hammer will move a distance so as to cover two adjacent annular columns of the drum, each containing type characters therein, for each revolution of the drum.

To operate the clutch device 43, a solenoid 53 is carried by the carriage for moving the clutch engaging member of the device downwardly into engagement with the teeth of the endless driving belt 41. When this occurs, the carriage will be brought into coupling engagement with the belt and thus be moved by the belt axially of the drum and against the yielding resistance of the return spring 39. Upon reaching the end of the line of print, a control device (not shown) is triggered, whereupon the clutch solenoid is de-energized and allows the spring 39 to return the carriage to home position and ready to be initiated for another line of printing.

The peripheral surface of the drum 10 carries a multiplicity of raised type characters 34 which in the disclosed embodiment of the invention are shown to be numerical symbols such as the numbers "0" through "9" as illustrated in FIG. 2. However the type characters on the drum may be alphabetical symbols and in either case include algebraic signs and punctuation markings.

With more particular reference to FIG. 2, the type character layout is illustrated by a developed view of the peripheral surface 36 of the drum showing it as if it was flattened out, it being understood that in reality this surface coaxially encircles the shaft 12. As shown in the right marginal portion of FIG. 2 the drum's periphery is divided into four angular portions or sectors 38, 40, 42 and 44, two of which contain type characters and are identified at 38 and 42 and the remaining two of which are deprived of characters and identified at 40 and 44. It is evident from the developed surface of the drum's periphery shown in FIG. 2 that the type devoid sectors 40 and 44 are interposed between the type bearing sectors 38 and 42. It is also evident from FIG. 2 that the surface dimensions of the sectors are approximately equal, although as shown in this illustrated embodiment of the invention the character containing sectors are slightly larger by 20.degree. than the character deprived sectors.

The periphery of the drum 10 may be considered as divided into a plurality of adjacent circumferentially extending columns 46 delimited by dotted lines in FIG. 2, each containing a group 48 of printing type characters 34 and extending in a row along its respective column in either the drum sector 38 sector 42. Moreover, the character groups 48 are alternately staggered with respect to one another in their respective columns and are axially aligned with one another in their respective sectors. Each group may be considered as an entire font of characters of a particular demoninational order such as the numerals "0" to "9." The type characters of each row are spaced circumferentially with respect to one another according to a given pitch. The character drum columns 46 are axially spaced apart along the drum in accordance with the desired spacing of characters but preferably such as to provide the conventional typewriter machine spacing.

As earlier mentioned herein, the print impression member and its hammer are moved continuously at a substantially constant rate of speed parallel to the axis of rotation of the drum. The path of the print member 26 across the drum's periphery is illustrated in FIG. 2 by the helicoidal band shown in dash lines at 50. The velocity of this print hammer motion is such that the band-path 50 will in one complete revolution of the drum overlay two groups of characters 48 in adjacent columns 46 of the drum. The striker head of the print impressing member 26 is wider than one character column 46 but less than two such columns of the drum as evidenced in FIG. 2, but is sufficiently wide enough so that for one revolution of the drum it's helicoidal band-path 50 traverses the character groups in two adjacent columns of the drum. The result is that in one revolution of the drum the print hammer is capable of printing a multiple number of characters, one from each character group 48 over which its band-path extends during this single revolution.

In a successful embodiment of the invention herein described, the apparatus is capable of printing at the relatively high speed of 45 characters per second. In such apparatus the drum has an approximate diameter of 2 inches, or more exactly 1.9 inches, and is driven at a rotational speed of 1350 r.p.m. With the characters on the drum spaced axially on centers 1/10 inch apart, the print hammer of this embodiment is capable of traversing 45 columns of the drum in one second and to print 45 characters in that time period, one in each column 46, if activated to do so. The sectors 40 and 44 of the drum which are devoid of type characters provide sufficient time for the hammer 28 and the interposer 22 to return and reset after performing a printing impression and before being presented with the next succeeding character group on the drum.

It should be understood that the invention is not limited to the particular illustrated embodiment. For example, it is possible to axially shift the drum instead of the print impression means, or move both, to achieve the relative motion therebetween. The ink ribbon, for example, may be fed through the apparatus in a different manner than that illustrated or even eliminated if the nature of the recording medium permits such.

While a particular embodiment of the invention has been shown and described, it will be understood, of course, that it is not desired that the invention be limited thereto since modifications may be made, and it is therefore contemplated by the appended claims to cover any such modifications as fall within the true spirit and scope of the invention.

Claims

What is claimed is:

1. A high speed printer apparatus for imprinting characters on a print receiving medium comprising in combination:

a cylindrical-type drum member having a plurality of annular columns on the periphery thereof,

means to rotatably support the drum in a laterally fixed position,

means for rotating the drum about its axis,

a print impacting member located in print relation with respect to the drum and having a width that spans more than one said columns and less than two said columns,

a plurality of adjacent ones of said annular columns on the drum containing type characters, the characters of each said column being grouped with each group disposed over a sector of its associated column position and adjacent character groups being angularly displaced with respect to one another in different sectors of the periphery of the drum with alternate non-adjacent character groups being in substantial axial alignment,

means for continuously moving said print impacting member in a direction parallel to the axis of said drum at such a substantially constant velocity as to cover two adjacent annular columns of the drum during each revolution thereof, and

means for causing the print impacting member to strike said drum in response to a selected type character being disposed in printing position with respect to the impacting member while the impacting member is continuously moving at said substantially constant velocity.

2. The printer apparatus defined in claim 1 characterized in that sectors of the drum devoid of any type characters intervene between the character containing sectors of the drum and subtend angles approximating those of the latter.

3. The printer apparatus defined in claim 2 characterized in the groups of type characters contained within the plurality of adjacent columns are all of the same length and contain the same number of type characters.

4. A high speed serial printing device having a type drum, means for supporting said drum for rotation in an axially fixed position, said drum having a plurality of adjacent circumferential columns on the periphery thereof each containing a denominational order row of type characters and each row comprising all of the figures of an order, the type characters of each of said rows being spaced circumferentially according to a given pitch and said columns being spaced axially of the drum in accord with a desired print spacing, said device distinguished by embodying in combination;

a. a first drum sector which bears parallel rows of said type characters in the odd numbered columns of the drum,

b. a second drum sector which bears parallel rows of said type characters in the even numbered columns of the drum,

c. third and fourth drum sectors which are angularly disposed between said first and said second drum sectors and which are devoid of type characters,

d. means to rotate said drum continuously,

e. a single print impacting member having a striking face for individual character printing coaction with the individual type characters along a printing line parallel to the axis of the drum,

f. means for continuously moving said print impacting member along said printing line to traverse the different denominational rows of type characters successively at such a substantially constant velocity as to cover two adjacent columns of the drum during each revolution of the drum, and

means to operate said print impacting member when a selected type of any of said rows comes into printing range of the impacting member and while the impacting member is moving at said substantially constant velocity.

5. The printing device defined in claim 4 characterized in that the said third and fourth drum sectors subtend an angle approximately that of said first and second drum sectors.