JPH0754250B2 - Position detector - Google Patents

Description

TECHNICAL FIELD The present invention relates to a position detector used in a triangulation type distance measuring device and for detecting the position of an imaging spot.

BACKGROUND ART Conventionally, a position detector of this type, which is used in a distance measuring device of a triangulation method and detects the position of an image spot, has a moving direction of the image spot as shown in FIG. 9 (a). A large number of light receiving elements (eg, photodiodes P _{1 to} P
n) is arranged so that the image forming position of the spot is detected based on the change in the amount of light detected by the array sensor 1, and each light-receiving element output of the array sensor 1 is extracted to obtain position information. It was. On the other hand, FIG. 9B shows a fiber light guide array in which _one ends of a large number of fiber light guides LG _{1 to} LGn are arranged in a straight line and a photodetector provided corresponding to each fiber light guide LG _{1 to} LGn. it is obtained by forming an array sensor 1 'in the P ₁ to PN. However, in such a conventional example, the outputs are obtained from the light receiving elements of the array sensors 1 and 1 ', respectively. Therefore, when configuring a position detector with high resolution and high dynamic range, the number of outputs is However, there is a problem that a realistic position detector cannot be configured because the configuration becomes complicated. A TV camera or a line sensor may be used to detect the position of the image formation spot, but it has a problem that the processing speed is slow and the dynamic range is low.

[Object of the Invention] The present invention has been made in view of the above points, and an object of the present invention is to simplify the configuration even when a high resolution and a high dynamic range are achieved, and to perform high-speed processing. It is to provide a position detector capable of

DISCLOSURE OF THE INVENTION (Structure) The present invention is a position detection that detects the position of an imaging spot based on a change in the amount of light detected by an array sensor in which a large number of light receiving elements are arranged in the moving direction of the imaging spot. In this device, two arrays of array sensors having the same number of light receiving elements are arranged side by side in a direction orthogonal to the moving direction of the image forming spots so that the light receiving elements are arranged in a one-to-one relationship with each other. One array is used as an upper array sensor and the other array is used as a lower array sensor, and both array sensors are divided into a plurality of groups each including the same number of light receiving elements, each of which has three or more light receiving elements. The elements are given different symbols, and the light-receiving element outputs in each set of the upper array sensor are combined together, and the light-receiving element outputs with the same symbol in each set of the lower array sensor are combined together. Form a matrix part, find the symbol of the maximum light intensity position of the imaging spot on the lower array sensor based on each combined output, and combine this symbol with the output corresponding to the position of the imaging spot on the upper array sensor. It is characterized in that a position detecting section for outputting coded position information is provided.

(Operation) In the present invention, as described above, two rows of array sensors are provided within the range of the size of the imaging spot in the direction orthogonal to the moving direction of the imaging spot, and one row is the upper array sensor and the other is the upper array sensor. Is used as a lower array sensor, and is divided into a plurality of sets including the same number of light receiving elements with three or more for both array sensors,
The light receiving elements within each group of the lower array sensor are given different symbols, the light receiving element outputs within each group of the upper array sensor are combined, and the light receiving element output with the same symbol of each group of the lower array sensor is added. Since the sensor part is formed so as to synthesize each other, even if the resolution of position information is increased by increasing the number of light receiving elements per unit size of the lower array sensor, the number of outputs related to the lower array sensor is a symbol. The number is the same as that of, and the increase in the number of outputs can be suppressed even if the resolution is increased. In addition, since the position information coded by the combination of the symbol relating to the lower array sensor and the output of the upper array sensor is output, which group the position where the imaging spot is formed in the lower array sensor is set for the upper array sensor. It suffices to be able to identify whether they belong, it is possible to distinguish a large number of position information with a relatively small number of codes, and as a result, a high resolution, high dynamic range position detector can be realized with a simple configuration, Moreover, since the code directly represents the position of the image formation spot, high-speed processing becomes possible.

For example, if it is assumed that the lower array sensor and the upper array sensor identify 8 types each, position information can be obtained by simply identifying 16 types of symbols (2 columns of 8 types for each column).
It can be detected in 64 steps. This is 64
Compared to the case of individually identifying the position information of the stages, the processing amount is significantly reduced, and if array sensors are provided in two rows, the array sensors can be straddled without using a special optical system. Such an imaging spot can be formed. On the other hand, if the light-receiving elements of a plurality of rows of array sensors are each identified by two symbols, six rows of array sensors are required to identify the position information in 64 steps. There are 12 types of information to be processed (6 columns of 2 columns for each column), but a special optical system for forming the image spot so as to extend over 6 columns is required. That is, the configuration of the present invention can be easily realized in both the optical system and the processing system.

By the way, in many cases, the image formation spot does not show a single peak like the normal distribution due to the secondary reflected light or the like. In this case, the imaging spot is formed so as to straddle a plurality of light receiving elements that are close to each other. That is, when the resolution is increased, the arrangement pitch of the light receiving elements becomes narrower, so that the phenomenon that an imaging spot is formed over three or more light receiving elements is likely to occur. However, if there are two types of lower array sensor symbols, the same symbol is attached to the light receiving elements on both sides of each light receiving element, so even if the position information is coded in combination with the output of the upper array sensor, the image is formed. It may not be possible to identify whether the spot extends over two light receiving elements or over three light receiving elements. On the other hand, in the present invention, the light receiving element has three
By attaching different symbols to each other, it is possible to identify even if an image spot formed across three or more light receiving elements is formed, and it is less likely to be affected by secondary reflected light or the like. Of. In short, if the number of symbols of the lower array sensor is small, the chance that the same code is assigned to different states increases, but the above configuration reduces the frequency, and as a result, the position information can be accurately obtained. Moreover, since the maximum light amount position of the imaging spot is detected as the position information, the code of the maximum light amount position can be easily specified. The influence of the secondary reflected light or the like is removed to detect the position information with high accuracy. You can do it. In particular, in the present invention, since the light receiving elements forming the lower array sensor and the upper array sensor are arranged in rows one by one, a resolution equivalent to the arrangement pitch of the light receiving elements can be obtained, and a high resolution is thereby obtained. It is possible.

Further, in the configuration of the present invention, the upper array sensor and the lower array sensor have the same number of light receiving elements, and the upper array sensor and the lower array sensor are arranged side by side so that the light receiving elements of each of them are aligned one to one. Therefore, the response of the imaging spot does not deviate between the upper array sensor and the lower array sensor, and the response is good and the position detection can be performed at high speed.

(Embodiment) FIGS. 1 to 5 show an embodiment of the present invention, in which the amount of light detected by an array sensor in which a large number of light receiving elements are arranged in the moving direction of an imaging spot (direction of arrow X). In a position detector similar to the conventional example that detects the position of the imaging spot based on the change, a plurality of rows (two rows in the embodiment) of array sensors are arranged in parallel in the direction orthogonal to the moving direction of the imaging spot. The upper array sensor 1a and the other are lower array sensors 1b, and a plurality of sets of both array sensors 1a and 1b (in the embodiment, 0 to
It divides into 7), and synthesize | combines the eight light receiving element outputs of each group of the high-order array sensor 1a, and also synthesize | combines corresponding (the same number) light receiving element output of each group of the lower array sensor 1b. The sensor unit 2 is formed as described above, and the position detecting unit 3 that detects the image forming position of the spot imaged on the array sensors 1a and 1b based on the combined output and outputs the encoded position information is provided. It is a thing. Each array sensor 1a, 1
b has the same number of light receiving elements (here, 64 each), and the light receiving elements of each array sensor 1a, 1b are arranged in a direction orthogonal to the moving direction of the imaging spot so as to correspond one-to-one. Be lined up. Here, in the embodiment, in the array sensors 1a and 1b of the sensor unit 2, one end of each fiber light guide is arranged in a straight line and the other end is appropriately bundled (the same number is bundled). Light guide array LG
The photodetector PH facing the other ends H _{0 to} H ₇ and L _{0 to} L ₇ of the a and LGb and the fiber light guide arrays LGa and LGb that are bound together.
_{0 ~PH 7,} PL _{0 ~PL 7} are formed by the photo detector
Composite outputs SH _{0 to} SH ₇ and SL _{0 to} SL ₇ can be obtained from PH _{0 to} PH ₇ and PL _{0 to} PL ₇ . In addition, the photodiodes are arranged at the positions of the fiber light guides of the fiber light guide arrays LGa and LGb, and the photodiode outputs are connected so as to obtain a combined output equivalent to the case where the fiber light guides are bundled as described above. It goes without saying that a photodiode array may be used.

In addition, the position detection unit 3 detects the upper position based on the combined outputs SH _{0 to} SH ₇ amplified by the amplifier AMP, and the lower position based on the combined outputs SL _{0 to} SL _7. It is formed by the lower position detection unit 6 for detecting. FIG. 3 shows the circuit configuration of the lower position detection unit 6, and the combined outputs SL _{0 to} SL ₇ are shown.
A / D converter AD _{0 to} AD
₇ and parallel / serial converters SP _{0 to} SP ₇ that convert the parallel data output from the A / D converters AD _{0 to} AD ₇ to serial data, and the maximum based on the input serial data A _{0 to} A _7. It is formed by a maximum position / maximum value detection unit MD that detects the position and the maximum value. The upper position detection unit 5
The circuit configuration of is also the same as that of FIG. Further, FIG. 4 shows a specific example of the maximum position detection circuit of the maximum position / maximum value detection unit MD, which includes OR circuits OR _{1 to} OR ₄ and AND circuit AN.
It is formed by D ₁ , AND ₂ , a flip-flop circuit FF ₁ , an inverter circuit IN _1, and an encoder EC for position output. FIG. 5 shows a specific example of the maximum value detection circuit, which is formed of a shift register SR and a latch circuit LC.

The operation of the embodiment will be described below. Now, in a triangulation type distance measuring device, a light projecting means for projecting a light beam to a detection area and a light receiving means for receiving the reflected light of the light beam by an object to be detected are arranged at an appropriate distance from each other. The position of the image forming spot is detected by the position detector provided on the image forming surface of the optical system of the light receiving means, and the distance to the detected object is determined based on the position information of the image forming spot. ing. Here, the imaging spot array sensor 1a, is adapted to be imaged straddling 1b, the position of the imaging spot on the basis of the photodetector _{PH 0 ~PH 7, PL 0 ~PL} 7 Output The position detecting section 3 for detecting the position of the upper array sensor 1a, which is divided into a plurality of groups, detects the maximum amount of light received, and the number of the fiber light of each group of the lower array sensor. It is detected that the amount of light received by the guide is maximum, and the position information is output by the high order number and the low order number. For example, if the maximum position of the light quantity of the image forming spot is the position shown by the slanted line S in FIG. 1, the position code of the high order number “7” and the low order number “5” is output. It can be seen that the imaging spot exists at the position of the 62nd (7 × 8 + 6) fiber light guide from the bottom of the array sensors 1a and 1b.

Therefore, in the present invention, the array sensors 1a and 1b are arranged in parallel in a direction orthogonal to the moving direction of the image forming spot (direction of arrow X), and both array sensors 1a and 1b are divided into a plurality of groups, respectively. The sensor unit 2 is formed so as to combine the light receiving element outputs of each set of the upper array sensor 1a and the corresponding light receiving element outputs of each set of the lower array sensor 1b, and the position detecting unit 3 In the case of high resolution and high dynamic range, it detects the image formation position of the spot imaged on the array sensors 1a and 1b based on the combined output and outputs the encoded position information. Even if it is, it is possible to provide a position detector having a simple structure and capable of high-speed processing. Further, in the embodiment, since there is provided a photodetector _{PH 0 ~PH 7, PL 0 ~PL} 7 to the binding unit using the fiber light guide array, photodetector PH ₀ ~PH _7, PL ₀ ~PL The number of ₇ can be greatly reduced as compared with the case of the conventional example. For example, when the resolution is set to 64 (8 × 8) as in the embodiment, 64 photodetectors are required in the conventional example shown in FIG. Upper and lower 8
Photo detectors PH _{0 to} PH ₇ , PL _{0 to} PL, one by one (8 + 8)
It can be configured with _7, which means that the configuration is simple and the cost can be reduced.

FIG. 6 shows a flow chart for obtaining the maximum position and the maximum value, in which each input gate Gi is set to the value High (= 1), and serial data of the light quantity for each input is input from the upper bits to the bit data Dij ( i input jth bit) and Gi
* Calculate the logical product of Dij. Only when one of all inputs has High by this operation, set the Gi of the input that became Low (= 0) to Low. This operation is performed up to the last bit of the serial data, and the position where Gi is High becomes the maximum position. At the same time, the bit j at which Gi * Dij becomes High
MAX data obtained as a result of setting MDj to High at is the maximum value. In the embodiment, since this processing is realized by the circuit, a position detector capable of high speed processing is obtained. In the specific example of FIG. 4, the serial bit number +
The maximum position can be obtained with one clock number.

The operation of a specific example will be described below. Now, set the High level (= 1) to reset to reset the entire, given a clock CL, trigger the flip-flop FF ₁ out pulse RCK1. Since data is High by reset, all Q outputs are High and G is also
Set to High. Here, paying attention to the serial input A _0, when the 7th bit data D ₀₇ of A ₀ comes in, SP ₀
Outputs the logical product of G ₀ , D ₀₇ and the clock CL. That is, when A ₀ is High, High is output to SP ₀ in synchronization with the clock. Only when any of SP _{0 to} SP ₇ is High,
A high pulse is output to RCK1, the value of each SP is held in the flip-flop FF, and output to Q. Further, when all the serial data inputs are Low (= 0), the pulse of RCK1 is not output, so that the previous data is held in Q. Once Q becomes low, G becomes low and is held until the next reset, so SP is not output either. When this process is performed from the 7th bit to the 0th bit, Q and G of the serial data having the maximum value become High. Since the position can be known by reading the positions of Q _{0 to} Q ₇ , it is encoded by the encoder EC and the position information is output.

The maximum value is the maximum serial input data, and when the bit data is High (or Low), it is High in RCK1.
Since (or Low) is output, the maximum value data can be obtained by latching the value of RCK1 bit by bit. In the specific example shown in FIG. 5, the shift register SR is used for RC.
The data of K1 is input and the above-mentioned clock CL is used as the shift clock. When the shift of all 8 bits is completed, the maximum value data is obtained by latching with the reset signal.

Note that the image formation spot may change due to the influence of the light reflection characteristics of the detected object and may not necessarily have a normal distribution. If the center of gravity of the light quantity of the image formation spot is the image formation position, position detection is performed. Although there is a problem that the accuracy becomes low, when the light amount maximum position of the imaging spot is the imaging position as in the embodiment, highly accurate position detection is performed. That is, as shown in FIG. 7 (a), a light beam such as a laser beam is irradiated onto the detected object Xa having an inclined surface, and in addition to the original beam spot Sb, a spot Sb 'due to secondary reflection (however, (A small amount of light) exists, as shown in FIG. 7 (b), the light beam is irradiated to the detection object Xb made of the laminated plate, and the spot diameter becomes large due to the scattering part Sb ″ in the laminated plate. If yes, the 7th
As shown in Figure (c), many spurious spots Sb
When the center of gravity of the imaging spot is determined and used as the position of the imaging spot in the case of a speckle pattern in which the image forming spot is formed, the original position of the imaging spot cannot be accurately determined. However, as in the embodiment, three or more kinds (eight kinds in the embodiment) of different symbols are given to the light receiving elements in each group of the lower array sensor 1b, and the maximum light amount position is set as the position of the imaging spot. When the determination is made, the frequency of assigning the same code to different states is significantly reduced even if the imaging spot is formed across multiple light receiving elements, and the light reflection characteristics of the detected object are reduced. Position detection is performed without being affected by the above, and when used as position detection means of a triangulation type distance measuring device, accurate distance measurement is always performed.

In addition, beam spots Sb, Sb ′, S as shown in FIG.
In order to form an image of b ″, Sb with an optical system so that the image forming spot straddles both sensor arrays 1a, 1b, a cylindrical lens is used to make a wide connection as shown in FIG. 8 (a). It is sufficient to obtain an image spot. Incidentally, as shown in FIG. 8 (b), the received beam is separated by using the beam splitter BS so as to obtain an image spot on each of the sensor arrays 1a and 1b. Is also good.

[Advantages of the Invention] As described above, according to the present invention, two rows of array sensors are provided within the range of the size of the imaging spot in the direction orthogonal to the moving direction of the imaging spot, one of which is the upper array sensor and the other is the upper array sensor. As a lower array sensor, each array sensor is divided into a plurality of groups including three or more light receiving elements of the same number, and the light receiving elements in each group of the lower array sensor are given different symbols.
Since the sensor unit is formed so as to combine the light receiving element outputs in each set of the upper array sensor and the light receiving element outputs with the same symbol in each set of the lower array sensor, the lower array Even if the number of light receiving elements per unit size of the sensor is increased to increase the resolution of position information, the number of outputs related to the lower array sensor is the same as the type of symbol, and even if the physical resolution is increased, This has the effect of suppressing the increase. In addition, since the position information coded by the combination of the symbol relating to the lower array sensor and the output of the upper array sensor is output, which group the position where the imaging spot is formed in the lower array sensor is set for the upper array sensor. It suffices to be able to identify whether they belong, it is possible to distinguish a large number of position information with a relatively small number of codes, and as a result, a high resolution, high dynamic range position detector can be realized with a simple configuration, Moreover, since the code directly represents the position of the imaged spot, there is an advantage that high-speed processing is possible.

Further, since three or more types of different symbols are attached to the light receiving elements, it is possible to identify even if an image spot formed across three or more light receiving elements is formed. Since it is less likely to be affected, there is an effect that position information can be obtained accurately as a result. Moreover, since the maximum light amount position of the imaging spot is detected as the position information, the code of the maximum light amount position can be easily specified. The influence of the secondary reflected light or the like is removed to detect the position information with high accuracy. It has the advantage that it can. In particular, in the present invention, since the light receiving elements forming the lower array sensor and the upper array sensor are arranged in rows one by one, a resolution equivalent to the arrangement pitch of the light receiving elements can be obtained, and a high resolution is thereby obtained. The effect that can be obtained is obtained.

Further, in the present invention, the upper array sensor and the lower array sensor have the same number of light receiving elements, and the upper array sensor and the lower array sensor are arranged side by side so that the light receiving elements of the upper array sensor and the lower array sensor are aligned one to one. Therefore, there is no difference in response to the imaging spot between the upper array sensor and the lower array sensor, and there is an advantage that the response is good and the position detection can be performed at high speed.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram of an embodiment of the present invention, FIG. 2 is a schematic configuration diagram of essential parts of the same, FIG. 3 is a block circuit diagram of essential parts of the same, and FIGS. 4 and 5 are essential parts of the same. Part specific circuit diagram, 6th
FIG. 8 to FIG. 8 are explanatory diagrams of the same operation as above, and FIGS.
Are schematic configuration diagrams of conventional examples. 1a and 1b are array sensors, 2 is a sensor unit, and 3 is a position detection unit.

Claims (2)

[Claims] 1. A position detector for detecting the position of an imaging spot based on a change in the amount of light detected by an array sensor having a large number of light receiving elements arranged in the moving direction of the imaging spot.
Two rows of array sensors having the same number of light receiving elements are arranged side by side in a direction orthogonal to the moving direction of the image forming spots so that the light receiving elements are arranged in a one-to-one relationship with each other. A row is an upper array sensor, the other row is a lower array sensor, and both array sensors are divided into a plurality of groups each including three or more and the same number of light receiving elements, and the light receiving elements in each group of the lower array sensor are different from each other. The sensor part is formed so as to combine the light receiving element outputs in each set of the upper array sensor with each other, and to combine the light receiving element outputs with the same sign of each set of the lower array sensor with each other, A symbol for the maximum light amount position of the imaging spot on the lower array sensor is obtained based on each combined output, and this symbol is combined with the output corresponding to the position of the imaging spot on the upper array sensor to obtain a code. A position detector, characterized in that a position detecting section for outputting a phased position information. 2. An array sensor is formed by arranging one end surface of a large number of fiber light guides in a row in the moving direction of an image forming spot, and arranging a photodetector on the other end surface of the fiber light guide which is properly bundled. The position detector according to claim 1, which is characterized in that.