GB2175390A

GB2175390A - Probe for sensing outlines

Info

Publication number: GB2175390A
Application number: GB08512189A
Authority: GB
Inventors: Dr Trevor Frank Jones
Original assignee: Coal Industry Patents Ltd
Current assignee: Coal Industry Patents Ltd
Priority date: 1985-05-14
Filing date: 1985-05-14
Publication date: 1986-11-26
Also published as: GB8512189D0

Abstract

A probe for sensing outlines, as for example, outlines of relatively dark or light areas on a photograph or illustration, comprises a holder (10) at least a part of which is light transparent or translucent, a lens (11) mounted in the holder to view the outline to be sensed, and a photoelectric diode unit (12) mounted on the holder and arranged to receive light waves from the lens. The photodiode unit derives electrical signals indicative of the outline sensed by the probe. The photodiode unit may comprise an annular portion and a circular portion of substantially equal areas. <IMAGE>

Description

SPECiFICATION Probe for sensing outlines This invention relates to probes for sensing outlines. In particular, although not exclusively, the present invention relates to probes for sensing outlines between relatively dark and light areas on a photograph or illustration.

It is known to place a photograph of a coal pile on a plotter and for an operator to manually control the movement of an eyepiece traversing around the outline of the coal pile.

The operator controls movement of the eyepiece such that the eyepiece is taken in a series of steps around the outline, the operator viewing the outline through the eyepiece and halting its movement when it reaches a desired aligned position. At each step a computer connected to the plotter monitors the co-ordinates of the desired aligned position.

Typically, about five hundred different steps are negotiated for each sensed coal pile so that upon completion of the traverse the computer has on record detailed profile parameters of the pile. Unfortunately, the task for the operator to conduct the traverse is time consuming and tedious.

An object of the present invention is to provide a probe for sensing outlines which tend to reduce or overcome the above mentioned problem.

According to the present invention a probe for sensing outlines comprises a holder at least part of which is light transparent or translucent, a lens mounted in the holder to view the outline to be sensed, and a photoelectric diode unit mounted on the holder and arranged to receive light waves from the lens, the photoelectric diode unit deriving electrical signals indicative of the outline sensed by the probe, in use, the derived signal being fed to processor means.

Preferably, the photoelectric diode unit comprises an annular photodiode.

Advantageously, the photoelectric diode unit also comprises a circular photodiode.

Preferably, the circular and the annular photodiode have substantially identical areas.

Conveniently, the probe is part of a plotter for including a mounting table for photographs or illustrations.

By way of example, one embodiment of the present invention will be described with reference to the accompanying drawings, in which: Figure 1 show a diagrammatic view of equipment including a probe and a plotter constructed in accordance with the present invention; and Figure 2 is a diagrammatic longitudinal section taken through a probe constructed in accordance with the present invention, the probe being shown on a greatly enlarged scale to that of Fig. 1.

Fig. 1 illustrates a plotter 1 having a mounting deck upon which is mounted a photograph or illustration showing the relatively dark outline of a coal pile 2. The plotter has a probe 3 movably mounted on a carrier arrangement 4 such that the probe can be positioned in a series of controlled steps over the entire area of the photograph. The probe is electrically connected to a processing control unit 5 via a lead 6. Typically, the probe 3 is provided in place of a pen usually provided on a plotter.

The equipment also comprises a computer and/or monitoring control unit 7 electrically connected to the processing control unit by a connecting lead 8.

Fig. 2 illustrates details of the probe 3 which comprises a tubular holder 10 of light transparent or translucent material such that the area of the photograph adjacent to the base of the holder is illuminated. A lens 11 is mounted in the holder at a distance substantially equal to its focal length above the base of the holder. The holder also supports a photoelectric diode unit 12 arranged to receive light waves from the lens and to derive electric signals indicative of the light received. The derived signals are transmitted via a connector 13 and the aforementioned lead 6 to the processing control unit.

Although details of the photodiode unit are not shown in the drawing in a preferred embodiment it comprises an annular photodiode mounted around a circular photodiode, each diode having a substantially equal area.

In use, a photograph or illustration of a coal pile is mounted on the plotter deck with the probe positioned at top left-hand corner as seen in Fig. 1. The plotter is activated such that it positions the probe until it senses the outline of the coal pile. The diodes are arranged, for example, such that when the probe is sensing the relatively light coloured background a positive signal is derived by the probe. If the probe is sensing the relatively dark coloured coal pile then a negative signal is derived by the probe. When the probe is positioned such that the outline of the coal pile is observed and half the view area is covered by the relatively light background and half is covered by the relatively dark coal pile then a zero signal is derived.

Upon the probe sensing the outline of the coal pile the computer records the co-ordinates of the probe and initiates a command signal to the processing control unit to move the probe in the x direction by a desired preselected amount. The probe is positioned in the y direction to relocate the outline of the coal pile. Again the co-ordinates of probe are recorded by the computer.

The process is repeated until the probe has fully traversed the outline of the coal pile and has reached the bottom left hand corner of the photograph or illustration as seen in Fig.

1. By this time the computer has recorded the required preselected number of co-ordinates around the outline of the coal pile.

From the above description it will be appreciated that the present invention enables the outline of the coal pile to be sensed and recorded with a minimum involvement of the operator.

The invention provides a relatively inexpensive means for sensing outlines on photograph or illustrations.

Claims

1. A probe for sensing outlines, comprising a holder at least part of which is light transparent or translucent, a lens mounted in the holder to view the outline to be sensed, and a photoelectric diode unit mounted on the holder and arranged to receive light waves from the lens, the photoelectric diode unit deriving electrical signals indicative of the outline sensed by the probe, in use, the derived signal being fed to processor means.

2. A probe as claimed in claim 1, in which the photoelectric diode unit comprises an annular photodiode.

3. A probe as claimed in claim 2, in which the photoelectric diode unit also comprises a circular photodiode.

4. A probe as claimed in claim 3, in which the circular and the annular photodiode have substantially identical areas.

5. A probe for sensing outlines, substantially as described herein and substantially as shown in the accompanying drawings.

6. A plotter including a probe as claimed in any one of the preceding claims.