JPH09239970A - Ink jet recording apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an ink jet recording apparatus capable of certainly detecting the position of a carriage. SOLUTION: When a printing head 19 is provided on a carriage 12 constituted so as to be capable of being reciprocally moved relatively with respect to a printing medium to perform printing, a sensor 4 detecting the state between a transmission part 41 and a reception part 42 and a shield member 3 shielding the transmission part 41 and the reception part 42 to bring the sensor 4 to a shield state are provided and the sensor 4 and the shield member 3 are constituted so as to be relatively moved accompanied by the movement of the carriage 12. Since the change of the sensor 4 from a continuity state to a shielded state and the change of the sensor 4 from the shielded state to the continuity state can be discriminated when the carriage 12 is moved in a definite direction, the positions capable of obtaining the respective states are set to an empty emitting position B and a home position (reference position) A' to make it possible to detect two positions by one sensor 4.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a technique for detecting the position of a print head of an ink jet recording apparatus, and more particularly to a technique for detecting an idle discharge position and a reference position.

[0002]

2. Description of the Related Art Generally, an ink jet recording apparatus is an apparatus for ejecting ink from a print head while reciprocating a carriage to print on a print medium.

A conventional art of such an ink jet recording apparatus will be described. Referring to FIG. 4, the conventional inkjet recording apparatus 102 has a carriage 112, and a print head 119 is provided on the carriage 112.
Is provided. Further, the carriage 112 is inserted through a guide rail (not shown) and is configured to be able to reciprocate in parallel with the print medium 111.

An ink receiver 114 is provided at a position aligned with the print medium 111 in the housing of the ink jet recording apparatus 102.
And the cap 115 are arranged in this order, and the sensor 121 is arranged at a position facing the cap 115 with the moving axis of the carriage 112 interposed therebetween.
When the carriage 112 is located at the position, the sensor 1
It is configured so that it can be detected by 21.
Also, if the carriage 12 is at that position, the cap 1
The print head 119 is capped by 15 (capping).

The position of the cap 115 is the home position
It is called a (reference position), and when there is no data to be printed or when the power is not turned on, the carriage 112 is located at its home position and the print head 119 is in a lid-covered state. The ink inside the nozzle tip portion (not shown) is prevented from being dried and solidified.

When the ink jet recording apparatus 102 is powered on, the control circuit 116 starts its operation. At this time, since the carriage 112 is detected by the sensor 121, the value of the counter is set to the initial value so that the position becomes the reference position.

When the data to be printed is received from the computer, the control circuit 116 outputs a pulse signal to the carriage motor 117. The carriage motor 117 moves the carriage 112 by a distance according to the number of received pulse signals.

At this time, the control circuit 116 counts the number of transmitted pulse signals and calculates the position of the carriage 112 from the value of the counter. When it is detected that the print head 119 has been moved to the predetermined print position from the calculated position, the head drive device 118 causes the print head 119 to eject ink and print on the print medium 111.

In such a printing operation, for example, when printing of the same character continues, a specific nozzle may not be used and the non-printing state of the nozzle may continue for a long time. Then, the viscosity of the ink in the tip of the nozzle becomes high, which may disturb the printing, and may cause clogging due to dry coagulation, resulting in an unprintable state.

Therefore, during the printing operation, the print head 11
9 is moved to the ink receiver 114 at a predetermined frequency so that the ink with increased viscosity is transferred from the nozzle tip to the ink receiver 114
It has been performed to prevent the nozzle tip portion of the print head 119 from being clogged by performing an idle discharge (flushing).

However, if the motor 117 goes out of step,
If the user carelessly moves the carriage 112, the counter value and the movement amount of the carriage 112 do not match, and as a result, the position of the print head 119 obtained from the counter value is not the actual position. However, there is a problem in that the printing is misaligned during printing, ink is not ejected into the ink receiver 114 during flushing, and the inside of the device is soiled.

Such positional deviation of the carriage 112 can be detected or corrected by once moving the carriage 112 toward the cap 115, returning it to the home position, and checking the counter value at that time. Is.

However, when the flushing is repeated while the printing operation is being performed, the carriage 112 does not return to the home position. In this case, it is possible to return the carriage 112 to the home position each time flushing is performed, but this is not practical because the printing speed becomes slow.

On the other hand, the sensor 121 is connected to the ink receiver 114.
If you place it in the position of, the carriage 1
Although the misalignment of 12 can be detected, there is no guarantee that the carriage 112 can be accurately placed at the position of the cap 115, and the print head 119 may remain uncovered for a long time, which is not desirable.

[0015]

SUMMARY OF THE INVENTION The present invention was created in order to solve the above-mentioned disadvantages of the prior art, and an object thereof is to provide an ink jet recording apparatus capable of surely detecting the position of a carriage. Especially.

[0016]

In order to solve the above-mentioned problems, the invention according to claim 1 is provided with a carriage configured to be capable of reciprocating relative to a print medium, and provided on the carriage. An inkjet recording device having a print head for ejecting ink onto the print medium, comprising a transmitter and a receiver, and a sensor for detecting a state between them and a gap between the transmitter and the receiver. A shield that shields the sensor so that the sensor is in a shielded state, and the sensor and the shield are configured to move relative to each other as the carriage moves, The invention according to claim 2 is configured to detect a state change and obtain an idle discharge position and a reference position of the print head. The invention according to claim 2 is characterized in that the sensor is in a shielded state. The invention according to claim 3 is characterized in that the carriage is configured to reciprocate a distance corresponding to the number of pulses, and the print head is based on the number of pulses. 3. The inkjet recording apparatus according to claim 1, wherein the position of the carriage is calculated from the reference position by integrating the number of pulses with the carriage from the reference position. The number of pulses required to move to the idle ejection position is obtained in advance, and the number of pulses when the print head is at the idle ejection position is compared with the number of pulses obtained in advance, and the difference is less than the predetermined value. If it is also large, it is configured to perform error processing.

The invention according to claim 4 is the ink jet recording apparatus according to any one of claims 1 to 3, wherein the sensor is a photo interrupter in which a light emitting element and a light receiving element are arranged to face each other. It is characterized in that the shield is made of a plate having a light shielding property.

According to the above-described structure of the present invention, when the printing is performed by providing the carriage configured to reciprocate relative to the printing medium with the printing head for ejecting the ink onto the printing medium, the ink jetting is performed. In the recording device, a sensor that detects the state between the transmission unit and the reception unit, and a shield that shields the sensor between the transmission unit and the reception unit to make the sensor in the shielding state are used for moving the carriage. It is provided so as to move relative to it. Therefore, when the carriage is moved in a certain direction, there are times when the sensor changes from the conductive state to the shielded state and times when the sensor changes from the shielded state to the conductive state. By setting the blank discharge position and the home position (reference position) with the obtained position as a reference, it is possible to detect two positions with one sensor.

Further, when the carriage is in the range between the idle discharge position and the home position, the sensor remains in the shielded state, so that the idle discharge is performed in such a cutoff state. If you try to allow
Even if there is a misalignment due to a malfunction or motor step-out, the print medium and the inside of the housing will not be contaminated.

In general, the ink jet recording apparatus is configured such that the carriage reciprocates a distance corresponding to the number of pulses, and the position of the print head is calculated from the number of pulses and the moving direction. However, when calculating the value, the number of pulses required to move the carriage from the reference position to the idle ejection position is calculated in advance by integrating the number of pulses with the home position as the reference, and printing on the print medium is performed. When the print head is at the idle discharge position, the number of pulses obtained in advance is compared with the number of pulses required to actually move to the idle discharge position, regardless of whether or not the idle discharge is actually performed. By comparison, it becomes possible to detect the positional deviation of the carriage.

When the amount of deviation exceeds a predetermined value, error processing for correcting the counter is performed,
The deviation can be eliminated, and if the error lamp is turned on, the operator can eliminate the cause of the motor step-out. If the predetermined value is set to zero, it is possible to immediately perform error processing when there is a difference between the two.

It is preferable to use a photo interrupter in which a light emitting element and a light receiving element are opposed to each other for the sensor used in the present invention, and to use a plate having a light shielding property for the shield because the cost is low.

[0023]

Embodiments of the present invention will be described with reference to the drawings.

With reference to FIGS. 1 and 2, reference numeral 2 is an ink jet recording apparatus according to an embodiment of the present invention, which is a carriage 12.
And a cap 51.

The carriage 12 is arranged in a housing (not shown), and can be reciprocated in a direction parallel to the print medium 11 by a pulse driving stepping motor (not shown) by a distance corresponding to the number of input pulses. Is configured.

A print head 19 is attached to the carriage 12.
And a nozzle tip 20 of the print head 19 is provided.
Are oriented toward the print medium 11. Further, the carriage 12 is provided with a shield 3 made of a plastic plate and having a light-shielding property along the moving direction of the carriage 12.

The ink jet recording apparatus 2 is provided with a counter for adding or subtracting (counting) the number of pulse signals input to the stepping motor according to the moving direction of the carriage 12, and by the stepping motor. When the carriage 12 is moved together with the print head 19 and the shield 3, the position of the carriage 12 can be calculated from the counted number of pulses.

On the other hand, when there is no data to be printed, the carriage 12 is located at the home position (reference position) A, and the cap 51 allows the print head 19 to move.
The nozzle tip 20 is configured to be covered with a lid.
It prevents dry solidification of the product and prevents clogging.

The cap 51 is connected to the ink discharge tank 54 via the pump 52 by a flexible hose 53. When the ink jet recording apparatus 2 is powered on, first, the pump 52 is activated. The inside of the cap 51 is sucked, and the ink remaining in the nozzle tip portion 20 is discharged to the ink discharge tank 54. At this time, the counter value is set to the initial value.

When the data to be printed is input,
With the print head 19 covered with the cap 51, the carriage 12 is moved in the direction in which the print medium 11 is arranged by the stepping motor. Carriage 12
However, when it is moved to the idle discharge position indicated by reference numeral B, the cap 5 is removed from the print head 19 by the attachment / detachment mechanism (not shown).
1 is removed, and the carriage 12 is moved toward the print medium 11 while leaving the cap 51 there.

During the above movement, the number of pulses output to the stepping motor is counted. The position of the carriage 12 calculated from the number of pulses enters the printable range L2, and when the print position is reached, ink is ejected from the print head 19 to start the printing operation. The printing operation is performed by reciprocating the carriage 12 within the printable range L2 until there is no data to be printed.

During the printing operation, it is necessary to cause the print head 19 to perform idle ejection every time a predetermined time elapses. In the ink jet recording apparatus 2, the ink is ejected at a position between the idle ejection position B and the print medium 11. Sensor 4 is provided,
When the carriage 12 is moved from the printable range L2 toward the home position A and the sensor 4 detects that the print head 19 has come to the idle discharge position B and faces the cap 51, the idle discharge can be performed. ing.

More specifically, the sensor 4 is provided with a transmitter 41 that emits light, and is arranged to face the transmitter 41.
The shield 3 provided on the carriage 12 has a receiver 42 that receives the emitted light.
It is fixed to the housing so that it can be located between the receiver and the receiver 42.

The output signal of the sensor 4 and the blank discharge position B
And the relationship with the home position A will be described with reference to the graph of FIG. In FIG. 3, when the light emitted from the transmitter 41 is received by the receiver 42, it is represented by high, and when it is not received, it is represented by low.

When the carriage 12 is moved from the printable range L2 toward the home position A, first, the end 31 of the shield 3 is inserted into the sensor 4, and the sensor 4
Output changes from high to low. Assuming that the position of the carriage 12 at the time of the change is b, the idle discharge position B is
Further, the carriage 12 is set at a position when the motor rotates 6 steps.

The number of pulses to be counted at that time is stored in advance. The number of pulses and the number of pulses actually required are collated and compared, and when the difference exceeds a predetermined value, It is considered that an abnormal situation such as motor step-out has occurred. In that case, for error processing, the error lamp is turned on and the counter value is corrected.

On the other hand, when it is within the predetermined range, the carriage 12 is decelerated while discharging the high density ink in the nozzle tip 20 by the idle discharge. After the carriage 12 is stopped, it is accelerated toward the print medium 11 this time, the cap 51 is removed at the idle ejection position B, and then the carriage 12 is moved to the printable range L2.
Continue printing.

At this time, the carriage 12 moves to the idle discharge position B.
When the print head 19 is located between the home position A and the home position A, the print head 19 is still covered with the cap 51.
Therefore, it is possible to perform the idle discharge while performing the acceleration / deceleration.

Next, the case of moving the carriage 12 to the home position A will be described. The printable range L2
When moving the carriage 12 in the same direction as the home position A, if the carriage 12 is continuously moved in the same direction even after passing the idle discharge position B, the inside of the sensor 4 is shielded by the shield 3 at the position b and once the low position is set. The resulting output signal returns high at a where the end 32 of the shield 3 is located in the sensor. The home position A is set at a position where the carriage 12 is located when the motor further rotates 6 steps therefrom. Cap 5 in this position
Nozzle tip portion 20 is prevented from being clogged even when 1 is sealed and the unused state continues for a long time.

Although the case where the sensor is provided on the housing side and the shield is provided on the carriage side has been described above, the present invention also includes the case where the shield is provided on the housing side and the sensor is provided on the carriage side. Be done. In short, the invention is included in the present invention as long as the sensor and the shield relatively move according to the movement of the carriage.

Further, the sensor and the shield are not limited to the combination of the one using light and the one having the light shielding property, and the sensor is cut off by the electrically connected contact. You may comprise a shield with an insulator. Alternatively, a sensor using magnetic coupling and a sensor that blocks it may be used. In short, the present invention includes any device that can detect the idle discharge position and the home position by one sensor and can maintain the same output signal while the carriage is in the position where the idle discharge can be performed. .

The home position A is the sensor 4
6 from the position a where the output signal of the signal changed from low to high
Although it is set at the position where the step has advanced, the setting is not limited to the case where the position is advanced, and it may be set at the position a, or, for example, the position where 6 steps have returned.

[0043]

Since one sensor can detect the idle discharge position and the home position, the control becomes easy and the cost is reduced. In addition, the print medium and the inside of the device will not be contaminated even when the motor is out of step and is discharged blank.

Each time the blank discharge is performed, the counter value is checked.
Since it is possible to make a comparison, it is possible to promptly deal with the occurrence of print misalignment.

Even if the cap is not at the home position, if the sensor state is in the shielding state immediately after the power is turned on,
Since it can be detected that the print head is covered with the cap, the state of the print head can be accurately grasped.

[Brief description of drawings]

FIG. 1 is a diagram for explaining a positional relationship between a sensor and a shield of an inkjet recording apparatus of the present invention.

FIG. 2 is a diagram for explaining a home position and an idle discharge position of the inkjet recording apparatus of the present invention.

FIG. 3 is a graph for explaining the relationship between the position of the home position and the idle discharge position and the signal output by the sensor.

FIG. 4 is a conventional inkjet recording apparatus.

[Explanation of symbols]

 2 ... Inkjet recording device 3 ... Shield 4 ... Sensor 41 ... Transmission unit 42 ... Reception unit 11 ... Print medium 12 ... Carriage 19 ... Print head A ... Reference position (home position) B ... … Empty discharge position

Claims (4)

[Claims] 1. An ink jet recording apparatus comprising: a carriage configured to reciprocate relative to a print medium; and a print head provided on the carriage for ejecting ink onto the print medium. A sensor having a transmitter and a receiver, and detecting a state therebetween, and a shield for shielding the sensor between the transmitter and the receiver to put the sensor in a shielded state, and the sensor, The shield and the shield are configured to move relative to each other as the carriage moves, and the state change of the sensor is detected at least twice so as to obtain an idle ejection position and a reference position of the print head. An inkjet recording apparatus comprising: 2. The ink jet recording apparatus according to claim 1, wherein the ink jet recording apparatus is configured to perform idle ejection of the print head while the sensor is in a shielded state. 3. An ink jet recording apparatus, wherein the carriage is configured to reciprocate a distance corresponding to the number of pulses, and the position of the print head is calculated from the number of pulses. The number of pulses is integrated as a reference, the number of pulses required to move the carriage from the reference position to the idle ejection position is obtained in advance, and the number of pulses when the print head is at the idle ejection position 3. The inkjet according to claim 1 or 2, wherein the number of pulses is compared with each other, and if the difference is larger than a predetermined value, error processing is performed. Recording device. 4. The sensor according to claim 1, wherein the sensor comprises a photo interrupter in which a light emitting element and a light receiving element are arranged to face each other, and the shield is a plate having a light blocking property. 2. The inkjet recording device according to item 1.