Distance measurement device

A distance measuring device including a casing bearing a visual display and incorporating therein a transmitter for directing signals toward a selected surface; a receiver for detecting echoes from the selected surface; distance calculating circuitry for measuring the distance to a selected surface in accordance with the transit time of the signal; visually displaying the calculated distance; memory for storing at least two displayed distances measured in perpendicular directions; multiplication circuitry for multiplying the stored measurements; and visually displaying the product of the multiplication. The device further includes a key to effect the operation of the device whereby a distance is displayed, another key to initiate the storage of a displayed distance; and a key to initiate the multiplication of the stored distance measurements.

The present invention relates to a distance measuring device. 
Distance measurement devices which operate by remote sensing are well 
known. Typically they use ultrasonic waves to measure the distance from 
the device to a remote object, such as the far wall of a room. It is known 
to provide a facility on such devices for automatically computing the 
floor area or volume of a room from the measured dimensions. 
According to the present invention there is provided a distance measuring 
device including a casing incorporating therein a transducer for 
transmitting and directing signals externally of the casing towards a 
selected surface and for receiving the signals reflected from the selected 
surface, circuit means for monitoring the transmission of the signals and 
the receipt thereof arranged to provide a distance output signal dependent 
upon the time that elapses between transmission and receipt of the signals 
from the selected surface, means for storing the distance output signals 
corresponding to at least two distances to respective surfaces in at least 
two planes at right angles to one another, one or more manually operable 
function keys on the casing, function circuit means connected to said 
function keys arranged to apply resective algorithms to the at least two 
distance output signals and arranged to drive a first visual display 
mounted on the casing to display directly the results of the distance 
output signals in terms of each respective function. 
The transducer may be an ultra-sonce transducer. 
The distance measuring device may include a generally conventional 
electronic calculator mounted in the casing, associated with a visual 
display, arranged to receive the distance output signals, in which the 
calculator is arranged to be manually controlled to add, subtract, 
multiple and divide the distance output signals in a normal way to provide 
a computed calculation signal based thereon, and in which each function 
key is operable to supply the computed calculation signal to said function 
circuit means. 
The first visual display and the display associated with the calculator may 
comprise a single display. 
The distance measuring device may include at least four different function 
keys and preferably eight or more. 
The function keys and function circuit means may be arranged to apply 
algorithms to produce displays of results based on area and volume 
measurements. 
By providing an electronic calculator on the device, the user can readily 
calculate quantities which are dependent on a measured distance, area or 
volume, such as, for example, the amount of paint or wallpaper needed to 
decorate the room. 
Preferably, the measured values are input directly to the calculator. 
Other preferred features and advantages will be apparent from the following 
description and the accompanying claims. 
The invention will be further described by way of example with reference to 
the accompanying drawings.

Referring to the drawings, a distance measurement device 1 in accordance 
with the invention comprises a plastics casing 2 having two halves 2a, 2b 
bonded or screwed together. The casing 2 has front and rear faces 4, 6, 
side walls 8, 10, a top wall 12 and a bottom wall 14. 
At the top wall 12 transducer means 16 is positioned for transmitting an 
ultrasonic signal and detecting the signal reflected from a distant 
object. The time elapsed between the transmission and detection of the 
reflected signal is measured by electronic circuitry (not shown) and used 
to estimate the distance of the object. Typically, the device will operate 
with acceptable accuracy over a range of 0.6 m to 10 m. 
The device is operated by an on board battery power supply. 
The front face 4 carries a liquid crystal display 17 and a keyboard 18. The 
keyboard has buttons labelled SUM, CLR SUM, MODE, RECALL, L, W, H, SQUARE 
and CUBE. The display displays the measured distance in imperial (feet and 
inches) or metric (meters) units and the units displayed are toggled 
between by pressing the mode key. 
To measure distance the `ON` button 28 on the side 8 is pressed. All digits 
in the display 17 are momentarily illuminated and then the measured 
distance calculated from the bottom wall 14 to the object is displayed. 
The displayed measurement is then stored as Length (L), Width (W) or 
Height (H) by depressing the appropriate button. This will replace any 
reading previously stored. Depressing the `SQUARE` key will cause the area 
(L.times.W) to be displayed, and depressing the `CUBE` key will cause the 
volume (L.times.W.times.H) to be displayed. 
The `SUM` key can be used to sum two consecutive measurements and the `CLR 
SUM` to clear the stored sum. Pressing `RECALL` will recall the last 
displayed figure. 
The distance measurement device 1 is provided on its rear face 6 with a 
calculator 20. Calculator 20 comprises a keyboard 22 and liquid crystal 
display 24. 
The keyboard 22 includes key inputs for numerals 0 to 9, arithmetic 
operations +, -, .times., .div.=, decimal point, .+-. toggle, %, AC (all 
clear), ON/CE (turn on from sleep mode, or cancel entry in operating 
mode), M+, M- (add or subtract displayed value from memory), M.sup.R c 
(memory recall and clear) and MU (mark-up). 
The operations performed on actuation of these keys are standard, the 
mark-up operation being as follows: 
EQU 100 [MU] 20 [%] giving 125 (100/(1-20%)) 
EQU 125 [-] 100 [MU] giving 20% (((125-100)/125) 100%) 
A RECALL key wakes up the calculator and causes the last displayed value to 
be displayed. The MODE key toggles between imperial and metric units. 
The upper bank of keys 26 is for performing predetermined functions. The 
functions are chosen to suit a particular trade, in this example the 
building or decorating trade. The keys operate as follows on the displayed 
figure. 
AIR: calculates the amount of cooling required for a room, and hence the 
initially displayed figure should be the room volume 
HEAT: calculates the amount of heating required for a room 
TILE C: calculates the number of ceiling tiles required, and hence the area 
(L.times.W) should be the initially displayed figure 
TILE F: calculates the number of floor tiles 
PAINT: calculates the volume of paint required 
RUG: calculates the area of carpet or the like required 
4.times.8: calculates the number of panels required 
ROLL: calculates the number of rolls of wallpaper required 
Preferable algorithms for the above calculations are as follows: 
__________________________________________________________________________ 
UNIT ANNUNCIATORS 
__________________________________________________________________________ 
[[IMPERIAL MODE]] 
[AIR] ROUND ((4300 + [(INP/8) - 100] .multidot. 13.5), 
BTU/HR BTUC/HR 
[HEAT] 
ROUND ((INP .multidot. 3.92495), 0) 
BTU/HR BTUH/HR 
[TILE-C] 
ROUND ((INP - 8), 2) TILES TILE-C 
[TILE-F] 
ROUND ((INP .multidot. 1.44), 2) 
TILES TILE-F 
[PAINT] 
QUARTER 
((INP - 300)) GALLON GAL 
[RUG] ROUND ((INP - 9), 2) SQ. YARDS 
SQ. YDS 
[4 .times. 8] 
ROUND ((INP - 32), 2) PANEL PNL 
[ROLL] 
ROUND ((INP - 57), 2) ROLL ROL 
[[METRIC MODE]] 
[AIR] ROUND ((4300 + [(INP .multidot. 4.405655) - 100] .multidot. 13.5), 
0) BTU/HR BTUC/HR 
[HEAT] 
ROUND ((INP .multidot. 138.33569), 0) 
BTU/HR BTUH/HR 
[TILE-C] 
ROUND ((INP .multidot. 1.3437248), 2) 
TILES TILE-C 
[TILE-F] 
ROUND ((INP .multidot. 100), 2) 
TILES TILE-F 
[PAINT] 
QUARTER 
((INP - 6.1335165)) LITERS LTR 
[RUG] ROUND ((INP), 2) SQ. METER 
SQ. MTR 
[4 .times. 8] 
ROUND ((INP - 2.9768), 2) PANEL PNL 
[ROLL] 
ROUND ((INP - 5.302425), 2) 
ROLL ROL 
__________________________________________________________________________ 
REMARKS: INP stands for the input value. 
[TILEC] stands for CEILING TILE. 
[TILEF] stands for FLOOR TILE. 
The algorithms assume, inter alia, that a floor tile is 10 inches square 
(imperial) or 10 cm square (metric), a ceiling tile is 2 ft..times.4 ft., 
a gallon of paint covers 300 sq.ft., a roll of wallpaper covers 57 sq.ft., 
and a panel is 8.times.4 feet. 
The values are round to n decimal places, where n is defined in ROUND 
(exp.sup.N, n), or to the nearest higher QUARTER, e.g. 123.1 becomes 
123.25. 
Cooling load estimation is calculated according to 
EQU BTU/Hr=4,300+[((SE/8)-100).multidot.13.5 
where SE is the volume in cubic feet and it assumes a room height of 8 
ft. 
In the device as described, the measured or calculated values on display 17 
are input manually to the calculator 20 via keyboard 22. However, means 
may be provided for automatically transferring the values on display 17 to 
the memory registers or buffer of the calculator 20. The arrangement may 
be such that once the length, width, and height have been input, via 
keyboard 18, the values are input automatically to a buffer or memory 
store of the calculator 20, whence they can be operated on by means of the 
function keys 26. Hence the calculator 20 need not include the numeric 
input keys or arithmetic operation keys, however these are currently 
desirable for general use. Also the displays 17 and 24 may be one and the 
same display, the keyboards being on the same face of the housing. 
The calculator has a sleep function which operates if there is no keystroke 
for 120 seconds. The operation of the calculator is outlined in the 
flowchart, FIG. 4. 
An on-off switch, not shown, is provided to switch the device, including 
calculator 20, on and off. 
A common chip or processor may be used for the calculator 20 and keyboard 
18. 
Various other modifications may be made to the described embodiment and it 
is desired to include all such modifications as fall within the scope of 
the accompanying claims. The distance measuring devices according to the 
invention can be tailored to suit different trades. This enables carpet 
estimater to simply measure an area, taking two distance readings in 
planes at right angles and reading either the no. of rolls required, or 
the price of the carpeting directly and so on. A constant or a factor 
facility may be added to any function to automatically adjust the 
displayed output. For example to price dark paint to be applied to a light 
wall will require a factor to increase the paint required, air 
conditioning in a warmer climate will require more capacity, etc. Such 
factors may be "built in" to the function or available to add under extra 
manual control.