US1821515A

US1821515A - Device for protecting

Info

Publication number: US1821515A
Authority: US
Publication date: 1931-09-01
Anticipated expiration: 1948-09-01

Description

Sept. 1, 1931. K. HOFFMANN ET AL 5 L DEVICE FOR PROTECTING FILMS AGAINST IGNITION Y Filed uar h 27. 1950 KLUZ 50 #133355 Patented Sept. 1, 1931 KURT HOFIHANN, F DRESDEN-Q AND MAX ENGELMAld'lN', OF LAUSA AT DRESDEN, GERMANY, ASSIGNOBS T0 ZEISS IKON AKTIENGESELLSGHAFT DRESDEN, 0F

antenna, GERMANY DEVICE FOR PROTECTING FILMS AGAINST IGNITION Application filed March 27, 1930. Serial No. 439,353.

This invention relates to improvements'in fire preventing devices, particularly devices for protecting the film of cinematographic projection apparatus against ignition in case 8' a break occurs in the film band.

It is'the principal object of our invention to provide an automatically acting 'fire-preventing device of simple construction, yet eflicient in its operation.

10 Another object of our invention is the provision of a fire-preventing device automatically protecting films againstignition as soon as the film band breaks between its feed roller and the film-way, .and which is operated by the enlarged loop formed by the filmcband in such cases.

Still another object of our invention is the provision of a device for protecting film bands of cinematographic apparatus against ignition, with which means are connected to stop the motor as soon as the protecting device comes into play.

A. further object of our invention is the .provision of a film actuated device for guidm a protecting shield between window and lig t-cone as soon asa break in the film-band occurs and in which the movement of the shield will operate a switch controlling the motor operation, while suitable means are provided to allow a resetting of the parts into their original operative position as soon as the break in the film band hasbeen paired.

A stilljfurther object of our invention is the provision of a device of the above type equipped with a means preventing the ends of a broken film band to ecome entangled in the mechanism." 7 Y I With these objects in view, our device principally consistsof a protecting shield normall heldinoperative through engagement h t e nose of a lever adapted to be swung about its fulcrum as soon as a loop of ab.-

normal size is formed in the -film band due' control switch the operation of the shield will operate this switch to 'stop the motor. A resetting of the parts can be conveniently efiected by a suitable switch handle.

The ends of the broken film band are prevented from becoming entangled in the mech' anism by means of a movable plate.

These and other objects and advantages of our invention will become more fully known as the description thereof proceeds and will then be specifically defined in the appended claims.

In the accompanying drawing forming a material part of this disclosure:

The single figure illustrates diagrammatically an automatically acting fire preventing device for protecting the films of cinematographic projection apparatus, constructed accord ng to our invention.

As illustrated, the film band 10 is guided about its feed roller 11, and'forming a 100 7 12 isguided in the usual manner throug the film-guides or way 13. If now the film band breaks and loop 12 in consequence thereof will assume abnormal proportions or size, as indicated in broken lines at 14:, it will engage a curved flange 15 of a substantially triangular lever 16 ful-. crumed at its apex, as at 17, to a part of the machine 18, and the loop will turn the lever about its fulcrum to disengage its nose 19 so from the end 20 of one arm of a two-armed lever pivoted intermediate its ends, as at 21, v the other arm of which carries at its outer end the protecting shield 22. r

The pivot 21 carries'also a roller 23 over which is guided an elastic band 24 or the like, secured at one end to the film guide and at its other end to the arm carrying the shield, and having the tendency to normally hold end 20 in engagement with nose 19.

About a shaft 25 a switch, preferably a mercury switch, is turnable for starting and stopping the motor oi the machine the lever 26 of which is connected by means of a bar r 15, a protecting plate'30 is movably arranged between both.

The device operates as follows:

Upon a break in the film 10 a comparatively large loop 14 will be-formed as indicated in broken lines which will engage under the flange 15 of lever 16 and turn" the same upwardly about its fulcrum 17. This movement will disengage nose 19 of this lever from the upper end 20 of the two-armed lever so that the same will now be turned about its pivot 21 by the pull of elastic bar 24: and W111 be swung into the position illustrated in broken lines in which the shield will come between window and light to protect the film.

Simultaneously by means of rod 27 the lever 26 of the switch 25 will be operated to stop the operation of the motor.

After the film has been repaired, an operation of lever 26 in'the opposite direction will start the motor and bring the two-armed lever 28 back into its original position and .the shield 22 will uncover the Window tensioning band 24 while the lever 16 executing a downward movement will bring its nose 19 again in engagement with one end 20 of the two.

armed lever so as to set the device for another operation in case of a break in the film band. The shield 30 will prevent the enlarged loop caused by the breaking of the film band from entering between feed roller and triangular lever.

It will be understood that we have disclosed the preferred form of our device only.

as one example of the many possible ways to practically construct the same, and that we may make such changes in its construction as I come within the scope of the appended claims without departure from our invention and the principles involved.

Having thus described our invention what we claim as new and desire to secure by Letters Patent is: V

1. A device for protecting the films in cinematographic projecting apparatus against ignition in case of a break in the film band forming an enlarged loop therein, comprising i a substantially triangular lever fulcrumed in the machine at its apex, an upper curved flange onsaid lever adapted to be engagedby thenlarged loop to swing said lever about said fulcrum, a protecting plate movably connected to said lever for preventing the loose ends of the film band to become entangled in the mechanism, a two armed lever pivoted intermediate its ends, a nose on said triangular leversnormally engaging the upper end of said two-armed lever adapted to be disengaged therefrom upon the operation of said triangular lever by said filmband loop, a motor control switch and connections between said two-armed lever and the motor control switch to stop the motor as soon as a break in the film-band occurs, and a movable protecting shield carried by the outer end of of March, A. D.

one arm of said two-armed lever for protecting the'film against ignition. I I

2. Ina cinematographic projection apparatus including its motor, film band, feed roller and guide therefore, a protectin shield,

a two armed lever pivoted interme iate its 1 connected to said loop operated means to prevent the loose ends of a broken film from becoming entangled inthe mechanism.

Signed at Dresden, Germany, this 4th day 'KURT HOFFMAN'N. MAX ENGELMANN.