US1516958A - Safety mechanism for moving-picture-projecting machines - Google Patents

Description

Nov. 25, 24-

J. H. DAVlTT ET AL SAFETY MECHANISM FOR MOVING PICTURE PROJECTING MACHINES Filed O 5 4 Sheets-Shae}. 2

Filed Oct. 5, 1920 J. H. DAVITT ET AL SAFETY MECHANISM FOR MOVING PICTURE PROJECTING MACHINES 1 :Tiii

Nov. 25, 1924.

J. H. DAVITT ET AL SAFETY MECHANISM FOR MOVING PICTURE PROJEC'IING MACHINES Filed Oct. 5, 1920 4 Shets-Sheet 5 Nov. 25, 24 1,516,958

'J. H. DAVITT ET AL S AFETY MECHANISM FOR MOVING PICTURE PROJECTING MACHINES Filed Oct. 5, 1920 4 Sheets-Sheet 4 Patented Nov. 25, 1924.

v UNITED STATES 1,516,958 PATENT OFFICE.

JOHN H. DAVITT, or mnnronn, AND HENRY c. COBNETTA, or BOSTON, MASSACHU- sE'r'rs; SAID DAVITT ASSIGNOR TO SAID CORNETTA.

SAFETY-MECHANISM FO'R MOVING-FICTUBE-PROJEGTING MACHINES.

- Application filed October 5, 1920. Serial No. 414,768.

' To albwho'm it may concern:

7 Be it known that we, JOHN'H. DAvrr'r and HENRY C. ConNE'rrA, citizens of "the United States, residing, respectively, at Medford,-in the county of Middlesex and State of Massachusetts, and at Boston, in the county of Suffolk and State of Massachusetts, have invented a new and useful Improvement in Safety Mechanism for MovingPicture-Projecting Machines, of which the following description, in connection with the accompanying drawings, is a specification, like reference characters on the drawings indicating like parts in the several figures.

As is well understood by those familiar with moving picture projecting machines, these machines usually comprise two reel magazines with mechanism between said magazines for feeding the strip of film from one magazine to the other, the film travelling during this feeding movement across an aperture or window against which a strong light is directed. The image on the film is thus projected through suitable lenses on to the screen. The film used for this purpose is highly inflammable and it is prevented from igniting under the heat of the strong light to which it is exposed only by virtue of the fact that it is moved through the light at a relatively rapid rate. If the film should be stopped for any reason in this light, even for a very brief instant, it would immediately be ignited. It has been deter mined that it takes less than two seconds under'ordinary conditions for the film to catch fire when it is exposed to the light. This fact is recognized by the designers of apparatus of this character and various provisions have been made to minimize this danger and to prevent the spreading of a fire originatlng from this cause. Notwithstanding these precautions, however, fires are still a very common occurrence. These fires may be caused by various accidents that result in exposing a given portion of the film for a substantial length of time to the projecting light, and among these accidents may particularly be mentioned the breaking of the film at certain points as it passes through the mechanism in the head of the machine, the breaking of a belt which stops the feeding of the film, and the tear: ing of the edges of the film in which the sprocket holes are made for a sufficient distance to prevent the film from feeding. It

is the chief object of the present invention to devise safety attachments which will substantially eliminate fires originating in the manner just described.

The nature of the invention will be readily understood from the following description when read in connection with the accompanying drawings, and the novel feaapparatus shown in Fig. 1;

Fig. 4 is a plan view showing an additional safety mechanism provided by this invention;

Fig. 5 is a side elevation of the parts shown in Fig. 4;

Fig. 6 is a plan view of additional parts of the safety mechanism;

Fig. 7 isa side View of the parts shown in Fig. 6; and

Fig. 8 is a plan view of the dowser and the mechanism that operates the same.

The accompanying drawings show the invention applied to the machine known commercially as Powers Cameragraph Model 6 B. This machine comprises an upper magazine 2 containing a reel 3 on which the supply of film F to be exhibited is mounted. This strip of film is led through the bottom of the magazine and around suitable guide rolls to a sprocket. feed roll 4 mounted at the upper end of the casing or housing 5 in which the objective lenses 6 are supported. The film travels downwardly in front of this housin across the exposure window or aperture to an intermittently rotating sprocket feed roll 8, and thence around the loop setter roll 9 and over another feed roll 10, commonly referred to as a take-up roll, into the lower magazine 11 where it is wound up on the take-up reel 12. This apparatus also comprises a lamp house 13 and a conical houschine have been omitted from the drawings for the purpose of clearness.

In the normal operation of this machine the feed rolls 4 and 10 are rotated con stantly, while. the roll 8 is rotated only intermittently. A loop B, therefore, is formed in the film between the rolls 8 and 10. The lower reel 12 is driven and consequently a' tension is placed on the film as soon as it passes the sprocket roll 10. This tension frequently causes a rupture of the film as it passes around the roll 10 or at a point between this roll and the magazine 11.. One of the common causes of fires in machines of this type is the fact that if the film breaks at this point the broken end will be fed upwardly between the roll 10 and the idler 15 that cooperates therewith and will be shot directly into the beam of light playing against the window 7 This piling up of the film may also be caused by the breaking of the belt that drives the reel 12.

The present invention provides means that prevent fires from originating from either of these causes. This mechanism comprises a shutter or dowser 17, Figs. 1 and8, which is pivoted to the upper edge of the cone 14 and is provided with a. tail piece 18 that normally is engaged by a spring latch 19 to which is secured an armature 20 of an electro-magnet 21. Normally the s ring arm 19 holds the dowser in its raise or inoperative position, as shown in Figs. land 8, but when the electro-magnet 21 is energized the latch is withdrawn from engagement with the tail piece 18 and the dowser drops by gravity into a substantially vertical position where it covers the end of I the cone 14 and cuts off the beam of light from the window 7.

For the purpose of energizing the electromagnet 21 when the film becomes broken or the tension on it is relieved, a roll 24, Figs.

1 and 4, is mounted to bear on the film at a.

point just below its point of entrance to the lower magazine. 'Thisroll is journaled on a shaft carried by an arm 25 which is secured to a rock shaft 26 mounted in a bracket 27 fastened to one wall of the mag.

azine. Another arm 28 also secured to the rock shaft 26 carries a weight 29 which holds the roll 24 yieldingly against the film F. An electrical conductor 30 leading from one terminal of the electro-magnet 21, as shown in Fig. 3, is connected to the bracket 27. The other terminal of this electro-magnet is connected to one pole of a battery, transformer, or other source of electrical strikes the binding post 33 it completes a circuit through the electro-magnet 21 thus energizing this solenoid and operating the dowser.

I It will now be understood that so long as the machine is working properly the switch 33-34 will be held open. If, however, the

I film F should break after it has passed the roll 10, or if the belt driving the reel 12 should break, thus stopping the rotation of this reel, the weight 29 would swing the roll 24 in a clockwise direction, as it appears in Fig. 1, thus moving the switch arm 34 into electrical contact with the binding post 33, closing this circuit and causing the dowser 17 to cut off the light from the film.

It sometimes happens that the marginal sections of film between the sprocket holes will become torn for a sufficient distance to stop the feeding of the film and a fire may therefore'be caused by an accident of this character. The present invention provides means for automatically operating the dowser 17 when the feeding of the film stops from this cause. For this purpose the mechanism connected with the loop setter 9 is utilized. That is, in machines of the type here shown this loop setter exerts a slight tension on the loop B of film and it is connected with the feed roll 10 in such a manner that if the loop is shortened abnormally the consequent raising of the loop setter will operate a clutch which interrupts for a brief interval the rotating movement of the feed sprocket 10. That is, this roll is mounted on an arm 40, Fig. 1, which is secured to a rock shaft 41 that projects through the side of the housing 5. Outside of this housing the shaft 41 carries a disk 42 having a cam face against which bears a pin 43 that is secured in one end of a lever 44 fulcrumed on the stud 45. The opposite end of this lever is worked to straddle the driving shaft of the roll 10 and is provided with a knob or handle 46. Figs. 2 and 3. The cam 42 is so shaped that when the take-up roll 9 is raised it wilt swing the pin 44 outwardly and the knob or handle 46 inwardly, that is, toward the right as shown in Fig. 2. This move ment is utilized to close a switch controlling the circuit that energizes the electro-magnet 21.

Referring more particularly'to Figs. 3, 6 and 7, it will be seen that a bracket 47 is secured to the frame of the machine and carries two electrically conducting members 48 and 49, respectively, which are electrically insulated from the bracket it and from each other. The plate L9 is made of resilient material and has an insulating plate 50 secured thereto which lies 0 posite the knob 46, as clearly shownin ig. 2. The plate 48 has an adjusting screw 51 threaded therethrough and lying opposite the end of the conductor 49. A conductor 52 connects the set screw 51. with one pole of the battery 31 or other source of current, and another conductor 53 connects the spring plate 49 with one terminal of the ,electro-magnet 21. This wiring diagram is clearly shown in Fig. 3.

If the sprocket holes should break out as the film travels over the intermittent feed roll 8 the result would be to shorten the loop B, Fig. 1, due tothe fact that the take-uproll 10 would continue to rotate. At the same time the film passing through the light would stop moving. This abnormal shortening of the loo-p B would raise the loop setter 9 thus forcing the knob 46, Fig. 2, against the insulating member 50 and pushing the spring arm 49 into contact with the end of the set screw 51. This would complete the electrical circuit through the electro-magnet 21 thus energizing this magnet, trip-ping the dowser, and cutting off the light from the film in the manner previously described.

It is evident that it a machine were not provided with the loop setting roll 9, a roll could be arranged to engage the loop be tween the feed rolls and could be connected to operate the dowser as above described. In this particular machine the loop setting mechanism has been used for this purpose to avoid a needless complication of the ma chine.

It will now be appreciated from the foregoing description that this invention provides safety apparatus which will eliminate the danger of fires from the more common causes; that this apparatus can be economically manufactured, and that it can readily be applied to existing machines. It will also be understood that while we have herein shown and described the invention as applied to one wellknown form of commercial machine, that this disclosure has been made by way of illustration rather than limitation and that the invention can be equally as well applied to many other forms of commercial machine.

Q An electric hell or other alarm may also be connected in the electrical circuit to be energized when one of the switches is closed in the manner above described. It has been found, however, that any separate alarm is usually unnecessary since the release of the dowser makes a noise that is distinctly heard and afibrds a suificient alarm.

What is claimed as new is:

1. in a moving picture projecting machine, the combination of an upper reel magazine, a lower reel magazine, a machine head between said magazines comprising mechanism for feeding the film past the exposure window in said head and'transferring it from one of said magazines to the other. a roll mounted to bear against said film in the lower magazine, an arm carrying said roll, a rock shaft supporting said arm and projecting through the-magazine case, means acting through said arm to hold said roll yieldingly against the film, a douser movable to cut ofi'the transmission of light through said window, a latch normally holding said douser in an inoperative position, an electro-magnet for releasing said latch, a switch outside of said casing and arranged to be operated by a movement of said rock shaft when a predetermined bodily displacement of said roll occurs. and a normally open electric circuit in which said magnet is connected, said circuit being arranged to be closed by said switch.

2. In a moving picture projecting machine, the combination of an upper reel magazine, a lower reel magazine, a machine head between said magazines comprising mechanism for feeding the film past the exposure window in said head and transferring the film from one of said magazines to the other, said mechanism including a loop setting roll, a normally open electric switch connected with said roll. another roll mounted. to bear against said film in the lower magazine. an electric switch controlled by the latter roll and arranged to be closed when a predetermined movement of said roll occurs. both of said switches being located outside of the machine casing. a douser mounted to swing from a normally' inoperative position into an operative position in which it cuts off transmission of light through said window, a latch for holding said douser in its inoperative position. an electro-magnet for operating said latch to release it, and a normally open electric circuit arranged to be closed by either of said switches. said clectro-imignet being included in said circuit and arranged to be energized upon the closing of the circuit. In testimony whereof we have hereunto signed our names to this specification.

JOHN H. DAVITT. HENRY C. CORNETTA.

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