JPS6056636B2 - Carriage return control device for serial printers - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a carriage and return (hereinafter referred to as CR) control device for a serial printer, and particularly to a CR control device that correctly returns a carrier to its home position during CR.

In conventional serial printers, if the number of moving pitches of the carrier during CR is incorrect, the carrier may not be able to stop correctly at the home position, and may collide with the frame, resulting in damage.

In such a case, subsequent printing operations will be interrupted, and such a situation must be prevented as much as possible. The present invention has been made to eliminate such drawbacks,
An object of the present invention is to provide a CR control device that can accurately return a carrier to its home position even if a count pulse generation error or a count error occurs. For this purpose, a detector is provided within a predetermined distance range from the home position of the carrier and detects the carrier itself;
A device provided with means for forcibly correcting the contents of the means for storing the current position of the carrier to the contents corresponding to the position where the detector is installed when the carrier is detected by this detector during R operation. It is.

In other words, even if the content of the current position storage means differs from the actual carrier position due to a count pulse generation error or a count error, the counted contents of the current position storage means are forced to change as soon as the detector detects the carrier. Since the contents are automatically corrected to correspond to the position where the detector is installed, the actual position of the carrier and the counted contents of the storage means match from then on, and the carrier can be accurately positioned at the target position. .

The present invention will be explained in detail below with reference to the drawings.

FIG. 1 is a block diagram of a position control circuit of a serial printer to which the present invention can be applied, in which 1 is an 8-bit target position register that stores the target position, and 2 is a moving direction in which the carrier moves by a predetermined pitch. 53 is an arithmetic circuit that generates a control signal according to the difference between the contents of the target position register and the current position register; 4 is a carrier drive circuit; 5 is a transducer which is a two-brush potentiometer described later, 6 is a multiplexer described later, 7 is a differential amplifier, 8 and 11 are known phase compensation circuits, 9 is a current amplifier, and 10 is the output of the differential amplifier 7. 12 is a speed detection circuit that differentiates the output of the differential amplifier 7 and generates a signal according to the carrier speed; 13;
is a speed designation circuit that designates the carrier speed during CR, 13
is a differential amplifier, and AS1-4 are analog switches.
Figure 2a is a schematic diagram of the potentiometer of Figure 1;
Figure 180 Two brushes STOl with phase difference, 2+6V
Power tap STDPlOV Power tap STDEll2
8 taps STDl~8 provided at equal intervals on the circumference
It is equipped with

Note that the arrows indicate the spacing direction, and FIG. 2b is an electrical diagram of the potentiometer.

Figure 3 shows the output SAl~4 of the current position register 2 in Figure 1.
, transducer 5, multiplexer 6, differential amplifier 7, and analog switch AS4.
Al to SA4 are the contents of the lower 4 bits of the current position register, and the fourth bit SA4 selects one of the potentiometer brushes STOl,...:Ni ST02, and the first to third bits SAl to 3 select the potentiometer brush STOl, ...: ST02. Any one tap STT) 1 to 8 is selected.

Now, in the illustrated state, if the lower four bits of the current value register 2 are 1000, the contact 2 of the analog multiplexer 6 corresponding to the tap STD2 is turned on, and the upper contact 1 of the analog switch AS4 is turned on. However, amplifier A
A difference occurs between the outputs of MP1 and 2, and this difference is amplified by the differential amplifier 7, and the compensation circuit 8 and analog switch AS in FIG.
The current is input to the current amplifier 9 via the current amplifier 9, where the current is amplified and rotates the motor 4.

When the motor rotates, the transducer 6 also rotates, and this brush STOl approaches the tap STD2.

As a result, the output voltage of the differential amplifier 7 gradually decreases (
(Refer to Figure 4 waveform PCT) Brush STOl is tap ST
When it matches D2, it becomes zero and the motor, that is, the carrier stops. On the other hand, the output voltage ℃T of the differential amplifier 7 is also given to the count pulse generation circuit 10, where it is sliced and waveform-shaped to become the SCP signal shown in FIG. 4, which increments the contents of the current position register by one. From then on, according to the table below, the motor repeats rotation and stop by an amount equivalent to one pitch each time the lower 4-bit signals SAl to SA4 from the current position register 2 are applied to the multiplexer 6 and the analog switch AS4. I'll give it back.

Therefore, if this one pitch corresponds to one space amount of the carrier, the spacing operation of the carrier can be performed. In FIG. 1, symbol SP is a signal that becomes "1" during the spacing operation, and CR is a signal that becomes "1" during CR, which will be described later.
Now, when there is a line feed command (NL command), a signal CR is generated from a control section (not shown), and the 8-bit target position register 1 in FIG. 1 is filled with all zeros (indicating the home position position).
is set.

At the same time, the arithmetic circuit 3 calculates the difference between the target value and the current position, and if the difference is 21 or more, generates the high speed designation signal CR■. The speed designation circuit 13 uses this CRV to generate a speed designation voltage V1 as shown in FIG. -Also, the arithmetic circuit generates a control signal CHS, which turns on the analog switch AS3 and turns off the analog switches AS1,2. However, the motor is driven by the DC voltage (1) and starts rotating at high speed in the direction of the home position. When the motor rotates by a predetermined amount, the differential amplifier 7 generates the waveform POT shown in FIG. 4 as described above, and the current value register counts down each time, and its contents approach the target value. In addition, in FIG. 5, the speed designation voltage waveform ■Output CV of the E1 speed detection circuit 12
The output SCP of the output POTl count pulse generation circuit 10 of the CSl differential amplifier 7 is shown. The output of the differential amplifier 7 is input to the speed detection circuit 12 and a speed signal C
VCS occurs.

The speed is controlled so that the carrier QVCS and the speed specified voltage 1 are equal, and finally the carrier moves toward the home position at the specified speed. Now, when the carrier approaches 20 pitches before the home position (when the difference between the target position register and the current position register becomes 20 pitches), the arithmetic circuit generates the signal HTS.

Using this HTS, the speed designation circuit 13 reduces the speed designation voltage from (1) to (2) and decelerates the carrier. Then, when the carrier reaches 4 pitches before the home position, the signal FSS is generated, the analog switch AS3 is turned off, and the AS
2 is turned on, and the constant speed control then shifts to fine control. That is, the contents of the current position register are advanced by four steps, thereby making the contents of the target position register and the current position register match, and from then on, the output POT of the differential amplifier 7 is
The carrier is servo controlled so that it becomes zero, and the carrier stops at the correct home position. Now, let us assume that the CR count pulse generation circuit 10 happens to not generate a count pulse due to some kind of failure.

Also, assume that even if a count pulse occurs, the current position register 2 does not count. In this case, the current position register is not advanced by one step, so the output waveform of the differential amplifier 7 becomes as shown in FIG. 6, and no count pulse is generated until the potentiometer rotates once.

However, as mentioned above, the motor continues to rotate at a constant speed with a constant voltage applied to it, so the motor is rotated for 16 pitches (
These 16 pitches correspond to one revolution of the transducer,
When it rotates (corresponding to the capacity of the lower 4 bits of the current position register), a count pulse SCP is generated again, and the current position register 2 counts down.

That is, when comparing the correct current position and the contents of the current position register 2, the lower 4 bits of the current position register are correct, but there is an error of 1 in the upper 4 bits, resulting in a total error of 16 pitches.

Similarly, if the current position register does not count the n-time count pulse due to some kind of failure, the lower 4 of the current position register
The bits are correct, and the upper 4 bits are shifted by n.

However, if the above-mentioned CR control is carried out as is, the carrier will not be able to return to the home position correctly, and will cross the wrong home position and collide with the frame, causing damage.

Therefore, in the present invention, as shown in FIG. 1, a mechanical position detector LECl, for example, a reed switch, called a left end contact is provided within 16 pitches in the right direction (opposite direction to the CR direction) from the home position. The carrier itself is directly detected, and when the position detector detects the carrier, the upper 4 bits of the current position register are set to all zeros.

In this way, the lower 4 bits are originally correct, and if the carrier is within 16 pitches from the home position, the upper 4 bits should be all zeros, so the contents of the current position register will correctly reflect the carrier's current position. This means that the value has been corrected to correspond to the position.

Thereafter, if the same CR operation as described above is executed, the carrier will correctly return to its home position. As described above, according to the present invention, even if a count pulse is not generated for some reason during CR, it is possible to correctly return the carrier to the home position.

As a result, the carrier will not be damaged due to collision with the frame, the printing position will not be misaligned, and furthermore, the printing operation will not be interrupted, which is extremely effective.

[Brief explanation of the drawing]

FIG. 1 is an embodiment of the present invention, FIG. 2 is a schematic diagram of a transducer, FIG. 3 is a detailed diagram illustrating carrier movement control in the present invention, and FIG. 4 is an output waveform of the differential amplifier shown in FIG. 1. and the waveform diagram of the count pulse, Figure 5 shows the first pulse at the time of CR.
Waveform diagrams of various parts in the figure, FIG. 6 is a waveform diagram when a count error occurs. 1...Target position register, 2...Current position register, 4...Motor, 5...Transducer, 10...Count pulse generation circuit, 13 ...Speed designation circuit, LEC...
position detector.

Claims (1)

[Claims] 1 storage means for storing the target position to which the carrier should move; storage means for storing the current position of the carrier; calculation means for calculating the difference between the stored contents of both storage means; A control circuit that drives the carrier drive motor according to the rotation of the drive motor, and a feedback system that supplies count pulses output according to the rotation of the drive motor to the current position storage means, and controls so that the difference becomes zero. In a serial printer, the carrier is located within a predetermined distance range from the home position of the carrier, and the carrier position detection detects that the carrier has arrived within the predetermined distance range by detecting the carrier itself. and correction means for correcting the stored contents of the current position storage means to contents corresponding to the position where the carrier position detector is installed when the carrier is detected during carriage return operation of the carrier. A serial printer carriage return control device featuring: