Geometrical instruments – Straight-line light ray type – Rod or target
Utility Patent
1998-12-01
2001-01-02
Gibson, Randy W. (Department: 2859)
Geometrical instruments
Straight-line light ray type
Rod or target
C033S294000, C356S370000, C356S004080, C702S154000
Utility Patent
active
06167629
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an electronic level for automatically determining a collimated position and a leveling rod which is used in combination with the electronic level.
2. Description of the Related Art
As an electronic level of this kind and a leveling rod to be used with the electronic level, there has hitherto been known, for example, in Japanese Published Unexamined Patent Application No. 4959/1995 the following. Namely, the leveling rod has thereon a first pattern in which marks having the same width are arranged at a first pitch and a second pattern in which marks are arranged at a second pitch which is different from the first pitch. The leveling rod is collimated to detect the first and second patterns, and then the detected signals are processed in an analog fashion, whereby the collimated position is obtained.
In the above-described conventional electronic level, the collimated position is obtained on the basis of analog processing of the first and second patterns arranged on the leveling rod. Therefore, it is likely to be subject to disturbances. For example, background or any obstacle between the leveling rod and the electronic level will disable the measurement.
Japanese Patent Application No. 194321/1996 discloses a leveling rod for an electronic level having a plurality of bar marks disposed adjacent each other in a longitudinal direction along the leveling rod and in parallel with each other. The width dimensions of the bar marks in the longitudinal direction of the leveling rod are identical with each other. The ratios of pitches of respectively adjoining bar marks are represented by a plurality of integers. A permutation of values continuously chosen in a predetermined number from a sequence of numbers of the ratios of respective pitches is made to be different from a permutation chosen from any other position of the sequence of numbers. There is also disclosed therein an electronic level having: a pattern detecting portion (or means) for detecting an array pattern of the bar marks on the leveling rod; a memory portion (or means) for storing therein the sequence of numbers in advance; and a computation portion (or means) for obtaining, based on a detected signal from the pattern detecting portion, with which part of a sequence of numbers in the memory portion a permutation of ratios of pitches of respectively adjoining bar marks coincides. The collimated position is thus obtained from the position of the part of the coincidence. In this prior art, since the array pattern of the marks on the leveling rod is digitally processed, it is less sensitive to disturbances than that of analog-processing type disclosed in the above-described Japanese Published Unexamined Patent Application No. 4959/1995.
In the art disclosed in the above-described Japanese Patent Application No. 194321/1996, however, there is a possibility that an obstacle lies between the leveling rod and the electronic level. In case one mark is thus hidden behind the obstacle, it is impossible to read both the upper pitch and the lower pitch of the marks which lie on the upper side and the lower side, respectively, of the hidden mark. It is therefore impossible to obtain a permutation made up of that number of integers which is required to obtain the collimated position from the image within the collimated range.
On the other hand, if the kind of integers forming the sequence of numbers is increased, it is possible to reduce the number of figures required to determine the collimated position, i.e. the predetermined number of integers to be extracted or chosen to form a permutation. This means that the number of marks which are present within the collimated scope may be smaller in number. Accordingly, measurement can still be carried out even if the distance between the leveling rod and the electronic level becomes smaller with a consequent smaller or narrower collimated scope. When the kind of integer is increased, on the other hand, the discrimination of marks becomes difficult. Also a mistake tends to be caused under the influence of disturbance when the distance between the leveling rod and the electronic level is large. Therefore, it is impossible to increase the distance between the leveling rod and the electronic level to a large extent.
Reduction in the kind of integers is advantageous for a large distance between the leveling rod and the electronic level. However it is required to increase the above-described predetermined number which is necessary to determine the collimated position. It is therefore impossible to largely reduce the distance between the leveling rod and the electronic level.
SUMMARY OF THE INVENTION
It is therefore an object of the present invention to resolve the problems mentioned above.
For achieving the object, there is provided according to the present invention a leveling rod for an electronic level having a plurality of bar-shaped marks disposed adjacent each other in a longitudinal direction along the leveling rod in parallel with each other and perpendicular to a length of the leveling rod, characterized in: that the marks are arranged at a constant pitch; that width dimensions of the marks in the longitudinal direction of the leveling rod are represented by a plurality of integers; and that a permutation of predetermined number of values chosen from a sequence of numbers made up of a sequential array of the ratios of the width dimensions is different from a permutation chosen from any other portion of the sequence of numbers.
In the prior art in which the pitch of marks is changed, it is impossible as mentioned above to discriminate two pitches if one mark cannot be detected. On the contrary, if the marks are arranged at a constant pitch and the permutation is obtained by changing the width dimensions of the marks, detection of only one width dimension is sacrificed should one mark be prevented from detection by an interfering obstacle which lies between the leveling rod and the electronic level.
Preferably, the width dimensions of at least two kinds of marks are set to such close values as will enable discrimination thereof when a distance between the electronic level and the leveling rod is shorter than a predetermined distance. A permutation of second predetermined number of values, which is different from said permutation of predetermined number of values, is made different from a permutation chosen from any other portion of the sequence of numbers even when the marks having close values are discriminated or regarded to be of the same dimension. Then, it is possible to reduce the number of marks to be chosen to form the permutation and thus to reduce the distance between the leveling rod and the electronic level since all marks can be clearly discriminated when the distance is small. In case the distance between the leveling rod and the electronic level is large, the distance at which the marks is discriminated can be made large by positively recognizing or regarding the width dimensions of at least two kinds of marks to be the same. If the width dimensions of a plurality of marks are recognized to be of the same dimensions, the kind of integers to represent the width dimensions of the marks is reduced. As a result, the number of marks necessary for determining or locating the collimated position is increased. However, when the distance between the leveling rod and the electronic level is large, the number of marks which fall under the collimated range is large, thereby offering no problem.
When the distance from the ceiling to the collimated position is obtained by suspending the leveling rod from the ceiling surface, it is impossible in the conventional art, in which the collimated position is obtained in an analog processing, to automatically detect that the leveling rod is in the inverted state. It is, therefore, necessary to memorize in the electronic level in advance that the leveling rod is in an inverted state and also to switch a calculating formula for processing analog signals obtained
Arent Fox Kintner & Plotkin & Kahn, PLLC
Gibson Randy W.
Sokkia Co. Ltd.
LandOfFree
Electronic level and a leveling rod for use in combination... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Electronic level and a leveling rod for use in combination..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Electronic level and a leveling rod for use in combination... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2441357