US3459287A - Rolling anvil member control means for serial printer - Google Patents

Description

DS- 5,1969 J. Y. AVINS ETAL 3,459,287

ROLLING ANVIL MEMBER CONTROL MEANS' FOR SERIAL PRINTER Filed um 7, 196'! v z Sheets-Sheet 1 li tdrv gy United States Patent 3,459,287 ROLLING ANVIL MEMBER CONTROL MEANS FOR SERIAL PRINTER Jeremiah Y. Avins, Kendall Park, and James C. Miller,

Pennington, N.J., assignors to RCA Corporation, a corporation of Delaware Filed Nov. 7, 1967, Ser. No. 681,286 Int. Cl. B41j 25/18 US. Cl. 197-1 Claims ABSTRACT OF THE DISCLOSURE A printer apparatus is operated in a predetermined sequence following an interruption of the printing instructions in order to provide an operator with an unobstructed view of all the printed characters.

Background of the invention High speed printers using a moving print structure positioned in front of the printing lines have been char- .acterized by a lack of clear visibility of the last characters which were printed before the occurrence of an interruption of the printing operations. In order to allow the operator to view all of the printed characters during such a break in the printing cycle, apparatus embodying the present invention is arranged to cycle the print structure through a predetermined sequence following an interruption in the print instructions in order to position the print structure at a location wherein it does not hide any of the printed characters.

Brief summary of the invention The present invention is directed to a printer apparatus having a printing mechanism arranged to print characters on the visible surface of a printing medium. The printing mechanism is actuated by control signals to print and to rnove .along a path adjacent to the surface of the printing medium duing the duration of each printing instruction signal. When the instruction signal sequence is interrupted by a time gap between instructions, he printer apparatus is effective to automatically move the printer mechanism to a predetermined position which provides an unobstructed view of all the printed characters. The printer mechanism is returned in a prearranged cycle to a printing position when a new printing instruction signal is supplied to the printer apparatus.

Brief description of the drawing FIGURE 1 is a pictorial diagram of a printer apparatus suitable for use with the present invention;

FIGURE 2 is a block diagram of a logic system suitable for use in practicing the present invention; and

FIGURE 3 is a block diagram of an anvil drive control circuit suitable for use with the logic system shown in FIGURE 2.

Detailed description of the invention Referring to FIGURE 1 in more detail, there is shown an example of a printer apparatus embodying the present invention. The printer uses a printing anvil structure 1 which is movably supported on a pair of locating ways 2, 3. The anvil 1 is uniformly moved (i.e., at a constant speed) with bidirectional motion along the ways 2, 3 by a motor drive means 4 connected to a first pulley 5 The pulley 5 supports a drive cable 6 which is attached at its ends to the anvil 1. The cable 6 is guided in a narrow loop configuration by a second pulley 10 which is spaced from the first pulley 6 by the length of the ways 2, 3 to maintain the cable 6 in a. tensioned state. The second pulley 10 is .attached to an analog-to-digital converter structure 12 arranged to provide a digital signal representative of the position of the pulley 10 and the anvil 1. An example of such a converter 12 is shown in FIGURE 1 in the form of a conventional code wheel 14 having perforations therein arranged in a coded pat te-rn. A light source 15 is arranged to illuminate a plurality of light sensitive transducers 16 through the code wheel perforations.

The anvil 1 is positioned in front of and separated from a printing surface comprising a first layer of socalled action paper 18 on which is produced a visible mark when pressure is applied to a selected .area thereon, such paper being well-known in the art. Behind the action paper 18, are positioned alternate layers of carbon papers and printing papers for producing multiple copies of the printed matter. The layers of printing papers and carbon papers, hereinafter referred to as a printing package 19 are positioned against a composite assembly of transverse printing bars 20. These printing bars 20 are selectively urged against the rear of the printing package 19 by respective ones of a plurality of solenoids 22 connected to the bars 20. This movement of the print bars is effective to bring the print package 19 into printing contact with the anvil 1. Thus, the vertical position and horizontal length of the print mark are determined by the position of the selected print bar and the distance that the anvil moves while it is in printing contact with the printing package 19, respectively.

The energization of the solenoids 22 is controlled by a print logic unit 24 which receives input signals at an input terminal 26. The output signals from the trans ducers 16 are applied to the print logic 24 to provide an indication of anvil position, while the motion of the anvil 1 is controlled by an output signal from the print logic 24 applied to the motor 4 along a line 28. Thus, the anvil 1 is uniformly driven by a signal from the logic 24. When the signals from the transducers 16 indicate that a print location has been reached, a selected number of the print bars 20 are actuated and a resulting print mark is made on the print package 19. A character is composed by a sequence of adjacent marks while spaces between characters are effected by moving the anvil 1 without actuating the print bars 20. It is to be noted that the anvil 1 is in continuous .and uniform motion during the printing operation while the print bars 20 are selectively moved against the print package 19. Further details of the structure and mode of operation of similar printing mechanisms may be found in Patent No. 3,317,017 of C. J. Young which issued on May 2, 1967 and .a patent application of E. J. West having Ser. No. 550,055, filed on May 13, 1966, both of which are assigned to the assignee of the present invention.

In the present invention, the anvil 1 and the print package 19 are oriented to allow an operator to view the printing as it appears on the surface of the front action paper 18. In order to permit a clear view of the printed characters, the print logic 24 is arranged to move the print anvil 1 during an interruption in the printing operation to a position wherein it does not cover the printed information. In order to resume the printing operation, the anvil 1 is returned to a print position when the print logic 24 detects the presence of input instructions for controlling further printing operations. Thus, the sequence of operations initiated by the print logic 24 following the end of a print operation and the absence of subsequent printing commands is as follows. First, the anvil 1 is moved several character spaces in the direction of printing motion, i.e. to the right as viewed in FIGURE 1. During this time, the print bars 20 are unactuated and no printing is performed. The anvil 1 is then stopped at a position which allows the operator a clear view of all the printed characters. When a new input instruction is sensed by the print logic 24, the anvil 1 is returned to a position which is over the printed characters and several characters before the last printed character. The anvil 1 is momentarily stopped at this position, its direction of motion is reversed and it is uniformly driven again in the print direction. When a print position is reached for a new character, as determined by the print logic 24 from the analog-to-digital converter means 12, the print bars 20 are selectively actuated to print the desired character. If the printing instructions are subsequently interrupted, the above cycle of the anvil 1 is repeated. Thus, when the anvil 1 is not being used for printing, it is automatically positioned in a predetermined location relative to the last printed character, which permits the operator to view all of the printed characters.

In FIGURE 2, there is shown an overall logic system suitable for operating the printer apparatus shown in FIGURE 1 while in FIGURE 3 there is shown an example of an anvil logic circuit suitable for use with the system of FIGURE 2. This anvil logic circuit is used to introduce a fixed cycle for the anvil 1, as previously described, following the interruption in the printing instructions. As mentioned previously, the general printer logic system 24 shown in FIGURE 1 detects the presence of input control signals at terminal 26 and converts these control signals into operating signals for the printer solenoids 22. In FIGURE 2, the printer logic 24 is enclosed by dashed lines. The input control signals representing characters to be printed are applied by a suitable source (not shown) e.g., a digital computer, to input terminal 26. The input terminal 26 is connected to an input buffer 31. The input butter is operative to temporarily store these input character signals and may also be used to perform a serial-to-parallel conversion.

The output signals from the buffer 31 are applied to a selection register 33 which produces an output signal in response to a character control signal. This output signal is applied to a character generator 35. The character generator 35, in turn, produces a group of actuating signals which are applied to the bar driver circuits 37 of corresponding printer bars. The bar drivers 37 supply the energizing signals to respective ones of the bar solenoids 22. Thus, the input signal is decoded by the character generator 35 into control signals for operating the solenoids 22 to produce a printed character as dictated by the input signal.

The movement of the anvil 1 (shown in FIGURE 1) is coordinated with the location of the last printed character by a comparator means 40. The comparator 40 detects an equality between a signal representative of the position of the last printed character and a signal representative of the anvil position, and produces an output signal on an output line 43 representative of a detected equality. Specifically, the position of the last printed character is stored in a counter means identified in FIG- URE 2 as a last character position means 42. This position means 42 counts discrete signals from a clock 54, which signals occur each time that either a character is printed or a space inserted. Thus, the count stored in the counting means 42 is representative of the number of character locations that have been used from the start of a printing line at the margin of the printing surface. Further, the counting means 42 has an initial count of one so that the total count is representative of a new printing location. This count is compared with a signal from an anvil position means 44- which may be a code wheel means 12 as shown in FIGURE 1.

The output line 43 is connected to an anvil control means 46 which is operative to control the anvil drive motor 4 by means of reverse and forward control signals applied thereto over a pair of output lines 50a and 50b, respectively (shown in FIGURE 1 as line 28). The anvil drive control 46 is also controlled by a pair of signals applied on lines 51a and 511) from the input buffer 31. A predetermined state of the signals on lines 51a and 51b is representative of the presence of an input signal in the buffer 31 while the reverse state of the signals on lines 51a and 51b is representative of the lack of an input signal in the buffer 31. A third output signal from the drive control 46 is applied over an output line 52 to the bar drivers 37 as a synchronizing, or strobe signal. The output signal on line 50b from the drive control 46 is further applied as an enabling level to a gate circuit 53. Thus, the gate 53 is enabled by a forward drive control signal from the drive control 46.

An input signal for the gate 53 is applied from the comparator output line 43. An output signal from the gate circuit 53 is applied as a reset signal to a system timing, or clock means 54 and to the selection register 33. The clock means 54 is operative to sequence the operation of the character generator 35 and to produce a timing signal for advancing the character counter 42. Thus, a first clock output signal for sequencing the character generator 35 is applied thereto on line 56. A second clock output signal for advancing the counter 42 at the end of each character is applied to the counter 42 over line 57.

In operation, the printer system shown in FIGURE 2 translates the input signals applied to the buffer 31 into drive signals for the printer bars and drives the anvil during the printing process. The anvil drive control 46 is also effective to drive the anvil during a nonprinting interval occasioned by a lack of input signals in the buffer 31 to a position wherein the anvil does not obstruct any of the printed characters from view by an operator. A suitable circuit for the drive control means 46 is shown in FIG- URE 3 and described in detail hereinafter. The input signals stored in the buffer 31 are sequentially transferred into the selection register 33. The character generator 35 is controlled by the input signals stored in the selection register 33 to produce actuating signals for the bar drivers 37 which control the solenoids 22.

The anvil drive means 46 produces forward and reverse drive control signals for the drive motor means 4. The forward drive signal is used to move the anvil during the printing operation and to position the anvil in a non-obstructing position between printing operations, while the reverse signal is used to return the anvil to a printing location following an interruption in the printing operation and to return the anvil to the starting margin at the end of a line of printing, The anvil drive means 46 is controlled by the output signal from the comparator 40 indicative of the location of the anvil in a proper printing position and by signals from the input buffer 31 indicative of either the presence or absence of input signals. As previously mentioned, the count in the counter 42 is representative of the number of character spaces which have been used from the start of the printing line plus one. This count is compared by the comparator 40 with a signal from the anvil position means 44 to determine when the anvil is in position for printing a new character. If an input signal is present in the buffer 31 at the time that the anvil is in a proper printing position and is moving in a forward direction, the drive control means 46 produces a timing, or strobe, signal on line 52 for the bar drivers 37. This signal allows the character generator 35 to operate the solenoids 22 during the time that the anvil is at the character printing position.

The forward drive signal is also applied to the gate 53 to control the gating of a timing signal from the comparator 40. This timing signal is normally applied to the selection register 33 to clear the register for the next input signal and to the clock 54 to reset its operation for the start of a new character. A first clock output signal is applied to the character generator 35 to sequence the operation of the character generator 35 in operating the bar drivers 37. A second clock output signal is applied to the character counter 42 to advance the stored count for each character or space which is used in the printing operation.

The counter 42 is automatically reset at the end of a printing line to return the count to a value representing the start of a new printing line i.e., a one count. Thus, during the continued presence of input signals in the bufifer 31, the anvil is uniformly and continuously driven across the printing line by the motor means 4 under control of the anvil drive 46, and the aforesaid printing cycle is repeated at each character location. This operation is partly controlled by the input signals to the anvil drive 46 on lines 51a and 51b from the buffer 31 indicative of the presence of input signals in the buffer 31. Further, at each character position, the comparator 40 is operative to produce an output signal on line 43, which signal is also applied to the anvil drive control 46 to generate the strobe signal on line 52. Concurrently with this forward motion of the anvil, the input signals are transferred to the register 33. The signals in the register 33 are applied to the character generator 35 which converts these input signals to energizing signals for the bar drivers 37.

The coincidence output signal from the comparator 40 on line 43 is also applied to the gate 53. This gate is enabled during the presence of the forward drive signal on the line 50b. The output signal from the gate 53 is applied to the register 33 to initiate a new signal loading operation for the input signals from the butter 31. Further, this output signal is applied to the clock 54 to initiate a new sequence cycle for the character generator 35. Accordingly, when a new character position is reached, the output signal from the comparator 40 is effective to control the loading of new character input signals into the register 33 and to initiate the character generator sequence to print the new character, At the end of the printing cycle of each character, the clock 54 is operative to supply a second timing signal on line 57 to advance the position counter 42. This advance terminates the output signal on line 43 from the comparator 40. Subsequently, at the next printing location a new coincidence is detected between the counter signal and the anvil position signal from the anvil position detector 44 to repeat the aforesaid printing cycle.

When the input signals in the bufiier 31 are interrupted, i.e., no new input signals are present in the butter 31, the output signal levels on lines 51a and 5112 are switched to corresponding signal levels indicative of the absence of input signals in the buffer 31. These signal levels alter the output signals from the drive control 46. Specifically, the strobe signal on line 52 is inhibited, and the forward drive signal on line 50b is terminated after a fixed time delay. This time delay is chosen to allow the anvil to move to a position which is several character spaces past the last printed character. The final position of the anvil, thus, is efiective to permit an unobstructed view of all the printed characters.

The presence of new input signals in the buffer 31 following the aforesaid interruption, reinstates the signal levels on the lines 51a and 51b to a state indicative of the presence of these signals in the butter 31. These new signal levels on lines 51a and 51b initiate an anvil control cycle by the drive control 46 to return the anvil to a printing position. First, the drive control 46 supplies a reverse drive signal on line 50a to the motor means 4 for a predetermined interval. This interval is selected to allow the anvil to return to a position preceding the last printed character. At the end of the reverse drive interval, the forward drive signal on line 50b is reinstated and the anvil is uniformly driven forward. When a coincidence is detected by the comparator 40 between the anvil position detector 44 and the count in the position counter 42, the comparator 43 applies a control signal pulse on line 43 t0 the drive control 46. In response thereto, the drive control 46 produces the strobe signal on line 52 and the printing cycle is repeated for the first of the new characters. Accordingly, during each interruption in the input signals, the anvil is moved to a position which is clear of the printed characters to permit the operator to view all the printed characters. Further, when new input signals are supplied to the buffer 31, the anvil is driven to a proper printing location, and the new input instructions are executed.

In FIGURE 3, there is shown an example of a suitable logic circuit for use as the anvil drive control means 46, shown in FIGURE 2. The input and output lines are numbered to correspond with the notation used in FIG- URE 2. The input line 51a is connected to a first input terminal of a first NAND gate 60. The input line 51b is connected to a first input terminal of a second NAND gate 62. The input line 43 is connected (a) through an inverter 63 to a second input terminal on the first NAND gate 60 and b) to the second NAND gate 62. An output line from the second NAND gate 62 is connected to the set input of a first flip-flop 64. The reset input of the flip-flop 64 is connected to the input line 51b. The 1 output terminal of the flip-flop 64 is connected to the input of a first single-shot 66. The output circuit of the single-shot 66 is connected to the set input of a sec ond fiip-flop 68 and to the reverse output line 50a. The 0 output terminal of the first flip-flop 64 is connected to the input of a second single-shot 70'. The output circuit of the second single-shot 70 is connected to the reset input of the second flip-flop 68. The 1 output terminal of the second flip-flop 68 is connected to the forward output line 50b and to a third input terminal of the first NAND gate 60. The output circuit of the first NAND gate is connected to the strobe line 52.

In operation, the circuit shown in FIGURE 3 is operative to maintain a forward drive control signal on line 58b during the time that the input signals on lines 51a and 51b are representative of the presence of input signals in the butter 31 (shown in FIGURE 2). Assume a high level signal on line 51a is representative of signals in the butter 31. Thus, the signal level on line 51a is high when signals are present in the butter 31 while, at this time, the signal level on line 51b is low. Assume that the second flip-flop 68 is in a set state. This state produces a high level signal from the 1 output of the flip-flop 68. This output level is applied as a forward drive signal to the motor means 4 (shown in FIGURE 2) on line 50b. Additionally, this output level is applied to the first NAND gate 60. Thus, two of the inputs to the NAND gate 60 are high level signals under the aforesaid operating conditions.

The third input to the NAND gate 60 from the inverter 63 goes high, i.e., a high level pulse, when the comparator 40 (shown in FIGURE 2) detects a coincidence between the anvil position and a proper printing location. In other words, the output level on line 43 is normally high and the occurrence of a detected coincidence produces a pulse signal comprising a change from the high level and return. This pulse is inverted by the inverter 63 and applied to the NAND gate 60. The output from the NAND gate 60 follows this level change and goes low to produce a strobe signal pulse on output line 52. Since the first two inputs to the NAND gate 60 will remain high when the buffer 31 has input signals and the forward drive signal is present, the strobe output on line 52 will be produced for each coincidence signal from the comparator 40 appearing on line 43. Further, since the signal level on line 51b is low when input signals are present in the buffer 31, the output signal from the second NAND gate 62 will remain high since one of its input signals is a low level signal. This high level signal has no effect on the flip-flop 64 since the flip-flop is actuated only by a low level signal. Accordingly, the anvil will continue to be driven forward and a character printed or space inserted at each printing location.

When the buffer 31 is empty, e.g., following an interruption in the input signals supplied thereto, the signal on line 51a goes low and the signal on line 51b goes high. The low level signal on line 51a maintains the output level from the NAND gate 60 at a high level to inhibit the strobe output level on line 52. With the normally high signal level on line 43, both inputs to NAND gate 62 are now high and its output goes to a low level which sets the first flip-flop 64. The output of the flip-flop 64 will, now, go low to trigger the second single-shot 70. Since the anvil is still moving, the comparator 40 will produce a coincidence signal pulse on line 43 at the next printing location following the interruption. This signal will have no effect on the first NAND gate 60 since the input on line 51a remains low.

At the end of the time delay represented by the duration of a high level pulse from the single-shot 70, the output signal level from the single-shot 70 goes low. This change in state is effective to reset the second, or output, flip-flop 68. When the flip-flop 68 is reset, its 1 output goes low to terminate the forward drive signal. It is to be noted that the forward drive signal was present during the time delay of the second single-shot 70. Accordingly, the anvil is driven past the location of the last printed character to a predetermined position before the forward drive signal is interrupted.

When new input signals are present in the buffer 31, the signal levels on lines 51 are again reversed with line 51a going high and line 51]) going low. The change in level on line 51b is effective to reset first flip-flop 64. Accordingly, the 1 output level goes low from the former high level state. This changes in state is effective to trigger the first single-shot 66. The output signal from the single- :shot 66 is a high level pulse having a predetermined duration. This high level pulse is applied over line 50a as a reverse control signal to the motor means 48 (shown in FIGURE 2. As a result, the anvil is driven backwards for a fixed period of time. This reverse drive period is arranged to bring the anvil to a position preceding the last printed character.

At the end of the pulse from the single-shot 66, the high level reverse signal is switched to a low level signal. This change in state is effective to terminate the reverse drive signal and to set the flip-flop 68. The flip-flop 68 then restores a high level forward drive signal on line 50b. Accordingly, the anvil is now driven forward. Concurrently, the high level signal .on line 51a is applied to the first NAND gate 60. When the comparator 40 detects a proper printing position, the coincidence signal on line 4-3 is inverted by the inverter 63 to a high level pulse, and the output from the first NAND gate 60 is a low level pulse since all three inputs thereto are now high. This output pulse appears on the strobe 52 to trigger a printing operation. Since the signal on line 51b will remain low until there is another interruption in the input signals in the buffer 31, the output level from the second NAND gate 62 will remain high and the output flip-flop 68 will be held in a set state. It is to be further noted that while a coincidence pulse appeared on the comparator line 43 during the reverse motion of the anvil when the anvil passed the proper printing location in a reverse direction, this level change has no effect on NAND gate 62 since the forward drive signal level was low during this time. Modifications may be made to the logic circuit of FIG- URE 3, e.g., to provide for a carriage return operation, to set the circuit in an initial state and to prevent reverse movement of the anvil when it is in the starting margin, Without departing from the scope of the present invention.

What is claimed is:

1. A printer comprising means for selectively printing symbols, input signal means operative to control a printing operation of symbols by said means for printing in response to input signals applied to said input means, means for translating said means for printing alon a printing line, control means connected to said means for translating, said control means being responsive to said input signal means to normally energize said means for translating to drive said means for printing during a printing operation along said printing line and being operative after an interruption in said input signals to drive said means for printing to a stop position along said printing line clear of all of the printed symbols and to return said means for printing to a printing position along said printing line for the next symbol to be printed when said input signals are again present in said input means.

2. A printer as set forth in claim 1 wherein said stop position is located along said line of printing in the direction of motion of said means for printing during said printing operation.

3. A printer as set forth in claim 2 wherein said input signal means includes an input signal buffer for temporarily storing said input signals and a character generator responsive to input signals in said buffer to generate printing control signals for operating said printing means.

4. A printer as set forth in claim 3, wherein said means for printing includes a plurality of stacked separately supported bars facing a printing medium and extending from side-to-side thereof, an anvil means positioned on the reverse side of the printing medium from said bars and arranged to be operatively associated with said bars, and solenoid means responsive to said character generator for selectively urging said bars against said anvil, and said means for translating includes a motor means for uniformly driving said anvil across the printing medium.

5. A printer as set forth in claim 4, wherein said control means includes means responsive to said input signals and operative to normally supply a forward drive signal to said motor means during said printing operation and after an interruption in said input signals in said buffer to terminate said drive signal to said motor means after a fixed time interval starting at the time of said interruption in said input signals.

6. A printer as set forth in claim 5, wherein said control means includes further means responsive to the presence of said input signals in the said input buffer following said interruption to provide a reverse energizing signal to said motor means for a predetermined period of time and, subsequently, to re-establish said forward drive signal to said motor means.

7. A printer as set forth in claim 1 wherein said control means includes means responsive to said input signals and operative to normally supply a forward drive signal to said means for translating during said printing operation and after an interruption in said input signals to terminate said drive signal to said means for translating after a fixed time interval starting at the time of said interruption in said input signals.

8. A printer as set forth in claim 7 wherein said control means includes further means responsive to the presence of said input signals in said input signal means following said interruption to provide a reverse energizing signal to said means for translating for a predetermined period of time and, subsequently, to re-establish said forward drive signal to said means for translating.

9. A printer as set forth in claim 8 wherein said control means includes a first signal delay means determina- 2,996,002 8/1961 Adler et a1. 101--269 tive of said fixed time interval and a second signal delay 3,058,416 10/1962 Grant et a1. 101269 means determinative of said predetermined period of 3,232,230 2/ 1966 Sheldon 101269 time. 3,291,042 12/1966 Christoff et a1 lOl---93 10. A printer as set forth in claim 9 wherein said means 5 3,292,530 12/ 1966 Martin 101-93 for printing includes means for signalling the position 3,317,017 5/1967 Young 197--1 of said means for printing along said printing line to 3,330,208 7/1967 Eckel 101-93 said input signal means to synchronize said printing opera- 3,358,597 12/ 1967 Barbour 101--269 tion with a printing location along said line of printing.

10 WILLIAM B. PENN, Primary Examiner References Cited UNITED STATES PATENTS 2,775,936 1/1957 Curtis 101269 101%; 197-176 2,831,424 4/1958 MacDonald 101--93

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