JP2005140685A - Range finder and range finding method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To accurately measure the distance from an object in a shorter time. <P>SOLUTION: PSD1(2 and 3), as a plurality of light receiving elements, are provided in which optical filters FIL1(2 and 3) are formed, as a pair, and to one, with a plurality of light emitting elements have different light emitting positions and light emitting wavelength bands, with the transmission characteristics of such transmission wavelength band as matches with the light emission wavelength band of the corresponding light emitting element. A plurality of pairs of light emitting elements and light receiving elements having different wavelength bands are driven at the same timing, to acquire a plurality of range finding information from the reception signals at the plurality of light receiving elements. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a distance measuring device and a distance measuring method suitable for, for example, a projector device having an AF (autofocus) function, a silver salt / digital camera, or the like.

  FIG. 5 shows the principle of a PSD (Position Sensitive Photo Detector) type distance measuring sensor applied to the projector apparatus. In the figure, the infrared light emitted in the projection direction of the projection system lens barrel 11 from the LED (light emitting diode) 12 which is an infrared lamp across the projection system lens barrel 11 is reflected by the projection surface 13. After that, the light enters the PSD 14 which is a light receiving element.

  In the PSD 14, the spot-like infrared light incident through the hole 14a is projected onto the one-dimensional PSD 14b. In the one-dimensional PSD 14b, the output current signal of the analog value varies depending on the projection position. It becomes.

  As the distance between the LED 12 and the projection surface 13 changes, the position of the infrared light projected onto the one-dimensional PSD 14b changes depending on the reflection angle. In addition, the exact distance between the LED 12 and the PSD 14 is Since it is known, as a result, according to the principle of triangulation, the distance between the LED 12, PSD 14 and the projection plane 13 can be measured by detecting the current signal output from the one-dimensional PSD 14b.

  The distance measuring sensor composed of the above-described LED 12 and PSD 14 is fixed in advance according to the projection direction of the projection lens barrel 11, and in principle, between one point on the projection surface 13. It can only measure distance.

  Therefore, when it is desired to measure the distance to a plurality of point positions on the projection surface 13, it is necessary to prepare a plurality of distance measuring sensors in advance.

  FIG. 6 illustrates the configuration of a distance measuring device that measures the distances to three positions on the projection surface 13 using a plurality of, for example, three sets of distance measuring sensors 15a to 15c. Each of the distance measuring sensors 15a to 15c includes a pair of LEDs (1 to 3) and PSDs (1 to 3) having the same characteristics as in FIG.

  Thus, by measuring the distance to three different points on the projection surface 13 using the three sets of distance measuring sensors 15a to 15c, the inclination of the projection surface 13 can be detected, and the distance of only one point can be determined. An appropriate projection distance can be obtained as compared with the case of obtaining.

In addition, a distance measuring sensor technique has been considered in which the distance between a plurality of positions within a predetermined range is measured while simplifying the configuration with one PSD as a light receiving element for a plurality of light emitting elements. . (For example, Patent Document 1)
JP 09-203631 A

  When ranging is performed by the three sets of ranging sensors 15a to 15c shown in FIG. 6, the ranging sensors 15a to 15c have the same transmission / reception characteristics. Therefore, for example, if the light emitted from the LED 1 of the distance measuring sensor 15a is received by the PSD 3 of the distance measuring sensor 15c, an erroneous distance measurement result is output. Therefore, these three sets of distance measuring sensors 15a to 15c are shown in FIG. It is necessary to drive in a time division manner.

  This is also the case with the technique of Patent Document 1 in which the light receiving side element is shared, and as is apparent from the description of FIG. 3 in the same document, measurement is performed by sequentially driving five light emitting elements in a time-sharing manner. You can see that the distance is being executed.

  In this way, if the number of distance measurement positions is increased, it is possible to accurately know the inclination of the surface to be projected, and to accurately measure the distance by absorbing errors of individual elements. However, there is a problem that the time required for ranging becomes long.

  The present invention has been made in view of the above circumstances, and its object is to provide a distance measuring device and a distance measuring method capable of accurately measuring the distance to an object in a shorter time. Is to provide.

  According to the first aspect of the present invention, a plurality of light emitting elements each having a different light emitting position and light emitting wavelength band and a pair of these light emitting elements that are provided in a one-to-one relationship and corresponding to the light emitting wavelength band of the corresponding light emitting element A plurality of light receiving elements in which filters having transmission characteristics in wavelength bands are formed, and a plurality of sets of light emitting elements and light receiving elements having different wavelength bands are driven at the same timing to receive a plurality of signals from received signals at the plurality of light receiving elements. Drive control means for obtaining distance measurement information.

  According to a second aspect of the present invention, in the first aspect of the present invention, the plurality of light emitting elements are LEDs each having a different emission wavelength band.

  According to a third aspect of the present invention, in the first aspect of the present invention, the light emitting element and the light receiving element that correspond to each other perform light transmission and reception through a filter having transmission characteristics in the same transmission wavelength band. It is characterized by that.

  According to the fourth aspect of the present invention, a plurality of light emitting elements having different light emitting positions and light emitting wavelength bands, and a pair of these light emitting elements that are provided in a one-to-one relationship, and transmission that matches the light emitting wavelength band of the corresponding light emitting elements. For a plurality of light receiving elements in which filters having transmission characteristics in wavelength bands are formed, a plurality of sets of light emitting elements and light receiving elements having different wavelength bands are driven at the same timing, and a plurality of signals are received from signals received by the plurality of light receiving elements. Ranging information is obtained.

  According to the first aspect of the present invention, a plurality of ranging information can be obtained by simultaneously driving the light emitting element and the light receiving element at the same time regardless of the number of sets of the light emitting element and the light receiving element. It becomes possible to accurately measure the distance to an object.

  According to the invention described in claim 2, in addition to the effect of the invention described in claim 1, LEDs having a wide variety of types and a wide range of selection of necessary emission characteristics such as emission wavelength band and emission luminance are used for the light emitting element. Thus, considering the matching with the filter used on the light receiving element side, the degree of freedom in design such as cost and sensitivity is high, and it can be easily applied by various optical devices.

  According to the invention described in claim 3, in addition to the effect of the invention described in claim 1, the filter having the transmission characteristics of the same transmission wavelength band is arranged in the corresponding light emitting element and light receiving element. The light transmission / reception characteristics of the light emitting element and the light receiving element can be more easily aligned.

  According to the fourth aspect of the present invention, a plurality of distance measurement information can be obtained by simultaneously driving the light emitting elements and the light receiving elements at the same time regardless of the number of pairs of the light emitting elements and the light receiving elements. It becomes possible to accurately measure the distance to an object.

  A distance measuring apparatus according to an embodiment of the present invention will be described below with reference to the drawings.

  The basic configuration of the distance measuring apparatus according to the present invention is the same as that shown in FIG. 6 and is not shown. However, a plurality of, for example, three sets of distance measuring sensors 15a ′ to 15c ′ are used to project the projection surface 13. The distance measuring devices 15a ′ to 15c ′ each have LEDs (1 to 3) and PSDs (1 to 3), respectively. It shall be configured in pairs.

  Here, it is assumed that the LEDs 1 to 3 which are the light emitting elements of the distance measuring sensors 15a ′ to 15c ′ are selected so that the light emission wavelength bands are different from each other and do not overlap.

  Corresponding to this, PSDs 1 to 3 which are light receiving elements are provided with optical filters FIL1 to FIL1 in holes for creating spot light as shown in FIG. Only light having a limited wavelength band is incident on any position within the light receiving surfaces of PSDs 1 to 3.

  In the above configuration, the LEDs 1 to 3 of the distance measuring sensors 15a 'to 15c' have different emission wavelength bands as described above as shown in FIG. Here, the bands are longer in the order of LED1, LED2, and LED3 (lower in frequency), and are set so as not to overlap each other as described above.

  On the other hand, the transmission characteristics of the optical filters FIL1, FIL2, and FIL3 that transmit the incident light to each PSD1, PSD2, and PSD3 are shown in FIG. 3 as the emission wavelength bands of the LEDs 1 to 3 shown in FIG. It shall be almost matched.

  That is, here, the optical filters FIL1, FIL2, and FIL3 are bands in which the transmission wavelength is long (frequency is low), the bands are separated and do not overlap, and the LEDs 1 to 3 shown in FIG. It is assumed that it substantially coincides with the emission wavelength band.

Accordingly, the distance measuring sensors 15a 'to 15c' have different wavelength bands for transmission and reception and do not interfere with each other, so that there is no possibility of malfunction even if they are driven simultaneously.
Therefore, as shown in FIG. 4, it is possible to simultaneously drive the distance measuring sensors 15a 'to 15c' and simultaneously measure the distance to the three points of the object by the distance measuring sensors 15a 'to 15c'. The time required for ranging of the object can be greatly shortened.

  This is more conspicuous as the number of distance measurement positions of the object increases, and even when measuring the position of many objects and more accurately grasping the state of inclination of the object, the distance measurement The time required for this will not be prolonged.

  As described above, according to the distance measuring apparatus of the present embodiment, a plurality of distance measurement information can be obtained by simultaneously driving them collectively regardless of the number of light emitting elements and light receiving elements. It is possible to accurately measure the distance to the object in a short time.

  In the above embodiment, since the light emitting element is an LED having a wide variety of types and a wide range of selection of necessary light emission characteristics such as a light emission wavelength band and light emission luminance, the filter used on the light receiving element side Considering this matching, the design flexibility such as cost and sensitivity is high, and it can be easily applied by various optical devices.

  Further, in the embodiment, PSD is used as the light receiving element, but this is for performing distance measurement based on the principle of triangulation. A photodiode, a phototransistor, or the like may be used as a light receiving element in the propagation time detection method in which the time until reception of the reflected wave is detected and converted into the distance to the object.

  Further, in the above-described embodiment, the optical filter having the transmission characteristics substantially similar to the emission wavelength band of the light emitting element is disposed only on the light receiving element side. However, the emission wavelength band is intentionally disposed on the light emitting element side. An extremely wide filter may be used, and an optical filter having transmission characteristics in the same wavelength band may be used for both the light emitting element and the light receiving element that form a pair.

  By doing so, the light transmission / reception characteristics of the light emitting element and the light receiving element can be more easily aligned without depending on the light emission wavelength band characteristic of the light emitting element itself.

  Further, the distance measuring device according to the present invention is not limited to the three distance measuring sensors as shown in FIGS. 2, 3, and 6, and any number of distance measuring sensors may be used. As described above, the time required for ranging is almost the same, but by increasing the number of sets, it is possible to obtain distance information up to a large number of positions. More accurate distance information according to need can be obtained from the state of the object.

  In addition, the present invention is not limited to the above-described embodiment, and various modifications can be made without departing from the scope of the invention.

  Further, the above embodiments include inventions at various stages, and various inventions can be extracted by appropriately combining a plurality of disclosed constituent elements. For example, even if some constituent elements are deleted from all the constituent elements shown in the embodiment, at least one of the problems described in the column of the problem to be solved by the invention can be solved, and described in the column of the effect of the invention. In a case where at least one of the obtained effects can be obtained, a configuration in which this configuration requirement is deleted can be extracted as an invention.

The figure which shows the structure by the side of the light receiving element of the ranging sensor which concerns on one Embodiment of this invention. The figure which illustrates the light emission wavelength band characteristic of LED which is the light emitting element which concerns on the embodiment. The figure which illustrates the transmission characteristic of the filter provided in the light receiving element side concerning the embodiment. The figure which shows the drive timing of the distance measuring sensor which concerns on the same embodiment. The figure for demonstrating the basic principle of a ranging sensor. The figure which illustrates the basic composition of the ranging sensor which measures a plurality of positions. The figure which illustrates the drive timing of a some distance measuring sensor.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 11 ... Projection system lens-barrel, 12 ... LED (1-3), 13 ... Projection surface, 14 ... PSD (1-3), 14a ... Hole, 14b ... One-dimensional PSD, 15a-15c, 15a'-15c ' ... distance measuring sensors, FIL1 to 3 ... optical filters.

Claims (4)

A plurality of light emitting elements each having a different emission position and emission wavelength band;
A plurality of light-receiving elements each having a filter having transmission characteristics in a transmission wavelength band matching the emission wavelength band of the corresponding light-emitting elements;
Drive control means for driving a plurality of sets of light-emitting elements and light-receiving elements having different wavelength bands at the same timing to obtain a plurality of distance measurement information from signals received by the plurality of light-receiving elements is provided. Distance measuring device.   2. The distance measuring device according to claim 1, wherein each of the plurality of light emitting elements is an LED having a different emission wavelength band.   2. The distance measuring apparatus according to claim 1, wherein the light emitting element and the light receiving element which form a pair corresponding to each other transmit and receive light through a filter having transmission characteristics in the same transmission wavelength band. A plurality of light emitting elements each having a different light emitting position and light emitting wavelength band, and a filter having a transmission characteristic in a transmission wavelength band that matches each of the light emitting wavelength bands of the corresponding light emitting elements. For multiple light receiving elements
A distance measuring method, wherein a plurality of sets of light emitting elements and light receiving elements having different wavelength bands are driven at the same timing to obtain a plurality of distance measuring information from received signals from the plurality of light receiving elements.

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