JP3244204B2 - Serial printer device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a serial printer, and more particularly to a serial printer having a synchronizing signal generating circuit for synchronizing the movement of a carriage having a print head and the printing operation of a print head.

[0002]

2. Description of the Related Art In a serial printer, recording (printing) is performed while a carriage having a print head as a recording means is scanned in a horizontal direction on a recording medium. The resulting density unevenness occurs. In particular, in a color printer, a shift in color registration occurs, which is a problem.

Conventionally, as one method for solving these problems, the amount of movement of a carriage equipped with recording means with respect to a main unit is detected, and the recording operation is performed by the recording means while synchronizing with the output result. It has been known.

That is, a scale section of a linear encoder is fixed on a main body side, and a detection section of a linear encoder is formed on a carriage that moves relatively to the scale section, while an output from the detection section is amplified to a carriage. The recording signal is generated in synchronization with the amplified signal, thereby preventing the occurrence of print density unevenness and color registration deviation.

However, when a magnetic linear encoder is used, the MR element (magnetoresistive element) and the circuit element of the detection unit have temperature characteristics, and the duty ratio of the pulse signal varies depending on the temperature. Therefore, it is very difficult to obtain stable recording (printing) quality over a wide temperature range.

For this reason, serial printers provided with means for suppressing a duty ratio that fluctuates due to temperature characteristics are disclosed in Japanese Patent Application Nos. 4-191504 and 4-25.
No. 5956 is proposed in the patent application.

In the invention described in Japanese Patent Application No. 4-191504, since the MR element of the magnetic head has a large temperature dependency, it is considered that a signal detected by the MR element mainly includes a fluctuation component due to temperature characteristics. 2. Description of the Related Art Fluctuations in the duty ratio are suppressed by providing a circuit for removing a fluctuation component or a circuit for extracting only a signal containing no fluctuation component.

In the invention described in Japanese Patent Application No. 4-255596, a temperature measuring section such as a thermistor is provided in the synchronous signal generating circuit to measure a temperature change at an appropriate position of the synchronous signal generating circuit. On the basis of the information obtained by the temperature measurement unit and the temperature-ideal reference voltage characteristics stored in advance in the memory, the reference voltage input to one input terminal of the comparator that outputs the synchronization signal is changed to change the duty ratio. Variations have been suppressed. The detailed description of the conventional synchronous signal generating circuit and the deterioration of the printing due to the fluctuation of the duty ratio is disclosed in Japanese Patent Application No. Hei.
Reference is made to US Pat. No. 2,559,56.

[0009]

However, any of the serial printers described in the above-mentioned prior patent application,
Although it has a certain effect on suppressing the fluctuation of the duty ratio, the following problems still exist. (1) Since the duty ratio fluctuation is constantly monitored from the start of the movement of the carriage and the function of suppressing the fluctuation is employed, it is good when the carriage is moving at a constant speed, but the movement starts and stops. During acceleration motion or deceleration motion such as running, the fluctuation of the duty ratio may increase conversely (at the time of acceleration motion or deceleration motion, the duty ratio is an ideal value in the first place). %). (2) Since the configuration is such that the fluctuation of the duty ratio is suppressed only after the carriage is operated, it is not possible to cope with the fluctuation at the time of starting or restarting recording (printing). (3) When measuring temperature and suppressing fluctuations based on the measurement result, in order to cope with individual differences in temperature characteristics, individual difference information is investigated in advance and the information is used as table data or the like. A non-volatile memory for recording is required separately.

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a recording apparatus which can more reliably suppress the fluctuation of the duty ratio and obtain good recording results in a wide temperature range in consideration of the problems of the above-mentioned patent application. It is to provide a serial printer device which can be used.

In order to achieve the above object, the present invention employs the following configuration. That is, according to the present invention, a carriage for mounting and reciprocating recording means, a scale portion provided on the apparatus body and provided with a magnetic pattern, a magnetic head mounted on the carriage and reading the magnetic pattern, A magnetic linear encoder comprising: a comparator that outputs a pulse signal by comparing a signal corresponding to the detection of the magnetic head with a reference voltage; a reference voltage variable unit that changes the reference voltage; and a moving speed of the carriage. A duty detection circuit for detecting a duty ratio of the pulse signal output from the comparator when the duty ratio is constant, and adjusting the reference voltage based on a detection result of the duty detection circuit. A thermistor for measuring a temperature in the vicinity of the magnetic head; A memory unit for storing temperature measured by the thermistor,
And when the difference between the temperature measured by the thermistor and the temperature stored in the memory unit during standby of the apparatus main body is equal to or greater than a predetermined value, the duty ratio of the pulse signal is detected by the duty detection circuit. And adjusting the reference voltage.

In another embodiment of the present invention, instead of the above (4), (5) during standby, it is determined whether or not an event to move the carriage has occurred, and the event to move the carriage is determined. If it has not occurred, the movement of the carriage is prohibited. Only when an event to move the carriage occurs, the carriage is moved without performing the printing operation, and the duty ratio fluctuation suppression processing described in (1) and (3) The memory of the temperature described in the above is stored.

[0013]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a perspective view of a main part of a serial printer device shown together with a recording medium. In FIG. 1, a carriage 1 indicated by a dashed line carries a recording portion 1h of an ink jet recording system or the like, and is guided by a guide shaft 11 having a spiral groove formed on an outer peripheral surface, and is locked by the rotation of the guide shaft 11. The recording sheet (not shown) is driven along the spiral groove, and is reciprocally driven in the direction of the arrow in the drawing with respect to the recording sheet (recording medium) 13 wound around the outer peripheral surface of the platen 12. A so-called serial printer is constructed in which dots D are recorded at a pitch P on the image 13 to form images and characters.

An encoder for obtaining a synchronization signal is built in the carriage 1 constructed as described above. This encoder is a magnetic linear encoder, which records a magnetic pattern on a magnetic material formed on the surface of a wire at a print pitch density corresponding to, for example, 180 dots / inch (dpi) or 360 dpi, or a scale portion of a linear encoder. A magnetic head 601 is fixed to the apparatus main body 100 while a magnetic head 602 including an MR element or the like is fixed inside the carriage 1 to enable position detection by movement of the carriage 1.

A flexible printed circuit board 603 for extracting an output signal from an MR element in the magnetic head to the outside is connected to the magnetic head 602, and a contact portion 604 is connected to a connector (not shown). And then
The connection is made to a substrate 5 mounted on the carriage 1 and shown by a broken line in the figure.

(Embodiment 1) FIG. 2 is a basic block diagram of Embodiment 1 of the present invention. In the figure, reference numeral 300 denotes a magnetic head (corresponding to 602 in FIG. 1) which reads a magnetic pattern of a scale portion and converts the magnetic pattern into an electric signal, and is constituted by an MR element or the like. The magnetic head 300 outputs a pseudo sine wave signal whose waveform resembles a sine wave by relative movement with respect to the scale unit. The output signal has two outputs, a first phase and a second phase, which are different from each other by 90 ° in order to detect the moving direction of the carriage. Reference numeral 302 denotes a constant current circuit that supplies a constant current to the magnetic head 300, and 301 denotes an amplifier that amplifies a signal of the magnetic head to a predetermined magnitude. 300 ~
These components indicated by 302 are mounted on the board 5 (see FIG. 1) on the carriage.

Reference numeral 303 denotes a comparator (comparing unit) for converting an output signal of the amplifier 301 into a pulse signal. The reference voltage (reference voltage) of the comparator 303 is given by the output of the D / A converter 304,
09 can be freely changed based on the command of 09. A position counter 305 counts information indicating the position of the carriage with respect to the scale unit from the phase delay relationship between the first-phase pulse signal and the second-phase pulse signal and the number of second-phase pulses. A duty detection circuit 306 detects the duty ratio of the first and second phase pulse signals. A thermistor 307 is disposed at an appropriate position on the substrate 5 (preferably a position close to the magnetic head) and measures the temperature of that portion. 308 is a thermistor 30
7 is an A / D converter that converts the output voltage of the A / D converter 7 into a digital value.
M, I / O ports, timer circuits and the like. The I / O port is used for input / output to / from the D / A converter 304, the position counter 305, the duty detection circuit 306, and the A / D converter 308, and the timer circuit is used for generating a timing signal for interrupt processing.

FIG. 3 is a specific circuit example of the position counter. In FIG. 3, reference numeral 400 denotes a D-FF, and 401 denotes an up / down counter. Since the pulse signals of the first phase and the second phase are different from each other by 90 °, it is possible to determine in which direction the carriage is moving based on the retardation relation. Therefore, the delay relation is detected by the D-FF, the output is connected to the up / down input terminal, and for example, the number of pulses of the second phase (or the first phase) is counted. Therefore, for example, when the carriage is moving in one direction, it is counted up, and when the carriage is moving in the opposite direction, it is counted down.
The current position of the carriage is obtained from the count of the up / down counter.

Reference numeral 402 denotes a home position sensor using a photo-interrupter. When the carriage is at the home position, the light interrupts light incident on the light-receiving element from the light-emitting element of the photo-interrupter, and the clear input of the up / down counter 401 is input. To clear the count of the up / down counter 401 to zero. Therefore, the counter number of the up / down counter 401 indicates the moving distance from the home position of the carriage, that is, the position of the carriage.

FIG. 4 shows a specific example of the duty detection circuit 306. FIG. 4 shows a circuit for detecting the duty ratio of a pulse signal of one phase. In order to detect a pulse signal of another phase, another set of the same circuit is actually prepared (in addition, Although not shown in FIG. 2, the magnetic head 300, the amplifier 301,
Another set of the constant current circuit 302 and the comparator 303 is provided, and the pulse signals from the two comparators are input to the position counter 305 as described above.)

The pulse signal is first supplied to the first stage D-FF 501.
Synchronizes with the clock cycle of the clock circuit 500. The clock cycle is selected to be sufficiently faster than the cycle of the pulse signal output by the movement of the carriage. Generally, the cycle of the pulse signal is 0.1 mSec (= 1
0 KHz), the clock cycle is several hundred nSec to several μSec (several hundred KHz to several Msec).
Hz). The clock circuit 500 may be provided independently, but usually the CPU clock in the control unit 309 can be used as it is or by appropriately dividing the frequency.

The output of the D-FF 501 is supplied to an AND circuit 502
Is ANDed with the output of the clock circuit, and the result is counted by a counter 503 having a predetermined number of bits. The counting is continued as long as the pulse signal is high. That is, only when the pulse signal is high, the AND circuit 50
2 passes the clock, and the counter 503 counts the number of clocks. When the logic of the pulse signal is inverted, that is, when the pulse signal becomes low, DF
F504 and the AND circuit 505 transfer the contents of the counter 503 to the D latch circuit 507 of a predetermined number of bits in synchronization with the next rising edge of the clock output. That is,
When the pulse signal goes low, the Q output of the D-FF 501 goes high, the Q output of the D-FF 504 goes high, and the next clock output is input to the clock input of the D latch 507 through the AND circuit 505. As a result, the contents of the counter 503 are transferred to the D latch 507.

Thereafter, the content of the counter 503 is DF
F504, cleared by the negative logic AND circuit 506 the next time the clock output goes low. That is,
As described above, when the pulse signal goes low, the D-FF5
Since the Q output of 01 goes high, the Q output of the D-FF 504 goes low. Therefore, when the clock output goes low, the output of the negative logic AND circuit 506 goes low, and this low output is input to the clear input of the counter to clear the counter 503. At this time, D-FF5
The D-FF 504 itself is also cleared because the low output of the negative logic AND circuit 506 is also input to the clear input of 04. As a result, the contents of the D latch circuit 507 are not updated until the next count of the counter 503 ends (until the count of the next high period of the pulse signal ends and the pulse signal goes low). In this way, the high duty time interval of the pulse signal is measured.

Similarly, an AND circuit 509, a counter 510, a D-FF 512, a negative logic AND circuit 513, D
The low duty time interval of the pulse signal is measured by the latch circuit 514.

The control unit 309 can read the contents of the D latch circuits 507 and 514 and the latest high duty time interval and low duty time interval of the pulse signal at an arbitrary timing. The duty ratio can be easily obtained by the following equation. Duty ratio = high duty / (high duty + low duty)

Next, a control method for suppressing the fluctuation of the duty ratio with the above circuit configuration will be described. First, when power is turned on, when the power is turned on, the output voltage of the D / A converter 304 is set to an appropriate initial value.
Next, the carriage is moved without performing the recording (printing) operation. At this time, the duty ratio of the output of the pulse signal of the comparator 303 is an appropriate value, but there is no problem if the output of the pulse signal does not affect the operation of the position counter 305. Next, the content of the position counter 305 is checked at predetermined intervals, and the carriage driving motor is controlled using a method such as PWM control so that the carriage moves at a constant speed. To perform this at a predetermined interval, the C
It can be easily realized by a software method using the interrupt processing function of the PU. Further, the moving speed can be easily calculated by dividing the difference between the contents of the counter by the interval time for each interval.

FIG. 5 is a diagram showing the moving speed of the carriage. As is apparent from the figure, the carriage gradually increases in speed, moves to a substantially constant speed when it reaches the target speed, and after moving a predetermined distance, gradually decreases in speed and stops. When the traveling speed reaches a constant speed at a significant level, the duty detection circuit 306 reads the duty time and calculates the duty ratio. Then, based on the result, the output of the D / A converter 304 (the reference voltage input to the comparator 303) is changed. If the duty ratio does not reach approximately 50% in this state, the duty ratio is calculated again, the output of the D / A converter 304 is changed, and the above steps are repeated until the duty ratio becomes approximately 50%. When the duty ratio becomes approximately 50%, the carriage is returned to the home position, and the temperature at that time, that is, the output of the A / D converter 308 is read and stored in the RAM of the control unit 309. After the carriage returns to the home position, a standby operation is started.

Incidentally, the calculation of the duty ratio may be performed each time for each pulse signal. However, even if the calculation is performed discretely, there is no practical problem. Therefore, the contents of the duty detection circuit 306 may be read together with the contents of the position counter 305 at the time of the above-described interrupt processing. Further, as shown in FIG. 5, since it is difficult to make the moving speed of the carriage completely constant, the reference voltage (the D / A converter 304 It is better to take the average of several measurements and make adjustments based on that average rather than to adjust the output).

Next, the operation during the recording (printing) operation will be described. During the recording operation, the carriage is constantly moving.
The carriage is moving at a constant speed except for the movement start and stop periods shown in FIG. Therefore, during the constant-speed movement section, the above-described reference voltage adjustment processing is executed each time an interrupt processing is performed, and the duty ratio of the pulse signal is reduced by approximately 5%.
Maintain at 0%. At this time, if the output of the D / A converter 304 is changed, the temperature is read and the RA of the control unit is read.
It is stored in M. A similar operation may be performed when the carriage is moved for a reason other than the recording operation.

Next, a description will be given of a standby state (for example, at the time of off-line). During standby, the control unit 309 monitors the temperature information at predetermined intervals, and compares the temperature information with the stored temperature information when the output of the D / A converter 304 is changed. Then, when the temperature difference becomes equal to or more than the predetermined value, a series of processes similar to those performed when the power is turned on are performed.

FIGS. 6 to 8 show the contents of the control described above arranged in a flowchart. Next, the control contents will be described with reference to this flowchart, but the main operation contents have already been described above, so that only the outline will be described.

6 to 8, after power is turned on, D / A
The output of the converter 304 is set to an initial value (Step S1). Next, the carriage is moved (step S
2) Wait until the speed becomes constant (step S3). After the speed becomes constant, the duty ratio is calculated as described with reference to FIG. 4 (step S4).

The calculated duty ratio is larger than 50%, smaller than 50% or almost 50% (for example, 50% ± 3%
Is determined (step S5). If it is larger than 50%, the output of the D / A converter 304 is increased (step S8). If it is smaller, the output of the D / A converter 304 is decreased. (Step S7) Then, the process returns to Step S2, and thereafter, Steps S2 to S8 or S7 are repeated until the duty ratio becomes approximately 50%.

If it is determined in step S5 that the duty ratio is approximately 50%, the carriage is returned to the home position (step S6). Next, the temperature is read by the A / D converter 308 (step S9),
It is stored in the RAM of the control unit (step S10). The carriage is in a standby state at the home position.

Next, whether a recording operation is instructed or not is determined.
That is, it is determined whether a recording operation is being performed or a standby operation is being performed (step S1).
1) If the printing operation is being performed, it is determined whether the carriage moves at a constant speed (step S12). If not, the steps S11 and S12 are repeated until the speed becomes constant. When the speed becomes constant, the duty ratio is calculated (step S13), and the calculated duty ratio becomes 50.
It is determined whether it is larger than, smaller than, or almost 50% (step S14). If it is larger than 50%, the output of the D / A converter 304 is increased (step S14).
15) If it is smaller, the output of the D / A converter 304 is reduced (step S16). Next, the temperature is read by the A / D converter 308 (step S1).
7) Store in the RAM of the control unit (step S1)
8). If it is determined in step S14 that the duty ratio is approximately 50%, the process returns to step S11.

When it is determined in step S11 that the A / D converter 308 is on standby, the A / D converter 308 is activated at predetermined intervals.
Is read (step S19). Then
It is determined whether the difference between the read temperature and the previously read temperature is smaller than a predetermined value (step S20). If the difference is smaller than the predetermined value, the process returns to step S11. If the difference is larger than the predetermined value, the carriage is moved (step S20). S21) Wait until the speed becomes constant (step S22), and calculate the duty ratio (step S23).

Next, it is determined whether the calculated duty ratio is larger than 50%, smaller, or almost 50% (step S24).
The output of the A converter 304 is increased (step S27),
If it is smaller, the output of the D / A converter 304 is reduced (step S26), and thereafter, the process returns to step S21, and thereafter, step S2 is performed until the duty ratio becomes approximately 50%.
Steps 1 to S27 or 26 are repeated.

If it is determined in step S24 that the duty ratio is approximately 50% (for example, within the range of 50% ± 3%), the carriage is returned to the home position (step S25). Next, the temperature is read by the A / D converter 308 (step S28), and the RAM of the control unit is used.
(Step S29). The carriage is in a standby state at the home position.

(Other Embodiments) In the above-described embodiment, when a temperature difference exceeding a predetermined value occurs during standby, the carriage automatically moves as can be seen from steps S20 and S21. I have. However, this may be inconvenient. For example, it is not convenient for the carriage to start moving automatically when the user attempts to replace an ink cartridge used for recording during standby. In order to avoid such inconvenience, it may be possible to deal with it by making a design change such that the ink cartridge can be replaced only when the power is turned off, but this may not be possible depending on the configuration of the device. It is possible.

Therefore, in this embodiment, the processing during standby is changed as follows. The control unit 309 determines whether or not the carriage is to be moved when the next event of moving the carriage (for example, resuming the recording operation) is performed, and the movement of the carriage is performed. If not, it returned to the standby state and did not move the carriage. Also, only when the carriage is to be moved, a series of processes similar to those performed when the power is turned on are performed.

FIG. 9 is a flowchart in which the changed portions of the control described above are arranged. In FIG. 9, if it is determined in step S11 that the apparatus is on standby, it is determined whether an event for moving the carriage has occurred (step S50). If no event for moving the carriage has occurred, step S11 is performed. When it is determined that the event of moving the carriage has occurred, the temperature is read by the A / D converter 308 (step S5).
1) It is determined whether the difference from the previously read temperature is smaller than or equal to a predetermined value (step S52). If the temperature difference is small, the process returns to step S11. If it is, the process proceeds to step S21. Step S2 similar to that at the time of insertion
Control of 2 to 25, 26 or 27 is performed.

In this embodiment, since the carriage in the standby state does not move without permission (ie, the step S21 for moving the carriage is performed unless an event for moving the carriage such as a recording operation command occurs). Therefore, inconvenience that may occur when the ink cartridge is replaced can be prevented beforehand.

[0043]

As described above, according to the present invention,
Since the control to set the duty ratio to 50% is performed in advance when the moving speed of the carriage becomes constant at power-on, a high-accuracy duty ratio of 50% can be obtained quickly, and when shifting to the printing operation, Also, the printing operation can be easily performed from the beginning with a duty ratio of 50% that gives a preferable printing result. Also, during the printing operation, the duty ratio is constantly controlled to be 50% when the moving speed of the carriage becomes constant, so that the duty ratio can be constantly maintained at 50% during the printing operation.

Further, taking into account the temperature characteristics of the position detection circuit including the magnetic head (change in duty ratio due to temperature change), the duty ratio is maintained at 50% when the temperature difference becomes large even during standby. In this case, the duty ratio of the pulse signal can always be maintained at approximately 50% not only during the recording (printing) operation but also during standby, and the recording operation at the duty ratio of 50% is performed when shifting to the recording operation. Can be executed quickly. Good recording (printing) over a wide temperature range even when the temperature changes during use
A serial printer that can obtain the result is feasible.

[Brief description of the drawings]

FIG. 1 is a perspective view of a main part of a serial printer shown together with a recording medium.

FIG. 2 is a basic block diagram of Embodiment 1 of the present invention.

FIG. 3 is a specific circuit example of a position counter in the basic block diagram shown in FIG. 2;

FIG. 4 is a specific example of a duty detection circuit in the basic block diagram shown in FIG. 2;

FIG. 5 is a diagram illustrating a moving speed of a carriage.

FIG. 6 is a part of a flowchart showing the contents of control.

FIG. 7 is a part of a flowchart showing the contents of control.

FIG. 8 is a part of a flowchart showing the contents of control.

FIG. 9 is a flowchart showing a changed part of the control.

[Explanation of symbols]

 300 Magnetic head 301 Amplifier 302 Constant current circuit 303 Comparator 304 D / A converter 305 Position counter 306 Duty detection circuit 307 Thermistor 308 A / D converter 309 Control unit

Claims (4)

(57) [Claims] A carriage mounted with a recording means for reciprocating; a scale provided on a main body of the apparatus and provided with a magnetic pattern;
A magnetic linear encoder including a magnetic head mounted on the carriage and reading the magnetic pattern; a comparator that compares a signal corresponding to the detection of the magnetic head with a reference voltage and outputs a pulse signal; A reference voltage varying unit for changing the duty ratio; and a duty detection circuit for detecting a duty ratio of the pulse signal output from the comparator when the moving speed of the carriage is constant, and a detection result of the duty detection circuit. In the serial printer device that adjusts the reference voltage based on the following, a thermistor that measures the temperature near the magnetic head; and a memory unit that stores the temperature measured by the thermistor when the reference voltage is changed. A temperature measured by the thermistor during standby of the apparatus main body and the memory When the difference from the temperature stored in the unit is equal to or greater than a predetermined value, the duty detection circuit detects the duty ratio of the pulse signal and adjusts the reference voltage. 2. The method according to claim 1, wherein the reference voltage is adjusted so that a duty ratio of the pulse signal detected by the duty detection circuit becomes approximately 50%.
2. A serial printer device according to claim 1. 3. The reference voltage is adjusted so that the duty ratio of the pulse signal detected by the duty detection circuit becomes approximately 50% when the power of the apparatus main body is turned on, and the duty ratio becomes approximately 50%. 3. The serial printer device according to claim 1, wherein the temperature is measured by the thermistor when the temperature is reached, and the temperature measured by the thermistor is stored in the memory unit. 4. An operation for determining whether or not an event for moving the carriage has occurred while the apparatus main body is on standby, and performing an operation of detecting the duty ratio of the pulse signal by the duty detection circuit when the event has not occurred. 4. The serial printer device according to claim 1, wherein the serial printer device does not perform the process.