JPH04198804A - Length measuring instrument - Google Patents

Abstract

PURPOSE:To measure the length of an object to be inspected at an extremely large number of locations along the width direction of the object by providing a plurality of photoreceptor elements arranged in parallel in the direction parallel to a glass tube and detecting the light reflected from the surface of the object. CONSTITUTION:A piece of plate glass 30 is carried in the direction A at a fixed speed by means of a carrying means 35 after the piece is cut to a prescribed length. A fluorescent lamp 10 is arranged perpendicularly to the carrying direction of the plate glass 30 so that the lamp 10 can radiate the surface 30a of the glass 30 with its fluorescence 20 in an oblique direction while the glass 30 is carried. The fluorescence 20 is converged to a narrow line at the surface 30a of the glass 30 after the fluorescence 20 is condensed through a cylindrical lens 31. The light 20R reflected from the surface 30a is made incident to a line sensor 33, the output signal S of which is inputted to a measurement circuit 34. The circuit 34 fetches the signal S and compares the received light quantity of each photoreceptor element 33a with a reference value. When the received light quantity of each element 33a is larger than the reference value, it can be discriminated that the reflected light 20a is made incident to each element 33a. Namely, it is discriminated that the glass 30 exists at the incident position of the fluorescence. Therefore, the propriety of the cut length of the glass piece 30 can be detected.

Description

Detailed Description of the Invention (Field of Industrial Application) The present invention relates to a length measuring device that measures the length of a sheet-like object to be inspected at multiple locations in its width direction, and in particular, The present invention relates to a length measuring device that measures the length by irradiating light onto the surface of a rapidly transported object and detecting the reflected light.

(Prior Art) Conventionally, measuring the length of a sheet-like member such as a glass plate, a plastic plate, a steel plate, etc. at a plurality of locations in the width direction has been widely used in product inspections in factories and the like.

Conventionally, as a length measuring device for such a sheet-shaped object to be inspected, the object to be inspected is conveyed at a constant speed in the length direction to be measured, and multiple points are conveyed in the width direction of the object to be inspected perpendicular to the conveyance direction. A light beam is emitted from each light source toward the surface of the object to be inspected, and each reflected light from the surface is detected by a separate photodetector, and the amount of light received by each photodetector is calculated. There is a known method in which the length of the object to be inspected is measured based on the time during which the light exceeds a predetermined value (that is, the reflected light from the object to be inspected is present) and the conveyance speed of the object to be inspected. There is.

(Problem to be solved by the invention) However, in such a conventional length measuring device, adjustment is troublesome because it is necessary to align the characteristics of the plurality of measurement light sources arranged, and the lifespan of each light source varies. It has been recognized that there is a problem in that maintenance work such as replacement becomes complicated because of the presence of such parts.

In addition, in the above-mentioned length measuring device, there is a natural limit to reducing the arrangement pitch of the plurality of light sources, so it is difficult to measure the length of the object to be inspected very precisely at many points in the width direction. There was also the problem.

The present invention has been made in view of the above circumstances, and provides a length measuring device that is capable of measuring the length of an object to be inspected at a large number of locations in the width direction, and that facilitates light source adjustment and maintenance work. The purpose is to

(Means for Solving the Problems) A length measuring device according to the present invention aims to solve the above problems by using a straight tube fluorescent lamp as a measurement light source,
Specifically, it has a straight glass tube whose inner wall is coated with a fluorescent substance, the fluorescent substance is applied leaving a slit-shaped uncoated part extending in the length direction of the glass tube, and the fluorescent substance is coated with the fluorescent substance. A fluorescent lamp with a reflective layer formed on the outside and light emitted linearly from the non-coated portion of the fluorescent lamp are incident on the surface of the sheet-shaped object to be inspected, and the object to be inspected is placed on the glass surface. A line sensor that has a conveying means that conveys at a constant speed in a direction perpendicular to the tube, and a plurality of light receiving elements arranged in parallel to the glass tube, and that detects light reflected on the surface of the object to be inspected. , The length of the object to be inspected in the conveyance direction is calculated based on the time period during which the amount of light received by the output from each light receiving element of this line sensor exceeds a predetermined value and the conveyance speed of the object to be inspected. It consists of a measurement circuit that measures the

(Functions and Effects of the Invention) Since the fluorescent lamp with the above configuration emits measurement light in the form of a linear light source, this light can be used to measure the length of an extremely large number of locations in the width direction of the object to be inspected. becomes possible. That is, in this case, the light source does not impose any restrictions on the pitch of length measurement, but it is regulated by the arrangement pitch of the light receiving elements of the line sensor.

As is well known, the arrangement pitch of this type of light-receiving element can be made sufficiently small, so this device can measure the length of an object to be inspected at an extremely large number of points in its width direction (in other words, at an extremely small pitch). ) It becomes possible to carry out detailed operations.

Furthermore, the measurement light source in the length measuring device of the present invention is
Since it is just a single fluorescent lamp, it is easier to adjust and maintain than when multiple light sources are installed.

(Example) Hereinafter, the present invention will be described in detail based on an example shown in the drawings.

FIG. 2 shows a length measuring device according to an embodiment of the present invention. Further, FIG. 1 shows a cross-sectional shape of a portion of a fluorescent lamp 10 used in this length measuring device taken along line I--■ in FIG.

First, this fluorescent lamp 10 will be explained. This fluorescent lamp 10 is equipped with caps 12 at both ends of a straight glass tube 11, like a normal fluorescent lamp.
2 parts each have 2 base pins (contact pins) 13
is installed. The glass tube 11 has a length of about 24 m and an outer diameter of about 20 mm, for example.

The inner wall 11a of the glass tube 11 is coated with a fluorescent substance 14. This fluorescent material 14 is formed into a slit-shaped non-coated portion (slit portion) 1 extending in the length direction of the glass tube 11.
The coating is applied to almost the entire surface of the inner wall 11a of the glass tube 11, except for 4a.

In this embodiment, the width of the slit portion 14a is 2 mm, and the slit portion 14a is formed over almost the entire length of the glass tube 11.

On the other hand, the outer wall 11b of the glass tube 11 is coated with a reflective paint 15 made of, for example, white paint. This reflective paint 15 is applied to almost the entire surface of the glass tube outer wall Ilb, except for the portion that matches the slit portion 14a of the fluorescent substance 14. Therefore, a slit portion 15a having a width of 2 mm is also formed on the surface to which the reflective paint 15 is applied.

Note that the fluorescent substance 14 is applied by a conventionally known coating method.
It can be applied to the inner wall 11a of the glass tube.

At this time, since the slit portion 14a may be formed at any position in the circumferential direction of the glass tube 11, the application of the fluorescent substance 14 can be performed without any particular difficulty.

Further, since the reflective paint 15 is applied to the outer wall 11b of the glass tube 11, the slit portion 15 is coated by a brush coating method, a spray method, etc. using masking tape as appropriate.
It is also easy to apply the fluorescent material 5g so that it is accurately aligned with the slit portion 14a of the fluorescent material 14.

Note that instead of this reflective paint 15, a reflective tape may be applied.

On the other hand, mercury vapor and argon gas are sealed in the glass tube 11. Further, within the glass tube 11, filaments 16 are arranged which are respectively connected to cap pins 13 at both ends of the tube.

The fluorescent lamp 10 having the above structure is lit in the same way as a typical fluorescent lamp by engaging the cap pins 13 with the sockets 17 as shown in FIG. That is, ultraviolet light is mainly emitted by the discharge of mercury vapor between the filaments 16 and 16, and the fluorescent material 14 is excited by the ultraviolet light and emits fluorescence 20.

This fluorescent light 20 is emitted directly or reflected by the reflective paint 15 and concentratedly from the slit portions 14a and 15a. In this way, the fluorescent lamp 10 emits fluorescent light 20 in the form of a linear light source.

This fluorescent lamp 10 is used for measuring the length of a rectangular glass plate 30, by way of example. After this plate glass 30 is cut into a predetermined length by a cutting device (not shown), it is transported at a constant speed in the direction of arrow A by a transport means 35 such as a belt conveyor. The fluorescent lamp 10 is oriented so that the fluorescent light 20 is obliquely incident on the surface 30a of the glass plate 30 being transported, in the glass plate transport direction (direction of arrow A).
is placed at right angles to.

As shown in the side view of FIG. 3, the fluorescence 20 is condensed by a cylindrical lens 31 and converged into a thin line on the plate glass surface 30g. 20R of light reflected there
is focused by another cylindrical lens 32 and then enters the line sensor 33.

This line sensor 33 includes, for example, several hundred to several dozen light receiving elements 3 across the width direction of the glass plate 300 (in the direction of arrow B).
3a, and its output signal S is input to the measuring circuit 34. The measuring circuit 34 takes in the signal S at 1/1000 second intervals, for example, and compares the amount of light received by each light receiving element 33a with a predetermined reference value. If the amount of received light exceeds the reference value, reflected light 2OR is incident. In other words, it is determined that the plate glass 30 is present at the position where the fluorescent light 20 is irradiated.

In this example, the transport speed of the glass plate 30 is set to 1 m/sec, so by doing as described above, the glass plate 30 can be transported at a speed of 1 m/sec.
In the length direction of 0, its presence or absence is detected with an accuracy of 1 mm. After each light receiving element 33a of the line sensor 33 first detects the reflected light 2OR, the measuring circuit 34 counts how many times this state is continuously detected in subsequent measurements at 1/1000 second intervals. For example, plate glass 3
If the normal length of 0 is 3 m, if the reflected light 2OR is detected in all 3000 consecutive measurements, it can be determined that the glass plate 30 has been cut to the normal length. On the other hand, for example, the reflected light 2OR is continuous 299
When it is detected only nine times, it can be determined that the glass plate 30 is 1 mm short of the regular length.

When the measuring circuit 34 detects that the length of the glass plate 30 is longer or shorter than the regular length as described above, it outputs a defective product detection signal Se.

The conveying means 35 is configured to store the plate glass 3 in a packaging means such as a wooden frame, for example.
The plate glass 30 is conveyed toward a device for storing zeros, and a means (not shown) is provided along the conveyance path for discharging defective products out of the path. Therefore, by inputting the defective product detection signal Se to this ejecting means, the defective glass plate 30 can be automatically removed.

In order to prevent the plate glass 30 from rattling and being damaged in a wooden frame during transportation, it is required to store the plate glass 30 tightly in the wooden frame or the like, but according to this device, the plate glass 30
Since the length of 0 can be measured with an accuracy of 1 mm, the above-mentioned requirements can be fully met.

Further, the light receiving element 33a of the line sensor 33 is set at 1 m, for example.
It is also possible to arrange them at a pitch of about m, and in this way, the above-mentioned length measurement can be performed finely in the width direction of the glass plate 30 at that pitch.

[Brief explanation of the drawing]

FIG. 1 is a sectional view showing an example of a fluorescent lamp used in a length measuring device of the present invention, FIG. 2 is a perspective view showing a length measuring device according to an embodiment of the present invention, and FIG. It is a side view of the said length measuring device. lO...Fluorescent lamp 11...Glass tube 11
a...Glass tube inner wall 11b...Glass tube outer wall 1
4... Fluorescent substances 14a, 15a... Slit portion 15... Reflective paint 30... Glass plate 30
a...Glass plate surface 3L 32...Cylindrical lens 33...Line sensor 33a...Light receiving element 34...Measuring circuit 35...Transporting means Fig. 1 5G Fig. 3

Claims (1)

[Claims] It has a straight glass tube whose inner wall is coated with a fluorescent substance. A fluorescent lamp having a reflective layer formed on the outside and light emitted linearly from the non-coated portion of the fluorescent lamp are incident on the surface of the sheet-shaped object to be inspected, and the object to be inspected is placed on the glass surface. A line sensor that has a conveying means that conveys at a constant speed in a direction perpendicular to the tube, and a plurality of light receiving elements arranged in parallel to the glass tube, and that detects light reflected on the surface of the object to be inspected. Based on the output of each light-receiving element of this line sensor and the time during which the amount of light received exceeds a predetermined value, and the conveyance speed of the object to be inspected, the direction of conveyance of the object to be inspected is determined. A length measuring device consisting of a measuring circuit for measuring length.