JP2621416B2 - Plate for measuring travel distance - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial application field) The present invention relates to a plate for measuring a moving amount, for example, in the XY direction of a moving object such as an electronic component mounting apparatus or an XY direction moving apparatus such as a machine tool. The movement amount can be easily and accurately measured.

(Prior Art) Conventionally, a pulse motor is generally used as an actuator in the above-described XY-direction moving device and the like. However, due to machining errors and mechanical errors based on assembly errors, and congestion in operation due to the load on the actuator, the movement command value does not always match the actual movement amount.
Therefore, when actually using the XY-direction moving device or the like, it is necessary to measure a unique error for each device, input this error to the control device, and correct the movement command value. .

FIG. 5 shows a conventional means for measuring such an error, in which 100 is an XY-direction moving device comprising XY tables 101 and 102, on which a mirror 103 is provided, and a laser light source device is provided beside it. 104 are provided, and the operation thereof will be described next.

The XY tables 101 and 102 are first moved in the X direction based on the movement command value while irradiating the mirror 103 with laser light from the laser light source device 104 and receiving the reflected light from the mirror 103. The difference between the movement command value in the X direction and the actual movement amount is detected by measuring the change in the distance between the light source device 104 and the mirror 103. Next, the same operation as described above is repeated, for example, by re-standing the mirror 103, thereby detecting the difference in the Y direction.

(Problems to be Solved by the Invention) However, the conventional means cannot simultaneously detect the amount of movement in the X direction and the Y direction. Since the measurement has to be performed separately, there is a problem that the work is required twice and the working efficiency is not improved. Further, the use of a laser light source device has a disadvantage that the device becomes extremely expensive.

Therefore, an object of the present invention is to solve the above-mentioned problems and to provide means for easily and accurately measuring an actual movement amount in a two-dimensional direction (XY direction).

(Means for Solving the Problems) According to the present invention, reference points having optical characteristics different from the surroundings are formed at a pitch in the XY direction on the main surface of a flat plate made of a transparent glass plate. And a backup sheet having optical characteristics different from those of the reference point.

Further, the backup sheet is mounted on a surface on which the reference point is formed.

(Operation) According to the above configuration, the glass plate on which the reference point is formed,
By mounting the backup sheet having different optical characteristics from the reference point, the reference point can be accurately identified with clear contrast.

By mounting the backup sheet on the surface where the reference points are formed, the reference points can be protected by the backup sheet.

(Example) Hereinafter, an example of the present invention will be described with reference to the drawings.

1 and 2, reference numeral 1 denotes a plate for measuring the amount of movement, and a large number of reference points 3 are arranged on the front or back surface of a rectangular flat plate 2 made of a transparent glass plate at a predetermined pitch t in the XY direction. Is formed. Reference numeral 4 denotes a backup sheet mounted on the surface on which the reference point 3 is formed. Since the flat plate 2 is a transparent glass plate, the flatness is good, the distortion is small, the stability against heat and aging is good, the refractive index of light is uniform in each part, and the surface hardness is high, so that the flat plate 2 is hard to be scratched. The reference point 3 formed on the main surface can be clearly seen through. The reference point 3 is formed as a chrome film by a photo etching method. According to the photo-etching method, the shape and position of the reference point 3 can be formed with extremely high accuracy. The backup sheet 4 attached to the formation surface of the reference point 3 has a chrome coating of the reference point 3 which is observed black with an industrial television camera described later, so that its position and shape can be clearly identified. For example, it is formed of a material having optical characteristics different from those of the reference point 3 such as white. Note that the reference point 3 only needs to have an optical characteristic that is clearly different from that of the surrounding area. Therefore, the reference point 3 is more easily distinguished as it has a distinctive difference in luminance, color tone, or the like and a higher contrast. The chrome film at the reference point 3 is protected by attaching a backup sheet 4 to the main surface of the flat plate 2 on which the reference point 3 is formed. The shape of the reference point 3 is arbitrary, but if the reference point 3 is formed in a rectangular shape as in the present embodiment, one side of the reference point 3 coincides with or is perpendicular to the direction of the scanning line of the industrial television camera. The contour of the reference point 3 in the field of view of the television camera is clearly observed, and the position detection accuracy of the reference point 3 is improved.

FIG. 3 is a perspective view showing a use state of the plate 1 for measuring the amount of movement. Reference numeral 5 denotes an XY direction moving device, which comprises an X table 6 and a Y table 7. Reference numerals 8 and 9 denote driving pulse motors. The XY direction moving device 5 serves as a means for moving the substrate in the XY direction in an electronic component mounting apparatus for automatically mounting electronic components on the substrate, for example. Reference numeral 1 denotes the above-mentioned measuring plate, which is positioned on the X table by the positioning means 12. Reference numeral 10 denotes an industrial television camera disposed above the camera. Reference numeral 11 denotes a control device composed of a computer or the like, which is connected to the driving pulse motors 8, 9 and the industrial television camera 10,
The operation will be described below.

When a number of pulses proportional to the amount by which the XY tables 6 and 7 are to be moved are output as movement command values from the control device 11 to the driving pulse motors 8 and 9 of the XY direction moving device 5, the number of pulses is proportional to the number of pulses. The X and Y tables 6 and 7 move by the set amount. However, the movement command value does not always match the actual movement amount due to a mechanical error due to a processing error or an assembly error of the XY-direction moving device 5, a variation in load applied to the driving pulse motors 8, 9, and the like. Exist in the XY direction moving device 5.

On the X table 6 of the XY moving device 5, the measuring plate 1 for the above moving amount is placed and fixed, and the position of the reference point 3 is observed by the camera 10 while the control device 11
The movement command value is output to the X, Y tables 6 and 7 and moved, and the difference between the calculated movement amount of the reference point 3 obtained from the number of pulses of the movement command value and the actual movement amount is measured.

FIG. 4 is a flowchart of a program for measuring the above difference. When the program is started, a movement command value to be moved to the first measurement point is output to move the XY direction moving device 5, and TV camera 10
Detects the difference between the observed position of the reference point 3 actually moved and the calculated position of the reference point 3 calculated from the movement command value, obtains data for correction, and then returns to the start point. This process is repeated a predetermined number of times (seven times in the present embodiment), and the average value of the correction data is calculated to improve the measurement accuracy. Then, the XY table is moved from the first measurement point in the X and Y directions, for example, between the position moved 5 mm in the XY direction and the first measurement point,
The measurement of the correction data is repeated to calculate an average value.
Repeating the measurement from different directions in this manner can improve the data accuracy accordingly. Next, the start point is moved to an arbitrary position, and the average value of the correction data is calculated between the start point and the second measurement point in the same manner as at the first measurement point. Hereinafter, the same operation is performed for the third, fourth,... Measurement points.

By repeatedly performing such data measurement on the X and Y tables 6 and 7, the difference between the movement command value and the actual movement amount over the entire operating range of the X and Y tables 6, 7 Corrective data can be obtained by measuring the unique error. Therefore, prior to use of the XY-direction moving device 5, if the movement command value is corrected with correction data based on the error of the five XY-direction moving devices measured as described above, the unique error is eliminated. X and Y tables 6 and 7 can be moved.

(Effects of the Invention) According to the present invention, a reference point can be accurately identified with a clear contrast by mounting a backup sheet having optical characteristics different from those of the reference point on the glass plate on which the reference point is formed.

By mounting the backup sheet on the surface where the reference points are formed, the reference points can be protected by the backup sheet.

[Brief description of the drawings]

FIG. 1 shows an embodiment of the present invention. FIG. 1 is an overall plan view of a moving amount measuring plate, FIG. 2 is a sectional view, and FIG. 3 is a perspective view showing a use state of the measuring plate. FIG. 4 is a flowchart of a movement amount measuring program, and FIG. 5 is a perspective view showing a conventional example. 1 ... plate for measuring the amount of movement 2 ... flat plate 3 ... reference point t ... pitch

Claims (2)

(57) [Claims] 1. A reference point having optical characteristics different from the surroundings is formed at a pitch in the XY direction on a main surface of a flat plate made of a transparent glass plate, and the reference point and the optical characteristics are formed on the glass plate. A plate for measuring the amount of movement, which is equipped with a back-up sheet having a different size. 2. The moving amount measuring plate according to claim 1, wherein said backup sheet is mounted on a surface on which said reference point is formed.