JPH09297007A - Size measuring apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a size measuring apparatus by which a size can be measured precisely without an individual difference even when a cursor is at a distance from a projector and even in a bright place by a method wherein the projector by which laser beams modulated at a constant frequency are radiated to four orthogonal directions is used jointly. SOLUTION: In a projector, a current flowing to a laser diode by a modulation circuit is continuted intermittently by using the output of an oscillator which generates a pulse signal at a constant frequency, and a laser beam is luminance-modulated. A window 7 which is marked with a reference line and photodetectors 4R, 4L are provided at a cursor 1. Then, when the luminance- modulated laser beam is incident on the photodetectors 4R, 4L, amplitude- modulated output signals R, L are generated, and the signals are amplified and rectified so as to be guided to a differential amplifier. When the output of the differential amplifier is discriminated by a comparison circuit, the incident state of the laser beam can be detected. Then, the cursor 1 is moved in such a way that a display lamp 49c indicating the center is turned on. When the display lamp 49c is turned on, a graduation which agrees with the reference line is read out by the window 7 at the cursor 1, and a size is measured.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a dimension measuring device for accurately measuring the actual dimensions of a space surrounded by walls or the like, for example, a room.

[0002]

2. Description of the Related Art As a method for measuring the size of a room surrounded by a wall, as shown in FIG.
A projector (marker) M that emits a beam is installed at a reference position in a room, and a ruler S whose one end is abutted against a wall is irradiated with a laser beam from the projector, and a bright spot of the laser beam is emitted. Techniques have been implemented to measure the laser beam bright spot to wall dimension by reading the scale.

In such a conventional dimension measuring method, when the ruler S is irradiated with the laser beam, the bright spot of the laser beam projected on the ruler S has a certain width, so that -It is difficult to accurately read the scale corresponding to the center of the bright spot of the beam, and it is unavoidable that there are individual differences in the measurement dimensions.

Therefore, in order to accurately read the center position of the bright spot of the laser beam without individual differences and to eliminate the reading error, as shown in FIG. 2, the rod member 2 and the rod member 2 are provided along the rod member 2. A cursor 1 that can be moved, and the cursor 1 detects an irradiated laser beam and an encoder that generates a pulse each time the cursor 1 moves a certain distance when the cursor 1 is moved along the rod member 2. A photodetector such as a pair of photodiodes installed close to each other
LCD display 5 that displays the measured dimensions of R and 4L
There has been proposed a dimension measuring device including switches for setting various conditions and a signal processing circuit.

In this dimension measuring apparatus, as shown in FIG. 7, two outputs R from the photodetectors 4R and 4L, depending on the incident state of the laser beam incident on the pair of photodetectors 4R and 4L, Since L is generated, when both outputs R and L are equal, the center of the bright spot of the laser beam is a pair of photodetectors 4.
When it is determined that the central position of R, 4L coincides, the count value of the pulse output from the encoder is converted into a scale or meter and displayed on the display unit 5.

[0006]

However, in such a conventional dimension measuring apparatus, when the cursor 1 moves away from the projector M, the laser beam spreads and the brightness is incident on the pair of photodetectors 4R and 4L. Is reduced. Also, when measuring in a bright room, the brightness of the surrounding light rays incident on the pair of photodetectors 4R, 4L becomes brighter than the brightness of the laser beam, and the two outputs R, L of large and small are detected. Sometimes it was impossible to distinguish.

Therefore, the present invention was conceived in order to provide a dimension measuring apparatus in which the cursor 1 does not become unmeasurable even in a bright place even if the cursor 1 moves away from the projector.

[0008]

A first embodiment of a dimension measuring apparatus according to the present invention comprises a projector 3 for emitting a laser beam whose intensity is modulated at a constant frequency, a bar member 2 with a scale, The cursor 1 is movable along the rod member 2. The cursor 1 includes a pair of photodetectors 4R and 4L for detecting a laser beam and a pair of photodetectors 4R and 4L.
Two amplifiers 43 that respectively amplify the AC component of the output of
44, two rectifier circuits 45 and 46 for rectifying the outputs of these two amplifiers 43 and 44, a comparison means (47 and 48) for comparing the two rectified outputs, and the output of this comparison means are displayed. The indicators 49R, 49C, and 49L are provided, and the scale of the rod member 1 is read based on the display of the indicators to measure the dimensions.

The second embodiment of the dimension measuring apparatus of the present invention is capable of moving along with the projector 3, which emits a laser beam whose intensity is modulated at a constant frequency, the rod member 2, and the rod member 2. And a cursor 1, which is
An encoder 6 that outputs a pulse corresponding to the distance moved along the rod member 2, a counter circuit 15 that counts the pulse output of this encoder 6, and a pair of photodetectors 4R and 4L that detect a laser beam, Two amplifiers 43 and 44 for respectively amplifying the AC components of the outputs of the pair of photodetectors 4R and 4L,
2 to rectify the outputs of these two amplifiers 43 and 44 respectively
One rectifying circuit 45, 46, a comparing means (47, 48) for comparing two rectified outputs, and a means for holding the count value of the counter circuit 15 by the coincident output of the comparing means (47, 48), It is composed of means for converting the held count value into a scale or meter conversion, and a display 5 for displaying the converted count value.

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION

(First Embodiment) A dimension measuring apparatus according to the first embodiment comprises a projector 3 for emitting a laser beam whose brightness is modulated at a constant frequency f, and a scale as shown in a perspective view of FIG. And a measuring device equipped with a cursor 1 that can move along the rod member 2.

As shown in the block diagram of FIG. 3, the projector 3 includes a laser diode 31 for emitting a laser beam, an oscillator 32 for generating a pulse signal having a constant frequency f, and a current flowing through the laser diode 31. It is provided with a modulator circuit 33 which intermittently emits a laser beam emitted by an oscillator 32 and modulates the intensity of the emitted laser beam at a constant frequency f.

The cursor 1 has a window 7 with a reference line,
It is provided with two photodetectors 4R and 4L and a received light signal processing circuit 4. As shown in the block diagram of FIG. 4, the received light signal processing circuit 4 includes an amplifier 4 that amplifies the outputs of the photodetectors 4R and 4L.
1, 42, capacitors C1 and C2 for blocking the DC component of each amplified output signal, and an amplifier 4 for amplifying only the AC component
3, 44 and rectifier circuits 45, 4 that rectify the amplified AC component
6 and a differential amplifier 47 that inputs two rectified signals
And a comparison circuit 48 for comparing the reference voltage (ground potential) and the output of the differential amplifier 47 to determine the magnitude and polarity of the output of the differential amplifier 47.

When the intensity-modulated laser beam is incident on the pair of photodetectors 4R and 4L, two amplitude modulations are performed by the photodetectors 4R and 4L according to the incident state, as shown in FIG. Since the output signals R and L are generated, the amplifiers 41 and 43 are respectively generated.
After being amplified by 42 and 44, they are rectified by rectifying circuits 45 and 46 and led to a differential amplifier 47. 2 from the differential amplifier 47
Since the output signals of the polarities and voltage levels corresponding to the output levels of the two photodetectors 4R and 4L are output, the incident state of the laser beam can be detected by determining the output of the differential amplifier 47 by the comparison circuit 48. You can

That is, when the center of the bright spot of the laser beam is deviated and incident on one of the photodetectors (4R or 4L), the output levels of both photodetectors 4R and 4L differ depending on the deviation. Therefore, the output level and the polarity of the differential amplifier 47 change, and the indicator lamp 49R or 49L in the biased direction is turned on. Bright spot of laser beam is a pair of photodetectors 4
When the center positions of R and 4L coincide with each other, the output levels of both photodetectors 4R and 4L become equal and the output level of the differential amplifier 47 becomes zero, so that the indicator lamp 49C indicating the center is turned on.

Therefore, while observing the lighting states of the three indicator lamps 49R, 49C and 49L, the cursor 1 is moved so that the indicator lamp 49C indicating the center is illuminated, and when the indicator lamp 49C is illuminated,
The scale corresponding to the reference line is read from the window 7 of the cursor 1 to measure the dimension.

(Second Embodiment) A dimension measuring apparatus according to the second embodiment is a projector 3 which emits a laser beam whose intensity is modulated at a constant frequency f, and a perspective view of FIG. And a measuring device equipped with a bar member 2 and a cursor 1 movable along the bar member 2. The same light projector 3 as the light projector 3 of the first embodiment is used.

The cursor 1 is installed in close proximity to an encoder 6 that generates a pulse each time the cursor 1 is moved along the rod member 2 when the cursor 1 moves along a fixed distance, and an irradiated laser beam. A pair of photodetectors 4R, 4L, such as photo diodes, and L to display the measured dimensions
It is provided with a CD display 5, switches for setting various conditions, and a data processing circuit.

As shown in the block diagram of FIG. 5, the data processing circuit 10 includes an up / down counter circuit 15 for counting the pulses output from the encoder 6, a CPU 11 for controlling the entire apparatus, and an up / down counter circuit. The count value of 15 and the output of the comparison circuit 48 are input to the CPU 11, and the LCD
It is provided with a PIO 14 for controlling the display device 5, a ROM 12 storing a processing program, and a RAM 13 temporarily storing data.

Further, there is provided a light reception signal processing circuit 4 shown in FIG. 4 for processing the signals output from the photodetectors 4R and 4L to detect the center position of the bright spot of the laser beam. Of the three outputs of the comparison circuit 48 of the received light signal processing circuit 4,
The output generated when the center of the bright spot of the laser beam coincides with the center position of the pair of photodetectors 4R and 4L is input to the PIO 14 of the data processing circuit 10.

Next, the procedure for measuring the dimensions of the room by the apparatus thus constructed will be described with reference to the flowchart of FIG.

Step 1: After turning on the power switch,
Move the cursor 1 to the reference position and activate the reset switch. By this resetting operation, the center of the pair of photodetectors 4R, 4L has a constant dimension from the tip of the rod member 2,
For example, it is set to 10 cm.

Step 2: Set initial conditions.

Step 3: The tip of the rod member 2 is aligned with the position to be measured, and the cursor 1 is moved along the rod member 2. Since a pulse is generated from the encoder 6 while the cursor 1 is being moved, if the counter circuit 15 counts this pulse, the moving distance of the cursor 1 can be obtained.

Step 4: Move the cursor 1 so that the bright spots of the laser beam cross both photodetectors 4R and 4L, and the bright spots of the laser beam are simultaneously incident on both photodetectors 4R and 4L, and rectified. Both outputs of the circuits 45 and 46 become equal, and the comparison circuit
At the moment when the center of the bright spot of the laser beam produces an output that coincides with the center position of the photodetectors 4R and 4L from 48, that is, at the moment when the indicator lamp 49C is turned on, the count value of the counter circuit 15 is set. Store in RAM13, Step 6: RAM13 based on initial set conditions
The count value stored in is converted into a scale or a meter and displayed on the LCD display 5.

(Other Embodiments) A pair of photodetectors 4
If a bandpass filter that passes the frequency f of the laser beam is provided between the output terminals of R and 4L and the input terminals of the rectifier circuits 45 and 46, the influence of disturbance can be reduced.

[0026]

As is apparent from the description based on the above-described embodiments, according to the dimension measuring apparatus of the present invention, a projector which emits a laser beam modulated at a constant frequency in four orthogonal directions is also used. This makes it possible to accurately measure the actual size of a space surrounded by walls or the like, for example, a room without individual differences even if the cursor moves away from the light projector, even in a bright place.

[Brief description of drawings]

FIG. 1 is a perspective view showing the configuration of a first embodiment of a dimension measuring apparatus of the present invention,

FIG. 2 is a perspective view showing the configuration of a second embodiment of the dimension measuring apparatus of the present invention,

FIG. 3 is a block diagram of a floodlight used in combination with the device shown in FIG. 1 or 2.

FIG. 4 is a block diagram of a light reception signal processing circuit in the device shown in FIGS. 1 and 2;

5 is a block diagram of a data processing circuit in the device shown in FIG.

FIG. 6 is a flowchart explaining the operation of the apparatus shown in FIG.

FIG. 7 is a waveform diagram showing the output of a pair of photodetectors in the device shown in FIGS. 1 and 2.

FIG. 8 is a plan view showing an example of a conventional room dimension measuring method.

[Explanation of symbols]

 1 cursor 2 bar member 3 light emitter 4 received light signal processing circuit 4R, 4L photodetector 5 LCD display 6 encoder 7 window 10 data processing circuit 11 CPU 12 ROM 13 RAM 14 PIO 15 counter circuit

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Takehiko Kumagashi 190 Hijiri, Tatsuno-cho, Tatsuno-shi, Hyogo Far East Industrial Machinery Co., Ltd. Machinery Co., Ltd.

Claims (2)

[Claims] 1. A light emitter for emitting a laser beam intensity-modulated at a constant frequency, a bar member having a scale, and a cursor movable along the bar member, wherein the cursor is the laser. A pair of photodetectors that detect the beam, two amplifiers that amplify the AC components of the outputs of the pair of photodetectors, and two rectification circuits that rectify the outputs of the two amplifiers And a display device for displaying the output of the comparison device. The scale of the rod member is read based on the display of the display device to measure the dimension. Dimension measuring device. 2. A light emitter for emitting a laser beam intensity-modulated at a constant frequency, a rod member, and a cursor movable along the rod member, the cursor being along the rod member. An encoder that outputs a pulse corresponding to the distance traveled, a counter circuit that counts the pulse output of the encoder, a pair of photodetectors that detect the laser beam, and an AC component of the output of the pair of photodetectors. Amplifiers for amplifying each of the two, two rectifying circuits for rectifying the outputs of the two amplifiers, comparing means for comparing the two rectified outputs, and a counter output of the counter circuit by the coincident output of the comparing means. A unit for holding a numerical value, a unit for converting the held count value into a scale or a meter, and an indicator for displaying the converted count value. Measuring device.