JP3271106B2 - Tension measurement method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a grid structure in which a plurality of grid bodies are stretched in parallel on a frame, and air is blown on the grid body to oscillate the grid body. The present invention relates to a tension measuring method that irradiates a laser beam from a meter, obtains a resonance frequency of a grid element from a change in the displacement amount of a reflected beam, and measures the tension of the grid structure from the resonance frequency.

[0002]

2. Description of the Related Art A conventional example of such a measuring method (Japanese Patent Application No. 2-25957) will be described below with reference to FIG.
No. 1) will be described. Reference numeral 1 denotes an aperture grill, which is a grid structure used as a color selection electrode of Trinitron (registered trademark).
A large number of fine grid elements (metal tapes) 1a are stretched in parallel so as to form a cylindrical surface. This grid structure 1 is fixed to a fixing part.

[0003] Reference numeral 2 denotes a measuring head for measuring the tension of a large number of grid elements 1 a of the grid structure 1, and includes a laser displacement gauge 3 and an air blow nozzle 4.
Air from a pump (not shown) is supplied to the air blow nozzle 4 through a pipe 6, and is blown to one of the grid bodies 1a of the grid structure 1 to vibrate. Reference numeral 11 denotes a manual throttle valve for adjusting the air pressure.

[0004] The laser displacement meter 3 includes a transmitter for intermittently emitting a pulsed laser beam based on a laser beam from a laser light source, a receiver for receiving a reflected beam,
There is provided a time measuring means for measuring a time from when the pulsed laser beam is transmitted from the transmission unit, is reflected by the grid element body 1a of the grid structure 1 and is received by the reception unit.
When the grid element 1a was vibrated by air blow, the time measured by the time measuring means, that is, the voltage proportional to the distance between the transmitter, the grid element, and the receiver was subjected to D / A conversion. After that, the DC component is supplied to the DC blocking capacitor and the DC component is blocked, so that a voltage corresponding to the variation of the distance is obtained.

The variation voltage corresponding to the variation of the distance is:
The signal is supplied to the microcomputer 8 and the filter amplifier 9 to remove unnecessary signal components.
It is amplified by a factor of 0. The fluctuation voltage from the filter amplifier 9 is supplied to the frequency counter 10. The frequency counter 10 detects the number of fluctuation voltage peaks in one second,
Frequency data indicating the resonance frequency of the grid element body 1a is obtained, and the frequency data is supplied to the microcomputer 8. The higher the resonance frequency of the grid element 1a,
The tension of the frame 1b stretched over the grid body 1a increases. Therefore, if the microcomputer 8 measures the resonance frequency of the grid element 1a within a predetermined frequency range (depending on the size of the grid structure 1), it is determined that the tension of the grid element 1a is appropriate. Is done.

The measuring head 2 is a motor 1 for driving the measuring head.
By 2, the grid structure 1 is moved in the arrangement direction of the grid element bodies 1 a. The motor 12 is controlled by the microcomputer 8. The rotation speed (rotation angle) of the motor 12 is detected by the rotation speed detector 13 and supplied to the microcomputer 8. The microcomputer 8 detects the amount of movement of the measuring head 2 by counting and calculating the detection pulses from the rotation speed detector 13.

Next, the operation of measuring the tension of the grid element 1a of the grid structure 1 will be described. The measurement head 2 is moved to an arbitrary position on the grid structure 1, and the air from the air blow nozzle 4 is blown onto any one grid element 1 a to vibrate the grid element 1 a, and the laser displacement meter 3 is vibrated. The distance between the transmission unit, the grid element body 1a, and the reception unit is measured by using the frequency counter 10, and the resonance frequency of the grid element body 1a is measured by the frequency counter 10. In this case, when the resonance frequency cannot be measured properly or when the measured resonance frequency is extremely low (in this case, the laser displacement meter 3
Generates an abnormal signal, which is supplied to the microcomputer 8) when the laser beam from the laser displacement meter 3 is irradiated on the side edge of the grid element 1a or when the grid element 1a and the grid element 1a Since the measurement head 2 is moved about 50 μm in the arrangement direction of the grid element bodies 1a,
The resonance frequency of the grid element body 1a is measured. If the measurement fails, the measurement head 2 is moved again to measure the resonance frequency. In this way, the resonance frequencies of all the grid elements 1a of the grid structure 1 or the arbitrary number of sampled grid elements 1a are measured.

[0008]

As described above, in the conventional tension measuring method, measurement is performed by cut and try.
Measurement efficiency is very poor.

In view of such a point, the present invention provides a method of vibrating a grid element of a grid structure in which a plurality of grid elements are stretched in parallel on a frame. A laser beam is applied, the resonance frequency of the grid body is obtained from the change in the displacement of the reflected beam, and the tension measurement method that measures the tension of the grid structure from the resonance frequency has improved measurement efficiency. It is what we are trying to figure out.

[0010]

SUMMARY OF THE INVENTION The present invention relates to a frame 1b.
In a state in which the grid element 1a of the grid structure 1 in which a plurality of grid elements 1a are stretched in parallel is vibrated, the grid element 1a is irradiated with a laser beam from the laser displacement meter 3 and reflected. From the change in beam displacement,
In the tension measuring method in which the resonance frequency of the grid element body 1a is obtained and the tension of the grid element body 1a is measured from the resonance frequency, one of the laser beams from the laser displacement meter 3 crosses the plurality of grid element bodies 1a. The laser displacement meter 3 and the grid structure are relatively moved in the direction, and after the reflected beams from the plurality of grid bodies 1a are no longer detected, one of the plurality of grid bodies 1a is turned off. The distance X from the start of the detection of the reflected beam to the start of the detection of the reflected beam is measured, and the laser beam from the laser displacement meter 3 is measured from the position where the reflected beam from one grid element 1a starts to be no longer detected. In a direction opposite to one direction crossing the plurality of grid elements 1a, the laser displacement meter 3 and the grid by approximately S (= X / 2). A tension measuring method characterized in that after a structure is relatively moved, the movement is stopped and a tension is measured.

[0011]

In accordance with the according the present invention, by relatively moving the laser displacement meter 3 and the grid structure 1 in one direction in which the laser beam from Les Za displacement meter 3 crosses a plurality of grid elements 1a, a plurality of grid After the reflected beam from the body 1a is no longer detected, the plurality of grid bodies 1
The distance X from the time when the reflected beam from one of the grid elements 1a starts to be detected until the time when it is no longer detected is measured, and the reflected beam from one of the grid elements 1a starts to be no longer detected. From the position, in the direction opposite to the one direction in which the laser beam from the laser displacement meter 3 crosses the plurality of grid elements, approximately S (= X / 2) ,
After the laser displacement gauge 3 and the grid structure 1 are relatively moved, the movement is stopped. Thus, the laser beam from the laser displacement meter 3 is applied to the center in the width direction of the grid element body 1a and is surely reflected. The reflected beam returns to the laser displacement meter 3 and the displacement is reliably measured.

[0012]

Embodiments of the present invention will be described below in detail with reference to the drawings. First, the tension measuring device according to the embodiment will be described with reference to FIG. 3, but portions corresponding to those in FIG. The microcomputer 8 controls the measuring head driving motor 12 to
The laser displacement meter 3 is moved relative to the grid structure 1 in one direction in which the laser beam from the laser displacement meter 3 crosses the plurality of grid elements 1a, and the plurality of grid elements 1a are moved.
After the reflected beam from is no longer detected, the microcomputer 8 determines the distance X from when the reflected beam from one of the plurality of grid elements 1a starts to be detected until the detection is no longer detected. Measure. The measuring head driving motor 12 is controlled by the microcomputer 8 to control one grid element 1a.
From the position where the reflected beam from the laser beam is no longer detected, the laser beam from the laser displacement meter 3 is substantially S (= X / 2) in a direction opposite to one direction crossing the plurality of grid elements.
Just move. As described later, X is X = W + D
(W is the width of the grid element 1a, D is the laser displacement
The diameter of the laser beam emitted from the total 3)
Thus, S can be expressed as S = (W + D) / 2. Thus, the laser beam from the laser displacement meter 3 is applied to the grid element body 1a at the center in the width direction and is reflected, and the reflected beam returns to the laser displacement meter 3 to reliably measure the displacement amount.

Incidentally, air from a pump (not shown) is supplied to the air blow nozzle 4 through a pipe 6.
The air pressure is controlled by an electro-pneumatic proportional valve 5. This valve 5 is electrically controlled by the output from the effective value conversion circuit / balance circuit 7. After the variation voltage from the filter amplifier 9 is supplied to an effective value conversion circuit of the circuit 7 and converted into an effective value voltage, the balance circuit makes the effective value voltage constant so that the effective value voltage becomes constant. A control voltage is applied to the valve 5 to control the air pressure.

Next, the embodiment will be further described with reference to FIGS. 1, 2 and 4. FIG. FIG. 1 is a flowchart showing a tension measuring method of the embodiment, FIG. 2 is a block diagram showing the microcomputer 8 of the embodiment of FIG. 3 by functional blocks, and FIG. 4 is a schematic diagram showing an operation explanation.

First, functional blocks in the microcomputer 8 in FIG. 2 will be described. 8a receives a resonance frequency detection signal from the frequency counter 10, calculates a resonance frequency of the grid element body 1a, and determines whether or not the resonance frequency falls within a predetermined resonance frequency range by the determination means 8b. That is, it is determined whether or not the tension of the grid element body 1a is appropriate, and the determination result is displayed on a monitor display device (not shown). Reference numeral 8c denotes a reflected light amount determining means which receives a reception signal from the receiving section of the laser displacement meter 8a, detects the reflected light amount, and determines the presence or absence of the reflected beam. The judgment result from the reflected light amount judging means 8c is supplied to the detecting means 8d of the number of times of the reflected light amount = 0. The reset signal input terminal t is provided in the number-of-times detecting means 8d. Number detection means 8d
The detected output is supplied to the motor control means 8e and the measuring head movement amount measuring means 8f. The motor control means 8e controls the rotation speed (rotation angle) and rotation direction of the measuring head driving motor 12. Moving amount measuring means 8f of measuring head 2
Receives the rotation number (rotation angle) detection signal from the rotation number detector 13 of the motor 12, and moves the measuring head 2, that is,
The movement amount of the laser displacement meter 3 is measured, and the motor control means 8e is controlled according to the measurement result.

Next, a method for measuring the tension of the embodiment will be described mainly with reference to FIG. First, a reset signal is supplied to the reset signal input t of the reflected light = 0 detection means 8d,
The number of times of reflected light = 0 is reset to zero. So,
The detection signal from the number-of-times detecting means 8d is the
And the measuring head driving motor 12 is fished (step ST-1) so that the laser displacement meter 3 moves in one direction (the direction of arrow a) as shown in FIG. Move to 2. The direction of the arrow a can be set arbitrarily.

It is determined by the reflected light amount determining means 8c whether the reflected light amount has become 0 (step ST-2), and NO
Then, the process returns to step ST-2, and if YES is reached as shown in FIG. 4A, the process proceeds to step ST-3. At this time, the count value of the number-of-times detecting means 8d becomes 1.

The reflected light amount judging means 8a judges whether or not the reflected light amount has exceeded 0 (step ST-3).
If so, the process returns to step ST-3, and if YES as shown in FIG. 4 (B), the process proceeds to step ST-4.
This data is also supplied to the number-of-times detecting means 8d.

It is determined by the reflected light amount determining means 8c whether or not the reflected light amount has become 0 (step ST-4).
Then, the process returns to step ST-4, and if YES is reached as shown in FIG. 4C, the process proceeds to step ST-5. At this time, the count value of the number-of-times detecting means 8d becomes 2.

The measuring head moving amount measuring means 8f determines the amount of reflected light = 0 in step ST-2 according to the rotation speed (rotation angle) of the measurement head driving motor 12 from the rotation speed detector 13.
Then, the distance X between the position S1 of the laser displacement meter 3 at the time when the reflected light amount becomes 0 and the position S2 of the laser displacement meter 3 when the reflected light amount becomes 0 at step ST-4 (step S-4).
At the same time as T-5), the motor control means 8e is controlled to move the rotation direction of the measuring head driving motor 12 in the opposite direction as shown by the arrow -a (step ST-6), and thereafter, the process proceeds to step ST-7. .

The measuring head moving amount measuring means 8f measures the moving amount of the laser displacement meter 3 in the reverse direction, and the moving amount is substantially
S (= X / 2) is determined (step ST).
-7), if NO, return to step ST-7, YES
, The motor control means 8e is controlled to
The movement of the laser displacement meter 3 is stopped as shown in (D) (step ST-8). At this time, the laser displacement meter 3
Is emitted from the grid element body 1a
That it is located substantially on the center line L ₀ in.

In FIG. 4D, W indicates the width of the grid element 1a, I indicates the interval therebetween, and D indicates the diameter of the laser beam emitted from the laser displacement meter 3. From this figure, the moving distance X of the laser displacement meter 3 from FIG. 4 (B) to FIG. 4 (C) is X = W + D. Then, the laser displacement meter 3 changes from the state shown in FIG. 4C to approximately S ｛= (W + D) /
2} when returning in the opposite direction -a only, the center of the laser beam 3a emitted from the laser displacement meter 3 is seen to coincide with the center line L ₀ in the width direction of the grid elements 1a. Since W + D is equal to X, S is expressed by S = X / 2.
Is done. When D is sufficiently smaller than W, D is
S is S = X / 2 ≒ W / 2,
Then, X ≒ W.

In step ST-9 following step ST-8, air is blown to the grid element 1a to oscillate it, and as described above, the laser displacement meter 3 is positioned substantially at the center of the grid element 1a in the width direction. The laser beam is irradiated to measure the resonance frequency, and the process ends.

FIG. 4A shows a laser beam emitted from the laser displacement meter 3. When there is a reflected beam from the grid element 1a, the reflected beam is superimposed on the laser beam 3a. is there. These beams are distinguished from the output beam and the reflected beam by arrows.

Also, instead of moving the measuring head 2,
The measurement head 2 may be fixed, and the grid structure 1 may be moved with respect to the measurement head 2.

[0026]

According to the present invention described above, in a state where a grid element of a grid structure in which a plurality of grid elements are stretched in parallel on a frame is vibrated, the grid element is applied to the grid element by a laser displacement meter. In the tension measurement method of irradiating the laser beam of the above, obtaining the resonance frequency of the grid body from the change in the displacement amount of the reflected beam, and measuring the tension of the grid body from the resonance frequency, the laser displacement meter The laser displacement meter and the grid structure are relatively moved in one direction in which the laser beam crosses the plurality of grid elements, and after the reflected beams from the plurality of grid elements are no longer detected, the plurality of grid elements are The distance X from when the reflected beam from one grid element of the body begins to be detected to when it is no longer detected is measured, and one grid is measured. From the position where the reflected beam is started will not be detected from the head element body, in the direction of the one direction opposite to the laser beam from the laser displacement meter crosses multiple grid elements, substantially S (= X / 2) only After moving the laser displacement meter and the grid structure relatively, the movement is stopped and the tension is measured, so that the laser beam emitted from the laser displacement meter automatically moves in the width direction of the grid body. Irradiates the center of the tension, thereby improving the efficiency of the tension measurement.

[Brief description of the drawings]

FIG. 1 is a flowchart showing a tension measuring method according to an embodiment of the present invention.

FIG. 2 is a block diagram showing a tension measuring device according to an embodiment showing functions of the microcomputer of the present invention.

FIG. 3 is a block diagram showing a tension measuring device according to an embodiment of the present invention.

FIG. 4 is a schematic diagram illustrating an operation of the embodiment of the present invention.

FIG. 5 is a block diagram showing a conventional tension measuring device.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Grid structure 1a Grid element 1b Frame 2 Measurement head 3 Laser displacement meter 4 Air blow nozzle 5 Electro-air proportional valve 6 Pipe 7 Effective value conversion circuit / balance circuit 8 Microcomputer 8a Resonance frequency calculation means 8b Judgment means 8c Reflection Light amount determination means 8e Motor control means 8f Measurement head movement amount measurement means 9 Filter amplifier 10 Frequency counter 11 Manual throttle valve 12 Measurement head drive motor 13 Revolution detector

Claims (1)

(57) [Claims] 1. A laser beam from a laser displacement meter is applied to a grid element in a state where the grid element is vibrated in a grid structure in which a plurality of grid elements are stretched in parallel on a frame. From the change in the displacement of the reflected beam, a resonance frequency of the grid body is obtained, and the tension of the grid body is measured from the resonance frequency. The laser displacement meter and the grid structure are relatively moved in one direction across the plurality of grid elements, and after the reflected beams from the plurality of grid elements are no longer detected, the plurality of grid elements are The distance X from when the reflected beam from one of the grid elements starts to be detected to when it is no longer detected is measured. From the position where the reflected beam is started will not be detected from the grid elements, in the direction of the one direction opposite to the laser beam from the laser displacement meter across said plurality of grid elements, substantially S (= X / 2 A) moving the laser displacement meter and the grid structure relative to each other, and then stopping the movement to perform the tension measurement.