SURVEYING INSTRUMENT HAVING MEASURING MODE SELECTING SWITCH MEANS

Abstract: A surveying instrument for electrically measuring angles and/or distances including measuring mode se­ lecting switches (7), which are of photoelectric non-­ contact type that turn ON upon interruption of light beam. The switches (7) are located on a side surface of a frame post (4, 4′) or on the upper surface of a carrying bar (6) interconnecting the frame posts (4, 4′).

Description: BACKGROUND OF INVENTIO: The present invention relates to a surveying instrument for electrically measuring angles and/or distances. In recent years, electronic measures have widely been adopted in optical surveying instruments. For instance, developments have been made on electronic distance measuring transit including an electro-optical distance measuring instrument which is adapted to perform a distance measurement using a modulated photosignals, as well as a transit telescope of which angle in a vertical and/or horizontal planes is measured by means of electric means such as encoders. Such electronic distance measuring transit is provided with processing means which automatically measures the actual distance and the angle of elevation between the body of the surveying instrument and a target, and calculates the horizontal distance and the difference in elevation from the results of the measurements. For the purpose, the processing means generally includes a micro-computor, or the like, and the modes of measurement and processing are appropriately selected by an operator through mode selecting switches provided on the instrument. Conventionally, there has been known such electro distance measuring transit that is provided on the frame or the body of the transit telescope with the measuring-mode selecting switches. However, in view of the fact that in the measur ing instrument, for the purpose of increasing the accuracy of the measurements, the measurements are conducted in two different positions of the frame and the telescope. More precisely, a first measurement is conducted with the frame and the telescope in normal positions and they are then turned by 1800 about their respective rotatable axes to perform a second measurement. Thus, in an arrangement wherein the mode selecting switches are located on the body of the telescope, it is required to provide such switches not only on the rear side of the frame or the upper surface of the telescope body but also on the opposite side thereof in order to make it possible to actuate them both in the normal and turned-over positions of the telescope. Where the measuring-mode selecting switches are arranged on the tube of the telescope, they can be actuated in either position of the telescope since the switches are turned together with the telescope. However, in that case, difficulties will be encountered because the direction of actuation of the switches will have to be changed and indications on the switch panel will be turned over. Generally, the measuring modes which are adapted to be selected by the measuring-mode selecting switches include the measurments of the actual distance, of the horizontal distance measurement, of the difference in elevation, as well as the measurements of the horizontal angle, of the zenith angle and of the elevation angle. Additionally, switches must be provided for utility systems such as a self-check switch1 a weather compensation switch, a switch for indicating the inclination of the instrument itself, a print-out switch, a memory read-on switch, and so on. Accordingly, one set of the surveying instrument requires ten or more selecting switches. Further, those measuring modes have to be selected in every measuring points so that such measuring mode selecting switches are very often actuated. It should further be pointed out that conventional instruments adopted pushbutton type switches for the measuring mode selection, so that problems have been encountered in that the external force applied for the actuation of the switch may cause a measurement error because the instrument is aimed to perform measurements with the accuracy in the order of 1 mm or 1 sec. of angle. For the purpose of overcoming the problem inherent to such push button type switches, there has been proposed in the U.S. Patent 3,832,056 issued to John I. Shipp et al. to use as the ON-OFF switch for instructing the start of measurement a non-contact type switch including a light emitting diode and a light receiving diode which are so arranged that the light beam from the light emitting diode is reflected by a finger of the operator toward the light receiving diode to be sensed thereby. However, since the non-contact switch disclosed therein is of a reflecting type, it is apt to be influenced by an external light. Further, such type of switches may undesirably be actuated simply when the operator moves his hand near the switch in order to operate any other switch, or they cannot be actuated where the operator wears gloves having less reflectivity. SUMMARY OF THE INVENTION: The present invention has been accomplished in view of the aforementioned problems of the conventional arrangements, and has an object to provide measuring mode selecting switches for an electronic distance measuring transit which are located so that they can readily be actuated even when the frame or the telescope is turned. Another object of the present invention is to provide measuring mode selecting switches, which are of such a type that can be actuated when light beam is interrupted. A further object of the present invention is to provide a distance measuring transit with non-contact type mode selecting switches which are substantially free from external influences. According to the present invention, the above and other objects can be accomplished by a surveying instrument for electrically measuring angles or a distance measuring transit for measuring a distance by means of electromagnetic wave, especially by a light beam and for electrically measuring angles, which includes measuring mode selecting switches of non-contact type provided on a side face of a frame post or on the upper surface of the arm portion connecting the upper portions of the frame posts. More particularly, anyone of the contactless switches is comprised of photoelectric switch including a light emitting element and a light receiving element which are so arranged that the switch is actuated when the light flux between the elements is interrupted. According to the features of the present invention, it is possible to avoid any influence of external light or any misoperation even when the operators hand is brought close to the switch. Further, the switch can be actuated even when the operator wears gloves. It is not required to provide more than one set of switches because the locations of the switches are not affected by the turning over of the telescope. The above and other objects and features of the present invention will become apparent from the following descriptions of a preferred embodiment taking reference to the accompanying drawings. DESCRIPTIONS OF THE DRAWINGS: Fig. 1 is a perspective view of a distance measuring transit in accordance with one embodiment of the present invention; Fig. 2 is a sectional view taken along the line II-II in Fig. 1; Fig. 3 is a sectional view showing a mode selection switch in accordance with another embodiment of the present invention; Fig. 4 is a sectional view similar to Figure 3 but showing a further embodiment; Fig. 5 is a circuit diagram of a measuring mode selecting switch; and Fig0 6 is a diagram showing wave-forms in various parts of the circuit in Fig. 5. DESCRIPTION OF THE PREFERRED EMBODIMENT: Referring to the drawings, particularly to Figure 1, there is shown a surveying instrument 1 for electrically measuring angles and distances which comprises a frame portion 3 provided rotatably on a base 2. The frame portion 3 consists of posts 4 and 4' and a carrying bar 6 which extends between the upper ends of the posts 4 and 4'. The posts 4 and 4' rotatably supports a transit telescope 5. The telescope 5 comprises a body 5' which supported for swinging movement about a horizontal axis on the posts 4 and 4' and carries a lens tube as in a conventional transit. In the body 5', there is provided a control device of a photoelectric distance measuring device. In the frame portion 3 and the post 4', there are housed an angle-measuring devices having encoders which function as detecting means. In the carrying bar 6, there is housed a battery (not shown). The post 4 is provided on the outer side surface with a measuring mode selecting switch assembly 7 of contactless type and on the front surface with an indicator 8 for indicating the measured values. The switch assembly 7 comprises a plurality of switches 7', 7", 7''' and on both sides of the switch assembly 7, there are provided identifications 7a', 7a", 7a"' ...... for indicating the functions of the associated switches 7', 7", 7' ' , , respectively. Referring to Fig. 2, there is shown an example of switch which can be adopted in the switch assembly 7. As shown, the switch comprises a light emitting section 10, a light receiving section 11 and an actuating section 12 located between the sections 10 and 11. The light emitting section 10 consists of a light emitting element 13 radiating infrared ray, a reflection mirror 14 and a dust-proof glass 18, and the light receiving section 11 consists of a light receiving element 16, a reflection mirror 17 and a wave-length selecting filter 18. The sections 10 and 11 are so arranged that the light from the element 13 is relfected by the mirror 14 and passed through the glass 15 and then through the section 12 and the filter 18 to the mirror 17 to be reflected thereby toward the element 16. The switch can be actuated by inserting a finger into the section 12 to block the light between the elements 13 and 16. Referring to Fig. 3, which shows another embodiment, the switch includes a switch housing 20 provided with a window opening 22 having a dust-proof glass 21. In the switch housing 20, Iliere is provided a light receiving element 23. The light receiving element 23 is normally in ON position as far as the external light is received through the window 22. The switch can be actuated by covering the window 22 to block the light to the element 23. A light source 24 may be provided to illuminate the element 23 when it is desired to use the instrument in dark such as in a tunnel or at night. Referring now to Figure 4 which shows a further embodiment of the switch, the switch includes a housing 32 having a light transmitting window 31 with a dustproof glass or a wave-length selecting filter 30. In the housing 32, there are a light emitting element 33 and a light receiving element 34 separated from each other by a partition plate 35. The element 33 radiates a modulated light toward the window 31 and the element 34 is arranged so that it receives the light from the element 33 as it is reflected at a position slightly outside the housing 32. Thus, the light from the element 33 does not reach the element 34 in normal condition but the switch can be actuated when a finger is placed as shown by phantom lines in Figure 4 to reflect the light from the element 33 toward the element 34. Referring now to Figures 5 and 6, descriptions will be made on the electric circuit for the measuring mode selecting switch assembly 7. In the embodiment shown in Fig. 5, the switch assembly 7 consists of ten light emitting elements, for example, iight emitting diodes 13a through 13j and corresponding number of light receiving elements, for example, photodiodes 16a through 16j. There is provided a scanning circuit 50 which consists of a counter and a decoder for scanning light emitting element drives 52a through 52j. An oscillator 51 is associated with the circuit 50 to apply a clock pulse 101 as shown in Figure 6 to the circuit 50. The circuit 50 energizes the drivers 52a through 52j upon receipt of the clock pulse 101. The output signals from the drivers 52a, 52b, 52c, 52j are shown by numerals 102, 103, 104, 105 in Figure 6, respectively. The light receiving element-s l6a through 16j are connected with an analogous switch 53 which is in turn connected with an amplifier 54. The switch 53 is also connected with the scanning circuit 50 so that it can be scanned in synthronism with the scanning of light emitting elements 13a through 13j. Thus1 when anyone of the photo-emitting elements 13 is energized to emit the modulated light, the output of the corresponding light receiving element 16 is passed to the amplifier 54. The output of the analogous switch 53 is shown in Figure 6'by the numerals 106 which indicates the signal as produced when the space between the light emitting element 13c and the light receiving element 16c is blocked to interrupt transmittal of light. The outputs of light receiving elements 16a through 16j are sequentially passed to the amplifier 54 in synchronisim with the clock pulses from the oscillating circuit 51. The output 106, which has been amplified to a suitable level by the amplifier 54, is applied to the input terminal of an averaging circuit 55 and one of the input terminals of a comparative circuit 57. The circuit 55 functions to provide an average of signals supplied from the amplifier 54 for a predetermined period which i substantially long as compared with the scanning frequencies of the light enitting elements 13a through 13j. The output of the averaging circuit 55 is applied through a voltage divider 56 to the other input terminal of the comparative circuit 57. The signal which has passed through the voltage divider 56 is shown by the -numeral 106' and functions as a reference level which is effective to eliminate or decrese the influence of external light on the switch. The comparative circuit 57 serves to compare the amplitude of the output 106 of the amplifier 54 with the amplitude of the output 106' of the voltage divider 56, and produce binary signals which are applied to a signal line 58. As shown in Figure 6, where the space between the light emitting element 13c and the light receiving element 16c is blocked to interrupt the light to pass therethrough, the output 107 becomes high level at the timing corresponding to the output of the element 16c. The signal line 58 is connected to the input line of a microprocessor which is not shown. The signal line 59, which supplies timing pulses (for example, pulses generated by the light emitting element 13c) for giving the scanning position reference, is connected to one of the input lines of the above-mentioned microprocessor. The microprocessor functions to detect the time interval until the input thereto is changed to a lower level to thereby judge which one of the switches is actuated and performs the measuring and processing operations. The illustrated embodiment is advantageous in that since the photoelectric switches are sequentially scanned, it becomes unnecessary to energize a plurality of light emitting diodes at the same time so that the electric power consumption can be reduced and the electric circuit can be of simple construction. As an alternative arrangement, the measuring mode selecting switch assembly 7 may be positioned on the carrying bar 6. Further, a partition plate may be provided between individual switches for the purpose of avoiding erroneous actuation of the switches due to leaking light. The invention has thus been shown and described with reference to specific embodiments, however, it should be noted that the invention is in no way limited to the details of the illustrated arrangements but changes and modifications may be made without departing from the scope of the appended claims.

Claims: CLAIMS: 1. A surveying instrument including a base and a frame supported on said base1 said frame comprising a pair of posts carrying a telescope and a carrying bar extending between said posts, electric means provided in said frame for electrically detecting an angle in a vertical plane of said telescope, measuring mode selecting switch means of contactless type provided on said frame. 2. A surveying instrument according to claim 1 wherein said measuring mode selecting switch means is a photo-electric switch. 3. A surveying instrument according to claim 2 wherein said photo-electric switch includes paired light emitting elements and light receiving elements which are so arranged that when a light path between one of said light emitting element and the light receiving element which is paired with said one light emitting element is blocked, measuring mode is changed. 4. A surveying instrument according to claim 3 wherein said measuring mode selecting switch means includes paired light emitting elements and light receiving elements, said paired light emitting and light receiving elements being synchronously scanned. 5. A surveying instrument according to claim 1 wherein said measuring mode selecting switch means is provided on said post. 6. A surveying instrument including a base and a frame supported on said base, said frame comprising a pair of posts carrying a telescope, electric means provided in said frame for electrically detecting an angle in a vertical plane of said telescope, measuring mode selecting switch means of contactless type provided on said frame.

Inventors: KIMURA, KAZUAKI, TAMAKI, HIROSHI
Applicants: TOKYO KOGAKU KIKAI KABUSHIKI KAISHA
Application year: 1982
Main classification: G01C3
IPC codes: G01C1, H03K17, G01C15