Field of the Invention This invention relates to a container having an audible warning device and particularly to a container for light-sensitive materials.

Background of the Invention

A common problem when working with photosensitive media such as photographic or radiographic paper or films or a phosphor material is that if their container is accidentally left open in the dark, the material may become exposed to light and wasted when, accidentally, a light is switched on or a door is opened. Occasionally the container may be opened when the light is on thus fogging the photosensitive contents. Problem to be Solved by the Invention

The problem faced in such circumstances is how to avoid having the container opened or left open in error.

Summary of the Invention

According to the present invention, there is provided a container containing or adapted to contain radiation-sensitive media comprising an audible indicator means and a switching means which triggers the audible indicator means when an operator opens the container.

.Advantageous Effect of the Invention The alarm will remind the operator that the container is open and needs to be closed. Brief Description of the Drawings

In the accompanying drawings:

Fig 1 is a perspective view of a container according to the present invention,

Fig 2 is a cross-section of another container according to the present invention, Fig 3 is a schematic view of a switching and signal generating device which can be used in the present invention, and

Fig 4 is a schematic diagram of the complete circuitry required for an embodiment of the present invention.

Detailed Description of the Invention

The container must, of course, be light-tight when closed. The preferred container has a body and a lid. The alarm may sound when the container is opened or when it has been open for a period of time, or both.

The present invention also provides a device comprising an audible indicator means, a switching means which is capable of triggering the audible indicator means and a radiation-sensitive means which is capable of modifying the behaviour of the indicator means.

In a preferred embodiment the container comprises thereon or therein radiation sensor means which may modify the behaviour of the audible and/or visible indicator means according to the ambient radiation conditions sensed by said sensor means. Such sensor means may be a radiation-sensitive diode, transistor, resistor or similar electronic component which may, for example, be sensitive to visible light, X-rays, gamma rays, UV or infrared radiation.

In another preferred embodiment the container comprises a second warning means which can emit radiation of a wavelength or level which does not fog

the radiation sensitive media. Examples of such means are an electric light bulb whose light passes through an appropriate filter, and a light-emitting diode which emits radiation of an appropriate wavelength or whose light passes through an appropriate filter. In one embodiment, the radiation emitted comprises radiation, invisible to the human eye, for example infrared or radio frequency.

In one embodiment the radiation emitted by the second warning means activates sensing and switching means in the darkroom which is capable of preventing the darkroom lights from being switched on.

In a preferred form of the invention, a delay of a few seconds is introduced when the box is opened in a dark environment (sensed by the radiation sensor) and before the alarm is sounded. This allows the material to be removed from the container and the box closed before the alarm sounds. The second warning means, if present, can be activated as soon as the container is sufficiently open.

In an alternative form an audible or visible warning is given immediately the container is opened, after which there is a pause of a few seconds for some media to be removed and then another alarm is triggered to remind the operator to close the container. The first warning is preferably rather short, eg a "bleep", while the second warning is longer or continuous indicating that the container is still open and needs to be shut. In another embodiment the radiation (eg visible light radiation) sensor is provided on the container which will cause a continuous alarm to be triggered when the box is opened sufficiently to trigger the switch in the presence of ambient light which would otherwise fog the radiation sensitive media.

The audible warning device may produce a "bleep", continuous tone or buzz, a musical tune or speech, for example recorded speech or speech from an electronic speech synthesiser. The radiation emitted by the second warning means may remotely activate a sensor in the darkroom which is capable of preventing the darkroom lights from being switched on. Clearly this is wired into the darkroom electrical system and does not form part of the container or device.

The elements of the warning device may be attached to the lid and body of the container in any suitable location. In one embodiment it is mounted as part of the normal labelling process. The label normally seals the lid to the body of the container hence when the seal is broken the two parts of the switching device are separated and automatically sited in their correct positions. In such an arrangement it is clearly preferred to have components (including the battery) which can be arranged in a flat configuration underneath the label.

The switching device may use one or two magnets. For example a magnet may be present on the lid and a reed switch mounted in the body of the container. Another arrangement can use two magnets to keep the switch normally open while one of them closes it when moved away. Alternatively a Hall effect device may be used. In still another embodiment the switching device may be a mechanical switch, eg a microswitch. Further useful switching devices are proximity switches, for example of the capacitative or inductive types. Additionally a light-emitting device and a light sensitive device may together be used to detect the opening of the lid by the removal or addition of an

opaque barrier between them. Other proximity devices can also be used.

The audible warning means may comprise a miniature loudspeaker or, preferably, a piezo-electric transducer driven by a suitable oscillator or other audio frequency signal generating device.

Specific embodiments of the invention will now be described by way of example with reference to the accompanying drawings. Figure 1 illustrates a side-opening film container (1) with lid (2) . A magnetic strip (3) is mounted on the lid while the remainder of the device

(4) is mounted on the container, for example with double sided adhesive tape or pads. The removal of the magnetic strip (3) from its closed position activates the switching means in (4) .

Figure 2 illustrates a top-opening film container

(5) comprising a lid (6) and a container body (7) . The magnetic strip (8) and the rest of the switching and audible signal means (9) are mounted on the lid and inside the body as shown.

Figure 3 illustrates the electronic componentry and battery arrangement within a device according to one embodiment of the invention. Mounted in casing (10) are batteries (11) , a light sensitive device

(12) , a piezo-electric transducer (13) , a reed switch or magnetised reed switching member (14) and a magnet (15) to close the reed switching member. As long as the magnet on the lid (not shown) remains close to the reed (14) the internal magnet's (15) field will be cancelled and the reed switch will remain open. Other components may include an oscillator and a timer.

In use, opening the lid of the container will trigger the reed (14) which then switches on the warning device. As an additional feature the light

sensitive device can be used to determine whether the ambient conditions are light or dark and affect the behaviour of the device accordingly.

Fig 4 is a block diagram showing the essential ^• elements and electrical connections of a device which can be used in the present invention. The device comprises a battery (18) , switch (19) operable by opening the lid of the container, an oscillator (16) and piezo-electric transducer (17) . The oscillator unit may also contain timing (or delay) circuitry, a light sensitive device and/or other sound generating elements.

The circuitry of fig 3 is designed for two modes of operation: 1. In the presence of low ambient light levels, as detected by a light sensor (12) and optional filter combination sensitive to the same light wavelengths to which the media is sensitive, delay circuitry will be activated by the opening of the lid and consequent closure of the reed switch to allow manipulation of the contents of the container for a predetermined period of time before the alarm is sounded. However a visual indicator such as a light emitting diode may be illuminated with no delay to indicate that the container is open.

2. When significant levels of light are detected the delay- is redundant, and the alarm sounds immediately the lid is opened and the reed switch thereby closed. When the container is empty it may simply be refilled with new film or other media taken from elsewhere. If the condition of the warning device or container deteriorates, either the audible warning device may be removed and the contents of the container transferred to a new alarmed container or,

the device may be transferred to a new container, respectively. Batteries (11) may be replaceable or the whole assembly may be disposable.