JPH03230985A - Printer - Google Patents

Abstract

PURPOSE:To print a character without generating positional shift by forming the printing timing signal corresponding to each printing pitch to accurately know a position where a carriage is present and a position having to be stored. CONSTITUTION:A printing head 2 is mounted on a carriage 1 and the carriage 1 is fixed to a part of a drive belt 4 and reciprocally operated by reversively rotating a stepping motor 3, and a printing head 2 performs printing operation according to a printing timing signal. Control is performed on the basis of the number of pulse steps from a home position and the signal obtained by detecting the slit of a linear encoder 5 with an optical sensor 6. As printing operation control, the position control of the carriage 1 and the printing timing control given to a printing head 2 are designated. At first, in the position control of the carriage 1, the home position of the slit of the linear encoder 5 is detected and the number of the steps of the drive signal to the stepping motor 3 is controlled on the basis of the home position to control a rough position and, further, by the operation based on the slit detection signal of the linear encoder 5, more detailed position data is obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a printer that performs a recording operation by reciprocating a carriage on which a print head is mounted.

2. Description of the Related Art In recent years, as personal computers and the like have become more widespread, printers have come to be widely used as output devices for documents, graphics, etc. that have been created. There are various types of printers, and among them, serial printers such as wired sotoprinters and inkjet printers, in which a print head is mounted on a carriage and performs recording operations by reciprocating the carriage, have become rapidly popular.

An example of a conventional serial printer is shown in Fig. 5 below.
explain. In the figure, 1 is a carriage that carries a print head 2 for printing and performs reciprocating motion, 3 is a stepping motor that is a driving source for reciprocating the carriage 1, and 4 is a part of which is fixed to the carriage 1. , is a drive belt that transmits the rotational movement of the stepping part 3 to the carriage 1 through a pulley and causes the carriage 1 to reciprocate. The movement of the carriage 1 on which the print head 2 is mounted is controlled by a stepping motor 3.
The current position of is managed by the number of steps from the home position. In addition, in order to shorten the print recording time, the carriage 1
can be moved in both directions from any position, quickly moving to the next recording start position and performing recording operations. Drive signal of the stepping motor 3 that actually operates the carriage 1, 1
An example of the relationship between step movement amount and print timing signal (
To explain the first method, the amount of movement of the carriage in one step of the motor is 1/60 inch - 0.428 mm.
In order to output a print timing signal at a pitch of 1/120 inch = 0.211 mm, it is necessary to divide the time of one step of the stepping motor drive signal into two and output the signal. In this case, it is necessary to select a stepping motor for driving the carriage that can respond to high-frequency step driving so as to follow the dot period of the print head.

The second method uses a linear encoder with a slit that corresponds to the printing pitch, uses a stepping motor or DC motor to drive the carriage, detects the slit of the linear encoder with an optical sensor, etc., and controls the printing timing. , 'carriage position control. For example, when printing at a pitch of 1/120 inch = 0.211 mm, set the slit of the linear encoder to 1
If the pitch is set to /120 inch, a print timing signal can be output by detecting this.

Problems to be Solved by the Invention However, the above printer has the following problems.

With the first method, there is no problem when printing and recording at low speeds, but when high-speed printing becomes necessary, a stepping motor with a high-speed response is required, and there are restrictions and limitations on motor selection. The print timing signal can generate signals corresponding to various pitches compared to the motor step drive signal, but position management becomes troublesome unless it is multiplied by an integer. Further, the actual position of the carriage may deviate from the position of the carriage managed from the motor drive signal due to the magnitude of the motor torque and torque fluctuations. This causes problems such as pitch unevenness of characters, deterioration of printing quality, and misalignment in the column direction between the rows of printing on the forward pass and the rows of printing on the return pass. The problem with misalignment in the column direction is to use an adjustment resistor.
This problem is often solved by temporally shifting the print timing signal using a switch or the like, but it is extremely difficult to completely solve this problem in printers that are equipped with various print modes and have multiple carriage movement speeds.

On the other hand, in the second method, an optical sensor is attached to the carriage carrying the print head, and the linear encoder is directly read and used as a print timing signal, so character pitch unevenness due to uneven movement speed caused by motor torque fluctuation etc. There is almost no deviation in the alignment of rows and columns during reciprocating printing. However, if a linear encoder's slits are installed at the same character pitch, the slit pitch will become very fine, making it difficult to detect, and correction of temperature characteristics and other adjustments will be required to handle delicate signals. Therefore, the circuit becomes complicated and the price increases. Furthermore, in a printer that is equipped with various printing modes and has a plurality of printing pitches, if the slits have a constant pitch, printing timing signals for other pitches must be generated, and character position management becomes complicated. Furthermore, when trying to control the carriage position based on slit detection and signals, an invalid signal is generated in the slit detection when the carriage stops, starts up, or changes direction, making it difficult to control the carriage position. had.

The present invention was made in view of these points, and uses a linear encoder with a coarse slit pitch, uses one optical sensor to detect the slit, and detects the position of the carriage and the printing position. Furthermore, it is an object of the present invention to provide a printer that generates printing timing signals corresponding to a plurality of printing pitches and has less printing deviation.

Means for Solving the Problems In order to achieve the above object, the present invention includes a drive means for reciprocating a print head and a carriage on which the print head is mounted, and a drive means for reciprocating a print head and a carriage on which the print head is mounted, and a drive means for reciprocating a print head and a carriage on which the print head is mounted. A linear encoder with slits carved so that the edge is aligned, an optical sensor that moves along the linear encoder and detects the slit as the carriage moves back and forth, and multiple printing pitches based on the output signal of the optical sensor. The apparatus is equipped with means for outputting a print recording signal according to the print head to the print head, and means for detecting the ratio of the widths of adjacent slits in the linear encoder to determine the position of the carriage.

Effect: By the above means, in a printer that performs reciprocating printing operation and has a plurality of different printing pitches, a printing timing signal corresponding to each printing pitch is generated, and the position of the carriage,
The position to be recorded can be accurately known, and characters can be printed without positional deviation.

Embodiment Hereinafter, an embodiment of the printer of the present invention will be described with reference to FIG.
Components that are the same as those in the conventional example shown in FIG. 5 are given the same reference numerals, explanations of which will be omitted, and only differences will be explained. In the figure, 5 is a linear encoder in which a slit is carved so that the edge of the slit is at a pitch corresponding to the printing pitch, that is, a pitch that is the overlapping of two printing pitches, in order to correspond to the recording operation of two different printing pitches; 6 is carriage 1
This is one optical sensor that moves along the linear encoder 5 and detects the slit as the linear encoder 5 reciprocates. Further, FIG. 2 shows a pattern diagram of the slits of the linear encoder 5. FIG. 3 shows a block diagram of the signal processing section, and FIG. 4 shows a timing diagram of each signal.

This will be explained in detail below.

The print head 2 is mounted on a carriage 1, and the carriage 1 is fixed to a part of the drive belt 4. The print head 2 moves back and forth by rotating a stepping motor 3 in forward and reverse directions, and moves the print head according to a print timing signal. 2
performs printing operation. This printing operation is controlled by the number of pulse steps from the home position and the signal detected by the optical sensor 6 from the slit of the linear encoder 5, as in the conventional example (single pitch). Printing operation control mainly involves controlling the position of carriage 1 and printing head 2.
There are two ways to control printing timing. First, the position control of the carriage 1 involves detecting the home position of the slit in the linear encoder 5, managing the number of steps of the drive signal to the stepping motor 3 based on this as a reference, and managing the approximate position. Calculate the detection signal to obtain more detailed position information.

In print timing control, print timing pulses are generated by further subdividing the slit detection signal obtained by optically reading the slit of the linear encoder 5.

Fig. 2 shows the slit pattern of the linear encoder 5, and in this example, the printing pitch is the pi force pitch - - =
10cpi (character per 1nc
h) The printer has two printing modes: printing 10 characters per inch and elite pitch...printing 10 characters per 12cpil inch, and each character consists of 12 dots horizontally. This is a pattern that takes into account the minimum slit width of 1/180 inch - 0,1
The diameter is 41 mm, which is sufficiently rough as a slit. A in FIG. 2 is an output signal when this signal is actually read by the optical sensor 6, which logically assumes a value of "O" or "1" depending on the presence or absence of a slit. The position control and print timing control of the carriage 1 using the linear encoder 5 having such slits will be explained with reference to FIGS. 3 and 4.

In FIG. 3, reference numeral 6 denotes the optical sensor described above, and a signal a is obtained as a detection signal of the slit of the linear encoder 5. The edge detection circuit 7 extracts the rising and falling edges of this detection signal a, and outputs two signals, a signal for Vika printing and a signal C for elite printing.

Signal S and signal C are input to data selector 8, and C
The input block of A is selected when the Pikabitch printing is performed by the select signal 0 from the PU (Central Processing Unit) 9.
During elite pitch printing, input block B is selected, and when block A is selected, output signal d is the content of signal S. When block B is selected, output signal d is the content of signal C. .

Here, input block A of the data selector 8 is selected. In other words, the explanation will be continued assuming that pie force pitch printing is performed. The signal d is input as a reset signal to the counter 10, and the counter 10 starts counting the clock signal f from the clock generation circuit 11. Next, signal d is generated when carriage 1 has advanced 1/30 inch. The counter 10 is reset again by this signal d, but
At the same time, the signal d is also input as a latch signal of the latch 12, and the value of the output g of the counter 10 is held in the latch 12. This value becomes an output and is input to the timer 13. The timer 13 performs a timer operation using a value obtained by dividing this value into four, and outputs an output i to the print head as a print timing signal. That is, as a result, a print timing signal is generated in the print head for each character consisting of 12 dots horizontally at a pi-force pitch, that is, every 1/30 inch/4=1/120 inch.

The above operation is similar in the case of elite pitch. Alternatively, the signal from the latch 12 may be once input to the CPU 9 for calculation, and then the calculation result may be set in the timer 13. In this case, even more various printing pitches can be created.

Next, regarding the position control of the carriage 1, the outputs of the edge detection circuit 7 and C are input to the OR circuit 14 to obtain the OR output j. This signal j is input as a reset signal to the counter 15, and the counter 15 is inputted to the clock generation circuit 1.
Start counting the clock signal f from 1. Signal J is then generated when carriage 1 has advanced to the next slit changeover. The counter 15 is reset again by this signal j, but at the same time, the signal j is also input as a latch signal of the latch 16, and the value is held in the latch 16 at the output of the counter 15. This value of 2 is output as an output l and input to the CPU 9.

That is, the CPU 9 can detect the width of the slit as a count value. Furthermore, the width of the slits is set so that the ratio of adjacent slits differs within a range of two characters (115 inches) based on the pi-force pitch. Therefore, by reading the count values of two adjacent slits and calculating the ratio between the count values, the CPU 9 can determine the position of the carriage 1 within the range of two characters in pica pitch. - For example, at position M in Figure 2, the ratio is 3/180 inch: 3/180 inch = 1:1;
At the N position, the ratio takes on different ratio values such as 2/180 inch:4/180 inch-1;2. Furthermore, in the embodiment, a stepping motor 3 is used as the drive motor for the carriage 1, and since the approximate position is managed by the number of steps of the drive signal, the exact position can be determined by combining it with the position information from the slit signal. You can know.

Effects of the Invention As is clear from the above embodiments, the printer of the present invention performs a reciprocating printing operation, accurately generates printing timing signals corresponding to each pitch of characters with different printing pitches,
Furthermore, the position of the carriage carrying the print head can be accurately controlled, making it possible to record high-quality characters with no uneven printing without positional deviation. In addition, the components needed to implement this are a linear encoder with coarse pitch slits and an optical sensor that does not require special performance.Furthermore, there is greater freedom in selecting the carriage drive motor, resulting in lower costs. This has the advantage of increasing the degree of freedom in carriage drive control.

[Brief explanation of drawings]

FIG. 1 is a perspective view of a main part of an embodiment of a printer according to the present invention, FIG. 2 is a diagram showing a pattern of a linear encoder in the same embodiment, and FIG. 3 is a block diagram of a signal processing section in the same embodiment. FIG. 4 is a timing diagram of signals in the signal processing section, and FIG. 5 is a perspective view of the main parts of the conventional printer. 1... Carriage, 2... Print head, 3... Stepping motor, 4...
Drive belt (4 stages of drive means) 5...Linear encoder, 6...Optical sensor.

Claims (1)

[Claims] A drive means for reciprocating a print head and a carriage on which the print head is mounted, a linear encoder having slits carved so that the edges of the slits are aligned at a pitch that is a combination of two different print pitches, and a drive means for reciprocating the carriage. an optical sensor that moves along the linear encoder and detects the slit in accordance with the operation, and means for outputting print recording signals corresponding to a plurality of print pitches to the print head from the output signal of the optical sensor; and means for detecting a width ratio of adjacent slits in the linear encoder to determine the position of the carriage.