Transparency projector having a device to allow the playback of sound recordings

Claim 2

In an automatic sound transparency slide projector, in combination; a compartmented transparency-supporting magazine for holding the transparencies radially arranged about a central axis; a control device adapted to provide a rotary movement by which the transparencies are successively projected by the projector; a ring on said magazine; a radially extending band supported on said ring in coaxial alignment with each transparency compartment and being disposed at the outer radii of the transparency compartments, said band being an endless magnetic recording tape located so that upon a given transparency being projected a corresponding associated recording on said tape is located in a playback position; a unit comprising a playback and recording apparatus being mounted on said projector for driving and reading the recording tape associated with the transparency being projected at any particular time intervals; projections on the outer edge of said ring in positions corresponding respectively to the axis of the transparency compartment; a solenoid including a circuit; switching means in said circuit of the solenoid; a mechanical connection extending between the armature of the solenoid and a playback head on said playback and recording apparatus whereby, when the solenoid is energised during the closure of said switch by one of the projections, the playback head is permitted to move into a position to start the playback.

Claim 3

A transparency projector according to claim 1 in which said unit comprising said playback and recording apparatus is detachably mounted on the projector.

Claim 4

A transparency projector according to claim 1, a first lever supporting said playback head and having a bushing, a rod extending through said bushing along which said lever is adapted to slide, a second lever being attached to said rod at the upper end of said rod, said second lever being tiltable about a pivot, said rod having an extending arm beyond the pivot, said solenoid including a release electromagnet actuating said arm upon being energised during closure of said switch by one of the projections of the ring, a bell-crank and an element attached to the arm of said second lever, said release electromagnet having an armature actuating said second lever through said bell crank and element, a third lever connected to said second lever and disposed at a lower level so as to form a fork therewith, a second rod extending between the arms of said fork, a rotatable control screw on said second rod for controlling the driving of the playback head through a spring, said second rod being attached at one end to the lever bearing the playback head, so that in the inoperative condition the spring does not co-operate with the screw, whereas when the electromagnet is energized during the closure of the switch by one of the projections of the circular ring of the magazine and the lever co-operating with the electromagnet tilts, the spring co-operates with the screw so as to move the head opposite the recording for playback thereof.

Claim 5

A device according to claim 3, said control screw including a sleeve extension, a plate being connected to said sleeve extension and supported on an interpolated bush, a further plate freely rotating on the sleeve, a drive belt rotating said further plate through a friction member, a gear wheel having said belt extending thereover, a spindle keyed to said gear wheel, a roller attached to the spindle for driving the recording tape, and a motor having a transmission for moving said gear wheel.

Claim 6

A device according to claim 1, comprising a detecting device for counteracting errors due to the movement of the head in relation to a spiral recording track, said device comprising means for automatically adjusting the position of the playback head in relation to a theoretical axis of the recording track, and a marker providing for adjustment connected to the recording support.

Claim 7

A device according to claim 5, comprising a photosensitive unit, said roller for driving the magnetic tape and said photosensitive unit being cooperatively engaged with the magnetic recording tape corresponding to the transparency projected so as to impart motion to the tape for playback in such a manner that, when the rotation of the transparency magazine has brought a particular transparency into the projection position, the corresponding projection provided on the ring having the transparency magazine being adapted to close the switch of the circuit of the electromagnet amd the armature thereof being actuated to tilt the lever supporting the playback head.

Claim 8

A device according to claim 6, comprising means which, when the playback head is brought into contact with the magnetic tape, locks against further tilting of the lever bearing the playback head, the lever bearing the driving screw having a further slight tilting movement imparted thereto so that the screw and the spring move into a cooperative position, and the spring being connected to the lever supporting the playback head for entraining the lever and the head in its displacement.

Claim 9

A device according to claim 7, the information to pass on to a following transparency being determined by the end of travel of the head.

Claim 10

A device according to claim 8, comprising a limit switch adapted to actuate the projector to pass to a successive transparency, said switch being actuated by the playback head when the playback of the recorded portion of the tape has been completed and the release electromagnet has been de-energised.

Claim 11

A device according to claim 8, the information given to the projector to pass on to a following transparency being determined by the end of playback.

Claim 12

A device according to claim 10, comprising an electronic assembly adapted to differentiate between a recording period and a period of silence.

Claim 13

A device according to claim 10, said electronic assembly comprising an input of a signal emitted from the playback head amplifier, and a capacitor which remains charged during periods of recordings, and upon silence intervals, the capacitor discharges whereby, after an interval of time, the capacitor reaches a value which actuates a circuit controlling a relay for sending information to the projector to pass on to a successive transparency.