JP2815968B2 - Recording device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention mounts a printhead on a carriage that reciprocates left and right along a platen, and is attached to a carriage motor while scanning in the line direction with the printhead. The present invention relates to a serial recording apparatus that performs recording using an output signal of an encoder or a linear encoder arranged in a line direction as a trigger source.

[Prior art] Scanning methods of a recording apparatus include a serial type, a line print type, a page print type, and the like. Among them, the serial type mounts a head on a carriage that reciprocates right and left along a platen, The recording is performed while the head scans in the line direction.

As a carriage driving source of the serial type recording apparatus, a DC motor, a step motor, or the like is used, and a method of attaching a rotary encoder to the motor shaft and determining a recording position based on an output signal thereof is generally widely used. .

As shown in FIG. 8, the encoder is a photosensor module comprising a photodiode, a phototransistor, and the like formed on a circular thin plate having slits cut at equal intervals around the periphery (there are portions that alternately pass light and cut off). A two-phase output signal (phase difference of 90 degrees) as shown in FIG. 9 together with the rotation of the carriage motor, that is, the movement of the carriage, is connected directly to the motor shaft.
Is generated. Conventionally, either one of these signals
A method of performing a recording operation at each rising edge of a phase or by using both rising and falling edges as triggers has been adopted. Other 90
The signals having different degrees are used to specify the rotation direction of the carriage motor.

[Problem to be Solved by the Invention] The conventional recording apparatus described above uses one of the encoder output signals.
When only the rising (falling) of a phase is used as a trigger of the recording operation, in the case of a recording device having a high recording density, the number of slits of a circular thin plate or a linear encoder must be increased. Alternatively, even if it can be realized, there is a disadvantage that the cost is greatly increased. Also, if both rising and falling edges are used to avoid an increase in the number of slits, the duty of the "H" level and "L" level of the signal will be 50% due to errors such as encoder mounting.
However, the accuracy between the rising edges (falling edges) is high, but the accuracy of the falling edges (rising edges) is low, so that there is a disadvantage that the recording accuracy is greatly reduced.

An object of the present invention is to provide a recording apparatus free from the above-mentioned disadvantages.

[Means for Solving the Problems] A recording apparatus of the present invention includes a drive motor for reciprocating a carriage on which a print head is mounted left and right, an encoder attached to the drive motor or arranged in a line direction, An output unit for outputting a recording timing signal for enabling recording by a recording head at a predetermined cycle based on a change in a logical level of an output signal of the encoder, wherein the recording timing signal Means for shifting the recording level by a predetermined time shorter than the predetermined cycle from a change in the logic level of the output signal of the encoder; and a recording density at a position which equally divides the cycle of the recording timing signal output by the forming means. Interpolating means for interpolating and outputting the recording timing signal in order to increase the recording timing signal.

[Operation] A recording timing signal periodically output in response to a change in the logic level of the output signal of the encoder is formed shifted by a predetermined time shorter than one period, and the period of the recording timing signal is equally divided. It is formed so as to be output to the position.

Example Next, an example of the present invention will be described with reference to the drawings.

FIG. 1 is a perspective view showing the whole of an embodiment of the recording apparatus of the present invention, and FIG. 2 is a block diagram showing a control circuit of the embodiment of FIG.

The carriage 2 on which the recording head 1 is mounted has a guide shaft
The recording head 1 is slidably supported by the recording heads 3 and 4 while engaging with the timing belt 8 and reciprocating in the recording row direction. The timing belt 8 engaged with the pulleys 6, 7 is driven by the carriage motor 5 via the pulley 7. A rotary encoder is directly connected to the shaft of the carriage motor 5. Recording paper 9
Is guided by a paper pan 10 and conveyed by being pressed against a paper feed roller (not shown) by a pinch roller. This conveyance is performed using the paper feed motor 14 as a drive source. The transported recording paper 9 is discharged under tension by the paper discharge roller 12 and the spur 13.

Next, the control circuit of the embodiment shown in FIG. 1 will be described with reference to FIG.

In this embodiment, a DC motor is used as the carriage motor 5, and the motor control method is a complete software servo system using the output signal of the rotary encoder 35 directly connected to the axis of the carriage motor.

The central processing unit 21 (hereinafter, referred to as CPU 21) is composed of elements such as a microprocessor and controls the operation of the entire recording apparatus. The data to be recorded and the command for controlling the operation of the recording device are transferred from a host device 20 such as a computer system to the CPU 21 via a recording data receiving unit 22 composed of a known interface such as a parallel interface or a serial interface. You. The CPU 21 controls the head control unit 2 based on the transferred data.
The print head 1 is controlled via the control unit 3 and the head drive unit 24. The drive pulse of the head is controlled to a predetermined value by using the timer 25.

If the recording data transmitted from the host device 20 is characters or symbols, the data is transmitted in the form of character codes, so that the recording device converts it to bit image data so that it can be recorded with a dot matrix type recording head. Is done. The character generator ROM (CGR
OM) 26 is provided. A control program to be processed by the CPU 21 is stored in the control ROM 27.
Further, the buffer area or CP for the transferred recording data
A RAM 28 is provided for use as a work area for U21.

External input device 30 such as various switches and sensors
An input port 29 is provided for detecting an input from the printer, and an output port 31 is provided for outputting a control signal to an external output device 32 such as a paper feed motor or a display.

Next, a method of controlling the carriage motor 5 will be described.

The DC motor used as the carriage motor 5 generates a torque proportional to the supplied current, and the motor current is obtained by subtracting the back electromotive voltage generated in proportion to the rotation speed from the voltage applied to the motor from the outside. It is proportional to the effective voltage. In other words, the DC motor starts rotating when a voltage is applied, but the number of rotations varies depending on the load.Therefore, it is necessary to control the current or voltage supplied to the motor by detecting the motor rotation angle and feeding it back. In the present embodiment, a complete software servo is employed using pulse width modulation (PWM). Pulse width modulation is a method in which the voltage applied to the motor is switched at high speed by a switching element such as a transistor, and a certain period (usually 20 kHz or more)
In this method, the motor current is adjusted according to the ratio of the on and off times between the two. This switching causes uneven torque in the motor, but the inertia exists in the rotor and load of the motor, so the uneven rotation is instantaneously averaged and absorbed, and the torque obtained as the motor output is almost constant. Become.

In FIG. 2, the driving of the carriage motor 5 is performed by PWM.
The switching is performed by switching the motor driver 34 by a wave, and is realized by giving a duty ratio of a PWM wave to a known PWM generator 33 as a control parameter for the carriage motor 5 in feedback control. A rotary encoder 35 is directly connected to the rotation shaft of the carriage motor 5, and outputs a signal as shown in FIG. 9 as the motor rotates. The signal has two channels and is 90 degrees out of phase. If these two-channel signals are named A-phase and B-phase, when the motor is rotating forward, the B-phase rises from “L” to “H” while the A-phase is “L”, and the motor rotates in the reverse direction. In this case, the B phase falls from “H” to “L” while the A phase is “L”. Thus, the rotation direction of the carriage motor 5 can be specified, and by counting this signal with the up / down counter 36, the rotation angle of the motor, that is, the position of the recording head 1, can be detected.

With the above configuration, the current position, speed, etc. are read at given time, time, etc. intervals determined by the inertia of the servo system for the given target values, such as position, speed, etc., and the control amount is controlled by software according to a certain control law. Calculate and P to PWM generator 33
The motor current is controlled by writing the duty ratio of WM.

FIG. 3 is a flowchart showing a procedure when simple control is performed without considering a recording direction using the control circuit shown in FIG. 2, and FIG. 4 is a waveform diagram showing a recording timing signal. Hereinafter, as a reference for facilitating understanding of the present invention, a case where a simple operation is performed without considering a recording direction will be described with reference to FIGS.

First, after the power of the apparatus is turned on, the apparatus is initialized (step S101). When the print data is received after the initial setting and a print start command is input (step S102), the carriage motor 5 is started (S103). After the motor current is controlled to reach a predetermined constant speed state (S104), the rising edge of the encoder signal immediately before the recording operation in step S105 is triggered to start timer 1 (S106). In S107, a period until the next encoder signal rises is counted using a clock that is sufficiently shorter than the cycle of the encoder signal. When the rising edge of the encoder signal is input in step S107, the timer 1 stops counting in step S108, and simultaneously inputs the count value of timer 1 to the register in step S109, and then the timer 1 automatically restarts counting. Next, in order to create a position signal that is half the time from the rise of the encoder signal to the next rise, that is, just the intermediate position signal, in step S110, a value of カ ウ ン ト of the count value of the timer 1 is set in the timer 2. And step S11
In step 1, timer 2 starts counting down with the same clock as timer 1. At this time, since the recording is enabled in step S112, the recording operation is performed simultaneously (step S11
3). When the value of the timer 2 becomes 0 in step S114, when the recording is enabled in step S115, the recording operation is performed at exactly half the position from the rising of the encoder signal to the next rising (step S116). Thereafter, the process jumps to step S107 again, and repeats the above operation. When the recording of one line is completed, step S112 or step S1 is performed.
Jump from step 15 to step S117 to jump to timer 1 and timer 2
Is disabled, the carriage motor 5 is decelerated and stopped (step S118), and the process jumps to step S102 to wait for a print start command to be input.

With the above control, as shown in FIG. 4, it is possible to perform the recording operation at exactly half the position from the rise of one phase of the encoder signal to the next rise. Although the rising edge of the encoder signal is used in the above reference example, a falling signal may be used. Alternatively, a signal of the other phase of the two phases of the encoder signal may be used.

FIG. 5 is a flowchart showing one embodiment of the control procedure of the present invention using the control circuit shown in FIG. 2, and FIG. 6 is a waveform diagram showing the recording timing signal.

In the reference example shown in FIG. 3, a recording operation is performed with a rising or falling edge of an encoder signal as a trigger, and interpolation of a recording position at a half of a rising edge from the next rising edge or from a falling edge to the next falling edge is performed. In contrast, in the present embodiment,
Considering the recording direction, a position shifted by a certain time T1 from the rising (falling) of the encoder signal as a trigger of the recording operation as shown in FIG.
This is a method of interpolating a half recording position C up to a position B shifted by T1.

Hereinafter, the operation of the present embodiment will be described based on a flowchart.

First, after the power of the apparatus is turned on, initialization of the apparatus is performed in step S201. After the initial setting, receive the recording data and
When a print start command is input in S202, the carriage motor 5
Is activated (S203). After the motor current is controlled to reach a predetermined constant speed state (S20), the rising edge (falling edge) of the encoder signal immediately before performing the recording operation in step S205 is triggered and the timer 3 is given a predetermined delay value. Is set and the timer 3 is started (S206). When the timer 3 times out in step S207, in step S208, the timer 1 is output with a clock that is sufficiently shorter than the cycle of the encoder signal.
Starts counting. When the rising (falling) of the next encoder signal is input in step S209, the timer 3
Is started (S210), and when the predetermined delay time T1 has elapsed in step S211, the timer 1 counts and stops in step S212. At the same time, in step S213, the count value of the timer 1 is input to the register, and the timer 1 automatically restarts counting. Start. Further, in order to create a recording position signal C that is just half of the recording position A delayed by T1 from the rise (fall) of the encoder signal and a recording position B delayed by T1 from the rise of the next encoder signal, in step S214, the timer 1 Set the value of 1/2 of the count value in timer 2 to timer 2 and
At 215, the timer 2 starts counting down with the same clock as the timer 1. At this time, since the recording is enabled in step S216, the recording operation is performed simultaneously (step S21).
6). When the value of the timer 2 becomes 0 in step S218, when recording is enabled in step S219, recording is performed at the position C which is exactly half of A and B (S220). Thereafter, the process jumps to step S209 again and repeats the above control.

When the recording of one line is completed, the process jumps from step S216 or step S219 to step S221 to disable the timer 1, timer 2, and timer 3, and then the carriage motor 5 is decelerated and stopped (S222). Steps
The process jumps to S202 and waits for the next print start command to be input.

With the above control, as shown in FIG. 6, it is possible to perform a recording operation at a position C which is a half of A and B, which is shifted from the rising (falling) of the encoder signal by a certain time T1, for a serial recording. This is effective when the apparatus performs dot correction according to the recording direction.

The present invention provides an excellent effect particularly in a bubble jet type recording head and recording apparatus proposed by Canon Inc. among the ink jet recording methods.

FIG. 7 is a configuration diagram showing a recording head of a bubble jet system.

The recording head 1A has a plurality of ejection ports provided in rows.
In order to eject the recording liquid from 41, an applied voltage is supplied and an electrothermal converter 40 for generating thermal energy is provided for each liquid path. Then, by applying a drive signal, heat energy is generated in the electrothermal transducer 40 to cause film boiling, thereby forming bubbles in the ink liquid path.
Then, ink droplets are ejected from the ejection ports 41 by the growth of the bubbles. For a typical configuration and principle of a recording apparatus using a valve jet recording head, for example, U.S. Pat. No. 4,723,129 and U.S. Pat. Are preferred. This method can be applied to both the so-called on-demand type and the continuous type. In particular, in the case of the on-demand type, it is arranged corresponding to the sheet or the liquid path holding the liquid (ink). Electrothermal transducers
By applying at least one drive signal corresponding to the recorded information and giving a rapid temperature rise exceeding nucleate boiling, heat energy is generated in the electrothermal transducer, and the film is heated on the heat-acting surface of the recording head. As a result, air bubbles in the liquid (ink) can be formed in one-to-one correspondence with the drive signal, which is effective. The liquid (ink) is ejected through the ejection opening by the growth and contraction of the bubble to form at least one droplet. When the drive signal is formed into a pulse shape, the growth and shrinkage of the bubble are performed immediately and appropriately, so that the ejection of liquid (ink) having particularly excellent responsiveness can be achieved, which is more preferable. As the pulse-shaped drive signal, those described in US Pat. Nos. 4,463,359 and 4,434,262 are suitable. Further, if the conditions described in US Pat. No. 4,313,124 relating to the invention relating to the temperature rise rate of the heat acting surface are adopted, more excellent recording can be performed.

As a configuration of the recording head, in addition to the combination configuration (a linear liquid flow path or a right-angled liquid flow path) of a discharge port, a liquid path, and an electrothermal converter as disclosed in each of the above-mentioned specifications, a heat acting section The configurations described in U.S. Pat. No. 4,558,333 and U.S. Pat. In addition, JP-A-59-123670 discloses a configuration in which a common slit is used as a discharge portion of an electrothermal converter for a plurality of electrothermal converters, and an aperture for absorbing pressure waves of thermal energy. The present invention is also effective as a configuration based on JP-A-59-138461 which discloses a configuration corresponding to a discharge unit.

In addition, the recording head of the interchangeable chip timer, which can be electrically connected to the apparatus main body or supplied with ink from the apparatus main body by being attached to the apparatus main body, or is provided integrally with the recording head itself. The present invention is also effective when a cartridge type recording head is used.

It is preferable to add recovery means for the printhead, preliminary auxiliary means, and the like, which are provided as components of the printing apparatus of the present invention, since the effects of the present invention can be further stabilized. More specifically, a pre-heating means for the recording head by a caving means, a cleaning means, a pressure or suction means, an electrothermal transducer or another heating element or a combination thereof. Performing a preliminary ejection mode in which ejection is performed separately from printing is also effective for performing stable printing.

Further, the printing mode of the printing apparatus is not limited to the printing mode of only the mainstream color such as black, but may be a printing head integrally formed or a combination of a plurality of printing heads. The present invention is extremely effective for an apparatus having at least one of the full colors.

In the embodiments of the present invention described above, the ink is described as a liquid. However, an ink that solidifies at room temperature or below and softens or becomes liquid at room temperature, or is generally used in ink jet printing The material may be softened or liquid in a temperature range of 30 ° C. or more and 70 ° C. or less, which is the temperature range of the temperature adjustment performed. In other words, any material may be used as long as it forms a liquid when the use recording signal is applied. In addition, positively prevent the temperature rise due to thermal energy by using the energy of the state change of the ink from the solid state to the liquid state, or prevent the ink from solidifying in a standing state for the purpose of preventing the evaporation of the ink. In any case, thermal energy such as one in which ink is liquefied and ejected as an ink liquid by application in accordance with a recording signal of thermal energy, or one which already starts to solidify when reaching a recording medium, etc. The use of an ink that liquefies for the first time is also applicable to the present invention. In such a case, as described in JP-A-54-56847 or JP-A-60-71260, the ink is held as a liquid or solid in a porous sheet recess or through hole, It is good also as a form which opposes an electrothermal transducer. In the present invention, the most effective one for each of the above-mentioned inks is to execute the above-mentioned film boiling method.

[Effects of the Invention] As described above, the present invention relates to a serial type recording apparatus that outputs a recording timing signal from a rotary encoder attached to a carriage motor or a linear encoder arranged in a line direction. Is output with a shift of a predetermined time, and the recording timing signal output with the shift is interpolated at a position where the period is equally divided and output.
As a result, without using a special encoder for high density with an increased number of slits, it is possible to improve the recording density even if an inexpensive and simple configuration for low density is used. The recording accuracy is greatly improved as compared with the case where both falling edges are used. In addition, by shifting the print timing signal by a predetermined time, the print head mounted on the reciprocating carriage can perform dot correction in the print direction, thereby improving print accuracy.

[Brief description of the drawings]

FIG. 1 is a perspective view showing an entire embodiment of a recording apparatus of the present invention, FIG. 2 is a block diagram showing a control circuit of the embodiment of FIG. 1, and FIG. 3 is control of the control circuit of FIG. 4 is a flowchart showing a reference example of the procedure, FIG. 4 is a waveform chart showing recording timing according to the control procedure of FIG. 3, FIG. 5 is a flowchart showing an embodiment of a control procedure of the control circuit of FIG. 2, and FIG. Is a waveform diagram showing recording timing according to the control procedure of FIG. 5,
FIG. 7 is a configuration diagram showing a bubble jet type recording head, FIG. 8 is a diagram showing a conventional rotary encoder, and FIG. 9 is a waveform diagram showing the operation of the rotary encoder of FIG. 1, 1A ... print head, 2 ... carriage, 3, 4 ... guide shaft, 5 ... carriage motor, 6, 7 ... pulley, 8 ...
... Timing belt, 9 ... Recording paper, 10 ... Paper pan, 12 ... Discharge roller, 13 ... Spur, 20 ... Host device, 21 ... CPU, 22 ... Record data receiving unit, 23 ... Head control section, 24 Head drive section, 25 Timer, 26
CGROM, 27 ... Control ROM, 28 ... RAM, 29 ... Input port, 30 ... External input device, 31 ... Output port, 32
... external output device, 33 ... PWM generator, 34 ... motor driver, 35 ... rotary encoder, 36 ... up-down counter.

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁶ , DB name) G01D 15/24 B41J 3/04 101 B41J 19/18 G01D 5/245 102

Claims (2)

(57) [Claims] A drive motor for reciprocating a carriage on which a recording head is mounted to the left and right, an encoder attached to the drive motor or arranged in a line direction, and a change in a logic level of an output signal of the encoder. Output means for outputting a recording timing signal for enabling recording by a recording head at a predetermined cycle, based on a change in a logical level of an output signal of the encoder. Forming means for shifting the recording timing signal by a predetermined time shorter than the predetermined cycle, and interpolating the recording timing signal at a position equally dividing the period of the recording timing signal output by the forming means in order to increase the recording density. A serial-type recording apparatus comprising: 2. The recording apparatus according to claim 1, wherein said recording head ejects ink from an ejection port using thermal energy, and has an electrothermal converter as a means for generating thermal energy.