CA2550191A1 - Portable inclinometer - Google Patents

Abstract

The present invention is to provide a portable electronic inclinometer with simplified structure, improved anti-impact and anti-vibration properties, and high precision. The inclinometer comprises a casing, a display unit and a set of operational buttons provided on the casing, a measuring circuit installed inside the casing and a power supply supplying power to the display unit and the measuring circuit. The casing includes a reference measuring surface. The measuring circuit includes a tilting angle sensing unit. The tilting angle sensing unit comprises a gas-filled sealed chamber, a heating element and a set of temperature ceasing elements arranged inside the chamber. The set of temperature sensing elements comprises at least one pair of temperature sensing elements symmetrically arranged about the heating element. The tilting angle sensing unit has a first axis extending across the heating element. A first pair of temperature sensing elements symmetrically arranged about the heating element is disposed along the first axis. The first axis is parallel to the reference measuring surface of the casing.

Description

AL~VI'ltCy ,LJt)Cket No. 486 P 116 PATENT
PORTABLE )<NCLINOMETER
DESCRIPTION
CROSS-REFERENCE TO RELATED APFLICATIONS
[OOOT] 'lltis application claims priority to Chinese Application No.
200320072771.$, filed on June 17, 2005, the entire disclosure of which is incorporated herein by reference.
TEC,fEVICAL 1=tELD

[0002] The present invention relates to an inclinornetar, and particularly to a partabla electronic inclinometer by utilizing the measurement ptinciple of hot air mass convection.

[0003] It is a common practice to measure the tilting angle of a plane surface in building engineering, house decoration and other constructional engineering. A simple inclinometer could be a calibrated bubble or a solid-petndulum with a poi»ter and a dial.
However, the measure precision with them is not sufFcient and the measurement error is rather high resulting from reading by an operator himself according to the indlcadng of the abova-mentioned devices.

(0004] More precise electronic inclinometers in the art normally are electrolytic type inclinometer and solid-pendulum typo inclinometer. Based on the principle that the surface of electrolyte always keeps level, an electrolytic type inclinometer measures the depth variations of its electrodes immerged in the electrolyte to obtain the tilting angle. A
solid-pendulum type inclinometer, based On the principle that the pendulum will always keep plurxtb under gravitation, converts the offset of the pendulum from a reference position into an electrical signal to calculaoe the tilting angle. However, these electronic inclinometers have rather complicated structures, and poor anti-impact and anti-vibration performance, and that' are easily damaged.
[0005 'The present invention is provided to solve the problems discussed above and other problems, and to provide advantages and aspects not provided by prior inclinometers of this type. A full discussion of the features and advantages of the present invention is deferred to Attorney bocket ~to. 4386 P 116 the following detailed description, which proceeds with reference to the accompanying r l drawings. ~' SUMMARY OF 'THE INVENTIQN
[0006] An object of the invention is to provide a portable electronic ineliaometer with simplified structure, improved anti-impact and anti-Vibration properties, and with high precision.
[0007] In order to fulfill the above object, as inclinometer provided by this invention comprises a casing, a measurement display unit and a set of operational buttons provided do the casing, a measuring circuit installed inside the casing and a power supply supplying power to the display unit and the measuring circuit. The casing comprises a reference measuring surface. The measuring circuit comprises a tilting angle sensing unit which includes a gets-filled sealed chamber. Inside the chamber, there is a heating element and a set of temperature sensing tlements which comprises at least one pair of temperature sensing elements symrnottlcally arranged about the hcadng element.
[0008] During measuring, the gas inside the sealed chamber is heated by the heating element with a result that a hot gas mesa which can be moved freely is the chamber is created. While the tilting angle sensing unit is placed. horizontally, the temperature distribution of the hot gas mass is centrally symmetric about the heating element. In this case, the temperatures detected by alI the temperature sensing elements are identical and therei'orc their output electronic signals are on a same level. 0a the other hand, when the dldng angle sensing unit is fitted, owing to the gravitation, free convection will occur with the hot gas mass, which will result in a variation o! the temperature distribution of the hot gab mass, so that there wilt be a difference between the output electronic signals from each pair of temperature sensing elements. The diPterenco is propordonal to the tilting degree of the tilting angle sensing unit and therefore, based on the diffcxence, the tilting angle can be calculated.
By utilizing the freely conveetable hot gas mass as a gravity block, the structure of the inclinometer can be simplified with greatly improved and-impact and and-vibration properties.

Attorney Docket No. 4386 P a 16 [0009] According to the present invention, the tilting angle sensing unit of the measuring circuit of the inclinometer has a lust axis extending across the heating element. A first pair ofl temperature sensing elements located symmetric about the heating element is disposed along ;
the first axis . The first axis is parallel to the reference measuring surface of the casing, so I
that the tiling angle of the first axis will be the tilting angle of the reference measuring surface.
[0010] 'r'he tilting angle sensing unit of the measuring circuit of the inclinometer according to the present invention may further have a second axis extending across the heating element and perpendicular to the first axis. A second pair of temperature sensing elements which are located symmetric about the heating element is disposed along the seeon~
axis. The second axis is perpendicular to the reference measuring surface of the casing.
Combining the measurements based on both ~e first axis and the second axis, the actor in the' temperature sensing part resulting from temperature variation can be partially decreased and the precision of measurement can be further improved.
(0011] Other features and advantages of the invention will be apparent from the following specification taken in conjunction with the following drawings.
HIUEF DESCRIPTION OF THir DRAWiTTGS
[OO1Z] To understand the present invention, it will now ba described by way of exempla, with mferenca to the accomipanying drawings in which:
[0013] IPtCi. 1 is a parapacdve view of an inclinometeac according to a prafanad embodiment of the preset invention;
[0014] FIQ. 2a is a schematic diagram of a tilting angle sensing unit in a measuring circuit of the inclinometer according to the preferred embodiment of the present invention;
[OOis] FIC3. 2b is a schematic diagram of the tilting angle sensing unit in Figure 2a during a measuring process;
[0016] FIG. 3a is a schematic diagram of a tilting angle sensing unit in a measuring circuit of an inclinometer according to another preferred embodiment of the present invention; and, Attorney Docket No. 4386 P 116 [0017] FIG. 3b is a schematic diagram of the tilting angle sensing unit in Figure 3a during', a measuring process.
DETAILED DESCRIPTION
[OOIBj While this invention is susceptible of embodiments in many different forms, thet'e is shown in the drawings and will herein be described in detail preferred embodiments of the invention with the understanding that the present diseiosurc is to be considered as as exemplification of the principles of the invention and is not intended to limit the broad aspect of the invention to the embodinnenta illustrated.
[0019] figure 1 illuminates an inclinometer 1 according to a preferred embodiment of the present invention. The inclinometer 1 comprises a casing I 1, a display unit 12 and a set of buttons on the casing 11, and a power supply (not shown in Figure 1) and a measuring circuit (not shown in Figure I) bath of which era installed inside the casing 11. The set aP buttons comprises a power button 14. Obviously, other buttons oar be provided according to requirements of the functions. For example, a storing button 16 can be added to store the last measurement data. The inclinometer 1 bas a reference measuring surface. It is preferred to predetemnine a bottom surface 18 of the casing 1 l as the reference measuring surface. 'Che displayed measurement data on the display unit 12 is the tilting angle of the reference measuring surface 18. During measuring, it is necessary to abut the reference measuring surface 18 against a surface to be measured. ?hose skilird in the art will understand that other appropriate portions of the casing can also be used as the reference measuring surface.
[0020] Figure 2a is a principle schematic diagram of a measuring circuit of the inclinometer 1 according to the preferred embodiment of the present invention.
The measuring circuit comprises a tilting $ngle sensing unit 20 ant! a signal processing unit (not shown). The tilting angle sensing unit 20 eamprisos a gas-filled sealed chamber ZO1. Inside the sealed chamber 201, a heating element 202 and a pair of temperature sensing elements 203 and 204 are contained. The gas filled in the sealed chamber 20I may be air or other type of appropriate gases. The heating element 202 is located in the central part of the sealed ehambar 201. The temperature sensing elements 203 and 204 are located symmetrically about the heating element 202. The tilting angle sensing unit 20 has an axis ~C
extending across the Attorney Docket No. 4386 P 116 heating element 202 and another axis Y which is also extending across the heating element 202 and orthogonal to the axis X. The temperature sensing elements 203 and 204 are both disposed along the axis X, arid their output cerminals are separately connected to the signal processing unit, which, in turn, will prrx:ess the output signals from tho temperature sensing elements 203 and 204 and calculate the tilting angle of the axis X.
[Op2I] While the inclinometer 1 is in operation, the heating element 202 will ba used to heat the gas in the sealed chamber 201 to create a hot gas mass. If the axis ~t is is horizontal direction, the temparattvre distribution of the hot gas mass is symmetric about the axis Y, the temperature values detected by the temperature sensing elements 203 and 204 are thus identical. And therefore their outpat electronic signals is identical too.
knee the axis X is tllted, due to the gravitation, free convection will occur with the hot gas mass, which will result in an asymmetric tesmperature disirlbution about the axis Y, the tennperature values detected by the temperature sensing ctemcnts 203 and 204 Is thus different from each other, and therefore, there is a differonce between tho two output electronic signals. The diPPerenca is a function of the tilting angle of the axis X, which can be expressed as: x r g sin a, wherein x is the difference between the output electrtmic signal from the temperature sensing elements 203 and 204 respectively, g is the acceleration of gravity and a is the angle between axis X and horizontal plane, as shown in Figure 2b, Then, a formula calculating the angle a between the axis X and the horizontal plant can Ix obtained: a = sill ~ (x1g).
Preferably, the axis X of the tilting angle sensing unit 20 is parallel to the reference surface 18 on the easing 1. In this case, the tilting angle of the axis X is the tilting angle of the rafetnnco surface and no additional calculation is needed.
[0022] By means of the above mentioned method, a precise mea~surerr~nt of a tilting angle relative to the horizontal plane can ba aahievcd in the range of 0-90 degrees. It should be noted that while a tilting angle is close to 90°, the variation of the difference betwoen the output electronic signals from the two temperature sensing elements will not ba big enough, and as a result, it is difficult for the signal processing circuit to precisely distinguish these angles. However, in most cases, ttte above mentioned method can satisfy the requirement for tilting angle measurement.
[0023] According to another preferred embodiment of the present invention, the tilting attgla sensing unit 20 may further include another pair of temperature sensing elements 205 Attorney Iaoeket No. 4386 P 11b and 206 which are locaeed along the axis Y and symmetric about the heating element, as shown in Figuro 3a. The output terminals of the temperature sensing elements 205, 206 are also connected to the signal processing unit of the measuring circuit. In this embodiment, the tilting angle sensing unit 20 is artanged vertically with its axis X parallel to the reference measuring surface and axis Y perpendicular to the reference measuring surface.
In this case, the angle between the axis Y and a horizontal plane is 90° - a. Since x a g sin a, then y = g cos a, where y is the diffcn:rtce between the output signals from temperature sensing elements 205 and 206 which are located along the axis Y respdctively. From the above formulae, a= tari' (x/y) can be derived. In this ease, based on the arctangent function, anglesi close to 90° can bo precisely distinguished by the tilting angle sensing unit. Moreover, the measurement errors of the tilting angle sensing unit 20 at the axis X and the axis Y, which rtsult from the influence oP the ambient temperature and the elevated temperature of the measuring circuit itself, can thus be offset against each other. Therefore the measurement precision can be further improved.
The above description and drawings of the preferred embodiments arc only used to describe and illustratie the principle and content of the present invention, but not to limit the claimed scope of the present invention. It will be understand by those ordinary skilled in the art that there will be other alternatives, modifications and equivalents within the spirit and scope of the present invention. The spirit and scope of the invention are defined by the appended claims.

Claims (20)

What is claimed is:

1. An apparatus for measuring an inclination of a substrate, comprising:

a casing having a measuring surface;

a chamber disposed within the casing;

a heating element for heating a gas within the chamber; and, a temperature sensor for sensing the temperature of the gas.

2. The apparatus of Claim 1, further comprising;

a processing unit far receiving a signal representative of the temperature of the gas.

3. The apparatus of Claim 2, wherein the processing unit comprises logic for determining a temperature differential based on data read from the signal.

4. The apparatus of Claim 2, wherein the processing unit comprises logic for executing a trigonometric function involving data read from the signal.

5. The apparatus of Claim 1, further comprising:

a second temperature sensor for sensing the temperature of the gas, wherein the temperature sensor and the second temperature sensor are positioned within the chamber symmetrically around the heating element.

6. The apparatus of Claim 5, wherein a difference between a first temperature sensed by the temperature sensor and a second temperature sensed by the second temperature sensor represents a temperature differential.

7. The apparatus of Claim 5, wherein the temperature sensor and the second temperature sensor form a first axis parallel to the measuring surface.

8. The apparatus of Claim 7, further comprising:

a third temperature sensor; and, a fourth temperature sensor, wherein trio third and fourth temperature sensors are positioned within the chamber symmetrically around the heating element, forming a second axis orthogonal to tho first axis and perpendicular to the measuring surface.

9. The apparatus of Claim 8, wherein a difference between a first temperature sensed by the third temperature sensor and a second temperature sensed by the fourth temperature sensor represents a temperature differential.

10. An apparatus for measuring an inclination of a substrate, comprising:

s sealed chamber disposed within a casing and containing a gas;

a heating element disposed in the middle of the sealed chamber, wherein the heating element heats the gas;

a first temperature sensor for measuring a first temperature of the gas at a first location within the sealed chamber;

a second temperature sensor for measuring a second temperature of the gas at a second location within the sealed chamber; and, a processing unit for determining the inclination of the substrate by executing a function on a temperature differential represented by a difference between the first and second temperatures.

11. The apparatus of Claim 10, wherein the first and second locations are positioned symmetrically around the heating element and form an axis parallel to the substrate.

12. The apparatus of Claim 10, further comprising:

a third temperature sensor for measuring a third temperature of the gas at a third position within the sealed chamber; and, a fourth temperature sensor for measuring a fourth temperature of the gas at a fourth position within the sealed chamber.

13. The apparatus of Claim 12, wherein the third and fourth locations are positioned symmetrically around the heating element and form an axis perpendicular to the substrate.

14. The apparatus of Claim 12, wherein the function is executed on the temperature differential and a second temperature differential represented by a difference between the third and fourth temperatures.

1S. The apparatus of Claim 10, further comprising:

a display disposed on an exterior of the casing, for displaying the inclination of the substrate.

16. The apparatus of Claim 10, wherein tho function is an inverse trigonometric function.

17. The apparatus of Claim 10, further comprising:

a power supply for supplying electrical power to the temperature sensors, the heating element and the processing unit.

18. The apparatus of Claim 10, further comprising:

an operational button disposed on an exterior of the casing, for transmitting a signal to the heating element to heat the gas.

19. The apparatus of Claim 10, wherein tho processing unit comprises logic for offsetting the first and second temperatures against a base reference temperature representing an ambient temperature of the casing.

20. An apparatus for measuring an angular inclination of a substrate, comprising:

a casing having a measuring surface to be positioned parallel to the substrate;

a sealed chamber disposed within the casing, wherein the sealed chamber contains a gas;

a heating element disposed at a central point within the sealed chamber for heating the gas;

a first temperature sensor disposed at a first position within the sealed chamber for sensing a first temperature of the gas;

a second temperature sensor disposed at a second position within the sealed chamber for sensing a second temperature of tip gas, wherein the first second positions are disposed symmetrically around the heating element and form a first axis parallel to the measuring surface;

a third temperature sensor disposed at a third position within the sealed chamber for sensing a third temperature of the gas;

a fourth temperature sensor disposed at a fourth position within the sealed chamber for sensing a fourth temperature of the gas, wherein the third and fourth positions are disposed symmetrically around the heating element and form a second axis orthogonal to the first axis and perpendicular to the measuring surface; and, a processing unit for receiving electrical signals representative of the first, second, third and fourth temperatures, wherein the processing unit comprises:

first logic for determining a first temperature differential between the first and second temperatures;

second logic for determining a second temperature differential between the third and fourth temperatures; and, third logic for executing an arctangent function on the first and second temperature differentials, wherein the arctangent function is the angular inclination of the substrate.