GB2188746A

GB2188746A - Protecting lens using fed transparent film

Info

Publication number: GB2188746A
Application number: GB08700447A
Authority: GB
Inventors: Geoffrey Healy; Robert Brear
Original assignee: AMALGAMATED TELEVISION SERVICE
Current assignee: AMALGAMATED TELEVISION SERVICE
Priority date: 1986-04-02
Filing date: 1987-01-09
Publication date: 1987-10-07
Also published as: GB8700447D0; DE3710847A1; NL8700092A; IT8747617A0; IT1205973B

Description

SPECIFICATION Lens protection housing The present invention relates to a lens protection housing and more particularly to a housing for a camera lens intended to be mounted in an exposed position on a racing car. In the reporting of motor races by television it has been found that the report can be greatly enhanced by including in one or more cars participating in a race a television camera which shows viewers a view of the track as seen by the driver. This has been done successfully in saloon cars in which the camera and its lens are protected by being enclosed in the cabin of the vehicle. However, in the application of the idea to open wheel racing cars difficulties have arisen due to debris and contaminant being thrown up from the race track by other vehicles on the track. If the lens of the camera is protected by some form of transparent cover, the cover itself very soon becomes coated with contaminants thrown up, thus degrading the image seen by viewers. Various efforts have been made to overcome this problem but so far none have been entirely successful. The object of the present invention is to provide a camera lens housing constructed in such a manner that an acceptable picture can be obtained through the camera for the duration of a race or at least a significant part thereof. The present invention thus consists in a lens protection housing adapted to be mounted externally on a motor vehicle with a camera lens therein directed in the direction of motion of the vehicle, the housing including mounting means for a camera lens, an opening at the front of the housing through which the camera lens is directed, a film feed spool on which a quantity of clear film mylar (RTM) or a functionally equivalent material is wound, guide means guiding the film from the feed spool past the said opening and onto a takeup spool, means in or adjacent to the opening for supporting the film during its passage past the opening and means for rotating the takeup spool to move the film past the opening. It is preferred that means be provided on the exterior of the casing to remove from the film any accretion of contaminants on the film, before it is wound onto the take-up spool. In order that the nature of the invention may be better understood preferred forms thereof are hereinafter described by, way of example, with reference to the accompanying drawings in which:- Figure 1 is a side elevation of a camera lens protection housing according to a first embodiment of the invention, with one side cover removed; Figure 2 is a plan view thereof; Figure 3 is a front elevation thereof; Figure 4 is a section on line A-A of Fig. 2 to an enlarged scale; Figure 5 is a section on line B-B of Fig. 2 also to an enlarged scale, and Figure 6 is a view corresponding to Fig. 5 of a modified and preferred form of the invention in which the optical window is replaced by a film support plate. The housing consists of a side plate 10 on which the working parts are mounted and a removable cover 11. At the front of the housing is an optical window 12 behind which is mounted a lens 13 which focusses an image onto an image sensing device 14 from which the image is transferred electronically to provide television pictures. This is done, for example, by means of a transmitter on the car which transmits signals to a helicopter flying overhead which in turn relays them to a ground station. These procedures are well known in the art. Within the casing behind the lens 13 are mounted a feed spool 15 and a take-up spool 16. On the feed spool 15 is wound a quantity of clear film which is preferably of mylar, (RTM), which is carried by guide rollers 17 to pass over the optical window 12. The film is arranged to lie very closely against the face of the window 12 and is held against the window by means of a frame 18. This arrangement of a minute clearance prevents contaminants from migrating to the back of the film. The guide rollers 17 are relieved over their central portions so that the part of the film that will pass in front of the lens 13 is not actually in contact with the rollers and thus is protected against scratching. The lower inner edge of the frame 18 indicated at 19 is in very close proximity to the outer surface of the film and is chamfered away from the film. This acts as a scraper to remove any contaminants that have accumulated on the surface of the film before the film passes over the lower guide rollers 17. This prevents the contaminants from being carried back into the camera. If this were allowed to happen the bulk of the film on the take-up spool 16 might become excessive and jamb the mechanism. The film passes from the lower guide rollers 17 onto the take-up spool 16 via a film advance sensor roller and sensor 21. These are arranged to operate in conjunction with the driving motor 22 for the take-up spool and its controls, to have three functions: (1) to move the film a predetermined distance at preset intervals so that clear film is brought before the camera lens at regular intervals; (2) to provide an override mechanism whereby the director may cause the film to move past the optical window at such times as he deems necessary; and (3) to provide the director with a record of the amount of film that has been used at any given time and the amount of film remaining. The drive motor 22 which is contained within the take-up spool 16 drives it through a reduction gear box 23 and drive dog 24. The side plate 10 is provided with captive shock mounts 25 by means of which it may be mounted to the car. To assist in keeping contaminants away from the optical window 12 the cover 18 is provided with a slight chamfer as indicated at 26 and as best seen in Fig. 5 with a view to producing an air flow across the surface of the film and removing loose contaminants. Suitable electric wiring (not shown) is provided to supply power to the drive motor 22 and take signals from the image serving device 14. In the form of the invention illustrated in Fig. 6 the housing is constructed in a manner substantially identical to what is shown in Figs. 1 to 5 with the exception of the portion shown in the accompanying drawing. In this form of construction the optical window 12 is replaced by a film support plate 27. As seen from the front the plate is of a rectangular U shape having side members 27A extending on either side of the opening that lies in front of the camera lens 13 and a lower member 27B on which the chamfered portion 26 of the cover 18 bears. The arrangement described above gives superior results over that described above in that contamination of the glass window itself tended to occur under some conditions. While it was first thought necessary to use a window to support the film, it has been found surprisingly, that even with the high speeds involved the film is quite adequately supported by the film support plate 27 and problems arising from contamination of the window are avoided. The first described arrangement, however, is an improvement over devices available before and in some circumstances will be found to be quite satisfactory. In use, the housing is mounted on the car preferably just to the rear of the driver's head pointing in a forward direction. From this, television pictures are picked up and presented to viewers at the director's discretion. A clear view is provided for the lens through the opening by moving a section of clear uncontaminated film in front of the lens as often as may be necessary.

Claims

1. A lens protection housing adapted to be mounted externally on a motor vehicle with a camera lens therein directed in the direction of motion of the vehicle, the housing including mounting means for a camera lens, an opening at the front of the housing through which the camera lens is directed, a film feed spool on which a quantity of clear film mylar (RTM) or a functionally equivalent material is wound, guide means guiding the film from the feed spool past the said opening and onto a take up spool, means in or adjacent to the opening for supporting the film during its passage past the opening and means for rotating the takeup spool to move the film past the opening.

2. A lens protection housing as claimed in claim 1, wherein the housing includes an optical window at the front thereof through which the camera lens is directed.

3. A lens protection housing as claimed in claim 1 or claim 2, wherein there is provided on the exterior of the casing means to remove from the film any accretion of contaminants on the film, before it is wound onto the takeup spool.

4. A lens protection housing as claimed in claim 3, wherein the means to remove contaminants consists of a member arranged in close proximity to the outer surface of the film and chamfered away from the film acting as a scraper to remove contaminants as the film moves past it.

5. A lens protection housing substantially as described with reference to and as illustrated in Figs. 1-5 of the accompanying drawings.

6. A lens protection housing substantially as described with reference to and as illustrated in Figs. 1-5 of the accompanying drawings but having the modifications described with reference to and as illustrated in Fig. 6 of the accompanying drawings.