JPS62103152A - Shuttle type serial line printer - Google Patents

Abstract

PURPOSE:To make the timing of printing accurate, by forming a position detection pulse by making reference to three reference voltages set near the central level of a sensor output signal. CONSTITUTION:Because when the level of the signal Sa from an amplifier 314a is higher than a zero cross level Vc in a printing stop period Co, Sa is not lower than Vc at the end of a period Cl and the start of a period Cl, the voltage Eal of an amplifier 320a keeps '0' level. Then, the last pulse Pie is generated at the end te of the period Cl' and the first pulse Pis is generated at the start ts of the period Cl. Further, when the level of Sa is lower than Vc, Sa is lower than Vc at both ends of the period Cl' and the start of the period Cl. Thereby, the voltage Eal changes from '0' level to '1' level at the end of the period Cl', keeps '1' level during the stop period Co and changes from '1' level to '0' level at the start of the period Cl. As a result, the first pulse Pis is generated at the time ts.

Description

Detailed Description of the Invention (Industrial Application Field) The present invention relates to a shuttle type serial line printer that uses a magnetic linear scale and a magnetoresistive element as a means for creating print drive timing, and in particular, to This is to obtain accurate and stable printing timing at the edge.

(Prior Art) / In the Yattle type soreal line printer, as shown in FIG. 10, the direction A is approximately perpendicular to the paper feeding direction B.

A' is equipped with a head bank 1 in which a large number of print elements (dot impact printing in Fig. 8) Di are attached in an array with a constant pitch in the thread direction.
A via the eccentric disk 2 by a drive motor (not shown)
, each print element D during reciprocating linear movement in the direction A''.
i is driven to print at a plurality of predetermined dot positions. In the figure, 3a
and 3b are rails for guiding the head bank 1 in the A and A' force directions. The movement of head bank 1 is the 11th
As shown in the figure, the print period (CI, C
The instantaneous position of the head bank 1 is detected at regular distance intervals by a position sensing device, and as shown in FIG. A position detection pulse Pi indicating the timing when the dot is a predetermined distance before the next dot position Qi to be printed is generated based on the position detection signal from the position detection device. Each printing element is excited in response to the detection pulse Pi and selectively prints at the dot position Qi (that is, selectively because there are dot positions within the character that are not printed).

Conventionally, a rotary encoder has been known as such a position detection device, but recently, a combination of a magnetic linear scale and a magnetoresistive element (MR element) has been used in this type of printer.

FIG. 13 shows a position detection device consisting of a magnetic linear scale and an MR element. The magnetic linear scale 10 is arranged in the direction A, A'' which is substantially perpendicular to the paper feeding direction B, that is, the head bank 1.
The N and S poles are set at a constant pitch H (
For example, 423 μm) are arranged alternately. The MR element mounting body 20 faces the magnetic linear scale 10.
'Supports the MR element Fl-F4 arranged in the force direction. These MR elements Fl-F4 are formed as a vapor deposited film or a sputtered film on a Si substrate or a glass substrate.
．． They are arranged at intervals of 5H and are bridge-connected as shown in FIG. When the MR element mounting body 20 moves in the A and A' force directions with respect to the magnetic linear scale 10, a sinusoidal sensor output signal is obtained from the output terminals 21a21b of the sensor circuit.

That is, a magnetic field parallel to its film is applied to each MR element Fi, and the direction of this magnetic field rotates once when the MR element Fi moves one pitch H relative to the magnetic linear scale 10.

The resistance value of the MR element changes sinusoidally in response to a change in the direction of the magnetic field, and the periodic speed appears to double. Therefore, in the sensor circuit of FIG. 16, the MR elements Fl, F3
The resistance value changes sinusoidally in the same phase, and 180° with these
MR element F with different phases 2. The resistance value of F4 changes to a sinusoidal wave in the same phase, which causes the output terminals 21a, 21
As shown in FIG. 17(a), a multiplied sinusoidal sensor output signal SO is taken out from b.

For example, as shown in FIG. 18, the magnetic linear scale 10 is integrally attached to the lower part of the bank 1.
The MR element mounting body 20 is mounted on the chassis base 11 facing the magnetic linear scale 10 in the arrangement relationship shown in FIG.
Fixed. So head bank 1 is A, A'
When linearly moving in the force direction, the magnetic linear scale 10 also moves together, and each MR element of the MR element mounting body 20 moves in the longitudinal direction, that is, A, with respect to the magnetic linear scale 10.

A' relative linear movement in the thread direction is performed, and as described above, a sinusoidal sensor output signal SO is obtained as a position detection signal from the output terminals 21a and 21b of the sensor circuit, and this sensor output signal SO has a rectangular waveform. By shaping and then differentiating, a position detection pulse Pi as shown in FIG. 17(b) is generated.

The position detection pulse Pi is generated when the MR element Fl-F4 faces the magnetized portion 10a of the magnetic linear scale 10,
This period becomes a printing period C1, c-bi. Further, as shown in FIGS. 14 and 15, when the MR element Fl-F4 faces the non-magnetized portion 10b, the position detection pulse Pi is not generated, and this period is the printing body stop period or the movement direction switching period c.
o, c o'. And the head bank is A,
During reciprocating linear movement in the A' force direction, the relative positional relationship between the magnetic linear scale 10 and the MR element Fl-F4 changes from the state shown in FIG. 14 (printed body retention period CO) to the state shown in FIG.
(printing period CI), the state shown in FIG. 15 (printed body period CO') is reached, and then the state shown in FIG.
The cycle of returning to the state shown in FIG. 14 (printing stop period CO) through the printing period CI' is repeated.

(Problem to be Solved by the Invention) However, when the MR element Fl-F4 passes through both ends of the magnetized portion 10a, that is, the boundary between the printing period CI (C-bi) and the printing body period CO (CO'). , the output signal S
The waveform of o was transiently disturbed as shown in FIGS. 19(a) and (c), which caused an error in the printing timing at the start and end of the printing period C1 (C1"). In FIG. , ta are the starting points of the predetermined (original) printing period CI, but printing is actually started from the wrong point of time ta'' due to the undesired position detection pulse Pa.

The above-mentioned disturbance in the waveform of the sensor output signal So is an undesirable disturbance that is formed from the end of the magnetized part 10a to the non-magnetized part 10b due to the hysteresis characteristic of the magnetization node during the manufacturing stage of the magnetic linear scale. It is thought that this is generated when the MR element Fl-F4 senses a magnetic field due to a magnetic domain.

The present invention was made in view of the above-mentioned problems of the prior art, and provides a shuttle type/real line printer that uses an improved magnetic linear scale and signal processing technology to obtain accurate and stable printing timing. The purpose is to provide.

(Means for Solving the Problems) The configuration of the present invention that achieves the above object is to move a head bank in which a plurality of print elements are attached in an array in a predetermined direction substantially perpendicular to the paper feeding direction in a straight line reciprocating in a predetermined direction. During the movement, each printing element is driven to print at a plurality of predetermined dot positions, and a magnetic linear scale having a magnetized part formed by alternately arranging N poles and S poles at a constant pitch in the predetermined direction, and a magnetic linear scale facing the same. Shuttle type serial in which one side of the magnetoresistive element moves integrally with the head bank while the other is fixedly arranged, and the timing for driving the print element to print is obtained based on the sensor output signal of the magnetoresistive element. In a line printer, N poles are placed at both ends of the magnetized part of a magnetic linear scale at such a small pitch that the magnetic field is not substantially sensed by the magnetoresistive element.
An auxiliary magnetization section having an array of S poles is provided; a first reference voltage is set near the center level of the sensor output signal.

a second reference voltage that is somewhat higher than the first reference voltage;
and a reference voltage generating means for generating a third reference voltage that is somewhat lower than the first reference voltage, and a period during which the sensor output signal reaches the second reference voltage from the first reference voltage. and means for generating a position detection pulse with each pulse width corresponding to a period from the first reference voltage to the third reference voltage in the sensor output signal.

(Function) When the head bank makes a reciprocating linear movement in a predetermined direction, the magnetoresistive element makes a reciprocating linear movement relative to the magnetic linear scale.

When the magnetoresistive element passes through the magnetized portion of the magnetic linear scale, a periodic waveform sensor output signal is generated in response to a periodic magnetic field of north and south poles arranged at a constant pitch.

Further, when the magnetoresistive element passes through a portion of the magnetic linear scale that is not magnetized, that is, a non-magnetized portion, there is no magnetic field large enough to be sensed, so no sensor output signal is generated.

When the magnetoresistive element passes both ends of the magnetized part of the magnetic linear scale, it faces the auxiliary magnetized part, but here the N and S poles are arranged at an extremely small pitch, and the magnetic field is magnetically linear. Since the magnetic field is not detected by the scale and is not detected by the scale and is based on the magnetic hysteresis characteristic of the magnetic node during the formation of the magnetized portion (unwanted magnetic domains are canceled), there is no magnetic field sufficient to generate a sensor output signal.

Therefore, when the magnetoresistive element passes from the non-magnetized part of the magnetic linear scale, passes through the auxiliary magnetized part, and comes to face the magnetized part, the sensor output signal with a normal (undisturbed) waveform instantly changes. This causes printing to start at a predetermined timing.

In addition, the sensor output signal, which was generated continuously with a normal waveform when the magnetoresistive element passes through the magnetized part, changes instantly when the magnetoresistive element comes to face the auxiliary magnetized part. The waveform stops without any disturbance.

A position detection pulse is generated by subjecting the sensor output signal obtained in this way to signal processing, but in the present invention, the sensor output signal not only cuts (exceeds or divides) the first reference voltage, but also A position detection pulse will not be generated unless the reference voltage or the third reference voltage is also turned off, so even if the level of the sensor output signal fluctuates, for example due to an offset, between the second reference voltage and the third reference voltage, , does not affect the timing at which the position detection pulse is generated, so that stable and constant printing timing can be obtained at the beginning and end of each printing period.

(Example) The present invention will be described in detail with reference to FIGS. 1 to 9. Note that the configuration shown in FIG. 10 is also used in this embodiment.

FIG. 1 shows a magnetic linear scale 100 according to this embodiment.

The magnetized unit 100a for obtaining the position detection signal of the magnetic linear scale 100 has an N pole and an S pole of 423μ, for example.
The structure is such that they are alternately arranged at a pitch Pa of m.

An auxiliary magnetic pole 100a'' according to the present embodiment is provided at both ends of the magnetized portion 100a, that is, at a portion adjacent to the non-magnetized portion 100b.The auxiliary magnetic pole 100a' has an N pole and an S pole connected to a magnetoresistive element. These auxiliary magnetic poles 100a are arranged alternately at a very small pitch p a + of, for example, 2 to 3 μm, so that the MR element (MR element) does not substantially detect the magnetic poles.
The length or extension range is approximately 1 pitch Pa (423
FIG. 2 shows the MR element mounting body 200 according to this embodiment.

This MR element mounting body 200 has a first MR element Fl-
F4 and second MR element G1-G4 are each 0.5
A, A' are arranged in the force direction with a pitch of H, Fig. 3(a),
The first and second bridge connected as shown in (b)
sensor circuits 202 and 204 are formed.

The magnetic linear scale 100 may be integrally attached to the lower portion of the head bank 1 (not shown), and the MR element mounting body 200 may be fixed to a chassis base (not shown). Therefore, when the head bank 1 moves linearly in the directions A and A'', the magnetic linear scale 100 also moves together.
Each MR element of the MR element mounting body 200 performs linear motion relative to the magnetic linear scale 100 in its length direction, that is, in the A and A' force directions, and the output terminals 210 and 212 of the first sensor circuit 202 A first sensor output signal Sa having a periodic waveform (more precisely, a sine wave) as shown in FIG. 4 is obtained.

According to this embodiment, when the MR element mounting body 200 passes the auxiliary magnetized section 100a' of the magnetic linear scale 100, that is, during the period Ta in FIG. 4, the waveform of the sensor output signal Sa is particularly disturbed (pulsates). Never. This is because the auxiliary magnetic pole 100a' cancels out the disturbed magnetic domain at the end of the magnetized portion 100a, and the auxiliary magnetic pole 100a'
'Because the pitch itself is extremely small, the magnetic field is MR.
This is because it is not detected by the element.

Note that the output terminal 214.21 of the second sensor circuit 204
A sensor output signal sb having the same waveform as the sensor output signal Sa of FIG. 4 is also obtained from 6, but the phase is different by 90 degrees. That is, when the head bank 1 moves in the A direction, the phase of the second sensor output signal sb with respect to the first sensor output signal Sa is 90 as shown in FIG. 5(a).
°Be late.

However, when the head bank 1 moves in the A'' direction, the first sensor output signal Sa
The phase of the second sensor output signal sb advances by 90' relative to the second sensor output signal sb.

By the way, the sinusoidal sensor output signal S a (S b) obtained as described above is waveform-shaped into a rectangular wave pulse as in the conventional method, and the position detection pulse Pi is generated at the timing of the rise and fall of the rectangular wave pulse. By doing so, the sensor output signal S during the printing stop period Co, Co''
The printing period CI is determined by the offset level of a (S b).
, CI' remains with the problem that the position detection pulse may or may not be output at the beginning and end of CI'.

The situation is shown in FIG. Print stop period Co (Co
'), there is no problem if the level of the sensor output signal S a (S b) matches the center level, that is, the zero cross level VC, but in reality, due to variations in the MR element and other circuit elements, the solid line in Fig. 6 (a) As shown, it is higher than the zero cross level VC, and as shown by the dotted line, it is lower than it.

Then, at the start and end of the printing period CI (C+°), in the case of the solid line level, the zero cross level V
Since position detection pulse P1 is not generated because C is not cut,
In the case of the level indicated by the dotted line, since the zero cross level VC is cut, a position detection pulse Pbi is generated, and as a result, the printing operation is uncertain and the printing quality is degraded.

However, in this embodiment, the above-mentioned problem is solved by the signal processing circuit shown in FIG.

This signal processing circuit has first and second circuits having the same configuration.
The signal processing units 300A, 300B and the AND gate 360
It consists of

In the first signal processing section 300A, the input terminal 302a
, 304a is the output terminal 21 of the first sensor circuit 202
0 and 212 (Fig. 3(a)), respectively, and the first
The sensor output signal Sa is received. The input first sensor output signal Sa is transmitted through the resistors 30E3a, 308a, 31
After being amplified by the operational amplifier 314a, which operates as a differential amplifier, into a signal waveform as shown in FIG. 8(a), the resistor 318a + 324a r
operational amplifiers 320a, 32 through 332a, respectively;
8a and the inverting input terminals of 336a. Non-inverting input terminals of these operational amplifiers 320a, 328a, 336a are supplied with first, second and third reference voltages Vl, V2 . V3 is supplied respectively. The first reference voltage Vl is set to approximately the center level (VC) of the first sensor output signal Sa, and the second reference voltage V2
is set somewhat higher than the first reference voltage Vl (higher than the offset level), and the third reference voltage V3 is set to be higher than the first reference voltage Vl.
The operational amplifiers 320a and 328a are set somewhat lower than the reference voltage Vl (lower than the offset level).
, 336a are connected with feedback resistors 318a, 326a, and 334a between their respective inverting input terminals and output terminals, and each output terminal is connected to a pull-up resistor 322a, 330.
a, 338 Power supply voltage Vcc (“1”) via a
is connected to each operational amplifier 320a, 328.
a, 336a are the first, second and third reference voltages Vl, V2 . Operates as a comparator or waveform shaping circuit for V3. Therefore, the operational amplifier 320a
, 328a.

8(b), (C), (d) to the output terminal of 336a.
) as shown in the square wave signal or pulse Eal, Ea
2°Ea3 is obtained respectively. The pulse Eat is the clock input terminal (CL) of the D-type flimp front panel 346a.
is supplied to the clock input terminal (CL) of a D-type flip-flop 348a through an inverting circuit 344a. Further, the pulse Ea2 is connected to the reset terminal (R) of the D-type flip-flop 346a to the inverting circuit 342a.
The pulse Ea3 is directly supplied to the reset terminal (R) of the D-type flip-flop 348a. The data input terminals (D) of these D-type flip-flops 346a and 348a always receive power supply voltage +Vcc (“1”). Therefore, the D-type flip-flop 346a
is the falling edge of the pulse Eal (that is, the inversion circuit 34
At the rise of the output voltage of 4a), data of "1" is taken in, and the output voltage of the inverted output terminal Q becomes "1".
0". Also, the D-type flip-flop 346a
is reset at the rising edge of pulse Ea2, thereby causing the output voltage of its inverted output terminal Q to fall to "1".

Therefore, from the D-type flimp flop 346a to the anime game
) 350a is given a pulse Jal as shown in FIG. 8(e). On the other hand, the D-type flip-flop 348a takes in data "1" at the rising edge of the pulse Eal, thereby causing the output voltage of its inverted output terminal Q to fall to "0", and the D-type flip-flop 348a takes in the data "1" at the rising edge of the pulse Ea3. As a result, the output voltage of the inverting output terminal Q rises to "1".
to the other input terminal of the AND gate 350a in FIG.
A pulse Ja2 as shown in f) is applied.

As a result, the output terminal of the anime game) 350a is shown in Figure 8 (
A pulse Ja as shown in g) is obtained, which is supplied to one input terminal of the controller 380.

The second signal processing unit 300B inputs the second sensor signal sb and performs the same signal processing on it, so that the output terminal of the AND gate 350b has a phase of 90° with respect to the pulse Ja.
``Different pulses Jb are obtained, which is determined by the AND gate 36
0 to the other input terminal. Therefore, a position detection pulse Pi as shown in FIG. 8(h) is obtained at the output terminal of the AND gate 360. Note that the second sensor output signal sb has a phase advance of 90° in the printing period CM with respect to the first sensor output signal Sa, and a phase of 90° in the printing period CI.
Delayed by 0°. Therefore, the pulse Ja from the AND gate 350a based on the first sensor output signal Sa becomes the last position detection pulse Pie at the end of the printing period CI', and becomes the first position detection pulse Pi at the beginning of the printing period CI.
It becomes s.

By the way, in the printing body period Co, the operational amplification W31
The level of the sensor output signal Sa from 4a is as shown in Fig. 8(a).
As shown by the solid line, when the sensor output signal Sa is higher than the zero-crossing level VC at the end of the printing period CI' and the beginning of the printing period CI, the sensor output signal Sa reaches the zero-crossing level VC.
Since the output voltage Eal of the operational amplifier 320a
maintains the “O” level. As a result, the output voltage Jal of the flip-flop 346a, the output voltage Jal of the flip-flop 346a,
The output voltage Ja2 of 48a and the output voltage Ja of AND gate 350a are shown in FIGS. 8(c), (d), and (e), respectively.
as shown by the solid line. Thus, at the end of the printing period CI', the last position detection pulse P1e is generated at time te, and at the beginning of the printing period C1, the first position detection pulse Pis is generated at time ts.

In addition, during the printing stop period Co, if the level of the sensor output signal Sa from the operational amplifier 314a is lower than the zero cross level VC as shown by the dotted line in FIG. At the beginning of period CI, the sensor output signal Sa crosses the zero cross level VC.As a result, the output voltage Eal of the operational amplifier 320a becomes
As shown by the dotted line in FIG. 8(b), the level changes from "0" to "1" at the end of the printing period C1", and remains at the "1" level during the printing stop period Co, and the printing period CI At the beginning of , the level changes from 111'' level to ``O'' level.

As a result, the output voltage Ja1 of the flip-flop 346a
1. The output voltage of the flip-flop 348a and the output voltage of the flip-flop 350a are shown in FIGS. 8(c) and 8(c), respectively.
As shown by the dotted lines in d) and (e), the pulse [J al
However, since the output voltage of the flip-flop 348a is "0", the pulse [Jal] does not appear at the output terminal of the flip-flop 350a, and as a result, the first position detection pulse is generated at time ts. Pis occurs.

In this way, even if the level of the sensor output signal Sa (and Sb) is offset and becomes higher (or lower) than the zero cross level VC during the printing stop period Co, the last position detection pulse Pie of the printing period CI' The first position detection pulse Pis of the printing period CI is always generated at a constant timing (te, ts).

In this embodiment, the print drive is triggered by the rise of the position detection pulse PI, so even if the output voltage of the AND gate 360 falls, no print timing is given.

FIG. 9 is a timing chart for explaining operations at the end of the printing period C1, the printing body stop period Co', and the beginning of the printing period CI'. Even in this case, the print stop period Co
When the level of the sensor output signal Sa becomes higher or lower than the zero cross level VC at 1, the output voltages of the operational amplifiers 320a, 1, flip-flops 346a, 348a) 350a, 360 change as shown by the solid line in the figure. As shown by the nine-dot line, the last position detection pulse pie is generated at a constant timing te' at the end of the printing period CI, and the first position detection pulse pie is generated at a constant timing ts'' at the beginning of the printing period CP. Pis occurs.In this case,
Contrary to FIG. 8, based on the second sensor output signal sb (pulse Jb from the AND gate 350b becomes the final position detection pulse Pie at the end of the printing period C1, and becomes the first position detection pulse Pie at the beginning of the printing period CI'). This becomes the position detection pulse Pis.

(Effects of the Invention) As described above, in the present invention, the N and S poles are arranged at both ends of the magnetized part of the magnetic linear scale at such a small pitch that the magnetic field is not substantially sensed by the magnetoresistive element. By providing an auxiliary magnetization section consisting of a The first thing that was done was Since position detection pulses are formed using the second and third reference voltages as comparison reference voltages, stable and constant printing timing is maintained at the beginning and end of the printing period even if the level of the sensor output signal is offset during the print stop period. can get.

[Brief explanation of drawings]

FIG. 1 is a perspective view showing the configuration of a magnetic linear scale 100 according to an embodiment of the present invention, and FIG. 2 shows magnetoresistive elements F1 to F1 in the above embodiment.
F4, a perspective view showing the arrangement configuration of G1-G4, FIG. 3 is a circuit diagram showing the connection configuration of the first and second sensor circuits 202 and 204 in the above embodiment, and FIG. First sensor circuit 202
A signal waveform diagram of the first sensor output signal Sa obtained from the output terminal of FIG. 5 is a signal waveform diagram showing the phase relationship between the first sensor output signal Sa and the second sensor output signal Sb. The figure is a timing diagram for explaining the inconvenience caused by the offset level of the sensor output signal S a (S b).
8 and 9 are timing diagrams showing signals of each part to explain the operation of the signal processing circuit, and FIG. 10 is a shuttle FIG. 11 is a diagram showing the motion characteristics of the head bank, and FIG. 12 is a schematic perspective view showing the head bank of the serial line printer. ), Figures 13, 14, and 15 are diagrams showing the relative positional relationship between the magnetic linear scale and the magnetoresistive element (MR element), and Figure 16 is the diagram showing the relative positional relationship between the magnetic A circuit diagram of a sensor circuit consisting of a resistance effect element, FIG. 17 is a waveform diagram of a sensor output signal generated by the sensor circuit, and FIG. 18 is a diagram of a magnetic linear scale and an MR element mounting body in the serial line printer. A perspective view showing the mounting positional relationship and FIG. 19 are signal waveform diagrams showing problems in the conventional 7 real line printer. l... Head bank, DI-Dn... Print element, 100... Magnetic linear scale, 100a...
...Magnetized part, 100a'...Auxiliary magnetized part, 100
b...Non-magnetized part, F1-F4, G1-G4...
・Magnetoresistive element (MR element), 200...MR
Element mounting body, 202, 204...sensor circuit, 30
0A, 300B...Signal processing section, 322a1322
b, 328a, 328b. 336a, 338b = operational amplifier, 340a, 340
'b ==...Reference voltage generator, 346a, 348b. 348a, 348b...D type flip-flop, 3
60...and gate.

Claims (1)

[Claims] While a head bank in which a plurality of print elements are mounted in an array in a predetermined direction substantially perpendicular to the paper feeding direction is linearly moved back and forth in the predetermined direction, each print element is moved to a plurality of predetermined dot positions. Printing is driven, and a magnetic linear scale having a magnetized portion in which N poles and S poles are alternately arranged at a constant pitch in the predetermined direction and one of the magnetoresistive elements facing the scale are moved integrally with the head bank. and the other is fixedly arranged to obtain a position detection pulse that provides timing for driving the print element for printing based on a periodic waveform sensor output signal obtained from the magnetoresistive element when the head bank moves. In the shuttle type serial line printer, auxiliary magnetization is provided by arranging N and S poles at both ends of the magnetized portion of the magnetic linear scale at such a small pitch that the magnetic field is not substantially detected by the magnetoresistive element. a first section set near the center level of the sensor output signal;
a reference voltage, a second reference voltage that is somewhat higher than the first reference voltage.
and a reference voltage generating means for generating a third reference voltage that is somewhat lower than the first reference voltage, and the sensor output signal reaches the second reference voltage from the first reference voltage. and a means for generating a position detection pulse having a pulse width of a period from the first reference voltage to the third reference voltage of the sensor output signal; Method serial line printer.