JP5315030B2 - Recording device - Google Patents

Description

  The present invention relates to an ink jet recording apparatus that records an image on a recording medium by moving a carriage on which a recording head is mounted.

  In a recording apparatus in which a recording head performs main scanning in a direction crossing the recording material conveyance direction (sub-scanning direction), the recording material is set at a predetermined recording position and then moved along the recording material (main scanning). The image is recorded by recording means (recording head) mounted on the carriage. After recording for one line is completed, a predetermined amount of paper feed (sub-scan) is performed, and then the image of the next line is recorded (main scan). By repeating these operations, an image is recorded in a desired range of the recording material.

  In a recording apparatus, high speed and high image quality are recently required, and accordingly, a controlled body such as a print head needs to be driven at high speed and with high accuracy. When vibration is transmitted to the print head mounted on the carriage during main scanning, the print quality is remarkably deteriorated. Therefore, low vibration of the carriage is required.

  The carriage can reciprocate along the guide shaft and is driven by a motor such as a DC motor. In the DC motor, even if the input to the motor is constant due to its structure, the torque during one rotation of the motor shaft is not uniform, and a periodic torque variation called cogging depending on the motor rotation angle occurs. For this reason, the driving speed of the carriage driven by the DC motor also periodically pulsates. As the speed pulsates, the carriage vibrates, and even in areas that should be recorded at a constant density, dark and light portions appear alternately, resulting in striped print unevenness and poor print quality. .

Therefore, a method has been proposed in which a pulsation of the carriage drive speed is reduced by superimposing a periodic signal having the same period as that of cogging and a phase shift of 180 ° on the DC motor drive signal (for example, patents). Reference 1).
JP 2006-95697 A

  In order to generate a periodic signal (vibration suppression signal) having the same cycle as that of cogging and having a phase shifted by 180 °, it is necessary to obtain the motor rotation angle.

  Normally, an ink jet recording apparatus is not equipped with a motor rotation angle sensor, but since the position of the carriage is detected by an encoder, the motor rotation angle can be obtained in a pseudo manner.

Pseudo motor rotation angle = Carriage position / Pulley radius ...... Formula (1)
However, when calculating from the encoder, the motor rotation angle cannot be determined accurately due to the effects of encoder accumulated error, belt expansion and contraction, and the like.

  Further, when slippage occurs between the pulley and the belt, the relationship between the carriage position obtained from the encoder and the motor rotation angle changes, and the influence of cogging cannot be suppressed.

  FIG. 8 is a diagram illustrating the relationship between the motor rotation angle and the pseudo motor rotation angle.

  In the figure, the solid line shows the case where the motor rotation angle and the pseudo motor rotation angle are correct, the dotted line shows the case where there is an encoder accumulated error, and the one-point difference line shows a slip between the pulley and the belt Show the case.

  If there is a cumulative error in the encoder, the difference between the pseudo motor rotation angle and the motor rotation angle increases as the rotation of the motor progresses, and can no longer be ignored. In addition, if slip occurs between the pulley and the belt, a shift occurs between the pseudo motor rotation angle and the motor rotation angle.

  When the above phenomenon occurs, the vibration suppression signal is generated on the premise that the motor rotation angle and the pseudo motor rotation angle are correct, so that the vibration suppression effect deteriorates, and in some cases, vibration There is a problem that it causes an increase in.

  The present invention provides a high-quality inkjet printer that suppresses periodic vibration components and does not cause uneven printing even if an encoder accumulated error occurs or the relationship between the carriage position and the motor rotation angle changes. The purpose is to provide.

The recording apparatus of the present invention includes a carriage mounted with a recording head and moving, a linear encoder used to determine the position of the carriage, a motor and a belt, and a driving means for driving the carriage, A rotation detecting means for detecting a rotation angle; a calculating means for calculating a deviation amount between the position of the carriage obtained from the detection of the linear encoder and an ideal carriage position obtained from the detection of the rotation detecting means; and the ideal carriage And generating means for generating a vibration suppression signal for compensation control that cancels periodic vibration when the motor is driven based on a pseudo motor rotation angle obtained from a position and the amount of deviation.

  According to the present invention, even when an accumulated encoder error occurs or when the relationship between the carriage position and the motor rotation angle changes, the periodic vibration component is suppressed and printing unevenness is not generated.

  The best mode for carrying out the invention is the following embodiment.

  FIG. 1 is a diagram schematically showing the configuration of an ink jet recording apparatus 100 that is Embodiment 1 of the present invention.

  A guide shaft 2 is slidably inserted in a carriage 1 on which a recording head (not shown) is mounted, and the carriage 1 can reciprocate along the thrust direction (main scanning direction) of the guide shaft 2.

  A driving pulley 4 is fixed to a shaft of a carriage motor 3 that is a carriage driving means. Between the drive pulley 4 and the idle pulley 5, a belt 6 serving as a carriage drive transmission means is stretched over, and a part of the belt 6 is fixed to the carriage 1. The belt 6 is moved by forward and reverse rotations of the carriage motor 3, and the carriage 1 moves forward and backward along the main scanning direction. The linear encoder 7 detects the position of the carriage 1. Further, a rotation angle detection means 8 is provided.

  FIG. 2 is a schematic view showing an example of the rotation angle detection means 8.

  A shielding plate 9 is attached to the rotation shaft of the carriage motor 3. When the light emitted from a light emitting element such as an LED is incident on a light receiving element such as a photodiode placed in front of the light emitting element and interrupts the optical axis between the light emitting element and the light receiving element, the optical sensor 10 This is an optical sensor in which the output signal level changes.

  When the shielding plate 9 blocks the optical axis of the optical sensor 10, the output changes, and one rotation (360 degrees) of the carriage motor 3 can be detected.

  FIG. 3 is a schematic diagram showing the configuration of another rotation angle detection means 8a.

  By using the shielding plate 9a shown in FIG. 3, the motor half rotation (180 degrees) can be known. In addition, although the case where a detection angle is 360 degree | times and 180 degree | times is shown here, a detection angle is not restricted to these, What is necessary is just an angle of equal intervals. Further, the rotation angle detection means may be constituted by a magnetic plate and magnetic detection means such as a Hall element.

  FIG. 4 is a block diagram illustrating the carriage control unit according to the first embodiment.

  The position control compensator (position control compensation means) 11 takes a difference between a predetermined driving pattern of the carriage 1 and the position of the carriage observed by the linear encoder 7. Then, the position control compensator (position control compensation means) 11 calculates so that the position of the carriage matches the drive pattern (this action is referred to as “compensation”). The output signal of the position control compensator (position control compensation means) 11 is compared with the carriage speed signal obtained by the speed calculation means 12, the PI compensator (speed control compensator) 13 performs a compensation operation, and the drive circuit 14 amplifies. And drive the motor.

  In general, PI compensation is often used. However, instead of PI compensation, for example, PID compensation, phase delay compensation, and phase delay advance compensation may be applied as a compensation algorithm.

  The vibration suppression signal calculation means 17 calculates the amplitude, phase, and deviation amount of the vibration suppression signal from the position and speed of the carriage 1, the output signal of the rotation angle detection means 8, and the output signal of the deviation amount calculation means 18. The vibration suppression signal output means 19 outputs a vibration suppression signal based on the amplitude and phase calculated by the vibration suppression signal calculation means 17.

  The deviation amount calculation means 18 uses the output of the rotation angle detection means 8 as a trigger to calculate the deviation amount between the ideal carriage position calculated by the following equations (2) and (3) and the value of the linear encoder.

Ideal carriage position = pulley radius x motor rotation angle ...... Formula (2)
Deviation amount = ideal carriage position-carriage position ...... Formula (3)
The vibration suppression signal calculation means 17 calculates the pseudo motor rotation angle from the deviation amount obtained by the deviation amount calculation means 18 by the following equation (4).

Pseudo motor rotation angle = ( ideal carriage position + deviation amount) ÷ pulley radius …… Equation (4)
Further, based on the pseudo motor rotation angle, the vibration suppression signal obtained by the following equation (5) is output,
Vibration suppression signal = A × sin (pseudo motor rotation angle / λ + φ) (5)
The amplitude A and the phase φ are determined so as to minimize the pulsation of the carriage speed. Note that λ is the period of vibration to be suppressed.

  The carriage 1 is an example of a carriage on which a print head is mounted. The linear encoder 7 is an example of carriage position detecting means for detecting the position of the carriage. The carriage motor 3 is an example of a carriage driving unit that drives the carriage via a belt.

  The rotation angle detection unit 8 is an example of a rotation angle detection unit that detects the rotation angle of the carriage drive unit. The deviation amount calculation means 18 is an example of a deviation amount calculation means for calculating the deviation amount between the signal detected by the carriage position detection means and the signal detected by the rotation angle detection means.

  The vibration suppression signal output means 19 is a vibration suppression signal that cancels the periodic vibration corresponding to the carriage, and corresponds to the output signal of the carriage position detection means, the output signal of the rotation angle detection means, and the output signal of the deviation amount calculation means. It is an example of the vibration suppression signal output means which outputs a vibration suppression signal.

  FIG. 5 is a diagram illustrating the relationship between the motor rotation angle and the pseudo motor rotation angle in the first embodiment.

  In FIG. 5, a thin line indicates a case where the motor rotation angle and the pseudo motor rotation angle are correct, a dotted line indicates a case where there is an encoder accumulated error, and a thick line indicates that the embodiment 1 is applied when there is an encoder accumulated error. It is a figure which shows a case.

  Since the deviation is corrected for each rotation of the motor, even if the rotation of the motor proceeds, the difference between the pseudo motor rotation angle and the motor rotation angle does not increase.

  FIG. 6 is a diagram illustrating each speed when the carriage 1 is in a constant speed state.

  FIG. 6A is a diagram illustrating a case where vibration suppression is not performed, and FIGS. 6B and 6C are diagrams illustrating the carriage speed when the conventional technique is used.

  FIG. 6B is a diagram showing a case where vibration suppression is effective, and FIG. 6C is a velocity waveform showing a case where there is an encoder accumulated error.

  There is a case where pulsation is larger than when vibration suppression is not performed. FIG. 6D shows a velocity waveform to which the first embodiment is applied when there is an encoder integration error. Even when there is an encoder integration error, the deviation is corrected for each rotation of the motor, so that vibration suppression can be realized over the entire area.

  FIG. 7 is a block diagram illustrating a carriage control unit in the inkjet recording apparatus 200 that is Embodiment 2 of the present invention.

  The ink jet recording apparatus 200 is an embodiment in which when a brushless motor is used as the carriage driving means, a Hall element used for phase switching of the brushless motor is used as the rotation angle detecting means.

  That is, the ink jet recording apparatus 200 is an example in which the Hall element 20 is used in the ink jet recording apparatus 100 instead of the rotation angle detecting means 8.

  The output signal of the Hall element 20 attached to the brushless motor is input to the drive circuit 14, and the drive circuit 14 performs phase switching to drive the motor. The output signal of the Hall element 20 is input to the deviation amount calculation means 18 and the vibration suppression signal calculation means 17. The deviation amount calculation means 18 uses the output signal of the Hall element 20 as a trigger, and calculates the deviation amount between the ideal carriage position and the value of the linear encoder obtained by the above formulas (2) and (3).

  Although the number of Hall elements and the detected rotation angle per rotation differ depending on the structure of the motor, the above embodiment can be applied in any case.

  In Embodiment 2, when a brushless motor is used as the carriage driving means, the rotation angle detecting means is a Hall element.

  If each means is replaced with a process in each of the above embodiments, each of the above embodiments is an example of an invention of a method for controlling an ink jet recording apparatus.

1 is a diagram schematically showing the configuration of an inkjet recording apparatus 100 that is Embodiment 1 of the present invention. FIG. FIG. 6 is a schematic diagram illustrating an example of a rotation angle detection unit 8. It is the schematic which shows the structure of another rotation angle detection means 8a. FIG. 3 is a block diagram illustrating a carriage control unit according to the first exemplary embodiment. In Example 1, it is a figure which shows the relationship between a motor rotation angle and a pseudo motor rotation angle. It is a figure which shows each speed in case the carriage 1 is a constant speed state. FIG. 6 is a block diagram illustrating a carriage control unit in an inkjet recording apparatus 200 that is Embodiment 2 of the present invention. It is a figure which shows the relationship between a motor rotation angle and a pseudo motor rotation angle.

Explanation of symbols

100: Inkjet recording apparatus,
1 ... carriage,
2 ... Guide shaft,
3. Carriage motor,
4 ... Drive pulley,
5 ... Idle pulley,
6 ... Belt,
7 ... Linear encoder,
8 ... Rotation angle detection means,
9 ... shielding plate,
10: Optical sensor,
11: Position control compensator (position control compensation means),
12 ... speed calculation means,
13 ... PI compensator,
14 ... Drive circuit,
15 ... proportional term,
16 ... integral term,
17 ... Vibration suppression signal calculation means,
18: Deviation amount calculating means,
19 ... Vibration suppression signal output means,
200: Inkjet recording apparatus,
20: Hall element.

Claims (4)

A carriage mounted with a recording head and moved;
A linear encoder used to determine the position of the carriage;
Drive means including a motor and a belt for driving the carriage;
Rotation detection means for detecting the rotation angle of the motor;
Calculating means for calculating a deviation amount between the position of the carriage obtained from the detection of the linear encoder and the ideal carriage position obtained from the detection of the rotation detecting means;
Generating means for generating a vibration suppression signal for compensation control that cancels periodic vibration when driving the motor based on a pseudo motor rotation angle obtained from the ideal carriage position and the deviation amount;
A recording apparatus comprising:   The recording apparatus according to claim 1, wherein a plate member is attached to a rotation shaft of the motor, and the rotation detecting unit detects passage of the plate member accompanying rotation of the motor.   The recording apparatus according to claim 1, wherein the motor is a brushless motor, and the rotation detection unit includes a Hall element.   The said production | generation means produces | generates the said vibration suppression signal based on the said deviation | shift amount calculated by the said calculation means for every rotation of the said motor, The any one of Claim 1 to 3 characterized by the above-mentioned. Recording device.

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