Level sensor

#1. Field of the Invention

#The present invention relates to a level sensor which measures a level by utilizing a laser beam emitted from an electronic leveling apparatus.

#2. Related Background Art

#FIG. 1 shows a plan view of the exterior of a prior art level sensor,

#FIG. 2 show a plan view of the exterior of a first embodiment of a level sensor of the present invention,

#FIG. 3 shows a plan view of the exterior of a second embodiment of the level sensor of the present invention,

#FIG. 2 shows a first embodiment of the present invention. In the present embodiment, the level sensor has a switch unit 12, including a power switch and an audio buzzer selection switch, and a photo-sensing unit 14 for detecting a laser beam emitted from a conventional electronic leveling apparatus, housed in a resin housing 11. A vertical deviation of the level sensor from the laser beam is detected in accordance with a signal detected by the photo-sensing unit 14. An LCD first display unit 13 and an LED second display unit 16 are provided to display the displacement, and a stepped scale 17 which has scales each corresponding to each of LED devices 16(+5)-16(-5) of the second LED display unit 16 is formed. A center scale 15 to allow center marking is provided, and an air bubble tube 19 for correcting the skew of the housing 11 and a buzzer opening 18 are formed.

#When the level sensor is vertically moved along the wall surface and the photo-sensing unit 14 detects the laser beam emitted from the electronic leveling apparatus, the output signal therefrom is processed by a signal processing circuit (not shown) so that an incident position of the laser beam to the photo-sensing unit is detected. Thus, the first LCD display unit 13 displays the relative displacement of the laser beam from the vertical center of the photo-sensing unit by a digital number and an arrow. The digital number is "0" for the center of the photo-sensing unit 14, and a plus or minus sign is associated with the digital number. In FIG. 2, "-2" is displayed. The LED device 16(-2) of the second LED display unit 16 which corresponds to "-2" is also energized. The stepped scale 17 having steps corresponding to the LED devices 16(+5)-16(-5) of the second LED display unit 16 has steps of 1 mm high. Thus, the operator may make a mark by a pencil 20 on the wall corresponding to the "-2" LED device 16(-2). Namely, if the displacement of the center of the photo-sensing unit 14 from the center of the laser beam is within .+-.5 mm, the operator can readily make the mark by following the lighting of the second LED display unit 16. Since the stepped scale 17 is formed on the top of the housing 11 of the level sensor to facilitate the marking, it is offset from the actual laser beam position. The conventional one-point detection (at the "0" position of the level sensor) may be attained by the arrow of the first LCD display unit 13 and the sensor scale 15.

#FIG. 3 shows a second embodiment of the present invention. It differs from the embodiment of FIG. 2 in that a first LCD display unit 31A, a second LED display unit 32A and a third LED display unit 32B for displaying an elevational position of the laser beam are provided on a longitudinal housing 31, and stepped scales 33A and 33B having steps corresponding to LED devices 32A(+5)-32A(-5) and 32B(+5)-32B(-5) of the second and third LED display units 32A and 32B, respectively, are formed. The two stepped scales 33A and 33B are vertically displaced from each other by 50 mm.