Position detection device, printing apparatus and position detection method
Provided are a position detection device, a printing apparatus equipped with the position detection device and a position detection method which make it possible to set an original point on a deviation-free appropriate position with no need of highly accurate adjustment of built-in positions of a linear encoder and an original point sensor. In a case where a point that low-to-high switching of an output from a scale sensor is detected is set as a light transmission timing, a point that high-to-low switching of the output is detected is set as a light shielding timing and an output change point that an original point sensor detects is set as a detection timing, in a duration time D 1 which lasts from the detection timing to a first light transmission timing which is the closest to the detection timing and a duration time D 2 which lasts from the detection timing to a first light shielding timing which is the closest to the detection timing, when the duration time D 1 >the duration time D 2 , a position of a moving body which is obtained at a second light transmission timing is set as an original point and when the duration time D 1 <the duration time D 2 , the position of the moving body which is obtained at a second light shielding timing (the first light shielding timing) is set as the original point.
1. A position detection device which detects a position of a moving body, comprising:
a position sensor which detects the moving body and outputs a detection signal;
an encoder which has a scale and a scale sensor and detects an amount of movement of the moving body in one direction; and
a processor which controls the position sensor and the scale sensor, wherein
a first section that an output from the scale sensor becomes low and a second section that the output from the scale sensor becomes high are alternately arranged on the scale, and
in a case where an output change point that the scale sensor detects switching from the first section to the second section is set as a light transmission timing, an output change point that the scale sensor detects switching from the second section to the first section is set as a light shielding timing and an output change point that the position sensor detects is set as a detection timing,
with the light transmission timing which is the closest to the detection timing being set as a first light transmission timing and the light shielding timing which is the closest to the detection timing being set as a first light shielding timing, the processor
sets a position of the moving body which is obtained at a second light transmission timing which is the light transmission timing which comes after the detection timing as an original point position in the one direction or a reference position which serves as a reference of the original point position, (1) in a case where a duration time D 1 between the detection timing and the first light transmission timing is longer than a duration time D 2 between the detection timing and the first light shielding timing, and
sets a position of the moving body which is obtained at a second light shielding timing which is the light shielding timing which comes after the detection timing as the original point position in the one direction or the reference position, (2) in a case where the duration time D 1 is shorter than the duration time D 2 .
2. The position detection device according to claim 1 , wherein
in a case where the duration time D 1 and the duration time D 2 are equal to each other, the processor sets the position of the moving body which is obtained at either the second light transmission timing or the second light shielding timing as the original point position in the one direction or the reference position.
3. The position detection device according to claim 1 , wherein
the processor compares the duration time D 1 with the duration time D 2 , in a case where the duration time D 1 is longer than the duration time D 2 , sets the position of the moving body which is obtained at the second light transmission timing as the original point position in the one direction or the reference position, and in a case where the duration time D 1 is shorter than the duration time D 2 , sets the position of the moving body which is obtained at the second light shielding timing as the original point position in the one direction or the reference position.
4. The position detection device according to claim 1 , wherein
the processor sets the light transmission timing and the light shielding timing which are the closest to the detection timing before and after the detection timing as the first light transmission timing and the first light shielding timing respectively.
5. The position detection device according to claim 1 , wherein
the processor, in a case where the duration time D 1 is longer than the duration time D 2 , sets the light transmission timing which comes after the detection timing and is the closest to the detection timing as the second light transmission timing, and in a case where the duration time D 1 is shorter than the duration time D 2 , sets the light shielding timing which comes after the detection timing and is the closest to the detection timing as the second light shielding timing.
6. The position detection device according to claim 1 , wherein
the moving body operates on the basis of instructions and control while reciprocally moving in a predetermined range and
the processor, in a case of setting either the light transmission timing or the light shielding timing of the moving body on a forward path as an operation instruction timing for making the moving body perform an operation which includes the reciprocal movement that a user wishes, sets a position of the moving body which is obtained at the operation instruction timing as an operation instruction position on the forward path and a backward path.
7. A printing apparatus comprising:
a position detection device which detects a position of a moving body and includes a position sensor which detects the moving body and outputs a detection signal, an encoder which has a scale and a scale sensor and detects an amount of movement of the moving body in one direction and a processor which controls the position sensor and the scale sensor, wherein
a first section that an output from the scale sensor becomes low and a second section that the output from the scale sensor becomes high are alternately arranged on the scale, and
in a case where an output change point that the scale sensor detects switching from the first section to the second section is set as a light transmission timing, an output change point that the scale sensor detects switching from the second section to the first section is set as a light shielding timing and an output change point that the position sensor detects is set as a detection timing,
with the light transmission timing which is the closest to the detection timing being set as a first light transmission timing and the light shielding timing which is the closest to the detection timing being set as a first light shielding timing, the processor
sets a position of the moving body which is obtained at a second light transmission timing which is the light transmission timing which comes after the detection timing as an original point position in the one direction or a reference position which serves as a reference of the original point position, (1) in a case where a duration time D 1 between the detection timing and the first light transmission timing is longer than a duration time D 2 between the detection timing and the first light shielding timing, and
sets a position of the moving body which is obtained at a second light shielding timing which is the light shielding timing which comes after the detection timing as the original point position in the one direction or the reference position, (2) in a case where the duration time D 1 is shorter than the duration time D 2 ;
the moving body includes a print head which performs an ink ejecting operation while moving reciprocally, and
the processor instructs and controls the operation of the moving body in accordance with a result of detection by the position detection device.
8. A position detection method for a position detection device which detects a position of a moving body and includes a position sensor which detects the moving body and outputs a detection signal, an encoder which has a scale and a scale sensor and detects an amount of movement of the moving body in one direction and a processor which controls the position sensor and the scale sensor, wherein
a first section that an output from the scale sensor becomes low and a second section that the output from the scale sensor becomes high are alternately arranged on the scale, and
in a case where an output change point that the scale sensor detects switching from the first section to the second section is set as a light transmission timing, an output change point that the scale sensor detects switching from the second section to the first section is set as a light shielding timing and an output change point that the position sensor detects is set as a detection timing,
with the light transmission timing which is the closest to the detection timing being set as a first light transmission timing and the light shielding timing which is the closest to the detection timing being set as a first light shielding timing, the method comprising:
setting a position of the moving body which is obtained at a second light transmission timing which is the light transmission timing which comes after the detection timing as an original point position in the one direction or a reference position which serves as a reference of the original point position by the processor, (1) in a case where a duration time D 1 between the detection timing and the first light transmission timing is longer than a duration time D 2 between the detection timing and the first light shielding timing; and
setting a position of the moving body which is obtained at a second light shielding timing which is the light shielding timing which comes after the detection timing as the original point position in the one direction or the reference position by the processor, (2) in a case where the duration time D 1 is shorter than the duration time D 2 .