JP2970250B2 - Distance measuring device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of irradiating an object to be measured with a light beam, receiving reflected light of the object by a light receiving element, performing a predetermined operation from an output current obtained as an output of the object, and arranging the object. The present invention relates to a distance measuring apparatus for measuring a distance of a measured object or a displacement of an object to be measured.

[0002]

2. Description of the Related Art As a distance measuring device of this type, a one-dimensional position detecting element (PSD: Position: PSD) receives reflected light of a light beam emitted from a light projecting unit onto a detection object through a light receiving lens.
Sensitive Detector)
After detecting the displacement of the detected object as a spot position change on the position detecting element, the output signal of the position detecting element is processed by a subsequent processing unit to measure the displacement amount of the detected object. Are well known, for example,
Japanese Patent Application Laid-Open No. 119006/1979 and Japanese Patent Application Laid-Open No. 57-67815 disclose the principle of its construction.

FIG. 3 is a block diagram showing a conventional example of such a distance measuring device. In FIG. 1, reference numeral 1 denotes a sensor head, 2 denotes a controller, and the sensor head 1 includes a light source 3, such as a semiconductor laser (LD) or a light emitting diode (LED), a light projecting lens 4, a light receiving lens 5, and a light receiving element. And the like. The controller 2 includes an arithmetic processing circuit 7 for processing an output signal of the position detecting element 6, a linear correction circuit 8, a digital display 9 of measured values, a driving circuit (driver) 10 for the light source 3, an oscillator 11, and the like. You. Further, the arithmetic processing circuit 7 includes amplifiers 12 and 13 for the output signals (currents I1 and I2) output from both poles of the position detecting element 6, an adder 14, a subtracter 15, a divider 16, and the like.

In such a configuration, when the light beam B emitted from the light source 3 of the sensor head 1 through the light projecting lens 4 is irradiated toward the detection object D, a part of the irregularly reflected light reflected on the surface of the detection object D becomes Then, an image is formed on the position detecting element 6 through the light receiving lens 5. When the detected object D is displaced from the solid line position to the dotted line position (displacement amount is dX), the position of the point image is moved on the position detection element 6 (movement amount dY). Here, dX and dY have a certain relationship, and the moving amount of the point image is an electric signal (current I1,
I2) is output from both poles of the position detecting element 6.

The output signal of the position detecting element 6 is subjected to calculation and processing as shown in the following (1) by an arithmetic processing circuit 7 of the controller 2, and is further subjected to linear correction by a linear correction circuit 8 to obtain a digital signal. Or it is output as an analog quantity. In the equation (1), dY is the amount of movement of the point image on the position detecting element 6, I1 and I2 are the output currents from the position detecting element 6, and K
0 indicates a constant. The controller 2 controls the drive current of the light source 3 by feeding back the light receiving signal (I1 + I2) to the driver 10 of the light source 3,
Is provided with a light quantity adjustment function for making the output of the camera always constant.

[0006]

By the way, in the conventional distance measuring apparatus as described above, when a sensor head (sensor section) and a controller (signal processing section) that are compatible with the configuration (measurement range) of the optical system are connected. Must connect a sensor head whose measurement range is suitable as shown in FIG. 4 to the controller. However, if a sensor head whose measurement range is not suitable as shown in FIG. 5 is connected to the controller, the measurement accuracy decreases. In addition, inconveniences such as inability to measure occur. That is, FIG. 4 shows the case where the measurement range of the sensor head and the range to be actually measured are -A to 0 to + A, which are the same, and FIG. 5 is the measurement range of the sensor head -A to 0
This is a case of non-conformity in which ~ + A does not match the range -A '~ 0' ~ + A 'to be actually measured.

When a semiconductor laser is used as the light source 3, if a sensor head incorporating a semiconductor laser having a different light output is connected, the semiconductor laser may be deteriorated and, in the worst case, destroyed. Therefore, when connecting the sensor head to the controller, it is necessary to pay attention to the structure and circuit configuration of the optical system in the sensor head, and to perform a complicated operation such as checking whether the sensor head is compatible. There is. Therefore, an object of the present invention is to make it possible to easily determine whether a connected sensor head is optically or circuit-compatible.

[0008]

In order to solve such a problem, according to the present invention, a light source for emitting a light beam is provided on an optical path in a direction in which a distance is to be measured. A light projecting lens for forming a bright spot by irradiating the light beam, a light receiving lens for condensing light reflected from the bright spot on an optical path in a direction different from the optical path of the light beam, and a light receiving lens for receiving a real image of the bright spot An element, an operation circuit for calculating the position of the real image on the light receiving element from position outputs obtained as two output currents, and a correction circuit for linearizing correction of the operation output. In a distance measuring device for measuring, a variable impedance element is provided in a sensor unit for converting the position of the bright spot into the position output signal, and a controller for amplifying, calculating, and linearly correcting the position output signal. An oscillator that outputs pulses having different periods according to the impedance value of the impedance element, a determination circuit that receives pulses from the oscillator and determines whether the sensor unit is compatible with the controller unit. It is characterized by having provided.

[0009]

A sensor head suitable for the discriminating circuit in the controller is connected in advance, and the cycle of the pulse output from the oscillator at that time is stored, and the signal is output when a non-compatible sensor head is connected. By comparing the pulse period with the stored pulse period, it is possible to easily determine whether the sensor head is appropriate or not.

[0010]

FIG. 1 is a block diagram showing an embodiment of the present invention. As can be seen from the figure, in the embodiment of the present invention, a variable resistor 17 is provided on the sensor head 1 side, and an inspection oscillator 18 and a suitable sensor discriminating circuit 19 are added on the controller 2 side. The feature is the point. The resistance value of the variable resistor 17 is changed for each sensor head 1 having a different optical system configuration (measurement range) or each sensor head 1 having a different circuit configuration. As shown in FIG. 2, the matching sensor determination circuit 19 is a memory unit that stores various pulse periods to be output when the variable resistor 17 in the sensor head 1 is connected to the oscillator 18 of the controller 2. 2
0 and a comparator 21 which compares a pulse output from the oscillator 18 and outputs a judgment output. It should be noted that other impedance elements such as a variable capacitor and a variable reactor can be used instead of the variable resistor 17.

The operation will be described. First, a variable resistor 17 provided in the sensor head 1 having a suitable optical system structure and circuit configuration is connected in advance to an oscillator 18 provided in a suitable controller 2 so as to output a pulse having a constant period. The resistance value of the variable resistor 17 in the sensor head 1 is obtained in advance, and the cycle of the output pulse is stored in the compatible sensor determination circuit 19 provided in the controller 2.
In this way, if the variable resistor 17 in the sensor head 1 whose optical system structure or circuit configuration is not suitable is connected to the oscillator 18 provided in the controller 2, the pulse of the cycle stored in the discrimination circuit 19 Different pulses are generated by the oscillator 18
As a result, the discrimination circuit 19 outputs an error signal indicating incompatibility. By doing so, it is possible to easily determine whether the sensor head 1 and the controller 2 to be connected are compatible with each other, and it is possible to prevent a measurement error caused by connecting an incompatible sensor head.

[0012]

According to the present invention, for example, a variable resistor is provided in the sensor head, and an oscillator capable of outputting a pulse having a different cycle in accordance with the resistance value is provided in the controller, and a pulse input from the oscillator is provided. And a determination circuit for determining whether the connected sensor head is suitable or not from the cycle of the sensor head 1. Therefore, it is possible to easily determine the suitability or unsuitability of the sensor head 1, and as a result, the unsuitable sensor head Can be avoided. In addition, since an unsuitable sensor head can be determined, there is an advantage that evaluation at the time of manufacturing the distance measuring device is facilitated.

[Brief description of the drawings]

FIG. 1 is a configuration diagram showing an embodiment of the present invention.

FIG. 2 is a block diagram illustrating a specific example of a compatible sensor determination circuit in FIG. 1;

FIG. 3 is a block diagram showing a conventional example.

FIG. 4 is an explanatory diagram for describing an example of a sensor head whose measurement range is suitable.

FIG. 5 is an explanatory diagram illustrating an example of a sensor head whose measurement range is not suitable.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Sensor head, 2 ... Controller, 3 ... Light source, 4 ...
Projection lens, 5: Light receiving lens, 6: Position detecting element, 7 ...
Arithmetic processing circuit, 8: linear correction circuit, 9: digital display, 10: driver (driving circuit), 11: oscillator,
12, 13 ... amplifier, 14 ... adder, 15 ... subtractor, 1
6 divider, 17 variable resistor, 18 oscillator for inspection, 1
9: compatible sensor discriminating circuit, 20: memory for storing suitable pulse, 21: comparator.

Claims (1)

(57) [Claims] 1. A light source for emitting a light beam, a light projecting lens installed on an optical path in a direction in which a distance is to be measured and irradiating the light beam onto an object to be detected to form a bright spot, and the light beam A light-receiving lens for condensing reflected light from the bright spot on an optical path in a direction different from that of the light-receiving element, a light-receiving element for receiving a real image of the bright spot, and a position of the real image on the light-receiving element as two output currents. A distance measuring device for measuring the position in the light beam direction, comprising: an arithmetic circuit for calculating by arithmetic operation from the obtained position output; and a correction circuit for linearizing correction of the arithmetic output. A variable impedance element is provided in a sensor unit for converting the position output signal, and a controller unit for amplifying, calculating, and linearly correcting the position output signal is provided in accordance with the impedance value of the impedance element. An oscillator for outputting a pulse of different periods, the distance measuring apparatus the sensor unit receives a pulse from the oscillator is characterized by providing a discriminating circuit for discriminating whether or not to conform to the controller unit.