GB2293711A - Setting up distance measurement device - Google Patents

Abstract

Device 1 measures the distance to target T and assigns it to one of three range bands. The two boundaries between the range bands are set by initial measurements, by the device, of the distance to targets (eg an orator's hand) placed at the boundaries (eg the edge of one of three conveyor belts) when switches 3a, 3b respectively are pressed; these are stored and the device then compares subsequently measured distances with these initial distances. A timer may be included (fig 6) to allow a delay in which the operator can move his hand to the correct position. A single measurement may be made (figs 7, 9) and the boundaries set with respect to this: this allows the device to be reset after it is moved with the minimum of fuss. <IMAGE>

Description

DISTANCE MEASURING DEVICE The present invention relates to the distance range setting of a distance measuring device that measures a distance to an object, judges to which range of a plurality of preset distance ranges the result of the distance measurement belongs, and outputs a signal indicating the judged range.

There is known a distance measurement device which, when the distance measurable range of the device is divided at a plurality of distance division points (hereinafter referred to as simply division points) into a plurality of distance ranges, judges to which of the ranges the result of the distance measurement of the device belongs and can output the result of the judgment.

Figure 4 is a circuit block diagram showing a known distance measurement device, and Figure 5 shows the relationship between a division point and a distance range. In Figure 4, reference numeral 41 denotes distance measurement means for measuring a distance to an object T, which takes a measurement when a start switch SS is on.

Reference numerals 43 and 44 respectively denote set means for setting a division point on a long distance side, Pan, and set means for setting a division point on a short distance side, Pbm. Here, m and n both represent an integer between 0 and 15. The set means are constructed so that 16 different fixed division points (referred to as PaO to Pal5 and PbO to PblS) may be set with the digital switches 43 and 44 each having four bits, as shown in Figures 5(a) and 5(b). Thus the range of distance measurement of a distance measurement device is divided by the two division points Pan and Pbm into three distance areas Z51, Z52, and Z53, as shown in a distance diagram (c) of Figure 5.

Assuming now that the measurable distance range of the distance measurement means 41 is between 0.5 m and 3.7 m, then the distance measurement area will be divided into 16 equal parts and therefore the division point will move by 0.2 m each time the set means is moved one step. If the division point Pan is set to Pa8, the distance from the distance measurement device to Pa8 will be 0.5 + 8 x 0.2 = 2.1 m. Also, if the division point Pbm is set to Pb3, the distance from the distance measurement device to Pb3 will be 0.5 + 3 x 0.2 = 1.1 m.

Judgment means 42 judges to which range of the set distance ranges Z51 to Z53 the distance measurement result of the distance measurement means 41 belongs, and outputs the result of the judgment to output terminals 45a, 45b, and 45c so that the distance range Z51 to Z53 corresponding to the detected object T can be detected.

In the method described above, the set means has to be manually set to a position equivalent to each distance value, for each division point, so the operator has to remember what distance one step of the set means is equivalent to. Also, calculations have to be made individually, as described above, and therefore setting is difficult to perform. Further, when the above described distance ranges are set, measuring a distance to an object is necessary in the actual field where this distance measurement device is used.

As an example, consider a situation in which this distance measurement device is used as a switch for an illuminator which is lit only when a human body is within a predetermined range from the device. In order to set this distance measurement device, it is necessary that a person stands at a position where the distance measurement device is actually operated, the distance between the distance measurement device and the person is measured, for example, with a measuring tape, and the set means is operated so that the distance measurement device can perform a desired operation at that position. Further, since the positions of 16 division points have been fixed in advance, the distance resolution is constant.

Therefore, in order to set a distance with finer resolution, the number of bits of the set means has to be increased to raise resolution. If so, the circuit scale and therefore cost will be increased.

The present invention seeks to provide a distance measurement device where calculation such as described above is unnecessary, the above described division point can be easily set at an actual field, and a finer distance can be set.

Figure 12 shows a known distance measurement device acting as an object detecting device M for detecting the passage of articles on belt conveyors BC1, BC2, and BC3 of width, w, arranged in parallel.

If the right hand end of the belt conveyor BC1 as shown in Figure 7 is set as division point Pb and the right hand end of the belt conveyor BC2 as shown in Figure 7 is set as division point Pa, then it will be possible to judge that an article S belongs to a distance area Z71 when it is on the belt conveyor BC1, to a distance area Z72 when it is on the belt conveyor BC2, and to a distance area Z73 when it is on the belt conveyor BC3.

However, it is necessary, in the known device, that an object is placed on the right hand end of the belt conveyor BC1 to set the first division point Pb and then the object is placed on the right hand end of the belt conveyor BC2 to set the second division point Pb. Therefore, when the distance between the object detecting device M and the belt conveyor is changed (in Figure 12, when the object detecting device M is moved from the position L1 indicated by solid lines to the position L2 indicated by broken lines), the above described operation has to be performed to reset both of the two distance divison points Pa and Pb to new distances.

The present invention therefore seeks to provide a distance measurement device that, when the width of a distance area desired to be detected has been fixed, can simply set the distance area, while overcoming the problems described above.

According to the present invention, there is provided a distance measuring device comprising: switch means for generating a start signal; distance measurement means for measuring a distance to an object responsive to said start signal; storage means for storing distance data of at least one division point, the division point or points dividing a measurement range of the distance measurement means into a plurality of distance ranges; and judgement means for judging within which distance range the measured distance falls during a distance measuring operation, wherein the distance data of at least one division point are derived from a distance measured to an object during an initial range-setting phase.

For a better understanding of the present invention, and to show how it may be brought into effect, reference will now be made, by way of example, to the accompanying drawings, in which: Figure 1 is a circuit block diagram showing a first embodiment of the present invention.

Figure 2 is a diagram indicating the operation of the first embodiment of the present invention.

Figure 3 is a circuit block diagram showing a second embodiment of the present invention.

Figure 4 is a circuit block diagram showing a known distance measurement device.

Figure 5 is a diagram indicating the operation of the known distance measurement device.

Figure 6 is a circuit block diagram showing a third embodiment of the present invention.

Figure 7 is a distance diagram indicating the operation of the third embodiment of the present invention.

Figure 8 is a further distance diagram indicating the operation of the third embodiment of the present invention.

Figure 9 is a circuit block diagram showing a fourth embodiment of the present invention.

Figure 10 is a distance diagram indicating the operation of the fourth embodiment of the present invention.

Figure 11 is a further distance diagram indicating the operation of the fourth embodiment of the present invention.

Figure 12 is a diagram indicating the problems associated with a known distance measurement device.

The present invention will hereinafter be described in detail in accordance with embodiments shown in the accompanying drawings.

Figure 1 is a circuit block diagram showing a first embodiment of the present invention. For simplicity, an example in which a measurable range is divided into three distance areas Z1, Z2, and Z3 with two distance division points Pa and Pb is shown. This relationship is shown in Figure 2.

Reference numeral 1 denotes distance measurement means for measuring a distance to an object T. The distance measurement means may comprise, for example, means for emitting infrared rays and detecting light reflected from the object T with a position sensing device (PSD), or means using ultrasonic waves. The distance measurement means 1 has switches 3a and 3b for setting two distance division points and a start switch SS for starting a normal distance measurement operation. The switch 3a sets a far division point Pa, and the switch 3b sets a near division point Pb. The switches 3a and 3b constitute the setting means 3.

Storage means 2 stores distance information on the short distance side division point or long distance side division point obtained by the operation of the switch 3a or 3b. Judgment means 4 judges to which distance range the distance measurement result of the distance measurement means 1 belongs, among the plurality of distance ranges where a plurality of division points are distance information stored in the storage means 2. Display means 5 displays that the distance data of the division points have been stored in the storage means 2. Also, the output terminals 6a, 6b, and 6c are output means for outputting information on a distance range where the object T exists.

Next, the operation of the embodiment of the present invention shown in Figure 1 is described.

First, when the far division point Pa is set, the operator places an object at a position spaced from the distance measurement device of the present invention by a desired distance and presses the switch 3a. The distance measurement means 1 performs a distance measurement operation, measures a distance to the object, and stores the distance data DPa (in this case, 2.1 m) in the storage means 2. At this time, the display means 5 displays that the distance data of the long distance side division point has been stored, during a predetermined period of time. Next, in order to set the near division point Pb, the operator first places the object at a position close to the distance measurement device of the present invention by a desired distance and then presses the switch 3b.In the same way in which the long distance side division point is obtained, the distance measurement means 1 performs a distance measurement operation, measures a distance to the object, and stores the distance data DPb (in this case, 1.1 m) in the storage means 2.

Likewise, the display means 5 displays that the distance data of the near division point has been stored in the storage means, during a predetermined period of time.

If the start switch SS is pressed in this state, the distance measurement means 1 will perform a normal distance measurement operation. Various kinds of steps for performing the distance measurement operation are possible. For example, a single distance measurement operation may be performed each time the start switch SS is pressed, or distance measurement operations may be performed at predetermined intervals (for example, at intervals of 0.5 seconds) during the period of time that the start switch SS is pressed.

If the distance measurement operation ends, the judgement means 4 will compare distance data DPx with the distance data DPa and DPb stored in the storage means 2. The judgment means 4 judges to which of the three distance ranges Z1, Z2, and Z3 divided at two division points Pa and Pb the distance data DPx belongs, and outputs the result of the judgment to the output terminals 6a, 6b, and 6c. As shown in Figure 2, the distance range Z1 covers a distance more than 0.5 m and less than Pb, the distance range Z2 covers a distance more than Pb and less than Pa, and the distance range Z3 covers a distance more than Pa.

When it is assumed that the distance value DPa of the division point Pa is 2.1 m and the distance value DPb of the division point Pb is 1.1 m, the distance measurement result will be within the distance range Z1 if it is, for example, 0.9 m. In this case, only the terminal 6a is made high (hereinafter referred to as "H"), and terminals 6b and 6c are made low (hereinafter referred to as "L"). Likewise, if the distance measurement result is 1.5 m and within the distance range Z2, then only the terminal 6b will be set to "H".

And, if the distance measurement result is 2.8 m and within the distance range Z3, then only the terminal 6c will be set to "H". With this arrangement, a distance range where an object exists can be detected. Other signalling methods may be employed, and the invention is not restricted to the method described above.

In the way described above, the division points can simply be set. But, there are some cases where a distance measurement device is fixed or difficult to move or where there is no appropriate object available for setting division points. In such a case, the division point may be set by interrupting the distance measurement range with the operator's hand, but in the case of one operator, the set distance will be limited to the range that can be reached by the operator's hand. Also, the same result as the switch 3a or 3b of the above described set means 3 can be obtained with remote control, but in this case, the circuit scale will be increased and the cost will be greatly increased. Next, a second embodiment of the present invention for overcoming this problem will be described.

Figure 3 is a circuit block diagram of a second embodiment of the present invention. The parts having the same reference numbers as Figures 1 represent the same parts. In Figure 3, timer means 7 starts time counting from the time that the switch 3a or 3b is pressed, and outputs a time-up signal after a predetermined period of time. Also, the distance measurement means 1 is provided with a mode switch MS for selecting the allowance or prohibition of the operation of the above described timer means 7. When the mode switch is off, the operation is the same as the first embodiment.

If the switch 3a or 3b of the set means 3 is pressed when the mode switch MS is on, then the timer means 7 will start its operation and the display means 5 will inform the operator that the timer means 7 is being operated. The time-up is set to 10 seconds. The display means 5 lights for the first 7 seconds of the period of time that the timer means operates, and is turned on and off for the remaining 3 seconds. With this, the operator is informed that the time-up is quite near. The distance measurement means 1 is in its standby state until the time of the timer means 7 is up and does not perform the distance measurement operation. The operator moves to a desired position during 10 seconds that the timer means 7 is operating, and stops at that position.

If the timer means 7 outputs a time-up signal after a predetermined period of time, the distance measurement means 1 will start the distance measurement operation and measure a distance to the operator. The distance data is stored in the storage means 2. If this timer 7 is used, division points will be able to be set without difficulty even when there is one operator.

Figure 6 is circuit block diagram showing a third embodiment of the present invention. For simplicity, a situation in which a measurable range is divided into three distance areas Z1, Z2, and Z3 with two distance division points is shown.

In Figure 6 reference numeral 1 is a distance measurement means for measuring a distance to an object T. The distance measurement means 1 has a switch 3 for generating a start signal for determining a specific distance point (hereinafter referred to as simply a specific point) which becomes a reference for setting two distance division points, and a start switch SS for starting a normal distance measurement operation.

Reference numeral 2 is a storage means for storing the distance information of a specific point obtained by pressing the switch 3. Reference numeral 4 is set means for setting a predetermined distance value on the near side or far side of the specific point described above, or on both of the near side and far side, respectively. In this embodiment, the set means uses digital switches having 16 settings with four signal lines 4a through 4d.

With combinations of the voltage levels of input signals IP1 and IP2 provided in the distance measurement means 1, a set method of divison points setting distance areas is determined. That is, when the input signal IP1 is a high voltage (hereinafter referred to as IP1 = "H") and the input signal IP2 is a low voltage (hereinafter referred to as IP2 = "L"), a predetermined distance value set by the set means 4 is set on the near side of the specific measured point, and when IP1 = "L" and IP2 = "H", the value is set on the far side (where a predetermined distance value is set on one side of the specific point will hereinafter be referred to as one-side setting).When IP1 = "H" and IP2 = "H", the distance value is set on both of the near and far sides (where a predetermined distance value is set on both sides of the specific point will hereinafter be referred to as both-side setting).

Reference numeral 5 denotes a judgment means for judging to which area out of a plurality of distance areas, the distance measurement result of said distance measurement means 1 belongs, where distance points that are set based on the specific points stored in said storage means 2 or distance information set by the set means are division points. Reference numeral 6 denotes a display means for displaying that the distance data of the divison points have been stored in the storage means 2. Also, reference numerals 7a, 7b, and 7c are output means for outputting in which area the distance measurement result obtained by the distance measurement means 1 exists, out of the plurality of distance areas set by the judgment means 5.

Reference numeral 8 denotes a timer means. If the switch 3 is pressed, the timer means 8 will start its operation and output the above described start signal after an elapse of a predetermined delay time to store the distance information of the specific point in the storage means 2. When the timer means 8 is operated, the mode switch MS connected to the distance measurement means 1 is switched on, and when not operated, the switch is switched off.

Now, the operation of the third embodiment of the present invention is described while referring to Figure 7. It is assumed that the distance measurable range of the distance measurement means 1 is between 0.5 m and 3.7 m and the set means 4 can set 5 cm per step, i.e., a maximum of 80 cm (5 cmx 16 steps).

Also, assume that the mode switch MS is off and input signals are IP2 = "H" and IP1 = "L" (one-side setting).

First, an operator using a device having the distance measurement device of the present invention incorporated therein places an object at a position spaced from the distance measurement device of the present invention by a desired distance and presses the switch 3. If the switch 3 is pressed, the start signal will be generated, and the distance measurement means 1 will perform a distance measurement operation to measure a distance to the object and will store the distance data DPA1 (for example, 2.3 m) in the storage means 2. At this time, the display means 5 displays that the distance data has been stored in the storage means, over a predetermined period of time. In the third embodiment, as shown in Figure 7(a), the point of this distance data is a specific point and becomes one division point PA1.Now, when the set means 4 has been set to the tenth step, i.e., 50 cm, the judgment means 5 sets, as the division point Pal on the far side, a value of 2.8 m obtained by adding 50 cm to the distance data DPA1 (2.3 m). And, for the distance areas that are divided at the division points PA1 and Pal, Z1 becomes 0.5 to 2.3 m, Z2 becomes 2.3 to 2.8 m, and Z3 becomes 2.8 to 3.7 m.

If the start switch SS is pressed in this stage, the distance measurement means 1 will perform a normal distance measurement operation. Various kinds of steps for performing the distance measurement operation are conceivable. For example, a single distance measurement operation may be performed each time the start switch SS is pressed, or distance measurement operations may be performed at predetermined intervals (for example, at intervals of 0.5 seconds) during the period of time that the start switch SS is pressed.

If the distance measurement operation ends, the judgement means 5 will judge to which area the distance data DPx belongs out of the three distance areas Z1, Z2, and Z3 determined as described above, and will output the result of the judgment to the output terminals 7a, 7b, and 7c. If the distance measurement result of the distance measurement means 1 is 1.9 m, it will be in the distance area Z1. Therefore, only the terminal 7a is set to an "H" level, and terminals 7b and 7c are set to "L" levels. Likewise, if the distance measurement result of the distance measurement means 1 is 2.5 m, it will be in the distance area Z2 and therefore only the terminal 7b will be set to an "H" level. And, if the distance measurement result is 3.0 m, it will be in the distance area Z3 and therefore only the terminal 7c will be set to an "H" level.With this, a distance area where an object exists can be detected. Other signalling methods may be used, and the present invention is not limited to the signalling method described above.

It is noted that if the step size of the set means 4 is changed, the point of a distance value where the distance value determined at that step is added to the distance value DPA1 of the specific point PA1 will become a new division point.

Next, consider a case where the voltage levels of input signals are IP2 = "L" and IP1 = "H" and, like the above described embodiment, the set means 4 has been set to the tenth step, i.e., 50 cm. As shown in Figure 7(b), the judgment means 5 sets a value of 1.8 m obtained by subtracting 50 cm from the distance data DPA1 (2.3 m), to the division point Pbl on the near side. And, for the distance areas that are divided at the divison points PA1 and Pbl, Z1 becomes 0.5 to 1.8 m, Z2 becomes 1.8 to 2.3 m, and Z3 becomes 2.3 to 3.7 m.

Figure 7(c) illustrates the case where a device having the distance measurement device of the present invention incorporated therein has been moved from the state of Figure 7(b) toward an object and the operator has pressed the switch 3. If the setting of the set means 4 has not been changed, the distance of the specific point can be changed without changing the width (50 cm) of the distance area Z2. That is, if the distance of the specific point PA2 (division point on the far side) becomes 2.05 m, then the distance of the specific point Pb2 on the near side will become 1.55 m.

If the width of a central belt conveyor BC2 is 50 cm in the case of an example of the belt conveyor shown in Figure 12, the set means 4 will be set to 50 cm.

With this, even if the distance measurement device of the present invention is moved from a position L1 to a position L2, a distance area would be automatically set only by placing the object on the right end of the belt conveyor BC1 and pressing the switch 3 and therefore only a single operation would be needed.

Next, a description will be made of the case where in Figure 6 the input signals IP1 and IP2 both have been set to "H" levels (both-side setting). As with the embodiment described above, the operator using a device having the distance measurement device of the present invention incorporated therein places an object in a position spaced from the distance measurement device of the present invention by a desired distance and presses the switch 3. The distance measurement means 1 performs a distance measurement operation to measure a distance to an object, and stores the distance data DPA3 (for example, 2.3 m) in the storage means 2. At this time, the display means 5 displays that the distance data has been stored in the storage means, over a predetermined period of time.

Now, when the set means 4 has been set to the fifth step, i.e., 25 cm, the judgment means 5 sets, as the division point Pa3 on the far side, a value of 2.55 m obtained by adding 25 cm to the distance data PDA3 (2.3 m) of the specific distance point PA3, as shown in Figure 8(a). Also, the judgment means 5 sets, as the division point Pb3 on the near side, a value of 2.05 m obtained by subtracting 25 cm. Therefore, for the distance areas that are divided at the division points Pa3 and Pb3, Z1 becomes 0.5 to 2.05 m, Z2 becomes 2.05 tO 2.55 m, and Z3 becomes 2.55 to 3.7 m.

Figure 8 (b) illustrates the situation in which a device having the distance measurement device of the present invention incorporated therein has been moved from the state of Figure 8(a) toward an object and the operator has pressed the switch 3. If the setting of the set means 4 has not been changed, only the distance from the distance measurement device of the present invention needs to be changed, without changing the width (50 cm) of the distance area Z2. That is, if the distance of a specific point PA4 becomes 1.85 m, then the distance of a division point Pb4 on the near side will become 1.6 m and a division point Pa4 on the far side will become 2.1 m.

At the time of this both-side setting and in the case of an example of the belt conveyor shown in Figure 12, if the width of the central belt conveyor BC2 is 50 cm, the set means 4 will be set to 25 cm. With this, even if the distance measurement device of the present invention were moved from the position L1 to the position L2, a distance area would be automatically set only by placing an object in the center of the belt conveyor BC2 and pressing the switch 3 and therefore only a single operation would be needed.

In the case of the both-side setting, if the distance step of the set means 4 is set so that it automatically becomes 1/2 the case of one-side setting, in the same step of the set means 4 the width of the distance area Z2 will be set to the same value at the time of both one-side setting and both-side setting.

In the way described above, the division points can simply be set. But, there are some cases where a distance measurement device is fixed or difficult to move or where there is no appropriate object available for setting division points. In such cases, division points may be set by interrupting the distance measurement range with the operator's hand, but in the case of one operator, the set distance will be limited to the range that the operator's hand can reach. Also, a method where a remote control unit is provided to obtain the same function as the above-described switch 3 is conceivable, but in this case, the circuit scale and the cost will be increased. The timer means 8 is used in such a case. If in Figure 1 the mode switch MS is turned on, the timer means 8 will be in its operating mode, in a manner to that described above.

If the set switch 3 of the specific point is pressed, then the timer means 8 will start time counting and the display means 6 will inform the operator that the timer is being operated. The timeup of the timer means is set to 10 seconds. The display means 6 lights for the first 7 seconds of the period of time that the timer means 8 operates, and is turned on and off for the remaining 3 seconds. With this, the operator is informed that the time-up of the timer means 8 is quite near. The distance measurement means 1 is in its standby state until the time of the timer means 8 has elapsed and does not perform the distance measurement operation. The operator moves to a desired position during 10 seconds that this timer means 8 is operating, and stops at the position. If the time of the timer means 8 is up after an elapse of a predetermined time, the start signal will be generated and the distance measurement means 1 will start the distance measurement operation and measure a distance to the operator. The distance data is stored in the storage means 2. If this timer means 8 is used, division points can set without difficulty even when there is one operator.

Now, the fourth embodiment of the present invention will be described. Since in the third embodiment the distance value that can be added to or subtracted from the distance value of a specific point has been set to a predetermined value by the set means 4, the set number of the set means 4 has to be increased in order to set a fine distance value. The fourth embodiment overcomes this problem. Consider a situation in which three distance areas are set with two distance divisions points, as in the third embodiment. Figure 9 is a circuit block diagram showing the fourth embodiment. The parts having the same reference numerals as Figure 6 represent the same parts as Figure 6.In Figure 9, a switch 3a is a switch for causing distance measurement means 1 to measure a distance to a specific point and store this in storage means 2, and a switch 3b is a switch for causing the distance measurement means 1 to measure a distance to another specific point. The switches 3a and 3b constitute a switch 3 for generating a start signal.

Reference number 9 denotes a second storage means, which stores the distance value ADn of the difference between the distance value of the other specific point obtained by pressing the switch 3b and the distance value of the specific point stored in the storage means 2 (this distance value will hereinafter the referred to as simply a distance difference ADn). Reference numeral 10 denotes an address set means for setting an address of the storage means when a plurality of distance differences ADn are stored. In this embodiment, with digital switches having four signal lines 10a to 10d, 16 addresses, i.e., 16 distance differences ADn (n = integer between 1 and 16) can be stored.

Next, the operation of the fourth embodiment will be described while referring to Figure 10 which is a diagram showing the relationship between a division point and a distance area. Assume that the mode switch MS is off and the input signals are IP2 - "H" and IP1 L (one-side setting).

First, as with the third embodiment described above, the operator using a device having the distance measurement device of the present invention incorporated therein places an object in a position away from the distance measurement device of the present invention by a desired distance and presses the switch 3a. The distance measurement means 1 performs a distance measurement operation to measure a distance to an object, and stores distance data PDA5 (for example, 2.23 m) in the storage means 2. At this time, the display means 6 displays that the distance data has been stored in the storage means, over a predetermined period of time. As shown in Figure 5(a), the distance represented by this distance data is a specific point and becomes one division point PA5.

Next, the operator places an object in a position spaced from the distance measurement device of the present invention by another desired distance and presses the switch 3b. The distance measurement means 1 performs a distance measurement operation to measure a distance to the object. The distance data of the "other specific point" obtained by pressing the switch 3b is set to DPBn (n is an arbitrary integer and, for example, is 5). The judgment means 5 calculates the difference (absolute value) between the distance data DPA5 of the specific point and the distance data DPB5 of the other specific point, and stores the calculated distance value in second storage means 9. At this time, the storage place of the second storage means is an address that is set by the address set means 10.

Now, if the address set means 10 is the first address, it will be stored in the first address as a distance difference bD1. If the distance data DPB5 is 1.78 m, the distance difference AD1 will become 0.45 m (2.23 m - 1.78 m).

Now, since input signals are IP2 = "H" and IP1 = "L," the judgment means 5 sets the other division point Pa5 to a distance point (2.68 m) obtained by adding the distance difference AD1 (0.45 m) to the distance value DPA5 (2.23 m) of the specific point PA5, as shown in Figure 10(a). Therefore, for the distance areas that are divided at the division points PA5 and Pa5, Z1 becomes 0.5 to 2.23 m, Z2 becomes 2.23 to 2.68 m, and Z3 becomes 2.68 to 3.7 m.

This is applied to an example of the belt conveyor of Figure 12. Assuming that the distance to the right end of the belt conveyor BC1 is DPA5, then the distance to the right end of the belt conveyor BC2 is PDaS and the distance difference AD1 is to be the width, w, of the belt conveyor BC2. And, if the width w has been stored once, a distance area will be able to be automatically set only by pressing the switch 3a to measure the distance to the right end of the belt conveyor BC1, even if the distance between the distance measurement device of the present invention and the belt conveyor is changed. Since the distance difference AD1 is a difference between two actually measured distances, an accurate distance can be set.

Also, by changing the address set means 10 to the nth address (n - integer between 2 and 16), and by changing the distance between the distance measurement device of the present invention and an object and pressing the switch 3b, the distance value ADn of the difference between the distance data of the specific point and the distance data of the other specific point can be set in the same way described above. Thus the distance measurement device can store the valuable width of the belt conveyor.

Next, if input signals are IP2 = "L" and IP1 = "H," the judgment means 5 sets the other division point Pb5 to a distance point (1.78 m) obtained by subtracting the distance difference ADl (0.45 m) from the distance value DPA5 (2.23 m) of the specific point PA5, as shown in Figure 10(b).

Figure 10(c) illustrates the situation in which a device having the distance measurement device of the present invention incorporated therein has been moved from the state of Figure 10(b) toward an object and the operator has pressed the switch 3a. If the setting of the set means 10 has not been changed, i.e., the distance difference AD1 has not been changed, only the distance of the specific distance point will be changed without changing the width (0.45 m) of the distance area Z2. That is, if the distance of the specific point PA5 (division point on the far side) becomes 2.03 m (point of PA6), then the distance of the division point Pb6 on the near side will become 1.58 m (2.03 m 0.45 m).Note that if in Figure 10(c) the address set means 10 is changed to the second address and the distance difference AD2 stored in the second address is 0.62 m, then the other division point Pb6 will become 1.41 m (2.03 m - 0.62 m).

Also, if input signals are IP2 = "H" and IP1 -"H," the address set means has been set to the second address, and a predetermined rate has been set to 0.5, then the judgment means 5 sets one division point to a distance point Pa7 (2.54 m) obtained by adding 50% (0.31 m) of the distance difference AD2 (0.62 m) to the distance value DPA7 (2.23 m) of the specific point PA7, as shown in Figure ll(a). Also, the judgment means 5 sets the other division point Pb7 to a distance point (1.92 m) obtained by subtracting 50% (0.31 m) of the distance difference 82 (0.62 m) from the distance value DPa7 (2.23 m) of the specific point PA7.

Figure ll(b) illustrates the situation where a device having the distance measurement device of the present invention incorporated therein has been moved from the state of Figure 10 (a) toward an object and the operator has pressed the switch 3a. If the setting of the address set means 10 has not been changed, i.e., the distance difference AD2 has not been changed, only the distance of the specific point will be able to be changed without changing the width (0.62 m) of the distance area Z2. That is, if the distance of the specific point PA8 becomes 1.7 m, then the distance of the division point Pa8 on the far side will become 2.01 m (1.7 m + 0.31 m), and the distance of the division point Pb8 on the near side will become 1.39 m (1.7 m - 0.31 m).

While in the above case the same distance value has been set on the far side and near side of the specific point, input terminals for switching may be provided in distance measurement means and judgment means to change a rate. For example, with combinations of the voltages of the input terminals, 30 percent (18 cm) of a distance value (for example, 60 cm) may be set on the near side of a specific point and 70 percent (42 cm) may be set on the far side.

The operation in the situation where the operator has pressed the start switch SS or the operation of the case where the mode switch MS is on is identical with that of the third embodiment.

While it has been described in the preceding embodiments, for simplicity, that the measurable range is divided at two distance division points into three distance ranges, the invention is not limited to this.

(k + 1) distance ranges (where k is an integer more than 3) can also be set with k division points. For example, four distance ranges can be set with three set means.

Also, while it has been described in the preceding embodiments that the set operation of the division points will be started if the switch 3a or 3b of the set means 3 is pressed, additional lock means may be provided since the set operation of the division points is not one which is often performed. Various modifications, such as a modification where a lock switch is provided, the set operation of division points is performed only when the lock switch is off, and previously set division points could not disappear even if the switch 3a or 3b were pressed by mistake or a modification where the switch 3a or 3b does not function unless it is pressed for a predetermined period of time, are possible.

Further, only one switch may be provided in the set means 3 and divison points to be set may be changed in sequence each time the switch is pressed.

Further, in the preceding embodiments, in order to inform the operator that distance data has been stored in storage means after the distance measurement, the display means may be lit with a pattern different from a pattern as the distance measurement is being made, or other display means may be lit for a predetermined period of time.

According to an embodiment of the present invention, a division point can be set if an object is placed at an actual division point desired and only a switch is pressed. Accordingly, when an operator sets the division point at an actual field, it becomes unnecesary to depend on his memory or perception, or to calculate, and the setting of the division point becomes easier.

Also, since a timer means may be provided in accordance with the invention, the setting of the long distance side division point is possible even with only one operator.

Further, in an embodiment of the invention set means such as digital switch means becomes unnecessary, so the device can cheaply be constructed. Moreover, since the division point can be set to any distance within the distance measurable range, it can be set with a higher degree of accuracy.

In addition, in accordance with another embodiment of the present invention, in the situation in which a distance area having a fixed width exists among a plurality of distance areas that are desired to be detected and the distance to that distance area is often changed, since the distance setting of division points can be performed only by placing an object at an easily measurable point and pressing a switch, the division points can be set with fewer settings.

Moreover, since a plurality of distance differences each representing a difference between two actually measured points can be stored, distance areas can be set accurately, and also handling various cases becomes possible.

Claims (18)

1. A distance measuring device comprising: switch means for generating a start signal; distance measurement means for measuring a distance to an object responsive to said start signal; storage means for storing distance data of at least one division point, the division point or points dividing a measurement range of the distance measurement means into a plurality of distance ranges; and judgement means for judging within which distance range the measured distance falls during a distance measuring operation, wherein the distance data of at least one division point are derived from a distance measured to an object during an initial range-setting phase.

2. A distance measuring device as claimed in claim 1 also comprising: timer means for starting time counting responsive to said start signal and for outputting a time-up signal after a predetermined period of time wherein the distance measurement means measures a distance to an object responsive to said time-up signal of said timer means.

3. A distance measuring device as claimed in any preceding claim, also comprising a display means for displaying an indication that the distance information of the division points have been stored.

4. A distance measuring device as claimed in any preceding claim, wherein the distance data measured by the distance measurement means is the or at least one of the division point distance data.

5. A distance measuring device as claimed in one of claims 1-4, wherein the switch means comprises a switch corresponding to each of the division points.

6. A distance measuring device as claimed in one of claims 1-4 also comprising: set means for setting at least one division point at a position having a predetermined relationship to the distance measured to the object.

7. A distance measuring device as claimed in claim 6, wherein the set means sets at least two division points, one on either side of the distance measured to the object.

8. A distance measuring device as claimed in claim 7, wherein the set means sets division points at preset equal distances on either side of the distance measured to the object.

9. A distance measuring device as claimed in claim 6, wherein the or at least one division point is set at a distance represented by a predetermined percentage of the distance measured to the object.

10. A distance measuring device as claimed in one of claims 6-9, wherein the set means is a digital switch.

11. A distance measuring device as claimed in one of claims 6-10, wherein the switch means comprises at least a first and second switch to cause the storage means to store the distance data of a first and second specific point respectively, wherein the difference between said first and second specific point is used by the set means to set at least one division point.

12. A distance measuring device as claimed in claim 6, wherein distance data are obtained by adding or subtracting a predetermined distance value set by said set means to or from the distance measured to the object.

13. A distance measuring device as claimed in claim 6, further comprising second storage means for storing a distance difference between two distance data measured in response to said start signal by said distance measurement means wherein the plurality of distance data stored in said storage means and distance data obtained by adding or subtracting the distance difference stored in said second storage means to or from said stored data are division points.

14. A distance measuring device as claimed in claim 6, further comprising second storage means for storing a plurality of distance differences between a plurality of distance data measured in response to said start signal by said distance measurement means wherein the plurality of distance data stored in said storage means, and distance data obtained by adding or subtracting one of the plurality of distance differences stored in said second storage means to or from said stored data are division points.

15. The distance measurement device claimed in any preceding claim, wherein there is provided a predetermined delay time between the time that said switch is switched on and the time that said start signal is generated.

16. A distance measurement device comprising: one or more switches for generating a start signal; distance measurement means for measuring a distance to an object in accordance with said start signal; storage means for storing a plurality of distance data measured by said distance measurement means; and judgement means for judging which distance area the result of the distance measurement of said distance measurement means belongs to, among a plurality of distance areas where the plurality of distance data stored in said storage means are division points.

17. A distance measurement device comprising: at least one switch generating a start signal for determining a specific point; distance measurement means for measuring a distance to an object in accordance with said start signal; storage means for storing a plurality of distance data measured by said distance measurement means; set means setting a predetermined distance value on the near side or far side of the distance data stored in said storage means; and judgement means for judging which area the result of the distance measurement of said distance measurement means belongs to, among a plurality of distance areas where the plurality of distance data stored in said storage means, and distance data obtained by adding or subtracting the predetermined distance value set by said set means to or from the stored data stored in said storage means are division points.

18. A distance measuring device substantially as herein described with reference to Figures 1-3 and 6-11 of the accompanying drawings.