Wire Printing Method

Abstract

A printing method for use with a wire printer designed for improved printing of both higher and lower case alphabetical characters wherein additional printing points and positions are added to write better-formed characters, and especially to print improved characters having diagonally extending and curved segments.

Description

CROSS-REFERENCES TO RELATED APPLICATIONS

This invention is designed for use with such wire printing heads as that described in the copending U.S. Pat. application Ser. No. 764,474 entitled Wire Printing Head, filed on Oct. 2, 1968 with E. A. Brown and A. S. Chou as inventors and assigned to the assignee of the present invention.

BACKGROUND OF THE INVENTION

In wire printing wherein the characters are formed by stamping a series of dots on a record member, which is usually paper, the square alphabetical symbols and numbers are formed in a clearly legible manner by the use of a normal dot matrix. Even where diagonal lines must be formed, so long as these lines extend generally at 45.degree. from the vertical, not too much difficulty is encountered in forming good appearing characters. However, a close investigation of many of the upper case alphabetical symbols and numbers shows that diagonal lines are needed extending at other than 45.degree. for the proper formation of legible images. When printing the lower case alphabet, it is found that the character quality suffers even more when limited to the 45.degree. diagonal lines.

In the past, such wire printing has been effected by a series of dots, usually in a 5.times.7 matrix, positioned adjacently but not overlapping in the vertical plane, thereby limiting the angle at which the diagonal lines can be formed. The primary reason for forming such characters was that the wire actuators could only be energized for printing the respective dots at predetermined time intervals. Thus, to improve the quality of the characters formed, a compromise had to be achieved between the quality of the character and the speed of the printing operations since wire printers usually are employed where speed and cost are factors considered at least as important as the quality of the type. Thus, any compromises have generally involved lessening the legibility of the printing and increasing the speed of the printer.

The primary purpose of this invention is to effect good quality wire-matrix printing with little reduction in the printing speed and at little or no additional cost of the wire printing device.

SUMMARY OF THE INVENTION

A method for forming characters with a wire printing device wherein the wires are actuated at predetermined time intervals but in a staggered fashion to form dots overlapping in the vertical plane thereby rendering more legible characters. Additionally the printing method of the subject invention teaches the employment of a wire printing device having strategically positioned printing wires for printing better quality upper and lower case characters.

Other objects and advantages of the invention will become apparent from the following detailed description taken in connection with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates one type of wire printing device in which the subject invention can be employed.

FIG. 2 illustrates on an enlarged scale one example of characters printed by use of wire printing devices employing previously known methods.

FIG. 3 illustrates the better quality upper case characters printed by use of one embodiment of the subject invention.

FIG. 4 shows one example of numbers printed with wire printers presently used.

FIG. 5 shows the better quality numbers that can be printed by using an embodiment of the subject invention.

FIG. 6 illustrates the printing end of a print head employing one embodiment of the subject invention.

FIG. 7 illustrates the printing end of a print head employing another embodiment of the subject invention, and

FIG. 8 illustrates selected lower case alphabetical symbols which can be printed by using the embodiments of the invention shown in FIG. 7.

DESCRIPTION OF PREFERRED EMBODIMENTS

The subject invention preferably is embodied in a printer head such as that shown in FIG. 1 and described in detail hereinafter. In such a wire printer head 10, individual wires 11 are actuated to press an inking ribbon 12 into contact with a record member such as the paper 13 resting against a platen 14 for printing characters comprised of a plurality of dots or impressions. In the embodiment shown, electromagnetic actuators 15 are energized to actuate each wire as needed to form the desired character as the head is translated across the paper. For translating the head, a rotatable threaded shaft 16 is passed through a threaded opening 17 in the frame 18 of the head to drive the assembly sidewise. An additional shaft 19 passing through a close fitting opening 20 in the frame holds the head steady as it is translated.

While not shown in detail, the individual actuators 15 generally comprise an electromagnet having an armature fastened to the wire 11 for movement thereof lengthwise through a wire guide 21. The guide is fastened to the frame by the screws 21a and extends from a position near the actuators to a location closely adjacent the platen 14. The inking ribbon is fed around the rollers 22 and across a guide 24 between the wire ends and the paper.

The individual actuators 15 are energized by the transmission of an electric current signal to the associated conductor 25 extending from an actuator energizer 26. In response to the input data signal calling for a specific character to be printed, the character code logic circuit 27 determines which of the wires should be actuated at each position and feeds the signal through the conductor 28 to the actuator energizer. In the past, the characters were formed by actuating selected ones of the several wires (usually seven) at each of several distinct and spaced positions (usually five in number) for printing the selected symbol.

Thus, in the presently used printers, the individual wires are actuated in synchronization with the translation of the head to form characters such as those indicated in FIG. 2 of the drawings. In this figure, the upper case letters are shown and it can be noted that little difficulty is encountered in printing a very legible character if the letters are square and do not call for curved or diagonally extending lines. For instance, the alphabetical characters "T" and "E" are shown in FIG. 2 printed in a normal manner of firing a seven-wire printing head at five laterally spaced positions to form a 5.times.7 matrix. It can be noted that the quality of the letters T and E is very good. In the same figure, are shown the higher case letters involving various diagonal and curved lines such as the "D" and"0." It can also be noted that such characters as these come out irregular in shape in that the diagonals needed to form the characters do not fit the diagonal lines necessary to form the letters properly. Specifically, the characters V, A, Y, W and X are difficult to form and the printing thereof with a 5.times.7 matrix can result only in a distorted character. While the characters can be read, they are not precise and distinct in form.

In FIG. 3 are shown various characters corresponding to those of FIG. 2 and which are printed by the subject invention. The improvement in the aesthetic qualities of the higher case characters is readily seen in comparing the characters of FIGS. 2 and 3. The characters in FIG. 3 are printed in accordance with the present invention by triggering or firing the wires at the normal five spaces as was accomplished in printing the characters in FIG. 2, and additionally by firing at half spaces positioned in between and in overlapping relationship to the five spaces, thereby making a total of nine positions overlapping or staggered in the vertical plane at which each wire can be triggered. The only qualification in the printing operation is that each firing of a wire must be spaced by a full print position, i.e., a complete space must exist between each position at which the wire is actuated. To elaborate on this requirement, if a wire is printed at half position, then the next possible location at which it can be printed or fired is at the next half position following that position. This requirement is necessary because a reset time must be allowed the printing head before the wire can again be actuated to the print position.

By accomplishing the printing of the higher case alphabetical characters in this manner, an overlap between adjacent vertical dots in the vertical plane normal to the direction of head movement is achieved to form diagonal lines positioned at 30.degree. from the vertical and to fit the needs for many of the higher case characters. As can be seen, the improvements in such characters as the O, V, A, Y and X are readily apparent because the diagonal lines now available with the 9.times.7 overlap matrix more distinctly fit that needed to print those characters. Thus, the continuous straight line in the diagonal segments of the characters necessary for printing X, Y and V's can be formed. For instance, with the X, the dots of the diagonal are printed every other one at the half-line position to form the diagonal segment as a continuous straight line. To illustrate, the dots 30 and 31 in FIG. 3 are printed at the standard firing positions while the dots 32 and 34 are positioned at the half-fire positions. Note that the adjacent dots 31 through 34 overlap in the vertical plane to enable the formation of the straighter lines extending diagonally across the plot of the normal 5.times.7 matrix. Thus, dots which "overlap" are dots printed at adjacent half-fire positions by different wires.

The heretofore described invention is also advantageous in printing numbers as is shown in FIGS. 4 and 5. In FIG. 4 are shown the numbers as previously printed and it can be noted readily that irregularly curved segments occur in such numbers as the 3, 6, 8 and 9 while irregular diagonal lines exist in the printed numbers 4 and 7. In FIG. 5, the subject invention is used in which the print wires are fired at the half positions. The improvement in the quality of the numbers is obvious. For instance, the number 2 is well-rounded with the dots 35, 36 and 37 overlapping in the vertical plane. The improved number 7 embodies a straight diagonal line formed by firing every other wire at the half-fire position. Improvements in the other numbers also are noted, i.e., the 0 is now the more pleasing oblong configuration instead of being square. The 6 also is improved by utilizing the diagonal line with overlapping dots achievable with the present invention. Thus, the advantages of the present invention are readily obvious in printing both the higher case alphabetical characters and the numeric characters.

Referring now to FIG. 9, the relationship between the various print positions will be described. Dots 51-55 are printed by a single wire which is caused to scan at an essentially constant velocity across the paper. Each dot 51-55 is printed at what is defined as a full position. Dots 71-74 are similarly each printed by a given wire but at half positions. In this figure, there are five spaced vertical rows, each headed by a dot 51-55, and 7 horizontal rows forming a 5.times.7 matrix, with four half position vertical rows including dots 71-74.

The relationship between the various dots with respect to the distance of travel of the pring head while printing is explained as follows. Referring to dots 81-83, the distance d' is defined as the distance traveled by the print head 10 in the minimum time required to actuate a given wire 11 twice and is related to the mechanical and magnetic characteristics of the print head requiring that a reset time be allowed before a given wire can be actuated to the print position again, for example, to form dot 82 after 81. The actual print timing for the head is established such that the distance d between dots 54 and 55 is equal to or greater than the distance d' and such that the distance 1/2d between dots 54 and 65, 74 is greater than d'. With this requirement, it is apparent that it would be impossible to fire a print wire to form, for example, dots 84 and 85 where 85 is on a half position adjacent to the full position of dot 84.

The above discussion has been with respect to the distance d, d' of travel of the head and was described in terms of a 5.times.7 matrix with half positions. Now, consider the spacing L, L' of possible print positions on a paper. As shown in FIG. 9, there are nine vertical rows and seven horizontal rows, forming what may be considered a 9.times.7 matrix. Each intersection of vertical and horizontal rows represents a potential print position. Once again, L' is defined as the space on the paper traveled by the print head in the minimum time required to fire, reset, and fire again. The spacing L between adjacent vertical rows of the 9.times.7 matrix is defined as being less than L', where 2L is equal to or greater than L'. With this requirement, it is apparent that it would be impossible to form print dots 84 and 85 on adjacent vertical rows of the 9.times.7 matrix. Herein, the L' and L dimensions are associated with the 9.times.7 matrix, and the d' and d dimensions are associated with the 5.times.7 matrix with four half positions.

In accordance with a second embodiment of the invention, upper and lower case letters can be printed with the same writing head by the use of additional wires positioned below the standard 7 wire alignment and used only to print the lower case characters. For instance, in the embodiment shown in FIG. 6, one preferred embodiment incorporates the aligned seven print wires for printing upper case letters and two additional print wires used only for printing the lower case letters. In this embodiment, the print wires positioned below the dotted line 38 and numbered 39 and 40 are used only to print lower case alphabetical characters and are not used to print higher case alphabetical characters and numeric characters. The advantages of this embodiment are shown in FIG. 8 wherein many lower case letters demand an extension below the normal base line of the higher case characters. For instance, the characters g, j, p, q and y extend below the line while the other lower case characters only extend above the print line. Thus, a method is provided for printing lower case characters by utilizing the top seven wires for printing most of the lower case alphabet and printing with the wires 39 and 40 positioned below the line only when the specific characters are to be printed which demand an extension below the print line. In this manner, the same print head can be utilized for printing both upper and lower case characters. In addition, the comma and semicolon are more legible as shown in FIG. 8. It is also known that foreign alphabets and irregular shapes are formed more easily with this embodiment of the invention.

In accordance with another embodiment of the invention, there is shown in FIG. 7 a printing head which embodies the print wires positioned in a vertical plane and in addition, incorporates an additional print wire 41 positioned adjacent the third and fourth wires 42 and 43 and at the half-fire position partially between those wires. Of course, the half-fire position of the additional wire could also preceed those wires with the same effect being rendered by firing this wire at the next following position while printing the character. It has been discovered that in printing such lower case alphabetical characters as the b, d, g, h, k, m, p, q, r, x and z, the additional wire position is needed to form a more perfect character. For instance, as shown in FIG. 8, these lower case alphabetical characters are formed in a much more precise manner in utilizing this additional wire. The dots numbered 41a all correspond to printing by the wire 41. It will be noted this dot location particularly enhances the printing of several of the characters.

There also is shown in FIG. 7 an additional wire 44 positioned adjacent the sixth and seventh wires 45 and 46 at the half-fire position. This wire is especially useful in printing many of the same characters as shown in FIG. 8 because they more logically form these characters in the manner in which they are normally written. For instance, in printing the lower case characters a, b, c, d, e, g, h, k, m, n, o, p, q, r and s, the dot 41a forms an integral part of the diagonal segment and enables the printing of a well-formed character. The wire 44 is used in forming the dot numbered 44a for printing more accurately the characters a, b, e, g, o, p, g, u, w and y. Thus, the half-firing of the print wires might be eliminated, i.e., operate with a 5.times.9 print matrix instead of a 9.times.9 as is supplied in the half-firing head, and still a more readable character be printed.

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

Claims

What is claimed is:

1. The method of printing upper and lower case characters on a record member with a wire printing machine having a printing head comprised of a plurality of print wires, said method comprising the steps of:

effecting relative movement at an essentially constant velocity between the head and record member;

selectively actuating said wires at predetermined intervals to form spaced imprints in a preset number of spaced rows, each row being spaced by a full position of distance d where d is equal to or greater than the distance d' traveled by said head in the minimum time required to actuate a given wire twice and where [1/2<d',] 1/2 d< d', and;

selectively actuating said wires for imprinting said record member at half positions between and overlapping adjacent spaced rows in the plane normal to the direction of relative movement between the member and head with each actuation of a given wire forming imprints spaced by at least a distance d' from the previous imprint of said given wire for forming the angular extending portions of the characters desired to be printed.

2. The method of printing as defined in claim 1 wherein said step of effecting relative movement further comprises the step of scanning parallel noncolinear print lines on said record member with a plurality of print wires arranged in a straight row.

3. A printing head for printing on a record member comprising a plurality of printing wires having a first end positioned adjacent said member and the second end positioned remote to said member,

an actuator for each wire operable upon energization to propel said wire first end into contact with said member for leaving an imprint thereon,

means for effecting relative movement at an essentially constant velocity between the head and record member,

a wire guide positioned between the actuators and record member functioning to align the wires in a single row extending normal to the direction of relative movement between the head and member,

means for energizing said actuators at preselected spaced positions along said member for imprinting said member to form a matrix of spaced dots forming characters desired to be printed, said matrix having rows separated by full positions of distance d, where d is equal to or greater than the distance d' traveled by said head in the minimum time required to actuate a given wire twice, and where 1/2d<d',

means for energizing selected ones of said actuators at intermediate positions between said rows of said matrix and in vertical overlapping relationship with said rows for forming angular extending segments of characters, each said actuator being energized to form dots in said member spaced by at least a distance d'.

4. A printing head as defined in claim 3 wherein seven printing wires are positioned in a single row for printing a line of impressions extending normal to the direction of movement between the head and record member.

5. The method of printing characters on a record member with a wire printing apparatus having a print head including a plurality of print wires, comprising the steps of:

effecting relative movement at an essentially constant velocity between the head and record member with said wires scanning parallel noncolinear print lines across a plurality of character print positions on said member;

selectively actuating said wires to form a matrix of dots forming the characters desired to be printed, the rows of said matrix being separated by a distance L where 2L is equal to or greater than the distance L' traveled by said head in the minimum time required to actuate a given wire twice and where L<L' and selectively actuating each given wire to form dots spaced by at least the distance L' from the dot formed by the previous actuation of said given wire.