US3283702A

US3283702A - High speed printing and graph plotting machine

Info

Publication number: US3283702A
Application number: US361303A
Authority: US
Inventors: Leonard J Higgins; Harold S Schwartz; Edward R Richardson
Original assignee: Potter Instrument Co Inc
Current assignee: Potter Instrument Co Inc
Priority date: 1964-04-20
Filing date: 1964-04-20
Publication date: 1966-11-08
Anticipated expiration: 1983-11-08
Also published as: DE1498176A1; GB1090653A

Description

Nov. 8, 1966 J. HIGGINS ETAL 3,283,702

HIGH SPEED PRINTING AND GRAPH PLOTTING MACHINE Filed April 20, 1964 9 Sheets-Sheet l N 1966 1.. J. HIGGINS ETAL 3,

HIGH SPEED PRINTING AND GRAPH PLOTTING MACHINE Filed April 20, 1964 9 Sheets-Sheet 2 T1 c1131- Z7 9 Sheets-Sheet 4 L. J. HIGGINS ETAL HIGH SPEED PRINTING AND GRAPH PLOTTING MACHINE Nov. 8, 1966 Filed April 20, 1964 Nov. 8, 1966 J. HIGGINS ETAL 3,283,702

\ HIGH SPEED PRINTING AND GRAPH PLOTTING MACHINE Filed April 20, 1964 9 Sheets-Sheet a I MNN \Qm' QM +l m L L. Qw

United States Patent 3,283,702 HIGH SPEED PRINTING AND GRAPH PLOTTING MACHINE Leonard J. Higgins, Smithtown, and Harold S. Schwartz,

White Plains, N.Y., and Edward R. Richardson, Philadelphia, Pa., assignors, by direct and mesne assignments, to Potter'lnstrument Company, Inc., Plainview, N.Y., a corporation of New York Filed Apr. 20, 1964, Ser. No. 361,303 35 Claims. (Cl. 101-93) This invention relates to apparatus for high speed plotting of curves and graphs along with data and information and more particularly to an apparatus for plotting curves and graphs at high speeds in response to digital input signals.

In digital data processing there has been a need for an output apparatus which will plot curves and graphs represented by the digital output of the computers and other types of data processing equipment. The plotters of the prior art such as XY plotters, electronic beam plotters and electrostatic plotters are not satisfactory for data processing output equipment. The XY plotters are not fast enough to handle the output data at the rate that it is produced by modern data processing equipment and the electrostatic or electronic beam plotters are not practical because of their cost and complexity.

The system of the present invention provides a relatively simple, high speed plotting apparatus which can also be used to print output data. In accordance with the present invention special characters in the form of dot configurations are raised in relief on a drum which rotates at a high speed. Means are provided to select any one of the special characters and to print it on paper. By controlling the selection of the special characters to be printed and by controlling the feed of the paper, any desired curve or graph may be printed out at a high speed with good resolution. Alpha-numeric characters are also provided on the drum and may be selected to print output data along with the curves and graphs.

Accordingly, an object of the present invention is to provide an improved curve and graph plotter.

Another object of the present invention is to provide a high speed curve and graph plotter.

A further object of the present invention is to increase the speed with which computer output data representing curves and graphs may be plotted.

A still further object of the present invention is to provide a high speed curve and graph plotter which will also function to print data along with the curves and graphs plotted.

A still further object of the present invention is to provide a plotter which will plot curves and graphs represented by digital data with good resolution.

Further objects and advantages of the present invention will become readily apparent as the following detailed description of the invention unfolds and when taken in conjunction with the drawings wherein:

FIG. 1 schematically illustrates the plotter of the present invention;

FIG. 2 illustrates the print drum of the plotter of the present invention;

FIG. 3 is an end view of the print drum of the present invention illustrating the distribution of the special characters for plotting curves and graphs;

FIGS. 4-10 illustrate the rows of special characters on the print drum for plotting curves and graphs;

FIG. 11 shows an example of a curve plotted with the apparatus of the present invention in actual size;

FIG. 12 is a block diagram illustrating the circuitry for controlling the plotting and printing operation in accordance with applied input digital data; and

FIGS. 13-18 are block diagrams of subcombinations of the block diagram shown in FIG. 12.

As shown in FIG. 1, the printer plotter of the present invention comprises a drum 21, which is rotated on its axis at a high speed, 1200 rpm, by a motor 23. As best shown in FIG. 2 the drum has on its cylindrical surface 4 axially disposed rows of characters with the rows being distributed around the circumference drum. All the characters of any given row are the same, different characters being found in different rows. The characters include 26 letters of the alphabet the numerals zero to nine and other characters needed in printing such as punctuation marks. These types of characters are referred to as alpha-numeric characters. The characters are raised in relief from the cylindrical surface of the drum so that they may be readily used for printing as will be described below. In addition to these characters, the drum is provided with 7 rows of special characters for plotting curves and graphs. These 7 rows of special characters are distributed at regular intervals about the circumference of the drum as is illustrated in FIG. 3, in which the rows of special characters are designated by the reference number 25 and the remaining alpha-numeric character rows are designated by the reference number 27. A row of 132 hammers 29, each actuated by a solenoid 31, are positioned extending axially along the drum 21. The faces of the hammers 29 are positioned and aligned so that each row of characters of the drum 21 will sequentially come under the striking faces of the hammers 29 and the characters of each row will simultaneously pass under the row of hammer faces. As pointed out above, 132 hammers are provided so that there is one hammer for each character in a row. When a row of characters passes under the row of hammer faces, each character in the row will be opposite the face of a different hammer. A web of paper 33 on which a curve is to be plotted is fed between the row of hammers and the drum 21 by means of a paper feeding mechanism 34. An ink impregnated ribbon 35 is fed between the drum 21 and the paper 33. When one of the solenoids 31 is energized it will drive its hammer against the paper and strike the paper and the impregnated ribbon against the drum. As a result whatever character on the drum is beneath the hammer will be printed on the paper at the spot where the hammer engaged the paper. By controlling the time that each hammer is driven against the paper in accordance with the position of the drum, any character on the drum may be printed on the paper. For example, if it is desired for the character A to be printed by one of the hammers 29, the solenoid operating this hammer will be energized as the drum rotates at a time relative to the position of the drum so that the hammer is driven against the paper just when the row of As on the drum comes under the row of hammers. The energizing voltage is applied to each hammer in the form of a pulse, which is referred to as a hammer driving pulse. The hammer driving pulse has to be applied to the solenoid 31 controlling the hammer under which it is desired to print a character before the row of desired characters actually comes under the row of hammers because the hammer 29 will be driven against the paper 33 a short interval after the hammer driving pulse is applied to the solenoid due to the inertia of the hammer and the inductance of the solenoid. The position which a row of characters occupy when the hammer firing pulse or pulses must be applied to print one or more characters in the row is referred to as the print position.

Each character has a field in which it is located. The field of a character is defined as the total area which can be occupied by a character. In the apparatus of the present invention the character fields are rectangular.

The special characters for plotting curves and graphs, as illustrated in FIGURES 4 through 10, comprise dots arranged in dilferent configurations and positions on their fields. Each special character in the row shown in FIG. 4 consists of a single dot in the middle of the left-hand side of the character field. Each special character in the row shown in FIGURE 5 consists of a single dot in the middle of the character field. Each special character in the row shown in FIG. 6 consists ,of a dot in the middle of the right-hand side of the char ac r field. Each special character in the row shown in FIGURE 7 consists ow two dots, one positioned in the middle of the lefthand side of the character field in the same position as the dots of the characters shown in FIGURE 4 and the other positioned in the middle of the character field in the same position as the dots of the characters shown in FIGURE 5. Each special character in the row shown in FIGURE 8 consists of two dots, one in the middle of the character field in the same position as the dots of the special characters shown in FIGURE 5 and one positioned in the middle of the right-hand side of the character field in the same position as the dots of the special characters shown in FIGURE 6. Each special character in the row shown in FIG. 9 consists of two dots, one positioned in the middle of the left-hand side of the character field in the same position as the dots of the special character shown in FIG. 4 and the other positioned in the middle of the right-hand side of the character field in the same position as the dots of the special characters shown in FIG. 6. Each special character of the row shown in FIG. 10 consists of three dots arranged horizontally, one positioned in the middle of the left-hand side of the character field in the same position as the dots of the special characters shown in FIGURE 4, one positioned in the middle of the character field in the same position as the dots of the special characters shown in FIGURE 5, and one positioned in the middle of the left-hand side of the character field in the same position as the dots of the special characters shown in FIGURE 6.

By selecting the proper ones of the special characters to be printed and by controlling the distance that the paper is fed between printings any desired graph or curve may be plotted with good resolution. Good resolution will be obtained horizontally because dots can be printed in any of three horizontally spaced positions in each character field. Good resolution is obtained vertically in accordance with the present invention by feeding the paper in small increments equal to a fraction of the vertical dimension of a character field. The dots of the special characters are spaced horizontally of an inch apart and when a surve is being plotted the paper is advanced in increments of of an inch. With this arrangement, curves and graphs may be plotted with a resolution to of an inch. An example of a curve plotted with the apparatus of the present invention is shown in FIG. 11 in actual size. The increased resolution is obtained with the present invention because the apparatus of the present invention can print a plurality of character dots at different positions in a space corresponding in size to the field of one character. This characteristic is referred to as subdivided character fields. It will be apparent that the resolution may be further increased just by further subdividing the character fields.

FIG. 12 is a block diagram of electronic circuitry for controlling the energization of the hammer solenoids to print characters on the drum 21 selected in accordance with coded input signals and controlling the feed of the paper on which the characters are printed. Coded binary signals representing the characters to be printed are applied in parallel over six input channels designated by the reference number 41. Each row of characters on the drum 21 is represented by a dilferent binary code on the six input channels 41. The codes representing a line of characters to be printed are fed in sequence to the circuit at input 41 and stored temporarily first in an input register 43 and then in a delay line storage 45. When a whole line of character codes is stored in the delay line storage 45, the characters represented by the codes in the delay line storage are compared with the counts represented by a binary counter 47. Counter 47 counts pulses from a tone wheel 49 fixed to the drum as illustrated in FIG. 1. The tone wheel 49 comprises a disc of low reluctance material, which has radial slots distributed around the circumference thereof. A transducer 50 positioned adjacent the periphery of the tone wheel 49 will produce a pulse each time one of the radial slots passes under it. The pulses produced by the transducer 50 are applied to a channel 53. Accordingly the tone wheel 49 produces on channel 53 via the transducer 50 one output pulse per row of characters as the character rows rotate past the hammers 29. A second tone Wheel 51 comprising a disc of low reluctance material like the tone wheel 49 but having a single radial slot is also fixed to the drum. The tone Wheel 51 produces on a channel 55 one output pulse per revolution of the drum by means of a transducer 52. The output pulses of the tone wheel 49 are called count pulses and the output, pulses of the tone wheel 51 are called index pulses. The counter 47 counts the pulses produced on channel 53 and each index pulse produced on channel 55 will reset the counter 47 to zero. Thus as each row of characters comes into the print position a different count will be registered in the counter 47. Each character code will be identical to the binary code of the count registered in the counter just before the character represented by such character code reaches the print position. Therefore, the six-place binary character code representing a particular character will be the same as the six-place binary coderegistered in the binary counter 47 just before the row of characters represented by the input code comes into the print position. Each count registered by the counter 47 is compared with all of the character codes representing the 132 characters to be printed in one line stored in the delay line storage 45. Each time that the comparison circuit 57 detects that a code in a delay line storage 45 is the same as the count registered in the counter 47, it produces a hit pulse. Each hit pulse produced by the comparison circuit 57 means that a character from the row of characters approaching the print position is to be printed. The column in which the character is to be printed is determined by the position of the code representing the characters in the delay line storage 45. A 132 stage hit register 59 stores the hit pulses produced by the comparison circuit 57. The hit register 59 has a different stage corresponding to each column on the paper and to each hammer. A selector matrix 61 stores the hit pulses produced by the comparison circuit 57 in the stages of the hit registers 59 corresponding to the columns in which the characters are to be printed. The next count pulse produced by the tone wheel 49 increasing the count in the counter 47 is also applied to a set of gates 63, which read out the stored pulses from the hit register 59 and apply them to hammer driving pulse generators 64. The generators 64 apply hammer driving pulses to the solenoids corresponding to the stages in which the hit pulses were stored. The solenoids receiving the driving pulses will then strike the corresponding hammers against the paper and will cause characters to be printed in the corresponding columns of the paper. The characters that will be printed will be from the row of characters which were approaching the print position when the comparison was made between the contents of the delay line storage 45 and the count registered in the counter 47. Each time the count registered by the counter 47 is changed by the application of a count pulse to the counter 47 the entire contents of the delay line 45 is compared to the new count registered by the counter 47 and new hit pulses are stored in the hit register 59 so that the characters selected in each column by the codes stored in the delay line 45 a stored clock pulse.

will be printed on the line of paper under the hammers. The paper will remain in its position until the drum has made one complete revolution so that all the rows of characters have had a chance to be printed in the line heneath'the hammers. In this manner, the character from any selected row may be printed in any selected column on the line of paper beneath the hammers. When the drum has completed one revolution and all of the rows on the drum have had a chance to be printed, the paper is advanced so that a new line of characters may be selected in the same manner.

A clock pulse is applied at an input channel 71 with each character code of parallel binary bits applied on input channels 41 from the information source. The clock pulse is applied to a gate 73, which will be enabled by a signal from a flip-flop 75 when the flip-flop 75 is in its A state. The flip-flop 75 will be in its A state when the circuit is in its data insertion phase ready to accept the character codes from the information source. When the gate 73 is enabled, each clock pulse applied over the input 71 will pass through the gate 73 and then through a 1.5-microsecond delay line 77. After passing through delay line 77, each clock pulse will be applied to a set of six gates 79 and will enable these gates. The character codes applied to input channel 41 are applied to the input register 43 through the gates 79. The clock pulses passing through the delay line 77 and applied to the gates 79 strobe the character codes into the input register. Thus, character codes can be applied to the input register only when the flip-flop 75 is in its A state and only if they are properly accompanied by a clock pulse.

The input register 43 comprises eight ranks of siX stages each. Each of the eight ranks is capable of storing one character code. Each character code passing through the gates 79 will be stored in a rank of the register 43 selected by an input counter 81 in accordance with the count registered thereby. The counter 81, which counts the passing through the delay line 77, has a capacity of eight different counts, zero to seven, and selects a difierent rank in the input register for each count registered thereby. As each clock pulse passing through the delay line 77 is applied to the counter 81, the count registered by the counter 81 will increase incrementally until the count registered by the counter 81 reaches 7. The next pulse applied to the counter 81 will recycle the count registered thereby to zero. Thus the counter 81 will select the ranks in the input register in sequence and will cyclically repeat the sequence. Since each clock pulse will incrementally change the count registered by the counter 81, each character code will be stored in the next sequential rank in the input register after the rank in which the preceding character code was registered. :In this manner, the input register keeps track of the sequence in which the character codes are applied to the input channels 41 so that the characters can be arranged in the same sequence when they are printed.

The clock pulses after passing through the delay line 77 are also applied through another 3-microsecond delay line 83 to a cynchronizer 85. The synchronizer 85 also receives pulses from a two-megacycle clock pulse generator 87 and produces one output pulse on a channel 89 for each clock pulse received from the delay line 83. Thus the pulses produced on channel 89 are clock pulses corresponding to the clock pulses accompanying each character code. The synchronizer 85 serves to insure that each clock pulse produced on channel 89 does not occur simultaneously with a tWo-megacycle clock pulse. The clock pulses produced in this manner on channel 89 are applied to the input register 43. Each rank of the input register 43 is provided with an additional flip-flop for storing the clock pulses on channel 89 to indicate that a character is stored in that rank. Thus, each rank of the input register 43 storing a character code will also have The purpose of this stored clock pulse is to enable the circuit to determine when it has 6 read out all of the stored character codes in the input register.

The character codes stored in the input register 43 are read out from the ranks of the register in the same sequence in which they were stored in the input register. Each character code read out from the input register 43 is applied directly to the delay line storage 45, in which the character codes are stored in the same sequence in which they are read out. The delay line storage comprises six delay channels, each of which provides a 66-microsecond delay. Each six-bit binary character code is stored in the delay line storage by applying each bit of the character code simultaneously to the input of a different delay channel. After a character code has been applied to the inputs of the delay channels it will continuously recirculate in the delay channels until the delay line storage is cleared. The two-megacycle clock pulses produced by the clock pulse generator 87 are applied to the delay line storage to gate each character code into the inputs of the delay channels so that each character code starts into the inputs of the delay channels simultaneously with a two-megacycle clock pulse. This gating of character codes into the inputs of the delay channels by the two-megacycle clock pulses takes place whether or not the character code is being applied to the delay channels from the input register or is being recirculated from the ends of the delay channels. In this manner the character codes stored in the delay line storage are synchronized and are maintained in synchronism with the two-megacycle clock pulses. Since the two-megacycle clock pulses are used to gate the character codes into the inputs of the delay channels, the character codes can be fed into the delay line channels at a rate of one every /2 microsecond. Since the length of the delay channels is 66 microseconds, the capacity of the delay line storage is 132 character codes.

Pulses from the two megacycle clock pulse generator 87 are applied through a gate 93 to an output counter 91. When character codes are being read out from the input register 43, the gate 93 will be enabled to allow the clock pulses to be applied to the counter 91. The counter 91 is similar to the counter 81 in that it has a capacity of 8 counts, 07, it increases its count by one increment in response to each pulse received from the clock pulse generator 87, and re-cycles to 0 after reaching a count of 7. The counter 91 selects the ranks of the input register 43 to be read out in accordance with the count registered thereby and selects the ranks in the input register 43 in response to the incrementally changing count in the counter 91 in the same sequence that the counter 81 selects the ranks in the input register. In this manner, the character codes are read out from the input register in the same sequence that they are stored and thus are applied to the delay line storage in the same sequence that they are applied on input channels 41. The enabling of the gate 93 is controlled by a flip-flop 95. When character codes are being read out from the input register, the flip-flop 95 will be in its A state and will apply an enabling signal to the gate 93. The pulses produced by the two-megacycle clock pulse generator 87 are also applied through a gate 97 to a counter 99, which is referred to as the column counter. The column counter has a capacity of 132, which is the number of characters that can be printed in a line of print by the printer and which is the capacity of the delay line storage 45. The enabling of the gate 97 is also controlled by the flip-flop 95. When the flip-flop 95 is in its B state, it will enable the gate 97 and allow the clock pulses from the clock pulse generator 87 to pass through the gate 97 to be counted by the column counter 99. Thus, the flip-flop 95 selects either the counter 91 or the counter 99 to count the pulses produced by the clock pulse generator 87. When the counter 99 reaches a count of 132, the next pulse will re-cycle the column counter 99 and will set a count of l in the column counter 99. Upon reaching a count of 132, the column counter 99 produces an output pulse on a channel 101. This pulse is applied through a gate 103 to set the flip-flop 95 in its A state. The gate 103 will be enabled by a signal from the flip-flop 75 through an OR gate 102 whenever the flip-flop 75 is in its A state or in other words when the circuit is in its data insertion phase.

Each time the counter 91 reads a character out from a rank in the input register 43, it senses whether the next rank has a clock pulse stored therein. If the next rank does not have a clock pulse stored therein, it will mean that all the character codes stored in the input register have been read out. clock pulse in the next rank to be read out, the input register 43 produces an output pulse on a channel 105 which pulse will set the flip-flop 95 into its B state. Thus in the data insertion phase the flip-flop 95 will be set into its A state each time the counter 99 reaches a count of 132 and the flip-flop 95 will be set to its B state when all of the character codes stored in the input register have been read out. By means of the flip-flop 95, the transferring of the character codes from the input register 43 to the delay line storage 45 is carried out so that the character codes are stored in the delay line storage 45 in their proper order, that is, the same sequence in which they are applied to the input channel 41. For example, when the delay line storage 45 has no character codes stored therein and the flip-flop 75 has been set into its A state indicating to the information source that the circuit is ready to receive character codes, the character codes will be stored in the ranks of the input register 43 in sequence. While these character codes are being stored in the input register 43, the column counter 99 will be counting the clock pulses from the two-megacycle clock pulse generator 87. When the column counter 99 reaches a count of 132, it will set the flip-flop 95 into its A state thus disabling the gate 97 and enabling the gate 93. Accordingly, the column counter 99 will stop counting and the output counter 91 will start counting. As a result, the counter 91 will count the clock pulses from the generator 87 and cause the ranks of the input register 43 to be read out in sequence and stored in the delay line storage 45 until all the character codes in the input register 43 have been read out. At this time the input register will produce an output pulse on channel 105 and set the flip-flop 95 to its B state. As a result the gate 93 will be disabled and the gate 97 will be enabled and the column counter 99 will begin to count again. While the column counter 99 is counting, additional characters will be stored in the input register. The column counter will count until it again reaches a count of 132 whereupon the flipflop 95 will again be set back into its A state. Since the column counter 99 will begin counting just after the last character was transferred from the input register 43 to the delay line storage 45, the column counter 99 will reach a count of 132 just at the time the characters that have been stored in the delay line storage 45 have been re-circulated and are in the same position in the delay line storage 45 that they were in when the last character was transferred from the input register 43. Accordingly, when the flip-flop 95 switches to its A state and the counter 91 commences to again count pulses from the clock pulse generator 87 causing the newly stored character codes to be read out from the input register, the new character codes will be stored in the delay line 45 right behind the previously stored character codes. Thus, in this manner, the character codes are stored in the delay line storage 45 in the same sequence that they were applied to the input channel 41. The process of new character codes being stored in the input register and then transferred to the delay line storage 45 right behind the previously stored characters in the delay line storage will continue until 132 characters have been stored in the delay line storage, thus filling the delay line storage to its capacity.

In response to the finding of no When the delay line storage has been filled to its capacity, the flip-flop 75 is switched to its B state thus indicating to the information source that the circuit is no longer ready to accept character codes and preventing the acceptance of character codes by removing the enabling signal from the gate 73 and thereby preventing the gates 79 from receiving the strobe pulses. The switching of the flip-flop 75 to its B state is accomplished by means of a counter 107 referred to as the line counter. The pulses produced by the synchronizer 85 on channel 89 are applied to the line counter 107 through an OR gate 109. As was pointed out above, the synchronizer 85 produces an output pulse on channel 89 for each clock pulse applied thereto through the delay line 83. Thus, when the flip-flop 75 is in its A state and is accepting information from the information source, the line counter 107 will receive one pulse for each character applied to the channels 41 and passing through the gates 79. Thus the line counter 107 will count the characters stored in the input register 43. When 132 characters have been stored in the input register 43 after the flip-flop 75 has been switched to its A state, the line counter 107 will register a count of- 132. Upon registering a count of 132, the line counter 107 resets itself to zero and applies a pulse to a gate 111 which will be enabled by the flip-flop 75 when the flip-flop 75 is in its A state. Accordingly, the

' pulse produced by the line counter 107 Will pass through the gate 111 whereupon the pulse will set the flip-flop to its B state, thus disabling the gate 73 and indicating to the information source that it is no longer accepting character codes. The pulse passing through the gate 111 will also set a flip-flop 113 in its B state. When the flipflop 113 is set into its B state, it will apply an enabling signal through the OR gate 102 to the gate 103 so that the gate 103 will continue to be enabled after the flip-flop 75 has been switched to its B state. This enabling of the gate 103 by the flip-flop 113 is to permit the remaining character codes that are stored in the input register to be read out after the line counter 107 has reached a count of 132. Thus, when the column counter 99 next reaches a count of 132 after the line counter 107 has reached a count of 132 it will switch the flip-flop to its A state and cause the remaining character codes stored in the input register 43 to be transferred to the delay line storage 45. The last character code read out from the input register 43 at this time will be the l32nd character code applied to the input channels 41 after the flipflop 75 was switched to its A state. Thus, the delay line storage 45 will be filled to its capacity with 132 character codes. When the last character code is read out from the input register 43 and an output pulse is produced on channel setting the flip-flop 95 back to its B state, the pulse produced on channel 105 will also set the flip-flop 113 back to its A state. Thus, the gate 103 will be disabled and subsequent pulses produced on channel 101 When the column counter 99 reaches a count of 132 will not be applied to the flip-flop 95 to set it back to its A state. When the flip-flop 113 is set back to its A state following the setting of the flip-flop 75 to its B state, the data insertion phase is ended and the print phase begins.

In the print phase when the flip-flop 75 has been set to its B state and the flip-flop 113 has been set to its B state and back to its A state, no pulses will be applied to the output counter 91 and no character codes will be accepted from the information source through the gates 79. The circuit will then be ready to carry out the operation of printing the charatcer codes that are stored in the delay line storage 45.

When the flip-flop 75 is in its E state, it will apply an enabling signal to a gate 115, which also receives the count pulses from the tone wheel 49 produced on channel 53. However, in order to be enabled and pass the count pulses on channel 53, the gate 115 must also receive an enabling signal from the flip-flop 113, which will apply an enabling signal to the gate 115 when it is in its A state. the gate 115 will be enabled to pass count pulses on channel 53 after the flip-flop 75 has been switched to its B state upon the 132nd character being stored in the input register 43 and after the flip-flop 113 has been switched back to its A state upon the 132nd character being transferred from the input register to the delay line storage. Each pulse passing through the gate 115 is applied to a multivibrator 117, which in response to each applied pulse produces a ISO-microsecond output pulse. This 100- microsecond output pulse will enable a gate 119 for its duration. The gate 119 is connected to receive the pulses produced on channel 101 by the column counter 99. Thus, the gate 119 will receive the pulse firom the column counter 99 each time the column counter 99 reaches a count of 132. When the vate 119 is enabled, the pulses produced on channel 101 by the column counter 99 will pass through the gate 119 and set a flip-flop 121 in its A state. Upon being set in its A state, the flip-flop 21 will enable a gate 122, which is also connected to receive the pulses produced on channel 101. Thus, the next pulse produced on channel 101 by the counter 99 after the one that has set the flip-flop 121 into its A state will pass through the gate 122 whereupon this pulse will set the flip-flop 121 back to its E state. Accordingly, the flipflop 121 will be in its A state for the period between the first two pulses produced on channel 101 after a pulse passes through the gate 115. In other words, the flipflop 121 will be set into its A state for the period between the next two pulses produced on channel 101 by the column counter 99 after each count pulse is produced on channel 53 by the tone wheel 49. In this manner the flip-flop 121 is set into its A state for a 66-microsecond time interval each time the tone wheel produces a count pulse on channel 53. Each 66-microsecond time interval will start when the count in the colmun counter 99 first reaches 132 after a count pulse is produced on channel 53 and will end when the column counter next reaches a count of 132.

As was pointed out above the count in the column counter 99 is held at 132 as new character codes are transferred from the input register to the delay line storage in the data insertion phase and then starts counting again with l on the next pulse produced by the two-microsecond clock pulse generator 87 after the last character code is transferred to the delay line storage. Thus, after the delay line storage has been filled with 132 character codes, the column counter will start with a count of one simultaneously with the time that the first character code that was stored in the-delay line storage recirculates from the ends of the delay channels to the inputs of the delay channels in the delay line storage. Accordingly, as each character code recirculates in the delay line storage from the ends of the delay channels to the inputs of the delay channels, the count registered by the counter 99 will correspond to the order in which such character code was transferred to the delay line storage and to the column position in which the character represented by such character code is to be printed.

As the character codes in the delay line storage 45 recirculate, they are compared with the counts registered by the counter 47, which as pointed out above registers a count corresponding to the character code of the line of characters on the drum about to come into the print position. Whenever a character code in the delay line storage equaling the code of the count registered in the counter 47 recirculates from the ends of the delay channels to the inputs of the delay channels, the identity of the two codes will be detected by the comparison circuit 57 which will then produce a hit pulse on a channel 123. Thus, a pulse will be produced on channel 123 each time a character code in the delay line storage identical to the code of the count registered in the counter 47 recirculates Thus,

from the ends of the delay channels to the inputs of the delay channels. The pulses produced on channel 123 are applied to a gate 125, which will be enabled whenever the flip-flop 121 is in its'A state. When the gate is enabled the hit pulses will pass through to the selector matrix 61. Thus, after a count pulse is produced on channel 53, the gate 125 will pass any hit pulses produced on channel 123 during the 66-microsecond interval starting at the time the counter 99 first reaches a count of 132 after the pulse produced on channel 53 and ending the next time thecounter 99 reaches a count of 132. Thus the gate 125 will be enabled to pass hit pulses to the selector matrix 61 for one-complete recirculation of all 132 character codes stored in the delay line storage.

The selector matrix 61 selects stages in the hit register 59 corresponding to the count registered by the counter 99 and stores the hit pulses in the stages selected thereby. The hit register 59 has 132 stages, one corresponding to each column of characters to be printed by the apparatus. If the columns are considered numbered 1 to 132 starting from the left-hand side of the paper, then the count registered by the counter 99 will equal the number of the column in which there is to be printed the character represented by the character code that is presently recirculating from the ends of the delay channels to the inputs of the delay channels in the delay line storage. Thus, when a hit pulse is produced on channel 123, the count registered by the column counter 99 will equal the number of the column in which there is to be printed the character represented by the character code which caused the hit pulse to be produced. The selector matrix 61 under the control of the count registered by the counter 99 stores each hit pulse applied thereto in the stage of the hit register 59 corresponding to the count represented in the counter 99 and thus corresponding to the column in which there is to be printed the character represented by the character code that caused the hit pulse. In this manner pulses are stored in the stages of the hit register 59 corresponding to the columns in which there is to be printed the character represented by the code of the count registered in the counter 47. The next pulse produced on the channel 53 will increase the count registered by the counter 47 incrementally by one and will also enable a .set of 132 gates 63 reading out the pulses stored in the hit register 59. When each count pulse is produced on channel 53, a row of characters will be in the print position. The code representing this row of characters will be the code of the count registered in the counter 47 just prior to the time the count pulse was produced. Each of the 132 output channels from the gates 63 is connected to the input of a difierent one of the hammer driving pulse generators 64, each of which is connected to apply a driving pulse to the solenoid of a dilTerent one of the print hammers. Each of the hammer driving pulse generators 64 is connected to receive a pulse from a different one of the stages of the hit register 59 when the gates 63 are enabled and the hammer solenoid which is connected to be energized by each hammer driving pulse generator is located opposite the column on the paper 33 corresponding to the stage of the hit register to which such hammer driving pulse generator is connected. The hammer solenoids upon receiving the hammer driving pulses Will strike the paper and the ink impregnated ribbon against the print drum and print the characters which are under the hammers at this time. The tone wheel 49 is positioned relative to the print drum so that the characters printed in this manner will correspond to the code of the count that was registered in the counter 47 just prior to the last count pulse which enabled the gates 63 and caused the energization of the appropriate solenoids. Thus the character represented by the code of the count registered in the counter will be printed in the columns on the paper corresponding to the order in which the character codes representing such character are stored in the delay of his pulses.

As each count pulse is produced on channel 53, the count in the counter 47 increases incrementally and as each new count is registered in the counter 47 it is compared with the entire contents of the delay line storage in the manner described above and hit pulses are stored in the stages of the hit register corresponding to the columns in which there is to be printed the character represented by the code of such new count. This process is continued until all of the characters stored in the delay line storage have been printed, each in the column corresponding to its position in the delay line storage.

Each count pulse produced on channel 53 and passing through the enabled gate 115 is also applied to the line counter 167 through the OR gate 109. Accordingly, the counter 107 will count the pulses passing through the gate 115. When the counter 107 reaches the count of 53, that is, about 4 /2 milliseconds before the drum has completed one revolution following the initiation of the print phase, the counter 197 will produce an output pulse on a channel 131. The pulse produced on channel 131 is referred to as the anticipated end-of-print pulse. This pulse is applied to a gate 133 which will be enabled by a signal from the flip-flop 75 when the flip-flop 75 is in its B state as .it will be during the print phase. Thus, the anticipated end-of-print pulse will pass through the enabled gate 133 whereupon it will be delayed by a delay line 135 sufficiently long for the drum to complete its revolution and for all of the characters on the drum to be printed. When the pulse has passed through the delay line 135, all of the columns in which characters are to be printed on the paper will be printed. The pulse after passing through the delay line 135 resets the counter 107 to zero and sets the flip-flop 75 back in its A state. The flip-flop '75 then sends a signal to the information source indicating that it is ready to accept more character codes and en abling the gate 73 so that more character codes may he applied to the input register 43. The pulse passing through the delay line 135 is also applied to a multivibrator 137 which applies a pulse to the delay line storage to inhibit recirculation in the delay lines for a period long enough to clear the delay line storage of all the characters stored therein. The pulse passing through the delay line 135 is also applied to the paper advance control circuitry and initiates an advance of the paper bringing the next line of the paper under the hammers to be printed. The process then repeats itself to print another line of characters selected in accordance with the character codes fed on input channels 41. In this manner any of the alpha-numeric characters or any of the special curve plotting characters may be printed in any line of the paper coming under the print hammers.

When the apparatus is to be operated in the alphanumeric rnode, a signal will be applied to an input channel 139 to set a flip-flop 141 in its A state. When the apparatus is to be operated in its plot mode, an input signal is applied on an input channel 143 to set the flip-flop 141 in its B state. To advance the paper one increment the pulse passing through the delay line 135 sets a flipilop 145 in its A state. When the flip-flop 145 is in its A state, it will apply an enabling signal to a gate 147 and a gate 149. When the flip-flop 141 is in its A state it will apply an enabling signal to the gate 147 and when the flip-flop 141 is in its B state, it will apply an enabling signal to the gate 149. When the gate 147 receives enabling signals from both the flip-flops 141 and 145, it will apply a signal to a clutch-driving circuit 151 which in response to receiving the signal will energize a clutch 153 and cause the clutch 153 to engage. Thus, the clutch 153 will be engaged in response to the pulse passing through the delay line 135 if the flip-flop 141 has been set into its A state 12 in response to a signal on input channel 139 calling for the circuit to operate in the alpha-numeric mode. cordingly, the clutch 153 is referred to as the alphanumeric clutch. When the gate 149 receives enabling signals from the flip-flop 141 and the flip-flop 145, it will apply agsignal to a clutch-driving circuit 155, which in response to the signal from the gate 149 will energize a clutch 157 and cause the clutch 157 to engage. Thus, the clutch 157 will be engaged when the flip-flop 141 is in .its E state and the flip-flop 145 is in its A state. Accordingly, the clutch 157 Will be engaged in response to a paper advance pulse from the delay line when the circuit has been placed in the plot mode by a signal applied on input channel 143. Accordingly, the clutch 157 is referred to as the plot clutch.

The

clutches

153 and 157 are schematically illustrated in FIG. 1. As shown in FIG. 1 the outputs of both of the

clutches

153 and 157 drive the paper drive mechanism 34 for the paper 33. A motor 159 drives the input side of the clutch 153 at one speed and drives the input side of the clutch 157 at a lower speed. The input side of the clutch 153 is driven at a speed such that when it is engaged, it will cause the paper 33 to be advanced at a rate of 25 inches per second. The input side of the clutch 157 is driven by the motor 159 at a speed such that when it is engaged, it will cause the paper 33 to advance at a rate of 9 inches per second. Thus, when a paper advance pulse is applied to the flip-flop set-ting the flip-flop 145 in its A state and the circuit is operating in the alpha numeric mode, it will cause the clutch 153 to engage and start the paper to advance at a rate of 25 inches per second. If the circuit is operating in the plot mode, then in response to a paper advance pulse applied to the flipflop 145, the clutch 157 will engage and cause the paper to start advancing at a rate of 9 inches per second.

Along with the paper drive mechanism the clutches 153 and are connected to drive tone wheels 161 and 163, which accordingly rotate at a rate corresponding to the rate that the paper 33 is advanced. The tone wheels 161 and 163 are like the tone wheel 49 in that they comprise low-reluctance material with radial slots distributed around their peripheries. The tone wheels 161 and 163 cooperate with

transducers

165 and 167, respectively. Each time a slot in the tone wheel 161 passes under the transducer 165, the transducer 165 will produce an output pulse and each time a slot on the tone wheel 163 passes under the transducer 167, the transducer 167 will produce an output pulse. The slots on the tone wheel 161 are spaced so that the transducer 165 will produce an output pulse for every of an inch that the paper 33 advances. The slots in the tone wheel 163 are spaced so that the transducer 167 will produce an output pulse for every of an inch that the paper 33 advances.

As shown in FIG. 12 the output pulses produced by the tone wheel 161 are applied to one contact of a relay 169 and the output pulses produced by the tone wheel 163 are applied to another contact of the relay 169. When the relay 169 is not energized, it will apply the pulses produced by the tone wheel 161 toa channel 171 and when the relay 169 is energized, it will connect the output pulses produced by the tone wheel 163 to the channel 171. The relay 169 will be energized whenever the flip-flop 141 is in its B state and will not be energized whenever the Hip flop 141 is in its A state. Thus, the output pulses produced by the tone wheel 161 will be applied to the channel 171 when the circuit is operating in the alpha-numeric mode and the output pulses of the tone wheel 163 will be applied to the channel 171 when the circuit is operating in the plot mode. Accordingly, the tone wheel 161 is referred to as the alpha-numeric tone wheel and the tone wheel 163 is referred to as the plot tone wheel. Each time a pulse is applied to channel 171 from either the tone wheel 161 or the tone wheel 163, it will set the flip-flop 145 to its B state and accordingly the flip-flop 145 will no longer apply an enabling signal to the gates 147 and 149.

If the circuit is operating the alpha-numeric mode so that the clutch 153 is engaged, then when the enabling signal from the flip-flop 145 is no longer applied to the gate 147, the clutch driving circuit 151 will no longer receive a signal from the gate 147 and accordingly will de-energize the clutch 153, which upon being de-energized will disengage. If the circuit were operating in the plot mode, then when a pulse from the tone wheel 163 sets the flipflop 145 in its B state so that the gate 149 no longer receives an enabling signal, the clutch-driving circuit 155 will no longer receive a signal from the gate 149 and in response to the termination of this signal will de-energize the plot mode clutch 157, whereupon the plot mode clutch 157 will disengage.

The flip-flop upon switching to its B state will apply an actuating signal to a brake-energizing circuit 173, which in response to receiving the actuating signal will energize a brake 175. The brake 175 as shown in FIG. 1 operates on the paper drive mechanism 34 and upon being energized will stop the paper drive mechanism and thus halt the advance of the paper 33.

Accordingly, if the circuit is operating in the alphanumeric mode so that pulses from the alpha-numeric tone wheel 161 are applied on channel 171 and so that the clutch 153 will be engaged in response to paper feed pulses applied to the flip-flop 145 from the delay line 135, the following action will occur in response to a paper feed pulse. First, the clutch 153 will engage thus causing the paper 33 to start advancing at a rate of 25 inches per second. When the paper has advanced to a point where the tone wheel 161 produces an output pulse, this pulse Will cause the clutch 153 to disengage and the brake 175 to engage stopping the paper advance. Since the alpha-numeric tone Wheel 161 produces an output pulse for every f an inch that the paper 33- advances, the paper will have advanced of an inch when it is stopped by the brake 175 and it will advance in increments of of an inch for each paper advance pulse applied from the delay line 135 to the flip-flop 145.

When the circuit is operating in the plot mode, each paper advance pulse applied to the flip-flop 145 will cause the plot mode clutch 157 to engage and cause the paper 33 to start advancing at a rate of 9 inches per second. When the paper has advanced to a point where the plot tone Wheel 163 produces an output pulse, this output pulse will switch the flip-flop 145 to its B state and cause the plot mode clutch to disengage and the brake 175 to be energized. Because the plot tone wheel produces output pulses at the rate of one output pulse per of an inch of paper advance, the paper will have advanced of an inch when it is stopped by the brake 175. In this manner, each paper advance pulse applied to the flip-flop 145 Will cause a paper advance of of an inch when the circuit is operating in the plot mode. In this manner the paper can be advanced in increments of of an inch or of an inch. When curves or graphs are being plotted the increments of of an inch provide good resolution in the vertical direction.

Each paper advance pulse passing through the delay line 135 is also applied to a ribbon advance apparatus 177 which advances the ribbon one increment in response to each received pulse in the conventional manner so that the ribbon is advanced each time the paper is advanced.

FIG. 13 illustrates the details of the input register in block form. In FIG. 13 the eight ranks of the input register are designated by the reference number 179. Each of the ranks 179 comprises six flip-flops so that the rank is capable of storing a six-bit binary code. The six-bit binary character codes passing through the gates 79 are applied into the input register on six input channels 181. A set of six gates 183 is associated with each of the ranks 179 and the six input channels are applied to each set of gates 183. The gates 183 are enabled in sequence by output signals produced by the counter 81 on channels 185 in sequence. The counter 81 conveniently may be a flip-flop ring counter to produce the output signals on the channels in sequence. Thus each character code applied on input channels 181 will pass through a different set of gates 183 depending upon the count registered by the counter 81. Upon passing through a set of gates 183, the character code is stored in the six flip-flop stages of one of the ranks 179. Associated with each rank 179 is an additional fiip-fiop 187 for storing the clock pulse. The clock pulses applied to the register on input channel 89 are applied to the flip-flops 187 through gates 189, there being one gate 189 associated with each flip-flop 187 and rank 179. When the counter 81 produces a signal on one of its output channels 185 to enable one set of gates 183 associated with one of the ranks 179, it will also enable the gate 189 associated with this rank 179 so that the clock pulse applied on channel 89 will be stored in the flip-flop 187 along with the character code stored in the rank 179. Each time the counter 81 produces a signal on an output channel 185 to enable a set of gates 183 associated with a rank 179, this signal will also be applied to the next succeeding rank 179 to set this rank to zero so that it will be ready to receive the next character code when it is applied on input channels 181. In this manner the character codes are stored in sequence in the ranks 179 and a clock pulse is stored in a flip-flop 187 along with each character code stored. When the counter 91 reads out the character codes from the input register, it produces enabling signals on output channels 191 in sequence. The counter 91 conveniently may be a flip-flop ring counter to produce the output signals on channels 191 in sequence. Each rank 179 has a set of output gates 193 associated therewith. These sets of output gates 193 are enabled in sequence by the output signals produced by the counter 91 on the channels 191. When one of the sets of gates 193 is enabled, it will read out the character code stored in the rank 179 with which it is associated and send the character code to the delay line storage. In this manner the character codes are read out of the ranks 179 in sequence. Each time a signal is produced on one of the channels 191 by the counter 91, it will set the clock pulse flip-flop 187 associated with the same rank back to zero and it will also enable a gate 195 associated with the next succeeding rank and the clock pulse flip-flop 187 associated with this rank. Each gate 195 is connected to read out the clock pulse flipflop that it is associated with when the gate 195 is enabled. Thus, while the counter 91 is reading out one of the ranks 179, it is also reading out the condition of the clock pulse flip-flop 187 associated with the next succeeding rank. The clock pulse flip-flops 187 are connected to the gates 195 so that they will produce output signals only if they do not store a clock pulse. Thus, the gate 195 associated with the next succeeding rank will produce an output signal when the preceding rank is read out if the clock pulse flip-flop 187 associated with the next succeeding rank does not store a clock pulse. The outputs of the gates 195 are all applied through an OR gate 197 to the output channel 105. In this manner an output pulse is produced on channel 105 when no character code is stored in the next succeeding rank when the preceding rank is read out.

FIG. 14 illustrates details of the synchronizer 85. As shown in FIG. 14 the character code clock pulses from delay line 83 are applied to a flip-flop 199 to set the flipflop 199 in its A state. The two-megacycle clock pulses from the clock pulse generator are applied to a flip-flop 201 to cause the flip-flop 201 to switch from whatever state it is in to the opposite state. Accordingly, the fiip-fiop 201 produces output pulses on a channel 203 at a frequency of one megacycle. These pulses are applied through a delay line 205 which delays the pulses by A of a microsecond so that the output pulses coming out of the delay line 205 will be between the two-megacycle clock pulses produced by the clock pulse generator. The flip-flop 199 upon being set into its A state applies a signal to a flip-flop 207.to set the flip-flop 207 in its A state. The pulses passing through the delay line 205 out of phase with the two-megacycle clock pulses are applied to the flip-flop 207 to set the flip-flop 207 in its B state. Thus, the flip-flop 207 will be set in its B state at a time between the two-megacycle clock pulses. Upon being set in its B state the flip-flop 207 produces an out put pulse on channel 89. In this manner the synchronizer produces output pulses on channel .89 between the tWo-megacycle clock pulses. When the flip-flop 207 is set into its A state by the signal from the flip-flop 199 it will enable a gate 209. The pulses produced on channel 203 by the flip-flop 201 are also applied to the gate 209 and when the gate 209 is enabled, they will pass through the gate 209 to set the flip-flop 199 back to its B state. In this manner the flip-flop 199 is made ready to receive the next character clock pulse from the delay line 83.

FIG. 15 is a block diagram of one delay channel in the delay line storage 45 and illustrates how the bits are transferred into the delay channel and recirculated in the delay channel. As shown in FIG. 15 each bit of a character code from the input register is applied through an OR gate 211 to a pulse shaper 213, which shapes the pulse from the input register and applies it to a gate 215. The gate 215 also receives the two-megcycle clock pulses from the clock pulse generator and thus will pass the bits represented by the pulses from the pulse shaper 213 simultaneously with pulses produced by the clock pulse generator. The pulse shaper 213 produces an output pulse of sufiicient length so that a two-megacycle clock pulse will occur while the pulse representing the character bit is being produced by the pulse shaper 213. The character bit pulses on passing through the gate 215 are applied to the input of a 66-microsecond delay line 217. Upon passing through the 66-microsecond delay line 217, the character bit pulses are applied to a normally enabled gate 219, which can be disabled by a pulse from the multivibrator 137 to clear the delay line storage. After passing through the gate 219 the character bit pulses are amplified by an amplifier 221 and then applied back through the OR gate 211 to the input of the pulse shaper 213. In this manner the character bits are continuously recirculated. In the delay line storage binary ones are represented by pulses and binary zeros are represented by the absence of pulses so a character bit pulse represents a binary one. Each of the six character stages comprising the six delay channels of the delay line storage is identical to the stage shown in FIG. 15.

FIG. 16 illustrates the details of the comparison circuit 57. As shown in FIG. 16 the six bit binary character codes recirculating in the delay line storage 45 are applied to input channels 223 of the comparison circuit as they recirculate. Each of the input channels 223 is applied to a different bit comparison unit 225. Each of the bit comparison units is connected to receive a signal from a different stage of the binary counter 47. Each bit comparison unit 225 compares the binary signals recirculating in the delay channel to which it is connected with the signal stored in the stage of the binary counter to which it is connected. Each time it detects that the two binary sig- :nals are the same, the bit comparison unit will produce an output pulse. Each of the outputs of the bit comparison units 225 are connected to a different input of a six-way AND gate 227. This six-way AND gate will produce an output pulse on channel 123 when it receives pulses on all :six inputs simultaneously from the bit comparison units 225. This simultaneous application of pulses to the gate 227 will only occur when a character code is recirculated from the ends of the delay channels identical to the code of the count registered in the counter 47.

FIG. 17 illustrates the details of a bit comparison unit 225. As shown in FIG. 17 the signal on one of the channels 223 is applied to a gate 229 and the signal from one stage of the binary counter 47 is applied to the gate 229 on a channel 230. Thus, when a bit pulse representing a binary one is applied to the channel 223 shown in FIG. 17 and a binary one is registered in the stage of the binary counter 47 connected to the channel 230, the gate 229 will pass the bit pulse on channel 223. The input channel 223 is also connected to an inverter 231, which applies an enabling signal to a gate 223 whenever it does not receive a bit pulse on channel 223. The channel 230 is also connected to an inverter 235, which will apply an enabling signal to the gate 233 whenever the stage of the binary counter 47 to which the channel 230 is connected registers a Zero. The clock pulses from the two-megacycle clock pulse generator are also applied to the gate 233. If the gate 233 receives enabling signals from both the inverters 231 to 235, it will pass a two-megacycle clock pulse from the clock pulse generator. Thus, the gate 233 will produce an output pulse if a signal representing a binary zero is recirculated in the delay channel connected to the channel 223 shown in FIG. 17, and a binary zero is stored in the stage of the binary counter connected to channel 230. The output of the gate 229 and the output of the gate 233 are connected through an OR gate 237 to the output of the bit comparison unit. Accordingly the gate 237 will produce an output pulse whenever the binary signal recirculating in the delay channel connected to the channel 223 in FIG. 17 is the same as the binary signal stored in the stage of the binary counter 47 connected to the channel 230.

FIG. 18 illustrates the details of the selector matrix and how it selects a different stage in the hit register for 'each of the 132 counts that can be registered in the counter 99, which is an 8-stage binary counter. As shown in FIG. 18 two

conductors

239 and 241 are connected to each stage of the binary counter 99 so that the conductor 239 will have a high potential applied to it when the stage registers a binary one and the conductor 241 will have a high potential applied to it when the stage registers a binary zero. These

conductors

239 and 241 are connected in different combinations to 132 output conductors 243. The

conductors

239 and 241 are connected to the output conductors 243 by means of diodes, which are represented by circles at the intersections of the conductors 243 with the

conductors

239 and 241 and which are designated by the reference number 245. Each of the conductors 243 is connected to at least one of the

conductors

239 and 241 connected to each stage of the binary counter 49 so that each conductor 243 is connected to a combination of eight

conductors

239 and 241. Moreover, each of the 132 conductors 243 is connected to a different combination of the

conductors

239 and 241. Each of the conductors 243 is connected through a resistor 247 to a source of potential applied at a terminal 249. With this arrangement only one of the conductors 243 will have a high potential applied thereto and the particular one of the conductors 243 that will have the high potential applied thereto will depend upon the count registered in the counter 99. A different conductor 243 will have a high potential applied thereto for each different count that can be registered in the counter 99. The conductors 243 are each connected to the input of a different gate 251, each of which is connected to receive the hit pulses from the gate 125. The one of the gates 251 which receives a high potential applied thereto will be enabled and pass the pulse. The outputs of each of the gates 251 are connected to a different stage of the hit register 59. In this manner the hit pulses are stored in the stages of the hit register 59 corresponding to the count registered in the counter 99. From the above description it will be apparent that the apparatus of the present invention can plot curves and graphs at a very high speed with good resolution. The good resolution is obtained because of the character configuration of the special characters and because the paper can be advanced at small increments in the plot mode. The incremental advance of the paper in the plot mode can also be used in place of column spacing between 1 7 groups of letters or number. For example, suppose it is desired to print a plurality of separate groups of numbers providing some information about a particular point on a curve. By advancing the tape by of an inch before each group of characters or numbers are printed, the column spacing between the groups can be eliminated because the groups will be clearly distinguishable from each other due to the fact that the individual groups will be offset from each other by increments of of an inch. In this manner, more information may be printed opposite a particular point on a graph or curve that is being plotted.

The above-described apparatus and the special characters disclosed therein is a preferred embodiment of the invention. Instead of using these particular dot configurations as the special characters for printing graphs, other configurations can be used. For example, instead of using the paper feed to obtain the desired resolution in the vertical direction, additional special characters could be provided with the dots positioned in the character fields to provide resolution in the vertical direction. For example, in one special character a dot could be located in the upper left-hand corner of the character field, in another special character the dot could be located in the upper right-hand corner of the character field, in a third special character the dot could be located in the middle of the upper side of the character field, etc. These particular special characters subdivide the character field in the vertical direction in the same manner the special characters of the preferred embodiment described above subdivide the character field in the horizontal direction. These and many other modifications may be made to the above described preferred embodiment without departing from the spirit and scope of the invention, which is defined in the appended claims.

What is claimed is: 1. A curve plotting apparatus comprising: means defining a plurality of characters, each of said characters having a character field in which a character mark adapted to be printed is positioned, each of said character fields being of the same size and shape, the character mark of each of said characters having the same shape but being located in a difierent position in its character field, means to select one of said characters, and means to print the character mark of the selected character in a predetermined area on a medium, said predetermined area having the same size and shape as said character fields and the character mark of said selected character being printed in the same position in said predetermined area that the character mark is positioned in the field of the selected character. 2. A curve plotting apparatus as recited in claim 1 wherein said character marks are in the form of dots.

3. A curve plotting apparatus as recited in claim 1 wherein said means for defining a plurality of characters defines at least one additional character to be selected by said selecting means, said additional character having a character field in which two character marks are positioned, the character field of said additional character having the same size and shape as the character fields of said plurality of characters, the two character marks of said additional character each having the same shape as the character marks of said plurality of characters and being located in the same position in the character field of said additional character as two of the character marks of said plurality of characters are located.

4. A curve plotting apparatus comprising: means defining a plurality of characters, each of said characters having a character field in which a character mark adapted to be printed is positioned, each of said character fields being of the same size and shape, the character mark of each of said characters having the same shape but being located in a different position in its character field,

18 means to select one of said characters for each of a plurality of adjacent predetermined areas on a medium, said predetermined areas having the same size and shape as said character fields, and means to print in each of said predetermined areas on said medium the character mark of the character selected for such area, the character mark printed in each selected predetermined area being located in such predetermined area in the same position that the character mark is located in the field of the character selected for such predetermined area. 5. A curve plotting apparatus comprising: means defining a plurality of rows of characters, each of said characters having a character field in which a character mark adapted to be printed is positioned, each of said character fields being of the same size and shape, said character marks of characters in different rows being in difierent positions in their respective character fields and occupying only a small portion of such fields, means to sequentially move said rows of characters past a print station, means to advance a web on which printing can be carried out incrementally past said print station, and means to print selected characters in the row of characters at said print station on areas of said Web at said print station opposite the selected characters. 6. A curve plotting apparatus as recited in claim 5 wherein said means defining a plurality of rows of characters is a drum defining said characters on the periphery of said drum and said means to move said characters sequentially past a print station comprises means to rotate said drum.

7. A curve plotting apparatus as recited in claim 5 wherein said character marks are dots.

8. A curve plotting apparatus as recited in claim 5 wherein said character marks have the same shape.

9. A curve plotting apparatus comprising: means defining a plurality of rows of characters, each of said characters having a character field in which a character mark adapted to be printed is positioned, each of said character fields being of the same size and shape, said character marks in characters of different rows being in different positions in their respective character fields and occupying only a small portion of such fields, means to sequentially move said rows of characters past a print station, means to advance a Web on which printing can be carried out incrementally past said print station in increments equal to a fraction of the length of said character fields, and means to print selected characters in the row of characters at said print station on areas of said web at said print station opposite the selected characters. 10. A curve plotting apparatus comprising: means defining a plurality of rows of characters, each of said characters having a character field in which a character mark adapted to be printed is positioned, each of said character fields being of the same size and shape, the character marks in a first one of said rows of said characters being positioned in the middle of their respective character fields and occupying a small portion of such character fields, the character marks of the characters of a second one of said rows being positioned in the middle of the left-hand side of their respective character fields and occupying a small portion of such fields, the character marks of the characters in a third one of said rows being positioned in the middle of the right-hand side of their respective character fields and occupying only a small portion of such fields, means to sequentially move said rows of characters past a print station,

19 means to advance a web on which printing can be carried out incrementally past said print station, and means to print selected characters in the row of characters at said print station on areas of said web at said print station opposite the selected characters. 11. A curve plotting apparatus comprising: means defining a plurality of rows of characters, each of said characters having a character field in which a character mark adapted to be printed is positioned, each of said character fields being of the same size and shape, the character marks in the characters of a first plurality of different ones of said rows being in different positions in their respective character fields and occupying only a small portion of such fields, the characters of a second plurality of said rows being alpha-numeric characters,

means to sequentially move said rows of characters past a print station, means to advance a web on which printing can be carried out incrementally past said print station, and means to print selected characters in a row of characters at said print station on areas of said web at said print station opposite the selected characters.

12. A curve plotting apparatus comprising:

means defining a plurality of alpha-numeric characters,

and a plurality of special characters, each of said characters having a character field in which a character mark adapted to be printed is positioned, each of said character fields being of the same size and shape, the character mark of each of said special characters having the same shape but being located in a different position in its character field,

means to select one of said characters, and

means to print the character mark of the selected character in a predetermined area on a medium, said predetermined area having the same size and shape as said character fields and the character markof said selected character being printed in the same position in said predetermined area that the character mark is positioned in the field of the selected character.

13. A curve plotting apparatus as recited in claim 12 wherein the character marks of said special characters are in the form of dots.

14. A curve plotting apparatus as recited in claim 12 wherein said means .for defining a plurality of characters defines at least one additional special character to be selected by said selecting means, said addition special character having a character field in which two character marks are positioned, the character field of said additional special character having the same size and shape as the character fields of said plurality of special characters and said plurality of alpha-numeric characters, the two character marks of said additional special character each having the same shape as the character marks of said plurlity of special characters and being located in the same position in the character field of said additional character as two of the character marks of said plurality of special characters are located.

15. A curve plotting apparatus comprising:

means defining a plurality of alpha-numeric characters and a plurality of special characters each of said characters having a character field in which a character mark adapted to be printed is positioned, each of said character fields being of the same size and shape, the character mark of each of said special characters having the same shape but being located in a different position in its character field,

means operable to select one of said characters for each of a plurality of adjacent predetermined areas on a medium, said predetermined areas having the same size and shape as said character fields, and

means to print in each of said predetermined areas on said medium the character mark of the character selected for such area, the character mark printed in 20' each selected predetermined area being located in such predetermined area in the same position that the character mark is located in the field of the character selected for such predetermined area.

16. A curve plotting apparatus comprising:

means defining a plurality of rows of alpha-numeric characters and special characters, each of said characters having a character field in which a character mark adapted to be printed is positioned, each of said character fields being of the same size and shape, said character marks of said special characters in different rows being in different positions in their respective character fields and occupying only a small portion of such fields,

means to sequentially move said rows of characters past a print station, means to advance a web on which printing can be carried out incrementally past said print station, and means to print selected characters in the row of characters at said print station on areas of said web at said print station opposite the selected characters. 17. A curve plotting apparatus as recited in claim 16 wherein said means defining a plurality of rows of char-acters is a drum defining said characters on the periphery of said drum and said means to move said characters sequentially past a print station comprises means to rotate said drum.

18. A curve plotting apparatus as recited in claim 16 wherein the character marks of said special characters are dots.

19. A curve plotting apparatus as recited in claim 16 wherein the character marks of said special characters have the same shape.

20. A curve plotting apparatus comprising: means defining a plurality of rows of alpha-numeric characters and special characters, each of said characters having a character field in which a character mark adapted to be printed is positioned, each of said character fields being of the same size and shape, said character marks in said special characters of different rows being in difierent positions in their respective character fields and occupying only a small portion of such fields, means to sequentially move said rows of characters past a print station,

means to advance a web on which printing can be carried out incrementally past said print station in increments equal to a fraction of the length of said character fields, and

means to print selected characters in the row of characters at said print station on areas of said Web at said print station opposite the selected characters. 21. A curve plotting apparatus comprising: means defining a plurality of rows of alpha-numeric characters and a plurality of rows of special characters, each of said characters having a character field in which a character mark adapted to be printed is positioned, each of said character fields being of the same size and shape, the character marks in a first one of said rows of said special characters being positioned in the middle of their respective character fields and occupying a small portion of such character fields, the character marks of the characters of a second one of said rows of said special characters being positioned in the middle of the left-hand side of their respective character fields and occupying a small portion of such fields, the character marks of the characters in a third one of said rows of said special characters being positioned in the middle of the right-hand side of their respective character fields and occupying only a small portion of such fields,

means to sequentially move said rows of characters past a print station,

means to advance a web on which printing can be carried out incrementally past said print station, and

meansto print selected characters in the row of characters at said print station on areas of said web at said print station opposite the selected characters.

22. A curve plotting apparatus comprising:

means defining a plurality of characters, each of said characters having a character field in which a character mark adapted to be printed is positioned, each of said character fields being of the same size and shape, a first of said characters consisting of a single character mark, a second of said characters consisting of a single character mark of the same size and shape as the character mark of said first character and located in a position in its character field different from the position of the character mark in the character field of said first character, a third of said characters comprising two character marks each of the same size and shape as the character marks of said first and second characters and located in the same positions in the character field of said third character as the character marks of said first and second characters are positioned in the character fields of said first and second characters,

means to select one of said characters, and

means to print the character mark configuration of the selected character in a predetermined area on a medium, said predetermined area having the same size and shape as said character fields, and the character mark configuration of the selected character being printed in the same position in said predetermined area that the character mark configuration is positioned in the field of the selected character.

23. A curve plot-ting apparatus comprising:

means defining a plurality of characters, each of said characters having a character field in which a character mark adapted to be printed is positioned, each of said character fields being of the same size and shape, a first of said characters consisting of a single character mark occupying a small portion of its character field, a second of said characters consisting of a single character mark occupying a small portion of its character field and located in a position in its character field different from the position of the character mark in the character field of said first character, a third of said characters comprising two character marks each occupying a small portion of the character field of said third character and located in the same positions in the character field of said third character as the positions of the character marks of said first and second characters in the character fields of said first and second characters,

means to select one of said characters, and

24. A curve plotting apparatus comprising:

means defining a plurality of said characters, each of said characters having a character field in which a character mark adapted to be printed is positioned, each of said character fields being of the same size and shape, a first of said characters consisting of a single character mark and occupying a small portion of its character field, a second of said characters consisting of a single character mark of the same size and shape as the character mark of said first character and located in a position in its character field different from the position of the character mark in the character field of said first character, a third of said characters comprising two character marks each the same size and shape as the character mark of said first character and located in the same positions 22 in the character field of said third character as the positions of the character marks of said first and second characters in the character fields of said first and second characters,

means to select one of said characters, and

25. A curve plotting apparatus comprising:

means defining a plurality of rows of characters, each of said characters having a character field in which a character mark adapted to be printed is positioned, each of said character fields being of the same size and shape, said character marks of the characters in difiFerent rows being in different positions in their respective character fields and occupying only a small portion of such fields,

means to sequentially move said rows of characters past a print station,

means to advance a web on which printing can be carried incrementally past said print station,

buffer storage means operable to store signals representing a row of characters to be printed, and means operable in response to the signals stored by said buffer storage means to print selected characters in the row of characters at said print station on areas of said web at said print station opposite the selected characters as each row of characters is moved past said print station to thereby print the row of characters represented by the signals stored in said bufier storage means. 26. A curve plotting apparatus as recited in claim 25 wherein said means defining a plurality of rows of characters is a drum defining said characters on the periphery of said drum and said means to move said characters sequentially past the print station comprises means to rotate said drum.

27. A curve plotting apparatus comprising: means defining a plurality of rows of characters, each of said characters having a character field in which a character mark adapted to be printed is positioned, each of said character fields being of the same size and shape, said character marks of characters of different rows being in different positions in their respective character fields and occupying only a small portion of such fields. means to sequentially move said rows of characters past a print station,

means to advance a web on which printing can be carried out incrementally past said print station in increments equal to a fraction of the length of said character fields,

bufi'er storage means operable to store signals representing a row of characters to be printed,

means operable in response to the signals stored by said bufier storage means to print selected characters in the row of characters at said print station on areas of said web at said print station opposite the selected characters as each row of characters is moved past said print stat-ion to thereby print the row of characters represented by the signals stored in said buffer storage means.

28. A curve plotting apparatus comprising:

means defining a plurality of rows of characters, each of said characters having a character field in which a character mark adapted to be printed is positioned, each of said character fields being of the same size and shape, the character marks of the characters in a first one of said rows being positioned in the middle of their respective character fields and occupying a

Claims

1. A CURVE PLOTTING APPRATUS COMPRISING: MEANS DEFINING A PLURALITY OF CHARACTERS, EACH OF SAID CHARACTERS HAVING A CHARACTER FIELD IN WHICH A CHARACTER MARK ADAPTED TO BE PRINTED IS POSITIONED, EACH OF SAID CHARACTER FIELDS BEING OF THE SAME SIZE AND SHAPE, THE CHARACTER MARK OF EACH OF SAID CHARACTERS HAVING THE SAME SHAPE BUT BEING LOCATED IN A DIFFERENT POSITION IN ITS CHARACTER FIELD, MEANS TO SELECT ONE OF SAID CHARACTERS, AND MEANS TO PRINT THE CHARACTER MARK OF THE SELECTED CHARACTER IN A PREDETERMINED AREA ON A MEDIUM, SAID PREDETERMINED AREA HAVING THE SAME SIZE AND SHAPE AS SAID CHARACTER FIELDS AND THE CHARACTER MARK OF SAID SELECTED CHARACTER BEING PRINTED IN THE SAME POSITION IN SAID PREDETERMINED ARES THAT THE CHARACTER MARK IS POSITIONED IN THE FIELD OF THE SELECTED CHARACTER.