GB2266145A

GB2266145A - Radiation sensing device

Info

Publication number: GB2266145A
Application number: GB9307579A
Authority: GB
Inventors: Mark Stuart Parker
Original assignee: Individual
Current assignee: Individual
Priority date: 1992-04-14
Filing date: 1993-04-13
Publication date: 1993-10-20
Anticipated expiration: 2013-04-13
Also published as: GB9307579D0; GB9208231D0; GB2266145B

Abstract

A radiation sensing device for a sunshine recorder consists of a circular base plate 12 having four sensors 14 mounted thereon in equi-angularly spaced-apart positions which are also equi-distant from a central point on the base plate, and radiation-shielding means in the form of plate members 16 extending upwardly from the base plate and radiating radially outwards from said central point between the sensors to shield at least one of the sensors from radiation emitted from a point source such as sunlight so that the output from at least one of the sensors is different from the other sensors. The sensors are connected to a comparison means which activates a time recording device when the above difference in outputs from the sensors is detected. <IMAGE>

Description

"Radiation Sensing Device" This invention relates to a radiation sensing device and more particularly, but not exclusively, to a device for sensing and/or recording radiation emitted from a point source such as1 for example, sunlight.

One known sunlight recording device which is frequently used in meteorological stations consists of a glass sphere supported on a structure so that the sphere focusses the sunlight onto a recording card The focussed sunlight burns a hole in the card as the sun moves across the sky, a trace is formed on the card enabling the number of hours of sunlight t.o be calculated therefrom. It will be appreciated that this known of sunlight recording device suffers from the disadvantages that the device is relatively expensive and has a long response tine before a trace is formed by burning the card thus making the device inaccurate particularly where short periods of intermittent sunlight are to be recorded.

Another known sunlight recording device utilises a column of mercury in a tube onto which sun light is focussed so that the heat of the sunlight causes the mercury to expand and connect two electrical contacts and initiate operation of a timer to record the duration of the sunlight Here again, it will be realised that the device is relatively expensive to produce and has a poor response time due to the time required for the thermal energy of the sunlight to be absorbed by the mercury to effect expansion thereof leading to inaccuracies in the recordal of periods of intermittent sunlight.

The object of this invention is to provide a sensing device In which the above disadvantage of the known recorders are alleviated.

According to this invention, a radiation sensing device for sensing and or recording periods of Padiation from a point source such as sunlight comprises at least two radiation sensors and radiation shielding means interposed therabetween, wherein when the device is subjected to raddiation from a point source one of the sensors is at least partially shielded from the radiation so that the output therefrom is different from the output from the other sensor or sensors.

Preferably, the radiation sensors are mounted on a plane surface and are subjected to radiation from thereabove.

Preferably, also, the radiation shielding means extend. upwardly from the plane surface.

Four radiation sensors are, preferably, provided and are disposed at equi-angularly spaced-apart positions on the plane surface.

Preferably, the radiation shielding means comprises plate members extending radially outwards fro a central point between each of the radiation sensors.

Preferably1 also, the radiation shielding means comrises an additional plate member disposed above the sensors to shield t least one of the sensors from direct radiation when the point. source of radiation is directly above the radiation recording device.

The sensors, preferably, comprise photo-electric devices for detecting sunlight.

Preferably, adjustment means is provided for adjusting and bala.ncing the output of the sensors under conditions of diffused ambient radiation.

Preferably, also, -the outputs from the sensors are connected to comparison means for comparing said sensor outputs and producing an output signal therefrom when the output from any one sensor is different from the or any of the other sensors The comparison means is, preferably, connected to a time recording means which is activated by the output signal from the comparison means.

Preferably, the time recording means is remote from the comparison means and the output signal from the comparison means is supplied thereto by any form of signal transmission means.

A preferred embodiment of the invention will now be described, b way of example only, with reference to the accompanying drawings of which:- Figure 1 is a diagrammatic plan view a sensor array of a radiation sensing and/or recording device; Figure 2 is a side elevation of the sensor array; and Figure 3 is a block circuit diagram of the radiation sensing and/or recording device.

Referring now to the drawings, a radiation sensing and/or recording device indicated generally at 10 fu recording radiation from a point souce such as a sunlight recording device comprises a circular base plate 12 having tour sensors 1t, such as photo-electric cells, LDR's or the like, mounted thereon in equi-angularly spaced-apart it Ions said positions also being equi-distant fro a central point on the base plate 12.

Plate members 16 extending upmardly from the base plate 12 radiate radially outwards from said central point between the sensors 14 to shield at least one ef the sensors 14 from radiation emitted from a po lilt source such as sunlight, when the radiation is impinging on the base plate 12 from an oblique angle. A further plate member 18 is mounted on the top of the members 16 to shield at least one of the sensors 14 when the radiation is impinging on the base plate 12 at a near vertical angle such as when the sun is at its zenith.

Referring particularly to Figure 3 of the drawings, the electrical outputs from the four sensors 14 are adjustable by means of four variable resistors 20 to trim and balance the outputs fro the sensors 14 under conditions of diffused light when the sensors 14 are subjected to the same intensity of light The outputs from the sensors 14 are supplied to a circuit indicated generally at 22 comprising operational amplifiers 24, inverter buffers 26 and an "AND" gate 28 which compares the outputs from the sensors 14 and produces an output from the "AND" gate 28 when the output fro any '/ one of the sensors 14 15 of different value to the outputs from the other sensors 14.

The output from the "AND" gate 26 of the circuit 22 is used to activate a timing device (not. shown) . The timing device can be formed as an integral part of the recording device 10 i itself whose information can be down- loaded at predetermined periods such as daily, or the timing device can be remote from the device 1O and transmission means such as a radio-link. can be provided for transmitting a signal to the timing device whenever there is an output from the "AND" gate 26.

The uncomplicated nature of the construction of the sensing and or recording device 10 and the associated electrical circuitry enable a relatively inexpensive device to be produced which allows the hours of sunlight to be accurately recorded.

Although the above described device 10 is provided with four sensors 14 which are particularly suitable for recording sunlight without the orientation of the device 10 being critical to its operation, i will be appreciated that it would be possible to provide a sensing and/or recording device 10 having only two sensors which would operate on the same principle.

Furthermore, although the sensing and or recording device is particularly suitable fo recording the hours of sunlight, it could be used for other purposes cording to the type of radiation sensors utilised without departing from the scope of this invention.

Claims

What I claim is-

1. Pz radiation sensing device for sensing and/or recording periods of radiation from a point source such as sunlight comprising at least two radiation sensors and radiation shielding means interposed therebetween, wherein when the device is subjected to radiation fro a point source one of the sensors is at least partially shielded from the rad lat ion so that the output therefrom is different from the output from the other sensor or sensors.

2. A radiation sensing device according to Claim 1, wherein the radiation sensors are mounted on a plane surface and are subjected to radiation from thereabove.

3. A radiation sensing device according to Claim 2, where in the radiation shielding means extends upwardly from the plane surface.

4. A radiation sensing device according to Claim 2 or Claim 3, wherein tour radiation sensors are provided and are disposed at equ I-angularly spaced-apart positions on the plane surface.

5. A radiation sensing device according to any one of the preceding claims, wherein the radiation shielding means comprises plate members extending radially outwards from a central point between each of the radiation sensors.

6. A radiation sensing device according to Claim 5, wherein the radiation shielding means comprises an additional plate member disposed above the sensors to shield at least one of the sensors from direct radiation when the point source of radiation is directly above the radiation recording device.

7. A radiation sensing device according to any one of the preceding claims, wherein the sensors comprise photo-electric devices for detecting sunlight.

8. h radiation sensing device according to any one of the preceding claims, where In adjustment means is provided for adjusting and balancing the output of the sensors under conditions of diffused ambient radiation,

9. A radiation sensing device accordion to any on of the preceo.inO ing claims, wherein the outputs from the sensors are connected to comparison means for comparing said sensor outputs and producing an output signal therefrom when the output from any one sensor is different from the or any of the other sensors.

10. A radiation sensing device according to Claim , wherein the comparison means is connected to a time recording means which is activated by the output signal from the comparison means.

11. A radiation sensing device according to Claim 10, where in the time recording means is remote from the comparison means and the output signal from the comparison means is supplied thereto by any form of signal transmission means.

12. A radiation sensing device according to Claim 1, constructed, arranged and adapted to operate substantially as hereinbefore described with reference to, and as illustrated by, the accompanying drawings.