JP5670829B2 - Light wave distance meter - Google Patents

Description

  The present invention relates to a phase difference type lightwave distance meter that photoelectrically measures a linear distance to a target reflector.

  In this type of lightwave distance meter, an intensity-modulated signal is transmitted as light from the light emitting element, one of the light is reflected by the target reflector, and the other light is emitted to the reference optical path. As the reference light obtained in this way, each light is received by a light receiving element and converted into an electrical signal, then passed through an amplifier, frequency converter, etc., then measured by an A / D converter, and converted from an analog signal to digital data Is done. Among the received light signals, signals in a measurable range that do not exceed the maximum input value of the A / D converter are analyzed by the arithmetic processing unit for signal amplitude and phase information, and the phase difference between the distance measurement signal and the reference signal is determined. By calculating, a linear distance (distance value) to the target reflector is obtained.

  In such a lightwave distance meter, the received light amount of the reflected distance measuring light varies depending on the distance from the lightwave distance meter to the target reflector and whether the target reflector is a highly reflective object such as a prism. This affects the calculation of distance measurement values. In other words, when the received light amount of the distance measuring light is large and the distance measurement signal is equal to or greater than the maximum input value of the A / D converter (when the distance measurement signal is in the saturation region of the A / D converter), The signal is not in the measurable range and the distance value is not calculated. On the other hand, when the received light amount of the distance measuring light is small, the amplitude of the received light signal is not properly decomposed by the A / D converter, an error occurs during signal conversion, and an error occurs in the distance measurement value. For this reason, it is necessary to adjust the amount of received light to the optimum amount of received light so that the distance measurement signal can be measured by the A / D converter.

  Therefore, as shown in Patent Document 1, for example, a variable light reception density filter driven by a motor is provided between the target reflector and the light receiving element, and the amount of received light is adjusted by gradually narrowing the filter to adjust to the optimum light receiving amount. There is. Alternatively, as shown in Patent Document 2, a digital potentiometer that digitally controls a variable resistor is connected to a light emitting element that emits light instead of a variable light reception density filter, and the resistance value loaded on the light emitting element is gradually reduced. Alternatively, there is an apparatus that adjusts the light emission amount of the light emitting element to increase the light reception light amount to the optimum light reception amount.

Japanese Patent Publication No.51-8340 (FIG. 2) Japanese Patent Laying-Open No. 2011-013108 (paragraph numbers 0030 to 0034, FIG. 1)

  However, in the light amount adjustment work in which the variable light-receiving density filter is gradually adjusted by the motor as in Patent Document 1, first, mechanical troubles occur due to the years of use of the motor, and second, the target is caused by atmospheric fluctuations. If the amount of reflected light from the reflector fluctuates greatly, the distance measurement signal that becomes the saturation area of the A / D converter increases, and the light quantity adjustment is repeated until they fall within the measurable area. There was a problem that it did not end within the distance measurement specification time.

  Further, in Patent Document 2, although the light amount adjustment work is electrical control using a digital potentiometer, the control time is faster than mechanical control, but the received light signal is within the measurable range of the A / D converter. It is the same as the variable light reception density filter in that the light amount adjustment operation is repeatedly performed (by gradually changing the resistance value), and it still takes time to adjust the light amount.

  The present invention has been made in view of such problems, and its purpose is to adjust the received light amount to the optimum received light amount without using mechanical drive for light emission amount adjustment and without repeating the light amount adjustment operation. An object of the present invention is to provide an optical rangefinder capable of high-speed and high-precision distance measurement.

In a lightwave distance meter according to an aspect of the present invention, a light transmission unit that transmits light modulated at a plurality of modulation frequencies, and a measurement that reciprocates light from the light transmission unit to a target reflector disposed at a measurement point. Light extraction means for transmitting to a selected one of the distance optical path or the reference optical path, and the distance measuring light that has passed through the distance measuring optical path or the reference light that has passed through the reference optical path, and outputs respective received light signals A light receiving means; a signal converting means for measuring the light receiving signal and converting the analog signal into digital data; a resistor loaded on the light sending means for adjusting the light emission amount; and a signal for the light receiving signal. An arithmetic processing unit that is set according to the amplitude and calculates a distance measurement value that is a linear distance to the target reflector based on a phase difference between the distance measurement signal digitized by the signal conversion means and a reference signal. Light wave distance meter The resistor includes a plurality of resistors, each having a predetermined fixed resistance value from a large resistance value to a small resistance value, one of which is selected by a selection signal corresponding to the resistor in a one-to-one relationship, Provided as a resistor group in which the light emission amount of the means is switched from small to large, and whether the signal amplitude of the received light signal input to the signal conversion means is greater than or equal to the maximum input value of the signal conversion means in the arithmetic processing unit The light receiving level determining means for determining whether or not the light receiving level determining means switches the light emission amount of the light sending means to a small value until it is less than the maximum input value when it is determined to be equal to or greater than the maximum input value. select signal, when it is determined that less than the maximum input value, the light quantity selection for selecting the selection signal for switching the light emission amount of the light transmitting means to atmospheric until the maximum light emission amount does not exceed the maximum input value And the stage, the provided.

  (Operation) A plurality of resistors having a predetermined fixed resistance value are provided from a large resistance value to a small resistance value, and one of them is selected while checking the received light signal amplitude in the arithmetic processing unit, and the light output of the light sending means is adjusted. Thus, the optimum light emission amount is determined from the intermittent light emission amounts of a plurality of patterns. That is, in the arithmetic processing unit, the maximum input value is determined while checking whether the signal amplitude of the received light signal input to the signal conversion unit is a saturation region greater than the maximum input value of the signal conversion unit or a measurable region less than the maximum input value. If it is determined as above, the signal selection is repeated so as to decrease the light emission amount from the current stage to the light emission amount in descending order or several steps smaller until it becomes less than the maximum input value. By repeating the signal selection so that the current light emission amount is increased in ascending order or several steps higher until the maximum light emission amount does not exceed the maximum input value, the light reception signal amplitude (light reception level) is optimal (the maximum input value is The maximum light emission amount that does not exceed (the maximum light emission amount) is determined.

In the lightwave distance meter of the above aspect, when the light quantity selection unit selects the selection signal for switching the light emission amount of the light transmission unit to be larger than the current stage, the number of the selection signals is n, and the selection signal corresponds to the selection signal. When the light emission amount of the light sending means is small to large, the light emission amount is 1, the light emission amount 2... The light emission amount n, and the current light emission amount is the light emission amount k (k <n). If the signal amplitude of the received light signal in the state of the light emission amount k is greater than or equal to r ^ 2 times the maximum input value, the selection signal that becomes the light emission amount k + 1 is selected and the maximum input value is selected. If r ^ 3 times or more and less than r ^ 2 times, a selection signal that gives a light emission amount k + 2 is selected, ... r ^ (n−k) times or more of the maximum input value r ^ ( If it is less than (n− (k + 1)) times, a selection signal for light emission amount (n−1) is selected, If it is less than r ^ (n−k) times the input value, a selection signal for the light emission amount n is selected (where r is a light emission amount attenuation constant (0 <r <1)), and the next light emission amount determination means is selected. Provided.

  (Operation) Since the light reception level measurable by the signal conversion means is in a range less than the maximum input value, if the light reception level in the state of the current light emission amount k is in the saturation region, how much the signal amplitude is the maximum input value. It cannot be judged by the signal conversion means whether it is larger. However, when it is not saturated with the current light emission amount k (in the range that can be measured), it is possible to measure the signal amplitude, and thus measure how small the light reception level of the current light emission amount k is relative to the maximum input value. Therefore, by calculating how many times the signal amplitude is the maximum input value, it is possible to determine how many steps the next light emission amount should be increased from the current light emission amount k.

Alternatively, in the light wave distance meter according to the above aspect, in the light quantity selection unit, the number of selection signals is n, the light emission amount of the light transmission unit corresponding to the selection signal is small to large, the light emission amount is 1, and the light emission amount is 2. When the light emission amount is n, the initial light emission amount is 2 ^ m (where m is an integer and 2 ^ (m + 1)> n ≧ 2 ^ m), which does not exceed the selection signal number n. Starting from m, if the current light emission level is determined to be greater than or equal to the maximum input value by the light receiving level determination means, the light emission quantity of the light transmission means is subtracted by the light emission quantity obtained by subtracting the order of the current light emission quantity by one. If it is determined that the value is less than the maximum input value, the order of the current light emission amount is subtracted by 1 and added by the amount of light emission. The order m is 0). Repeat until from among the light emission amount of searching in the order acceleration operation, it provided the optimum light emission amount search means for selecting the selection signal having the maximum light emission amount not exceeding the maximum input value.

  (Operation) For example, when the number of selection signals is n = 100 and the optimum light emission amount is the light emission amount 47, the initial light emission amount is 2 ^ m corresponding to the maximum power of 2 ^ m not exceeding n. Start with m, ie 100> 2 ^ 6 = 64 (m = 6). When the light reception level is determined, since the initial light emission amount 64> 47, the order is reduced by 1 (m = 5), the light emission amount is reduced by half to 32 (64-32), and m ≠ 0, so the light reception level is determined. Then, since 32 <47, the light emission amount obtained by further reducing the order by 1 (m = 4) is added to 48 (64−32 + 16), and since 48> 47, the order is further decreased by 1 (m = 3) The light emission amount is subtracted to 40 (64−32 + 16−8), and 40 <47. Therefore, the light emission amount obtained by lowering the order by 1 (m = 2) is added to obtain 44 (64−32 + 16). −8 + 4) and 44 <47, the order is further reduced by 1 (m = 1), and the light emission amount is added to obtain 46 (64−32 + 16−8 + 4 + 2). Since 46 <47, the order is further reduced. 47 (64) by adding the light emission amount lowered by 1 (m = 0) 32 + 16-8 + 4 + 2 + 1) and, when determining the received light level because the degree drops to m = 0, do not exceed the maximum input value in the light-emitting amount 47. The light emission quantity is 64 → 32 (64−32) → 48 (64−32 + 16) → 40 (64−32 + 16−8) → 44 (64−32 + 16−8 + 4) → 46 (64−32 + 16−8 + 4 + 2) → 47 (64 Among the light emission amounts operated as −32 + 16−8 + 4 + 2 + 1), the light emission amounts that do not exceed the maximum input value are the light emission amounts 32, 40, 44, 46, and 47. Of these, the maximum light emission amount can be selected as 47. The number of signal selections for finding the optimum light emission amount 47 is seven.

  When the optimum light emission amount is 96, since the initial light emission amount 64 <96, the light emission amount 32 obtained by reducing the order by 1 (m = 5) is added 96 (64 + 32) to the current light emission amount. Since the light emission amount 96 does not exceed the light emission amount 100 and m ≠ 0, if the light reception level is determined, 96 = 96 and the maximum input value is not exceeded, so the order is further reduced by 1 (m = 4). Is 112 (64 + 32 + 16), the amount of light emission exceeds 100. Therefore, the light amount is returned to 96 before addition, and the amount of light emission obtained by lowering the order by 1 (m = 3) is added to 104 (64 + 32 + 8). Then, since the light emission amount exceeds 100, the light emission amount is returned to the pre-addition light emission amount 96, and when the light emission amount obtained by lowering the order by 1 (m = 2) is added to 100 (64 + 32 + 4), 100> 96. Further, the light emission amount with the order lowered by 1 (m = 1) is subtracted to 98 (64 + 32 + 4-2), and 98> 96. Therefore, the light emission amount with the order lowered by 1 (m = 0) is subtracted. 97 (64 + 32 + 4-2- ) And the order has decreased to m = 0, and when the light reception level is determined, the light emission amount 97 exceeds the maximum input value. Therefore, the light emission amount 64 → 96 → 100 → 98 → 97 The maximum amount of light emission that does not exceed the input value can be selected as 96. Note that the number of signal selections for finding the optimum light emission amount 96 is five.

In the lightwave distance meter of the above aspect , when the target reflector is a non-prism distance measurement that is not a highly reflective object, the light amount of the light sending means is switched by the light quantity selecting means, and the target reflector is a highly reflective object. In the case of prism distance measurement, a preset light emission amount is transmitted from the light transmission means, and when the light reception signal is less than the maximum input value of the signal conversion means, distance measurement is performed as it is. When the received light signal is equal to or greater than the maximum input value, density filter insertion / extraction means is provided so that a density filter is inserted between the distance measuring optical paths to perform distance measurement.

  (Operation) When the non-prism distance measurement is selected, the amount of light reflected from the target reflector differs depending on the target reflector, and it is difficult to determine the optimum light emission amount. Is useful. On the other hand, when prism distance measurement is selected, it is empirically known that the amount of reflected light from the target reflector is greater than that of non-prism distance measurement, so that it will not exceed the maximum input value of the signal conversion means. A light emission amount, for example, a minimum light emission amount among the light emission amounts prepared in a plurality of stages is set in advance. Even if the minimum light emission amount is above the maximum input value of the signal conversion means, a highly reflective object (reflecting prism, mirror, etc.) is installed at a short distance (about 0 m to 10 m), and all the transmitted light enters the light receiving side. In this case, as the distance from the highly reflective object increases, the transmitted light is diffused and is not incident on the light receiving side. Therefore, if a fixed density filter is inserted to attenuate the received light amount of the distance measuring light by a certain amount so as not to saturate even a highly reflective object at a short distance, the received light signal is reliably signaled regardless of the distance to the highly reflective object. Enter the measurable range of the conversion means.

In the lightwave distance meter of the above aspect , even if the selection signal that minimizes the amount of light emission is selected in the non-prism distance measurement, the signal amplitude of the light reception signal is the maximum input of the signal conversion unit. A distance measuring means automatic changing means for automatically shifting to the prism distance measurement is provided when the value exceeds the value.

  (Operation) In the non-prism distance measurement, even if the minimum light emission amount is used, if the received light signal enters the saturation region of the signal conversion means, the arithmetic processing unit determines that the target reflector is collimating the highly reflective object. And automatically shifts to prism distance measurement.

According to the lightwave distance meter of the present invention , unlike the conventional digital potentiometer, the resistance value is gradually changed (continuously), and the light amount is not adjusted so as to find the optimum light emission amount. Therefore, the number of signal selections can be as many as the number of resistors prepared at the maximum, and the light quantity adjustment work is greatly accelerated.

  Also, for example, when it is determined that the light emission amount selected for the first time is greater than or equal to the maximum input value, the light emission amount for the second time is selected to be several steps smaller, and thereafter the light emission amount is increased in ascending order, or the initial light emission amount If it is determined that the light emission amount is less than the maximum input value, select the light emission amount that is several steps larger than the second light emission amount and then decrease the light emission amount in descending order. Therefore, the number of signal selections is reduced, and the light quantity adjustment work becomes faster.

  In addition, since the light amount adjustment is performed regardless of the mechanical operation, no mechanical malfunction occurs with the passage of years of use.

  In addition, since the optimum light emission amount is determined so that the received light signal surely falls within the measurable range, almost all received light signals can be used for distance measurement calculation, so a highly accurate distance measurement value can be obtained. Can do.

According to the next light emission amount determination means , when selecting a selection signal for switching the light emission amount of the light transmission means to be larger than the current stage, a determination criterion can be provided, and the optimum next light emission amount is predicted and the light emission amount at once. So that the optimum amount of light emission can be found immediately by two signal selections.

According to the optimum light emission amount search means, when there are n selection signals and the initial light emission amount starts from the largest power of 2 ^ m not exceeding n (where m is an integer and 2 ^ (m + 1)> n ≧ 2 ^ m), and the number of times that the optimum light emission amount can be found ends within m + 1 times. Since the optimum light emission amount is searched in the binary system, it can be found efficiently with a small number of signal selections.

Further , in the case of non-prism distance measurement, the light amount adjustment work is shortened by the light amount selection means. In the case of prism distance measurement, since there are two choices of using a fixed density filter or not, there is no longer a light amount adjustment work. As a result, in either case, the light amount adjustment is completed much faster than the conventional adjustment using the variable density filter or the adjustment using the digital potentiometer.

Even if the user makes a mistake between non-prism distance measurement and prism distance measurement, appropriate distance measurement is automatically performed.

Block diagram of a lightwave distance meter according to a first embodiment of the present invention. The flowchart figure which shows the procedure of ranging when prism ranging mode is selected in the same optical distance meter The flowchart figure which shows the procedure of ranging when the non-prism ranging mode is selected in the same optical distance meter The flowchart figure which shows the procedure of ranging when the non-prism ranging mode is selected in the light wave rangefinder according to the second embodiment of the present invention. The flowchart figure which shows the procedure of ranging when the non-prism ranging mode is selected in the light wave rangefinder which concerns on 3rd Example of this invention. The flowchart figure which shows the procedure of ranging when the non-prism ranging mode is selected in the light wave rangefinder according to the fourth embodiment of the present invention. Block diagram of a lightwave distance meter according to a fifth embodiment of the present invention. The flowchart figure which shows the procedure of ranging when the non-prism ranging mode is selected in the same optical distance meter The flowchart figure which shows the procedure of ranging when the non-prism ranging mode is selected in the same optical distance meter Conceptual diagram for explaining light amount adjustment work when the optimum light emission amount is 47 Conceptual diagram for explaining light amount adjustment work when the optimum light emission amount is 1 Conceptual diagram for explaining light amount adjustment work when the optimum light emission amount is 96 Conceptual diagram for explaining light amount adjustment work when the optimum light emission amount is 64

  The configuration of the first embodiment of the lightwave distance meter according to the present invention will be described below with reference to FIG. FIG. 1 is a block diagram of a lightwave distance meter according to a first embodiment of the present invention. The light wave distance meter of the embodiment is a phase difference type light wave distance meter that calculates the distance to the target reflector 33 from the phase difference between the distance measuring light and the reference light, and is a light transmission means (light emitting element 29) described below. ), Light extracting means (switching shutter 37), light receiving means (light receiving element 40), signal converting means (A / D converters 44, 47, 50), and arithmetic processing unit 60. Including. Further, the variable density filter provided in the distance measuring optical path 31 in order to adjust the amount of light received by the conventional light receiving element 40 is omitted. Instead, a resistor group 70 described later is provided in the light emitting element 29.

  The signal F1 output from the oscillator 1 is divided into a plurality of signals by the frequency divider 2 to generate signals F2 and F3 having different frequencies. The signals F1, F2, and F3 are superimposed by the frequency superimposing circuit 3. The drive circuit 4 that receives the voltage supply drives the light emitting element 29 with an AC signal based on the superimposed signals F1, F2, and F3. The frequencies F1, F2, and F3 have a lower frequency in order from F1, and each digit of the distance measurement value is determined according to each resolution. The signal F1 is also input to a PLL (Phase Locked Loop) 5 and a frequency generation circuit 7, and F1 + Δf1 signals and F2 + Δ are input from the local signal oscillator 6 and the frequency generation circuit 7 to the frequency converters 42, 45, and 48. The f2 signal and F3 + Δf3 signal are output.

  The light emitting element 29 is driven by AC signals F1, F2, and F3, and includes four load resistors (resistors) 8, 9, 10, and 11 each having a predetermined fixed resistance value connected in parallel. The DC power supply 16 is also driven through the resistor group 70. The resistor group 70 includes load resistors 8, 9, 10, 11, these resistors and a pair of analog switches 12, 13, 14, 15. The load resistors 8, 9, 10, and 11 have different resistance values, and the resistance values increase in the order of the load resistors 8, 9, 10, and 11. That is, the light amount of the light emitting element 29 decreases in the order of the load resistances 8, 9, 10, and 11. This is because the load resistance is generally called a current limiting resistor, and the larger the value, the smaller (limited) the current flowing through the light emitting element, and the smaller the amount of light.

  The load resistor 8 and the analog switch 12 can be operated by the selection signal (4), the load resistor 9 and the analog switch 13 can be operated by the selection signal (3), and the load resistor 10 and the analog switch 14 can be operated by the selection signal (2). ) And the load resistor 11 and the analog switch 15 can be operated by the selection signal (1). That is, when the operation becomes possible by the selection signal, any one of the load resistors 8, 9, 10, and 11 is loaded on the light emitting element 29.

  Which one of the selection signals (1), (2), (3), and (4) is selected is determined by the light quantity selection means of the arithmetic processing unit 60 described later. Thereafter, when the number of selection signals corresponding to the number of resistors to be prepared is n, the light emission of the light emitting element 29 switched by the selection signal (1), the selection signal (2),... The amount level is hereinafter expressed as light emission amount 1, light emission amount 2, light emission amount 3,...

  The light transmitted from the light emitting element 29 is divided into two by the beam splitter 30 and selectively emitted by the switching shutter 37, and one light is reflected by the target reflector 33 through the distance measuring optical path 31. The light is collected by the light receiving optical 34 and input to the light receiving element 40. The other light passes through the reference light path 35, passes through the light quantity adjusting fixed density filter 36, and is input to the light receiving element 40. The distance measuring optical path 31 is provided with a fixed density filter inserting / extracting means 80. When a prism distance measuring mode to be described later is selected, a density filter 32 that attenuates the received light amount of the distance measuring light by a certain amount. It can be inserted.

  The light received by the light receiving element 40 is converted and converted into a signal having three frequencies F1, F2, and F3. The signals F1, F2, and F3 are amplified in signal amplitude by an amplifier 41 connected to the light receiving element 40, and then frequency-multiplied by frequency converters 42, 45, and 48, respectively. f2, Δf3. The noise generated by the frequency converters 42, 45, and 48 is removed by the low-pass filters 43, 46, and 49, and the analog signals are converted into multi-value digital signals by the A / D converters 44, 47, and 50. The arithmetic processing unit 60 can acquire signal amplitude information and phase information. The amplitude information here is used for the light reception level determination means of the arithmetic processing unit 60 described later.

  The A / D converters 44, 47, and 50 are connected to the arithmetic processing unit 60. The arithmetic processing unit 60 analyzes the signal amplitude and phase information of the signals Δf1, Δf2, and Δf3, and the distance measuring light. And distance measurement data of the reference light are calculated. Since the temperature phase drift of the transmission light drive circuit and the light receiving unit and the delay due to the electric circuit are errors that are included in both the distance measurement light and the reference light, the phase difference between the distance measurement light and the reference light is taken. A linear distance (range value) to the target reflector 33 is calculated.

  The arithmetic processing unit 60 is provided with light reception level determination means and light quantity selection means. Depending on the determination of the light reception level determination means, the light quantity selection means selects the selection signals (1), (2), (3). , (4) is selected and transmitted to the corresponding load resistors 8, 9, 10, 11 and the pair of analog switches 12, 13, 14, 15.

  In the light reception level determination means, it is determined whether the signal amplitude of the light reception signal input to the A / D converters 44, 47, 50 is a saturation region greater than a preset maximum input value or a measurable region less than the maximum input value. judge. Since the light reception level measurable by the A / D converters 44, 47, 50 is up to the range of the maximum input value, when the light reception signal amplitude is in the saturation region, the signal amplitude is not measured. And if it is a measurable range, it will be analyzed by the arithmetic processing part 60 and used for ranging value calculation.

  The arithmetic processing unit 60 selects one resistor from the resistor group 70 while looking at the light reception level by the light quantity selection means. That is, when the light reception level determination means determines that the light reception signal amplitude of the distance measuring light is greater than or equal to the maximum input value, the light emission amount of the light emitting element 29 is larger than the light emission amount by the currently used resistor (current A selection signal for switching to a smaller amount of light emission (less than the stage) is repeatedly transmitted until it becomes less than the maximum input value. On the other hand, when it is determined that the light reception signal amplitude of the distance measuring light is less than the maximum input value, the light emission amount of the light emitting element 29 is larger than the light emission amount by the resistor currently used (than the current stage). The selection signal to be switched is repeatedly transmitted until the maximum light emission amount (maximum light reception level) does not exceed the maximum input value. As a result, one of the load resistors 8, 9, 10, 11 is selected, the light emission amount of the light emitting element 29, and the light receiving signal of the distance measuring light becomes the maximum input value of the A / D converters 44, 47, 50. The optimum light emission amount is determined to be the optimum light reception amount that is the maximum light emission amount not exceeding.

  Further, the light quantity selection means includes the following next light emission quantity determination means. In the next light emission amount determination means, when selecting a selection signal for switching the light emission amount of the light emitting element 29 to be larger than the current stage, the number of selection signals is n, and the light emission amount of the light emitting element 29 corresponding to the selection signal is small to large. Assuming that the light emission amount is 1, the light emission amount 2... The light emission amount n, and the current light emission amount is the light emission amount k (k <n), the light emission amount selected next to the current light emission amount k is the light emission amount k. If the signal amplitude of the received light signal in the state is equal to or greater than r times the maximum input value when the signal amplitude of the received light signal is greater than or equal to r times the maximum input value, the selection signal for the light emission amount k is selected. When r ^ 2 times or more and less than r times, a selection signal is selected that gives a light emission amount k + 1, and when r ^ 3 times or more and less than r ^ 2 times the maximum input value, a selection signal that gives a light emission amount k + 2 is selected. Selection: ... more than r ^ (n-k) times the maximum input value and less than r ^ (n- (k + 1)) times If so, the selection signal for the light emission amount (n-1) is selected, and if it is less than r ^ (nk) times the maximum input value, the selection signal for the light emission amount n is selected (where r is the light emission amount). Attenuation constant (0 <r <1)). In this embodiment, the light emission amount attenuation constant r = 0.5, the light emission amount 3 is 0.5 times the light emission amount 4, the light emission amount 2 is 0.5 times the light emission amount 3, and the light emission amount 1 is the light emission amount 2. It is set to 0.5 times. That is, the light emission amount 2 is 0.25 times the light emission amount 4, and the light emission amount 1 is 0.125 times the light emission amount 4. From this relationship, in the next light emission amount determination means, “if the light reception signal amplitude in the state of light emission amount 2 is 0.5 times or more of the maximum input value of the A / D converter 44, the light emission amount 2 is selected, If the maximum input value of the A / D converter 44 is 0.5 ^ 2 (= 0.25) times or more and less than 0.5 times, the light emission amount 3 is selected, and the maximum input value of the A / D converter 44 is selected. A criterion of “selecting a light emission amount of 4 if it is less than 0.5 ^ 2 (= 0.25) times” is provided.

  Here, the light wave distance meter of the present embodiment performs light amount adjustment by several patterns of load resistors 8, 9, 10, and 11 instead of the conventionally used variable density filter. The resolution of the A / D converters 44, 47, 50 is increased compared to the conventional one. Hereinafter, the signals F2 and F3 have the same principle as that of F1, and the description thereof is omitted.

In a conventional optical distance meter using a variable density filter, for example, if the gain of the amplifier is 80 dB and the resolution of the A / D converter is 12 bits, the variable density filter is adjusted so that the range can be measured when the saturation range is reached. Do. On the other hand, in this embodiment, when the saturation region is reached, the output of the light emitting element 29 is stepwise. Therefore, in the case of non-prism distance measurement where the target reflector 33 is not a highly reflective object such as a prism or mirror, Adjustment becomes difficult. Therefore, by reducing the gain of the amplifier 41 to 56 dB, for example, the possibility of becoming a saturation region can be reduced. Further, by reducing the amplification factor, the received light signal amplitude is reduced, and the risk that the A / D converter 44 does not properly resolve the amplitude and that the signal amplitude is accidentally digitized to a small signal amplitude is avoided. Therefore, the resolution of the A / D converter 44 is increased to 16 bits, and the A / D conversion value is improved to the same level. Note that the gain of the amplifier 41 is, for example, KODAK at a short distance of 5 m.
A highly reflective object such as a gray card white surface was used as a reference. Note that the gain of the amplifier 41 in the case of prism distance measurement using the target reflector 33 as a highly reflective object was the same value as in non-prism distance measurement.

  In the case of the prism distance measurement, the selection signal (1) is set so that the first light emission amount is the minimum light emission amount 1. If the received light signal amplitude falls within the saturation region of the A / D converter 44 even when the minimum light emission amount 1 is selected, the density filter 32 is inserted between the distance measuring optical paths 31 by the density filter insertion / extraction means 80, and the measurement is performed. The received light amount of the distance light is attenuated by a certain amount. The density filter 32 uses a filter having a larger attenuation than the conventional fixed density filter.

  Further, in the case of non-prism distance measurement, the arithmetic processing unit 60 selects the selection signal (1) with the minimum light emission amount of 1 and the received light signal amplitude is in the saturation region of the A / D converter 44. A distance measuring means automatic changing means for automatically shifting to prism distance measurement is provided.

  Next, the prism distance measurement procedure of the optical distance meter according to the embodiment will be described based on the flowchart of the distance measurement procedure when the prism distance measurement mode is selected in the optical distance meter shown in FIG. To do. When the prism distance measurement mode is selected, first, in step 1, a selection signal (1) is output from the arithmetic processing unit 60 so that the light emitting element 29 has the minimum light emission amount 1. Next, in step 2, the A / D converter 44 measures the light reception signal amplitude of the distance measuring light with the light emission amount 1. In step 3, it is determined by the light reception level determination means of the arithmetic processing unit 60 whether or not the light reception signal amplitude exceeds the maximum input value. In the case of a measurable range where the light reception level does not exceed the maximum input value (less than the maximum input value), the process proceeds to step 5 where distance measurement is performed with the light emission amount of 1 and the process ends. On the other hand, if the received light signal amplitude is in a saturation region where the amplitude exceeds the maximum input value (greater than or equal to the maximum input value), the process proceeds to step 4, and after the density filter 32 is inserted by the density filter insertion / extraction means 80, in step 5. The distance measurement is performed and the process ends.

  Next, the non-prism distance measurement procedure of the light wave distance meter according to the embodiment is shown in FIG. 3 based on the flowchart showing the distance measurement procedure when the non-prism distance measurement mode is selected in the same optical distance meter. explain.

  When the non-prism distance measurement mode is selected, first, in step 1, a selection signal (2) is output from the arithmetic processing unit 60 so that the light emitting element 29 has a light emission amount of 2. Next, at step 2, the received light signal amplitude at the light emission amount 2 is measured by the A / D converter 44, and at step 3, the received light signal level determination means of the arithmetic processing unit 60 determines whether the received light signal amplitude exceeds the maximum input value. It is determined whether or not. If the maximum input value is exceeded, the process proceeds to step 9 where the selection signal (1) is output so that the light emission amount 1 is smaller than the current light emission amount 2, and in step 10, the light reception level determination means again at the light emission amount 1. Thus, the light reception level is determined. If the maximum input value is not exceeded, the process proceeds to step 11 where the light emission amount 1 is optimum, the process proceeds to step 13 and the distance measurement is performed and the process ends. If the maximum input value is exceeded in step 10, the process proceeds to step 12, and the user automatically determines that the ranging mode is selected by the ranging means automatic changing means and automatically shifts to the prism mode, and the prism mode is changed. The process ends after a distance measurement flow.

  On the other hand, if the maximum input value is not exceeded in step 3, the process proceeds to step 4 and whether or not the received light signal amplitude at the light emission amount 2 is 0.5 times or more of the maximum input value by the next light emission amount determination means. If the maximum input value is 0.5 times or more, the selection signal (2) is output so that the process proceeds to step 5 so that the light emission amount becomes 2, and the distance measurement is performed with the light emission amount 2 in step 13. End. If it is less than 0.5 times in Step 4, the process proceeds to Step 6 where the light reception signal amplitude at the light emission amount 2 is 0.25 (= 0.5 ^ 2) times or more of the maximum input value by the next light emission amount determination means. It is determined whether or not it is less than 0.5 times. If it is 0.25 times or more and less than 0.5 times the maximum input value, the process proceeds to step 7 where the selection signal (3) is set so that the light emission amount is 3. In step 13, the distance is measured with the light emission amount of 3 and the process ends. If it is determined in step 6 that the received light signal amplitude of the light emission amount 2 is less than 0.25 times the maximum input value, the process proceeds to step 8, the light emission amount 4 is optimized, the process proceeds to step 13, and the light emission amount 4 Measures the distance and ends.

  According to the present embodiment, when the prism distance measurement mode is selected by the user's judgment, the distance measurement is performed in either the preset light emission amount 1 or the state in which the density filter 32 is inserted at the light emission amount 1. Is done. In the prism distance measurement mode, there are two choices of whether or not to insert the density filter 32 using a preset light emission amount 1, so that there is no more light amount adjustment work, and light amount adjustment is immediately terminated. Even if the minimum light emission amount is 1, the A / D converter 44 becomes a saturated region by using a highly reflective object as the target reflector 33 and installing it at a short distance (about 0 m to 10 m). In this case, as the distance from the target reflector 33 increases, the transmitted light is diffused and is not incident on the light receiving side. If the object is not saturated, the received light signal reliably enters the measurable range of the A / D converter 44 regardless of the distance from the target reflector 33.

  When the non-prism distance measurement mode is selected, the light emitting element 29 starts from the light emission amount 2, and the next light emission amount determination means determines the optimum light emission amount by the next signal selection. That is, since a determination criterion is provided when selecting a selection signal for switching the light emission amount of the light sending means to be larger than the current level (steps 4 and 6), the optimum next light emission amount is predicted and the light emission amount is determined. It is possible to jump at a stretch, and the optimum light emission amount can be found by selecting the signal twice. Therefore, when the optimum light emission amount is the light emission amount 4, the optimum light emission amount is predicted and jumps from the initial light emission amount 2 to the light emission amount 4 at a stretch. Therefore, the light emission amount 2 → the light emission amount 3 → the light emission amount 4 The light quantity adjustment work is greatly shortened compared with the case of selecting in ascending order.

  If the light reception level is in the saturation region even when the minimum light emission amount 1 is used, the arithmetic processing unit 60 determines that the highly reflective object is collimated, and automatically shifts to the prism distance measurement mode. Since (Step 12), even if the user makes a mistake in the determination of the distance measurement mode, appropriate distance measurement is automatically performed.

  As a result, regardless of whether the non-prism distance measurement mode or the prism distance measurement mode is selected, the light amount adjustment operation is completed much earlier than the conventional adjustment using the variable density filter or the adjustment using the digital potentiometer.

  Furthermore, since the light quantity adjustment is performed regardless of the mechanical operation of the motor or the like, no mechanical malfunction will occur with the passage of the years of use. Further, since the light receiving signal is surely entered into the measurable range by determining the optimum light emission amount, almost all the light receiving signals can be used for distance measurement calculation, and a highly accurate distance measurement value can be obtained.

  Further, among the prepared light emission stages (1, 2, 3, 4), the light emission amount 2 on the smaller side of the light emission stage is divided into the initial light emission quantity, so that the next light emission quantity judging means (step 4, Step 6) is functioning effectively. That is, if the light reception level in the state of the light emission amount k is in the saturation region, the A / D converter 44 cannot determine how much the signal amplitude is larger than the maximum input value. However, when the light emission amount k is not saturated (in the range where the distance can be measured), the signal amplitude can be measured. Therefore, measure how small the light reception level of the light emission amount k is relative to the maximum input value. Therefore, if the initial light emission amount is reduced, the next light emission amount determination means can predict how many steps the next light emission amount should be increased from the light emission amount k.

  Further, as a modification of the first embodiment, when the number of selection signals is 6 (six resistors), the next light emission amount determination means in the light quantity selection means performs the first light emission amount 2 to the light emission amount 3 and the light emission amount 4. The criterion for selecting one of the light emission amount 5 and the light emission amount 6 is “the light reception signal amplitude in the state of the light emission amount 2 should be 0.5 times or more of the maximum input value of the A / D converter 44. If the amount of light emission is 2 or more and less than 0.5 ^ 2 times the maximum input value of the A / D converter 44, select the amount of light emission 3 and the maximum input of the A / D converter 44 If the value is 0.5 ^ 3 times or more and less than 0.5 ^ 2 times, the light emission amount 4 is selected, and the maximum input value of the A / D converter 44 is 0.5 ^ 4 times or more and 0.5 ^ 3. If it is less than twice, the light emission amount 5 is selected, and if it is less than 0.5 ^ 4 times the maximum input value of the A / D converter 44, the light emission amount 6 is selected.

  Further, in general, when n selection signals (n resistors) are prepared, the determination criterion in the next light emission amount determination means is “the light reception signal amplitude in the state of light emission amount 2 is A / D converter. If the maximum input value of 44 is 0.5 times or more, the light emission amount 2 is selected, and if it is 0.5 ^ 2 times or more and less than 0.5 times the maximum input value of the A / D converter 44 Select light emission amount 3, select light emission amount 4 if it is 0.5 ^ 3 times or more and less than 0.5 ^ 2 times the maximum input value of A / D converter 44, ... A If the maximum input value of the / D converter 44 is 0.5 ^ (n-2) times or more and less than 0.5 ^ (n-3) times, the light emission amount (n-1) is selected, and A / D If it is less than 0.5 ^ (n-2) times the maximum input value of the converter 44, the light emission amount n is selected ".

  It should be noted that the general formula of the next light emission amount determination means when the initial light emission amount is larger than the light emission amount 2 (starting from 2 <k) is “the light reception level is A / D converter 44 in the state of the light emission amount k”. If the maximum input value is 0.5 times or more, the light emission amount k is selected, and if the maximum input value of the A / D converter 44 is 0.5 ^ 2 times or more and less than 0.5 times, light emission is performed. Select the amount k + 1, select the light emission amount k + 2 if it is 0.5 ^ 3 times or more and less than 0.5 ^ 2 times the maximum input value of the A / D converter 44, and the maximum input of the A / D converter 44 If the value is 0.5 ^ 4 times or more and less than 0.5 ^ 3 times, the light emission amount k + 3 is selected, and the maximum input value of the A / D converter 44 is 0.5 ^ 5 times or more and 0.5 ^ 4. If it is less than twice, the light emission amount k + 4 is selected,..., 0.5 ^ (n−k) times or more of the maximum input value of the A / D converter 44 and 0.5 ^ (n− ( k + 1)) The light emission amount (n−1) is selected if it is less than 0.5, and the light emission amount n is selected if it is less than 0.5 ^ (nk) times the maximum input value of the A / D converter 44. Become. If the predicted next light emission amount exceeds the maximum input value, the subsequent light emission amount is shifted to small in descending order, and the optimum light emission amount is selected by pinching, and the light reception signal is selected several times. Since the amplitude surely falls within the distance measurement range, the light amount adjustment work is much faster than before. Note that the number n of selection signals can be increased as long as the calculation processing unit 60 can process the balance with the distance measurement specification time.

  FIG. 4 is a flowchart showing a distance measurement procedure when the non-prism distance measurement mode is selected in the lightwave distance meter according to the second embodiment of the present invention. Since the second embodiment is the same as the first embodiment except that the initial light emission amount starts from the light emission amount 1, description thereof will be omitted using the same reference numerals.

  As shown in FIG. 4, when the non-prism distance measurement mode is selected, first, in step 1, a selection signal (1) is output from the arithmetic processing unit 60 so that the light emitting element 29 has a light emission amount 1. Next, at step 2, the light reception signal amplitude at the light emission amount 1 is measured, and at step 3, the light reception level determination means of the arithmetic processing unit 60 determines whether or not the light reception signal amplitude exceeds the maximum input value. If the maximum input value is exceeded, the process proceeds to step 11 and, like the first embodiment, it is determined that the user has made a mode selection error and prism distance measurement is automatically performed.

  If the maximum input value is not exceeded in step 3, the process proceeds to step 4 to determine whether or not the received light signal amplitude at the light emission amount 1 is 0.5 times or more of the maximum input value by the next light emission amount determination means. If it is determined that the value is 0.5 times or more of the maximum input value, the process proceeds to step 5 where the light emission amount 1 is optimum, and distance measurement is performed with the light emission amount 1 in step 12 and the process is terminated. If it is less than 0.5 times in step 4, the process proceeds to step 6 where the light emission signal amplitude at the light emission amount 1 is 0.25 (= 0.5 ^ 2) times or more of the maximum input value by the next light emission amount determination means. It is determined whether or not it is less than 0.5 times, and if it is 0.25 times or more and less than 0.5 times the maximum input value, the process proceeds to step 7 where the selection signal (2) is set so that the light emission amount becomes 2. In step 12, the distance is measured with the light emission amount 2 in step 12, and the process ends. If it is determined in step 6 that the light reception signal amplitude of the light emission amount 2 is less than 0.25 times the maximum input value, the process proceeds to step 8, and the light reception signal amplitude at the light emission amount 1 is maximum by the next light emission amount determination means. It is determined whether or not the input value is 0.125 (= 0.5 ^ 3) times or more and less than 0.25 times, and if it is 0.125 times or more and less than 0.25 times the maximum input value, Step 9 , The selection signal (3) is output so that the light emission amount becomes 3, and the distance measurement is performed with the light emission amount 3 in step 12, and the process is terminated. If it is determined in step 8 that the received light signal amplitude of the light emission amount 1 is less than 0.125 times the maximum input value, the process proceeds to step 10 where the light emission amount 4 is selected, and the process proceeds to step 12 where the light emission amount 4 Measures the distance and ends.

  Also in this embodiment, the first light emission amount is set to the minimum light emission amount 1 in the prepared light emission stages, so that the next light emission amount determination means (step 4, step 6, and step 8) function effectively, and twice. The optimal light emission can be found by selecting the signal. Therefore, as in the first embodiment, the light amount adjustment is completed much earlier than in the past, regardless of whether the non-prism distance measurement mode or the prism distance measurement mode is selected.

  FIG. 5 is a flowchart showing a distance measurement procedure when the non-prism distance measurement mode is selected in the lightwave distance meter according to the third embodiment of the present invention. The third embodiment has the same configuration as that of the first embodiment, and the flow in the prism distance measurement mode is the same as that of the first embodiment. In the third embodiment, in the non-prism distance measurement mode, the initial light emission amount starts from the light emission amount 3, and the arithmetic processing unit 60 uses only the light reception level determination unit and the light amount selection unit.

  When the non-prism distance measurement mode is selected, first, the light emission amount 3 is selected in step 1, and the light reception signal amplitude is measured in step 2. In step 3, the light reception level is determined by the light emission level 3 by the light reception level determination means, and when the maximum input value is exceeded, the light emission level 2 is switched in step 4, the light reception level is determined in step 5 and the light emission level 2 is determined. If the maximum input value is exceeded, the light emission level is switched to 1 in step 6, the received light level is determined based on the light emission level 1 in step 7, and if the maximum input value is exceeded, the mode is automatically shifted to the prism mode in step 8. If the maximum input value is not exceeded in step 5, the process proceeds to step 12 to perform distance measurement with the light emission amount 2 as it is, and the process is terminated. On the other hand, if it is determined in step 3 that the maximum input value is not exceeded, the light emission level is switched to 4 in step 9, the light reception level is determined in step 10 based on the light emission level 4, and the maximum input value is not exceeded. When the process proceeds to step 12 and the distance is measured with the light emission amount 4 and the maximum input value is exceeded at step 10, the light emission amount is switched to 3 at step 11, the process proceeds to step 12 and the distance measurement is completed.

  According to this embodiment, the light reception level determination means determines whether the light reception signal amplitude is greater than or equal to the maximum input value of the A / D converter 44 (whether it is a saturation region or a measurable region) (steps 3, 5, In step 7 and step 10), in the saturation region, signal selection is performed until the light-emitting element 29 enters the measurable region so as to decrease the light emission amount from the current stage in descending order (step 3 to step 6, step 10 to step 11). ). On the other hand, in the measurable range, signal selection is performed to a level that does not exceed the maximum input value so as to increase the light emission amount of the light emitting element 29 in ascending order from the current stage (step 3 → step 9). If the light emission amount is saturated even when the light emission amount is 1, the system automatically shifts to the prism mode as in the first embodiment (step 8).

  As a result, it is only necessary to determine the optimum light emission amount that is the optimum light reception amount from the intermittent pattern light emission amount, so the number of signal selections can be the same as the number of resistors prepared at the maximum, and the light intensity adjustment than before The work is completed much earlier.

  FIG. 6 is a flowchart showing a distance measurement procedure when the non-prism distance measurement mode is selected in the lightwave distance meter according to the fourth embodiment of the present invention. In the fourth embodiment, in the non-prism distance-measuring mode, only the point that the light emission amount selected for the second time from the start of the mode is the light emission amount 1 that is several steps smaller than the initial light emission amount 3 is selected. Different.

  When the non-prism distance measurement mode is selected, first, the light emission amount 3 is selected in step 1, the light reception signal amplitude is measured in step 2, and the light reception level is determined in step 3. If the maximum input value is exceeded in step 3, the light emission level is switched to 1 in step 4, and the light reception level is determined based on the light emission level 1 in step 5. If the maximum input value is exceeded, the prism distance measurement mode is determined in step 6. If the maximum input value is not exceeded in step 5, the light emission level is switched to 2 in step 7, the light reception level is determined based on the light emission level 2 in step 8, and the maximum input value is not exceeded. The process proceeds to step 13 and ends after the distance is measured with the light emission amount 2. If the maximum input value is exceeded in step 8, the light emission amount is switched to 1 in step 9 and the distance is measured in step 13 and the process ends. On the other hand, when it is determined in step 3 that the maximum input value is not exceeded, the same as in the second embodiment.

  According to the present embodiment, when the light receiving level determining means in step 3 determines that the light is saturated, the light emitting amount of the light emitting element 29 is lowered from the light emitting amount 3 to the light emitting amount 1 that is several steps smaller (step 4). The signal selection is performed until the light emission amount is selected in ascending order and the light emission amount becomes the optimum light emission amount (steps 5 to 9).

Also in the present embodiment, the light emission adjustment work is completed much earlier than in the prior art because only the optimum light emission amount is determined from the intermittent patterns. Furthermore, when the initial light emission amount is determined to be a saturated region, the light emission amount is selected by several steps smaller than the second light emission amount, and thereafter the light emission amount is increased in ascending order, so that the optimal light emission amount can be determined by pinching. Therefore, the number of signal selections is reduced, and the light amount adjustment work is faster than in the second embodiment.
Note that the emission amount attenuation constant r = 0.5 in Examples 1 to 4 is an example, and is not limited to this as long as 0 <r <1.

  FIG. 7 is a block diagram of an optical distance meter according to a fifth embodiment of the present invention. In the fifth embodiment, a plurality of resistors are prepared in the resistor group 70 in the first embodiment, and light emission of the light emitting element 29 is performed according to the number of selection signals corresponding to the received light signal amplitude from the arithmetic processing unit 60. Except for the configuration in which the amount can be selected, the configuration is the same as that of the first embodiment, and the flow of the prism distance measurement mode is also the same. In the light wave distance meter in this embodiment, in the light quantity selection means, the number of selection signals is n, and the light emission quantity of the light sending means corresponding to the selection signal is changed from small to large. When the amount is n, the initial light emission amount starts from the light emission amount equal to the maximum power of 2 (2 ^ m) that does not exceed the number of signals n. The amount is determined.

  As shown in FIG. 7, in the lightwave distance meter of the present embodiment, 100 resistors, that is, a load resistor 101 to a load resistor 200 and a pair of analog switches 201 to 300 are prepared. Corresponding selection signals (1) to (100) are transmitted from the unit 60, and the light emission stages of the light emitting elements 29 are configured in 100 patterns.

  Next, the optimum light emission amount searching means will be described with reference to the flowchart shown in FIGS. 8a and 8b, which shows the distance measurement procedure when the non-prism distance measurement mode is selected in the same optical distance meter. FIG. 8a is a flow for searching from a light emission amount smaller than the initial light emission amount because the initial light emission amount exceeds the maximum input value. FIG. 8b is a flow from the initial light emission amount because the initial light emission amount does not exceed the maximum input value. This is a flow for searching from a large light emission amount.

  When the non-prism distance measurement mode is selected, first, the initial light emission amount starts from the maximum power of 2 ^ m that does not exceed the selection signal number n = 100. That is, in step 1, the light emission amount 64 corresponding to 100> 2 ^ 6 = 64 (m = 6) is selected. Next, after the light reception signal amplitude measurement in step 2, the light reception level is determined by the light reception level determination means in step 3. When the signal amplitude of the received light signal input to the A / D converter 44 with the light emission amount 64 exceeds the maximum input value, the process proceeds to step 4 where the order is decreased by 1 (m = 5) and light emission of half of 64 is performed. After the amount is reduced to 32 (= 2 ^ 5), it is determined in step 5 whether m = 0. If m ≠ 0 in step 5, the received light level is determined again in step 6. If the maximum input value is exceeded in step 6, the subtraction is performed in step 9 by the light emission amount 16 (= 2 ^ 4) which is half of 32 and 32. Next, in step 10, it is determined whether m = 0, and if the order has decreased to m = 0, the light reception level is determined in step 11 by the light reception level determination means. If m = 0 is not true, the process returns to step 6. If the maximum input value is not exceeded in step 6, the light emission amount 16 which is half of 32 and 32 (= 2 ^ 4) is added in step 7. Next, in step 8, it is determined whether m = 0, and if the order decreases to m = 0, the light reception level is determined in step 11 by the light reception level determination means. If m = 0 is not true, the process returns to step 6. Thereafter, in the same case, step 6 to step 10 are repeated, the order is lowered, and the light emission amount is increased or decreased. If it is determined in step 11 that the maximum input value is not exceeded, the maximum light emission amount that does not exceed the maximum input value among the light emission amounts operated so far is set as the optimum light emission amount. If m = 0 in step 5, the process proceeds to step 11. Next, in step 12, when even the light emission amount 1 exceeds the maximum input value, the process proceeds to prism ranging in step 13. When the light emission amount is 1 or more and optimal, the process proceeds to step 14 and the distance measurement is completed.

  On the other hand, if the received light signal amplitude does not reach the saturation region at the initial light emission amount 64 in step 3 (in the measurable region), the process proceeds to step 15 where the order is lowered by 1 (m = 5) and is half of 64 and 64. The amount of light emission is 32 (= 2 ^ 5), and it is determined in step 16 whether the amount of light emission exceeds 100. If it exceeds, the light emission amount is returned to before addition in step 17 and the process returns to step 15 with the order m reduced, but now 64 + 32 = 96 and does not exceed 100, so the process proceeds to step 16. In step 18, it is determined whether m = 0, and if m = 0, the process proceeds to step 26 where the light reception level is determined by the light reception level determination means. If m = 0 is not satisfied, the light reception level is determined in step 19. If the maximum input value is not exceeded in step 19, then in step 20, next 16 and half of 96 and 32 are added to increase the light emission amount, and in step 21, it is determined whether the light emission amount exceeds 100, If it exceeds, the value is returned to 96 before the addition in step 22, and the order m is returned to step 20 while the order m is reduced. If the light emission amount does not exceed 100 in step 21, it is determined in step 23 whether m = 0. If m = 0, the received light level is determined by the received light level determining means in step 26. If m = 0, the process returns to step 19. If the maximum input value is exceeded in step 19, then in step 24, the next half of 96 and 32 is subtracted to reduce the light emission amount, and in step 25, it is determined whether m = 0. If m = 0, the received light level is determined by the received light level determining means in step 26. If m = 0, the process returns to step 19. Thereafter, in the same case, the light emission amount is increased or decreased by repeating Step 19 to Step 25, and if it is determined in Step 26 that the maximum input value is not exceeded, the maximum light emission that does not exceed the maximum input value among the light emission amounts operated so far. The amount is set to the optimum light emission amount. In step 27, if the maximum input value at the light emission amount 1 is exceeded, the process proceeds to prism distance measurement in step 28. When the light emission amount is 1 or more and optimal, the process proceeds to step 29, where the distance is measured and the process ends.

  Next, the optimum light emission amount searching means will be described with a specific example. FIG. 9 is a conceptual diagram illustrating the light quantity selection work when the optimum light emission amount is 47. A black circle indicates that the light emission is saturated (greater than the maximum input value), and a white circle indicates that the light emission can be measured (less than the maximum input value).

  When the number of selection signals n = 100 and the optimal light emission amount is the light emission amount 47, the initial light emission amount is 100> 2 ^ 6 = 64 (m = 6) (step 1). Since the initial light emission amount 64> 47 (step 3), the order is reduced by 1 (m = 5), the light emission amount is half (step 4), and m ≠ 0 (step 5). When the determination is made (step 6), 32 <47, so the light emission amount obtained by lowering the order by 1 (m = 4) is added to obtain 48 (64−32 + 16) (step 7), 48> 47 (step 6), the light emission amount obtained by further reducing the order by 1 (m = 3) is subtracted to 40 (64-32 + 16-8) (step 9), and 40 <47 (step 6). The light emission amount obtained by lowering the order by 1 (m = 2) is added to obtain 44 (64−32 + 16−8 + 4) (step 7), and 44 <47 (step 6). Therefore, the order is further decreased by 1 (m = 1) The amount of emitted light is added to obtain 46 (64-32 + 1). −8 + 4 + 2) (step 7), and 46 <47 (step 6). Therefore, the light emission amount obtained by lowering the order by 1 (m = 0) is added to obtain 47 (64−32 + 16−8 + 4 + 2 + 1) (step 7). ), The order has decreased to m = 0 (step 8), and when the light reception level is determined, the light emission amount 47 does not exceed the maximum input value. The light emission quantity is 64 → 32 (64−32) → 48 (64−32 + 16) → 40 (64−32 + 16−8) → 44 (64−32 + 16−8 + 4) → 46 (64−32 + 16−8 + 4 + 2) → 47 (64 Among the light emission amounts operated as −32 + 16−8 + 4 + 2 + 1), the light emission amounts that do not exceed the maximum input value are the light emission amounts 32, 40, 44, 46, and 47, and the maximum light emission amount can be selected as 47 (step 11). ). Thus, the number of signal selections for finding the optimum light emission amount 47 is seven.

  FIG. 10 is a conceptual diagram for explaining the light amount selection work when the optimum light emission amount is 1. FIG. When the optimum light emission amount is 1, since the initial light emission amount 64> 1 (step 3), the order is decreased by 1 (m = 5), and the light emission amount is halved (step 4), and m ≠ 0. Therefore (step 5), if the light reception level is determined again, 32> 1 (step 6). Therefore, the light emission amount obtained by lowering the order by 1 (m = 4) is further subtracted 16 (64-32-16) ( Since Steps 9) and 16> 1 (Step 6), the order is further lowered by 1 (m = 3) and 8 (64-32-16-8) (Step 9), and the order is further lowered by 1 (m = 2). ) 4 (64-32-16-8-4) (step 9), the order is further lowered by 1 (m = 1), 2 (64-32-16-8-4-2) (step 9), and further Decrease the order by 1 (m = 0) to 1 (64-32-16-8-4-2-1) (step 9), until m = 0 If the number has dropped (step 10) to determine the received light level does not exceed the maximum input value in the light-emitting amount 1. The maximum light emission amount that does not exceed the maximum input value among the light emission amounts operated as 64 → 32 → 16 → 8 → 2 → 1 can be selected as 1 (step 11). Thus, when the optimal light emission amount is less than the initial light emission amount 64 (2 ^ m = 6), the number of signal selections for finding the optimal light emission amount is always determined within 7 times.

  FIG. 11 is a conceptual diagram illustrating the light quantity selection work when the optimum light emission amount is 96. Since the initial light emission amount 64 <96 (step 3), the light emission amount 32 obtained by reducing the order by 1 (m = 5) is added to the current light emission amount to 96 (64 + 32) (step 15). Since the light emission amount 96 does not exceed the light emission amount 100 (step 16) and m ≠ 0 (step 18), if the light reception level is determined again, 96 = 96 and the maximum input value is not exceeded (step 19). If the order of emission is reduced by 1 (m = 4) to add 112 (64 + 32 + 16) (step 20), the emission exceeds 100 (step 21), so the emission is returned to 96 before addition (step 22). ) Further, when the light emission amount obtained by lowering the order by 1 (m = 3) is added to 104 (64 + 32 + 8) (step 20), the light emission amount exceeds 100 (step 21), so the light emission amount 96 before the addition is restored. (Step 22) Further, when the light emission amount obtained by lowering the order by 1 (m = 2) is added to be 100 (64 + 32 + 4) (Step 20), 100> 96 (Step 19). Further, the emission amount obtained by lowering the order by 1 (m = 1) is subtracted to 98 (64 + 32 + 4-2) (step 24), and 98> 96 (step 19), so the order is further reduced by 1 (m = 0) is subtracted to 97 (64 + 32 + 4-2-1) (step 24), and the order is reduced to m = 0 (step 25), so the light reception level is judged (step 26) and the light emission amount. In 97, the maximum input value is exceeded. Then, the maximum light emission amount that does not exceed the maximum input value among the light emission amounts operated as 64 → 96 → 100 → 98 → 97 can be selected as 96 (step 26). Thus, the number of signal selections for finding the optimum light emission amount 96 is five.

  When the light emission amount is 95, the light emission amount is 64 → 96 (64 + 32) → 80 (64 + 32-16) → 88 (64 + 32-16 + 8) → 92 (64 + 32-16 + 8 + 4) → 94 (64 + 32-16 + 8 + 4 + 2) → In the selection of 95 (64 + 32-16 + 8 + 4 + 2 + 1), the maximum light emission amount not exceeding the maximum input value can be selected as 95, and the number of signal selections for finding the optimum light emission amount is seven. Thus, even when the optimum light emission amount exceeds 64, it is always determined within 7 times.

  FIG. 12 is a conceptual diagram for explaining the light amount selection work when the optimum light emission amount is 64. When the optimal light emission amount is 2 ^ m = 64 (m = 6), the light emission amount 64 → 96 (64 + 32) → 80 (64 + 32-16) → 72 (64 + 32-16-8) → 68 (64 + 32-16-8) -4) → 66 (64 + 32-16-8-4-2) → 65 (64 + 32-16-8-4-2-1), and the optimum light emission amount not exceeding the maximum input value is 64 The number of signal selections for finding is 7 times. Thus, even when the optimum light emission amount is 64 (2 ^ m), it is always determined within seven times.

  That is, when there are n selection signals and the initial light emission amount starts from the largest power of 2 ^ m that does not exceed n (where m is an integer and 2 ^ (m + 1)> n ≧ 2 ^ m), it is optimal. The number of times that a suitable amount of light emission can be found ends within m + 1 times. Since the optimum light emission amount is searched in the binary system, it can be found efficiently with a small number of signal selections.

  In the first to fifth embodiments, the light can be emitted from the light emitting element 29 even if several selection signals are operated simultaneously. However, since the load resistance is synthesized and the light power cannot be accurately grasped, the selection signal is independent. It is preferable to operate.

29 Light emitting element (light transmission means)
31 Distance optical path 33 Target reflector 35 Reference optical path 37 Switching shutter (light extraction means)
40 Light receiving element (light receiving means)
44, 47, 50 A / D converter (signal conversion means)
60 arithmetic processing unit 70 resistor group 80 density filter insertion / extraction means

Claims (4)

Light transmitting means for transmitting light modulated at a plurality of modulation frequencies;
A light extraction means for sending the light of the light sending means to a selected one of a distance measuring optical path or a reference optical path that reciprocates to a target reflector disposed at a measurement point;
A light receiving unit that receives the distance measuring light that has passed through the distance measuring optical path or the reference light that has passed through the reference optical path, and outputs respective light receiving signals;
Signal conversion means for measuring the light reception signal and converting the analog signal into digital data;
A resistor that adjusts the amount of light emitted from the light sending means;
The resistor is set according to the signal amplitude of the light reception signal, and a distance measurement value that is a linear distance to the target reflector is calculated based on a phase difference between the distance measurement signal digitized by the signal conversion means and a reference signal. An arithmetic processing unit to perform,
A lightwave distance meter with a
There are a plurality of resistors, each having a predetermined fixed resistance value from a large resistance value to a small resistance value, one of which is selected by a selection signal corresponding to the resistor in a one-to-one relationship, and the light emitting means emits light. It is provided as a group of resistors whose amount can be switched from small to large,
In the arithmetic processing unit,
A light receiving level determining means for determining whether a signal amplitude of the light receiving signal input to the signal converting means is equal to or greater than a maximum input value of the signal converting means;
When the light receiving level determining means determines that the light intensity is equal to or greater than the maximum input value, the selection signal for switching the light emission amount of the light transmitting means to a small value is selected until the light input level is less than the maximum input value, and less than the maximum input value. A light amount selection means for selecting the selection signal for switching the light emission amount of the light transmission means to a large value until a maximum light emission amount not exceeding the maximum input value is provided ,
In the light amount selection means, when selecting the selection signal for switching the light emission amount of the light transmission means to be larger than the current stage,
The number of the selection signals is n, the light emission amount of the light transmission means corresponding to the selection signal is changed from small to large, the light emission amount 1, the light emission amount 2... The light emission amount n, and the current light emission amount is the light emission amount k (k <k n), the light emission amount to be selected next to the current light emission amount k is
The signal amplitude of the received light signal in the state of light emission amount k is
If the maximum input value r ^ 2 times or more, select a selection signal that gives a light emission amount k + 1,
If the maximum input value is r ^ 3 times or more and less than r ^ 2 times, a selection signal for light emission amount k + 2 is selected.
If the maximum input value is r ^ (n−k) times or more and less than r ^ (n− (k + 1)) times, a selection signal for light emission amount (n−1) is selected.
If the maximum input value is less than r ^ (n−k) times, a selection signal for light emission amount n is selected (where r is a light emission amount attenuation constant (0 <r <1)), and next light emission amount determination. A light wave distance meter characterized in that means are provided .
Light transmitting means for transmitting light modulated at a plurality of modulation frequencies;
A light extraction means for sending the light of the light sending means to a selected one of a distance measuring optical path or a reference optical path that reciprocates to a target reflector disposed at a measurement point;
A light receiving unit that receives the distance measuring light that has passed through the distance measuring optical path or the reference light that has passed through the reference optical path, and outputs respective light receiving signals;
Signal conversion means for measuring the light reception signal and converting the analog signal into digital data;
A resistor that adjusts the amount of light emitted from the light sending means;
The resistor is set according to the signal amplitude of the light reception signal, and a distance measurement value that is a linear distance to the target reflector is calculated based on a phase difference between the distance measurement signal digitized by the signal conversion means and a reference signal. An arithmetic processing unit to perform,
A lightwave distance meter with a
There are a plurality of resistors, each having a predetermined fixed resistance value from a large resistance value to a small resistance value, one of which is selected by a selection signal corresponding to the resistor in a one-to-one relationship, and the light emitting means emits light. It is provided as a group of resistors whose amount can be switched from small to large,
In the arithmetic processing unit,
A light receiving level determining means for determining whether a signal amplitude of the light receiving signal input to the signal converting means is equal to or greater than a maximum input value of the signal converting means;
When the light receiving level determining means determines that the light intensity is equal to or greater than the maximum input value, the selection signal for switching the light emission amount of the light transmitting means to a small value is selected until the light input level is less than the maximum input value, and less than the maximum input value. A light amount selection means for selecting the selection signal for switching the light emission amount of the light transmission means to a large value until a maximum light emission amount not exceeding the maximum input value is provided ,
In the light quantity selection means, when the number of the selection signals is n and the light emission quantity of the light sending means corresponding to the selection signal is set to light emission quantity 1, light emission quantity 2... The light emission amount starts from a light emission amount 2 ^ m corresponding to 2 ^ m (where m is an integer and 2 ^ (m + 1)> n ≧ 2 ^ m), which does not exceed the number of selection signals n. When it is determined that the current light emission amount is greater than or equal to the maximum input value, the light emission amount of the light sending means is subtracted by the light emission amount obtained by subtracting the order of the current light emission amount by 1, and determined to be less than the maximum input value. In this case, the light emission amount obtained by subtracting the order of the current light emission amount by 1 is added (however, if the result of addition exceeds the light emission amount n, the light emission amount is returned to the pre-addition light emission amount and the order is further reduced by 1). Repeat until the order m becomes 0, and search by the order addition / subtraction operation. From among the light emission amount, the light wave distance meter, wherein the optimum that the emission amount search means is provided for selecting the selection signal having the maximum light emission amount does not exceed the maximum input value.
In the case of non-prism distance measurement where the target reflector is not a high reflector, the light emission amount of the light sending means is switched by the light quantity selecting means,
In the case of prism distance measurement in which the target reflector is a high reflector, a preset light emission amount is sent from the light sending means, and the received light signal is less than the maximum input value of the signal converting means. Is provided with a density filter insertion / extraction means so that a density filter is inserted between the distance measuring optical paths when the received light signal is equal to or greater than the maximum input value. The light wave distance meter according to claim 1 or 2, wherein
Even if the selection signal that minimizes the amount of light emission is selected in the non-prism distance measurement to the arithmetic processing unit, if the signal amplitude of the received light signal is equal to or greater than the maximum input value of the signal conversion means, 4. The light wave distance meter according to claim 3, further comprising a distance measuring means automatic changing means for automatically shifting to the prism distance measurement.

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