JPH03169697A - Paper detection method in paper driving type automatic drawing machine - Google Patents

Abstract

PURPOSE:To detect the end position of paper with high accuracy without being affected by sensor mounting accuracy, in detecting the edge position of the paper placed on a paper placing member prior to drawing, by correcting the offset quantity to an image line head of a sensor on the basis of offset correction quantity. CONSTITUTION:When the offset automatic correcting operation of a paper edge sensor 52 is started with respect to an image line sensor 18, a controller 42 moves the sensor from the left to the right with respect to a correction mark 58 at first and confirms the point of time when a light detection element 56 is turned ON to calculate the correction mark detection position due to the sensor 52. Next, the difference of the physical detection position of the correction mark 52 with respect to the logical detection position thereof due to the sensor 52 is operated to calculate offset correction quantity A. When it is judged that the sensor 52 detects the edge of paper 16 on the left side with respect to said edge, the offset correction quantity A is set to X. Next, offset quantity is added to the count value of a counter when the sensor 52 is turned ON.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a method for detecting the position of paper on a paper placement member in a paper-driven automatic drafting machine.

[Conventional technology]

The paper position detection device in conventional automatic drafting machines of this type is
A light reflection type sensor is installed in the printing head, and the printing head is moved from the origin reference position in a direction across the paper placement member on the paper placement member, and the amount of movement of the printing head is calculated from the pulse encoder. The paper is counted by feedback pulses, and is calculated from the amount of movement of the print head when the sensor detects the edge of the paper on the paper placement member and turns on or off, and the amount of offset of the sensor with respect to the print head. Detecting the edge position. [Problems to be Solved by the Invention] If the paper detection point of the sensor is always constant, the position of the edge of the paper can always be accurately measured. However, the paper detection point of the sensor, that is, the timing when the sensor turns on and off, physically varies depending on the sensor characteristics and installation accuracy. As shown in FIG. 6, the paper detection point 4 of the sensor 2 is
It is theoretically set on the center line 10 between the light emitting element 6 and the light receiving element 8. Therefore, theoretically, when the paper detection point 4 of the sensor 2 is located at the edge of the paper 12, as shown in FIG. 6A, the sensor 2 should detect the edge. When the sensor 2 is scanned in the arrow direction, when the detection point 4 reaches the edge, the output of the sensor changes from on to off. However, in reality, as shown in FIG. 6B, the sensor 2 detects the edge of the paper 12 behind the theoretical paper detection point 4, and there is a discrepancy between the theoretical paper detection point 4 and the actual paper detection point 4. An error α will occur between the paper detection point and the paper detection point. The offset amount Q of the sensor 2 with respect to the drawing head is set as the distance on the Y axis between the center of the pen 14 held by the drawing head and the theoretical paper detection point 4 set on the sensor 2. , Actual paper detection point 4! is different from the theoretical paper detection point 4, paper 12
It is not possible to accurately detect the position of the edge, and an error α occurs. The present invention aims to eliminate the above-mentioned defects.

[Means to solve problems]

In order to achieve the above object, the present invention provides a method of scanning the edge of paper on a paper placement member with a light reflection type sensor provided in a printing head and detecting the position of the edge. setting an offset amount of the sensor with respect to the drawing head, arranging a correction mark made of blank paper or a similar member on the scanning direction of the sensor of the paper placement member;
The difference between the detected position of the edge when the sensor detects the edge of the correction mark and the actual position of the edge is stored in advance as an offset correction amount, and the paper is placed on the paper prior to drawing. When the sensor detects the position of the edge of the paper placed on the member, the offset amount of the sensor with respect to the printing head is corrected based on the offset correction amount.

〔Example〕

The configuration of the present invention will be explained in detail below with reference to embodiments shown in the accompanying drawings. In FIG. 1, reference numeral 16 denotes a paper mounting member (platen) fixed to the body of the paper-driven automatic drafting machine. A Y rail (not shown) is fixedly installed. A printing head 18 is attached to the Y rail so as to be movable along the longitudinal direction of the Y rail. The printing head l8 is provided with a pen holder 20 that is connected to an elevating drive device consisting of a solenoid 20 (see FIG. 5) built therein, and the pen holder 20 removably holds a pen 22. ．． A groove is provided in the sheet mounting member 16 in a direction parallel to the Y rail, and a drawing roller 24 is rotatably disposed in the groove. A plurality of holes are formed in the sheet placement member l6 on an axis parallel to the drawing roller 24, and a drive roller 26 fixed to an X drive shaft (not shown) is arranged in the holes. ing. The drawing roller 24 and the driving roller 26 are connected to an X motor 28 (see FIG. 5) so that they are driven in the same direction at substantially the same circumferential speed. On the drive roller 26 is a pressure roller 2.
8 is arranged to be able to rise and fall freely, and during the drawing operation, the pressure roller 28 presses against the drive roller 26 from above the paper 30 on the paper placement member 16, and the drive roller 26 and the pressure roller 2
8 and clamp the paper 30. The printing head 18 is connected to a Y motor 34 via an endless power transmission belt 32, and when the Y motor 34 is driven, it reciprocates in the Y-axis direction along the Y rail, that is, along the drawing roller 24. It is being arranged to be moved. Said XY motor 28, 34
and solenoid 20, as shown in FIG.
6.38.40, it is connected to an output port 44 of a controller 42 consisting of a microcomputer. The controller 42 has an input port 4
6, receives drawing data from the host computer, and controls the XY motors 28, 34 and the solenoid 20 based on the data. By rotation of the drive roller 26 driven by the X motor 28, the paper 3o is sent on the paper placement member 16 in the front-rear direction, that is, in the X-axis direction. Further, the printing head 18 is driven by the Y motor 34 to move the printing head 18 along the Y rail, that is, to move the paper 3
Direction perpendicular to the forward and backward feeding direction of o (Y-axis direction)
sent to. On the other hand, by energizing the solenoid 2o, the pen holder 20 is lowered, and the tip of the pen 22 is pressed against the surface of the drawing roller 24 from above the paper 30. When the solenoid 20 is de-energized, the pen 22 separates upward from the paper 30. A predetermined drawing is performed on the paper 30 by feeding the paper 30 in the X direction, feeding the drawing head l8 in the Y direction, and moving the pen 22 up and down. The pen 22
The position signal on the XY coordinate axes of the center of the paper 30 is sent to input port 4 by XY encoder 48.
6 to be fed back to the controller 42. 52 is a light emitting element 54 and a light receiving element 5
A reflective paper edge detection sensor consisting of 6,
A lens system (
(not shown) are arranged. The light emitting element 54 of the sensor 52 is controlled on and off by the controller 42, and the detection signal of the light receiving element 56 is sent to the input port 46.
The information is configured to be input to the controller 42 via the . A correction mark 58 made of white paper or the like is pasted at a predetermined position on one side of the paper placement member 16. The light emitting element 54 and the light receiving element 5 of the sensor 52
The distance between the center line 60 of the pen 22 and the center line 60 of the pen 22 is stored in the RAM of the controller 42 as an offset amount of the sensor 52 with respect to the print head 18. Next, the automatic offset amount correction operation of the paper edge sensor 52 with respect to the printing head 18 will be explained in detail with reference to the flowchart of FIG. When the automatic offset correction operation starts from label 1, the controller 42 first performs the following steps.
In FIG. 2, the sensor 52 is moved from left to right with respect to the correction mark 58. The sensor 52 is moved by moving the print head 18 along the Y rail. sensor 5
2 moves on the paper placement member 16 from left to right in FIG.
When it reaches above 8, it turns on. The controller 42 recognizes when the light receiving element 56 is turned on and turns the sensor 52 on.
Find the correction mark detection position by. In reality, the controller 42 counts the feedback pulses of the Y encoder 50 that are generated as the printing head 18 moves from the reference point (Y reference point) at the left end of the Y rail of the printing head 18, and the sensor When 52 is turned on from off,
The position of the left edge of the correction mark 58 is recognized from the amount of movement of the drawing head 18 from the reference point and the above-mentioned offset amount. In this way, the controller 42 recognizes the physically detected position of the left edge of the correction mark 58 through the detection operation of the sensor 52 (block 3), and stores the value in the RAM. Next, the controller 42 controls the sensor 5
The offset correction amount A is calculated by calculating the difference between the theoretical detection position of the correction mark 58 according to No. 2 and the physical detection position (block 4). The theoretical paper detection point 60 of the sensor 52 is theoretically set on the center line 62 between the light emitting element 54 and the light receiving element 56. That is, when the edge of the paper is located at the detection point 60 of the sensor 52, the sensor 52 is theoretically set to be turned on. Therefore, the theoretical detection point 60 of the sensor 52 is the second
As shown in Figure A, the sum of the amount of movement of the print head 18 from the Y reference point and the amount of offset when it matches the left edge of the correction mark 58 is the theoretical detection position of the correction mark 58 by the sensor 52. Become. In reality, this theoretical detection position can be found from the design value of the distance between the Y reference point and the left edge of the correction mark 58, or by actually measuring the distance using a measuring instrument. can. The controller 42 controls the correction mark 5 by the sensor 52.
The theoretical detection position of the left edge of 8 is stored in advance in RAM. FIG. 2B shows that the sensor 52 detects the paper at the paper detection point 60.
However, even when the left edge of the correction mark 16 is reached, it is not turned on, but is turned on with a delay of the offset correction amount A. Next, the controller 42 moves the sensor 52 to the correction mark 58 as shown in FIG. 3B.
Moving from right to left (block 5), the physical position of the print head 18 when the sensor 52 detects the right edge 58a of the correction mark 16 is determined (block 6). Next, in block 7, the controller 42 calculates the difference B between the theoretical paper detection position of the right edge 58a of the correction mark 58 by the sensor 52 and the physical detection position of the right edge 58a by the sensor 52, that is, the offset correction amount B. Store in RAM. Next, in the initial operation of automatic drawing, the controller controls the paper 16 on the paper placement member 16 in block 8.
Start detecting edges on both sides of . The controller 42 detects the sensor 5 with respect to the edge of the paper 16 in a judgment block.
2 determines whether the edge is detected from the left side, and if the determination is affirmative, the offset correction amount A is set to X in block 10. Next, in block 12, the controller 42 corrects the value obtained by adding the above-mentioned offset amount to the count value of the counter when the sensor 52 is turned on, that is, the value where the edge is actually detected, by adding the above-mentioned X, With this correction value, the controller 42 adjusts the Y of the left edge of the paper 16.
Recognize the position relative to the reference point. If a negative decision is made in decision block 9, offset correction amount B is set to X in block 1l.
Then, move to block l2. [Effects] As described above, the present invention automatically offsets the physical detection position of the sensor during the initial setting of automatic drafting, so that the paper edge position detection is not affected by the accuracy of sensor installation. It has the advantage that it can be performed with high accuracy.

[Brief explanation of the drawing]

Figure 1 is an external view, Figure 2 is an explanatory diagram, Figure 3 is an explanatory diagram, Figure 4 is a flowchart, Figure 5 is a block diagram, and Figure 6 is an explanatory diagram.
The figure is an explanatory diagram. 2... Sensor, 4... Paper detection point, 6... Light emitting element, 8... Light receiving element, 10... Center line, 12...
Paper, 14... Pen, 16... Paper holding member. 18
... Drawing head, 20... Pen holder 22...
- Pen, 24... Drawing roller, 26... Drive roller, 28... Pressure roller, 30... Paper, 32...
Belt, 34...Y motor, 42...controller, 52...sensor, 54...light emitting element, 56...
Light receiving element, 58...correction mark. 60...Paper inspection point, 62...Center line.

Claims (1)

[Claims] (1) In a method of scanning the edge of paper on a paper placement member with a light-reflecting sensor provided on a printing head and detecting the position of the edge, the amount of offset of the sensor with respect to the printing head is determined in advance. is set, a correction mark made of blank paper or a similar material is placed in the scanning direction of the sensor of the paper placement member, and the detection position of the edge when the sensor detects the edge of the correction mark is set. and the actual position of the edge is stored in advance as an offset correction amount, and when the sensor detects the position of the edge of the paper placed on the paper placement member prior to drawing, A paper detection method in a paper-driven automatic drafting machine, characterized in that an offset amount of the sensor with respect to the drawing head is corrected based on the offset correction amount.