US2440184A - Electric change-over system - Google Patents
Electric change-over system Download PDFInfo
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- US2440184A US2440184A US674762A US67476246A US2440184A US 2440184 A US2440184 A US 2440184A US 674762 A US674762 A US 674762A US 67476246 A US67476246 A US 67476246A US 2440184 A US2440184 A US 2440184A
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04H—BROADCAST COMMUNICATION
- H04H60/00—Arrangements for broadcast applications with a direct linking to broadcast information or broadcast space-time; Broadcast-related systems
- H04H60/02—Arrangements for generating broadcast information; Arrangements for generating broadcast-related information with a direct linking to broadcast information or to broadcast space-time; Arrangements for simultaneous generation of broadcast information and broadcast-related information
- H04H60/04—Studio equipment; Interconnection of studios
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- G—PHYSICS
- G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
- G03B—APPARATUS OR ARRANGEMENTS FOR TAKING PHOTOGRAPHS OR FOR PROJECTING OR VIEWING THEM; APPARATUS OR ARRANGEMENTS EMPLOYING ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ACCESSORIES THEREFOR
- G03B21/00—Projectors or projection-type viewers; Accessories therefor
- G03B21/14—Details
- G03B21/32—Details specially adapted for motion-picture projection
-
- G—PHYSICS
- G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
- G03B—APPARATUS OR ARRANGEMENTS FOR TAKING PHOTOGRAPHS OR FOR PROJECTING OR VIEWING THEM; APPARATUS OR ARRANGEMENTS EMPLOYING ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ACCESSORIES THEREFOR
- G03B31/00—Associated working of cameras or projectors with sound-recording or sound-reproducing means
Definitions
- This invention relates to motion picture apparatus, and particularly to a system for changing over from one picture projector and sound reproducer to a second picture projector and sound reproducer.
- Changeover systems are known, some being semi-automatic, and others completely so.
- a changeover system for picture and sound is shown in Strong U. S. Patent No. 1,796,970, of March 17, 1931, the system controlling light dowsers and circuit making and breaking contacts for. the sound channels
- Certain other systems employ mechanical connections between the sound and picture projection apparatus as shown in Owens U. S. Patent No. 2,054,268, of September 15, 1936.
- An automatic system is shown in Di Stefano U. S. Patent No. 2,343,046, of February 29, 1944. It has been found, however, that an all-electric system under manual control is preferable from many standpoints, and the present invention is directed to such a system.
- the non-operating motor or motors may be jogged while one projection equipment is operating, the picture may be changed over independently f the sound, and the sound changed over subsequently, or both sound and picture changed simultaneously, while the volume may be increased or decreased from the same control box.
- the exciter lamps of the sound reproducing soundheads may be independently controlled.
- the principal object of the invention is to facilitate the changeover or switching from one picture projector and sound reproducing equipment to another.
- Another object of the invention is to provide an improved changeover system under manual control.
- a further object of the invention is to provide an all-electric changeover system for controlling the driving motors, the sound and picture equipments, and the volume oi the reproduced sound.
- a still further object of the invention is to provide an improved changeover system in which the picture changeover may be accomplished in dependently of the sound changeover, or the changeover of both picture and sound may be accomplished simultaneously.
- an exciter lamp source of energy is obtained over conductors 5, while the driving motor supply is obtained over conductors 6.
- Control box No. 1 is shown at 8
- control box No. 2 is shown at 9, while soundhead No. 1 is shown at li and soundhead No. 2 Since this system is all-electric, the control boxes may be located either at each projector or placed together at a convenient location remote from the projectors.
- Dowser coils A .and B open and close a dowser for projector No. 1, while dowser coils C and D perform the same function for projector No. 2.
- Pilot lights I5 and I6 indicate when a respective projection equipment is in operation.
- an interlocking relay having coils E and F for controlling the sound changeover.
- the output conductors i9 feed the voltage and power amplifiers and eventually the ioudspeakers of the sound system, while an add and subtract relay 20 may be of any well-known commercial type to vary the volume in small steps.
- exciter lamps are shown at 22 and 23, while manual control switches therefor are shown at 2li and 2li, respectively, the switches being operated in the event that it is desired to maintain the exciter lamps energized continuously.
- the interlocking relay il is in the position indicated in the drawing with Contact 63 closed and contact B open. Furthermore, contact 'ifi is closed, shorting out the output from soundhead No. l and Contact 'il is open to permit the output from soundhead No. 2 to belfimpressed on the speakers. Also, contact 8l in conductors 84 is open to permit energization oi" indicator lamp I6 for projector No. 2 and contact 82 in conductors 85 (one Two rectifiers for the accorse conductor being common) is closed to short out indicator lamp i for projector No. 1.
- the rst step is to thread the iilm through the projector and soundhead Il. or No. l. If the threading of the film does not bring the start marks at the proper points, the operator may jog the motor in soundhead No. 1 simply by operating the motor switch in control box No. l to the left so that contacts 44 and 45 are closed, thus completing a circuit over conductor 3i, contacts I4 and 45 in parallel, conductor 4l, the driving motor in box il, and conductor 33. Since the motor switch has a spring return, it immediately returns to o3 position. The operator now watches for the motor cue on the iilm being projected by equipment No.
- the volume from soundhead No. 2 may be varied by operation of the switch 9d in a similar manner.
- VThis type of volume control permits whatever type attenuator is used to be located on the amplifier rack or other convenient place.
- the switching circuits for the out- Duts may be eliminated entirely and only the energization and de-energization of the exciter lamps constitute the sole means of changing over the sound.- This may be accomplished by eliminating contacts 52 and 29, closing switches 24 and 25, disconnecting conductors l5 and 18 from the outputs of the soundheads and connecting contacts 'le and 'H to conductors 35 and 55 feeding the exciter lamps.
- the operator need only close the proper switches to energize the motors for the respective picture and sound head mechanisms, to change over the projector lights, and to energize the soundheads and transfer the sound outputs.
- the projectors may be positioned in any arrangement, such as opposite sides of a room. ⁇ With. mechanical interlinkage systems, a line arrangement is practically required.
- a volume control for each of said equipments a control box for each of said equipments, and a plurality of interconnecting circuits between said control boxes and equipments adapted to remotely change from one projection light beam to another, ⁇ for energizing a respective motor for each of said equipments, for changing over from one of said scanning light beams to another, for simultaneously changing over from one of said projection light beams to another, and from one of said scanning light beams to another, and for remotely varying the volume of said sound reproducing equipments.
- a system for remotely controlling theV changeover from one motion picture projection and sound reproducing equipment to another motion picture projection and sound reproducing equipment comprising a projection light beam in each of said equipments, a sound scanning light beam in each of said equipments, a film advancing motor in each of said equipments, a volume control device for each of said equipments, and a control box for each said equipments, said control boxes including a switch for momentarily and continuously energizing the motors in each ot said equipments, a momentary switch for simultaneously changing over ⁇ from one light projection beam to another, and from one sound scanning light beam to another, a switch for remotely controlling the volume control device in each of said equipments, and a momentary switch for shitting solely from the projecting iight beam oi' one equipment to the projecting light beam of another equipment.
- a motion picture changeover system comprising a pair of dowsers, a pair oi' exciter lamps, a pair of motors, a pair of output circuits. a Pair of volume control devices, a pair ot control boxes, one oi' each of said pairs being associated as a sound motion picture projection equipment, said control boxes 4including a motor and exciter lamp energizing switch, s. dowser changeover switch, a combination dowser and output circuit changeover switch, and a switch for varying said volume control device.
- a motion picture changeover system comprising a pair of picture projection units. a pair oi sound reproducing units, a pair of motors for advancing iilm through said units, a pair of control boxes, one of each of said pairs being associated together as a sound motion picture projection equipment, said control boxes including a switch for energizing and deenergizing said motors, a switch for simultaneously switching from one picture projection unit to the other and switching sound from one of said reproducing units to the other, a switch for changing over from one picture projection unit to the other only, and a switch for varying the volume output of each of said reproducing equipments.
- a motion picture changeover system in accordance with claim 11, in which an interlocking relay is provided, said relay being under control of said switch for simultaneously changing over said picture projection units and said sound reproducing units.
- a motion picture changeover system in accordance with claim 1l, in which an interlocking relay is provided together with an energizing circuit therefor, said energizing circuit being under control of said second mentioned switch through the closed contacts of said third mentioned switch.
- a motion picture changeover system for motion picture projection and sound reproducing equipments comprising a plurality of units each ofA which includes a motion picture projector, a dowser therefor, a sound record scanning system, a film advancing motor and a changeover control box, an interlocking relay common to said units energizable from said changeover control box for changing over from one of said projectors to another, and from one of said sound record scanning systems to another, said relay also switching between the output circuits of said sound record scanning systems, and a sound volume control for said units, the volume being control-led from said control boxes.
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Description
J. D. PHYF E ELECTRIC CHANGEOVER SYSTEM Filed June 6, 1946 April 20, 1948.
Patented Apr. 20, 1948 ELECTRIC CHAN GE-OVER SYSTEM James D. Phyfe, Gloucester, N. J., assignor to Radio Corporation of America., a corporation of Delaware Application June 6, 1946, Serial No. 674,762
This invention relates to motion picture apparatus, and particularly to a system for changing over from one picture projector and sound reproducer to a second picture projector and sound reproducer.
Changeover systems are known, some being semi-automatic, and others completely so. For instance, a changeover system for picture and sound is shown in Strong U. S. Patent No. 1,796,970, of March 17, 1931, the system controlling light dowsers and circuit making and breaking contacts for. the sound channels, Certain other systems employ mechanical connections between the sound and picture projection apparatus as shown in Owens U. S. Patent No. 2,054,268, of September 15, 1936. An automatic system is shown in Di Stefano U. S. Patent No. 2,343,046, of February 29, 1944. It has been found, however, that an all-electric system under manual control is preferable from many standpoints, and the present invention is directed to such a system. In the electrical system of this invention, the non-operating motor or motors may be jogged while one projection equipment is operating, the picture may be changed over independently f the sound, and the sound changed over subsequently, or both sound and picture changed simultaneously, while the volume may be increased or decreased from the same control box. Also, the exciter lamps of the sound reproducing soundheads may be independently controlled.
The principal object of the invention, therefore, is to facilitate the changeover or switching from one picture projector and sound reproducing equipment to another.
Another object of the invention is to provide an improved changeover system under manual control.
A further object of the invention is to provide an all-electric changeover system for controlling the driving motors, the sound and picture equipments, and the volume oi the reproduced sound..
A still further object of the invention is to provide an improved changeover system in which the picture changeover may be accomplished in dependently of the sound changeover, or the changeover of both picture and sound may be accomplished simultaneously.
Although the novel features which are believed to be characteristic of this invention will be pointed out with particularity in the appended claims, the manner of its organization and the mode of its operation will be better understood by referring to the following description read in lis shown at l2.
conjunction with the accompanying drawings, forming a part hereof, in which the single diagrammatic circuit embodies the invention.
Referring now to the drawing, an exciter lamp source of energy is obtained over conductors 5, while the driving motor supply is obtained over conductors 6. Control box No. 1 is shown at 8, and control box No. 2 is shown at 9, while soundhead No. 1 is shown at li and soundhead No. 2 Since this system is all-electric, the control boxes may be located either at each projector or placed together at a convenient location remote from the projectors. Dowser coils A .and B open and close a dowser for projector No. 1, while dowser coils C and D perform the same function for projector No. 2. Pilot lights I5 and I6 indicate when a respective projection equipment is in operation. At il, is shown an interlocking relay having coils E and F for controlling the sound changeover. The output conductors i9 feed the voltage and power amplifiers and eventually the ioudspeakers of the sound system, while an add and subtract relay 20 may be of any well-known commercial type to vary the volume in small steps. exciter lamps are shown at 22 and 23, while manual control switches therefor are shown at 2li and 2li, respectively, the switches being operated in the event that it is desired to maintain the exciter lamps energized continuously.
Referring now to the operation of the circuit, it will be assumed that projector No. 2 and soundhead No. 2 are operating. This is indicated by the closed contacts 2l, 23, and 2Q or the motor switch in control box No. 2 shown at With these contacts closed, energy is supplied to the l motor in soundhead it" over conductor 3i, contacts 2l and 28 in parallel, conductor 32, the driving motor of soundhead No. 2, and conductor 33. Energy is supplied i'rom the exciter lamp supply 22 over conductors 35, since a circuit over conductor 36, conductor lil, closed contact 29, conductor 39, and conductor il@ is closed. Since the momentary switch l2 was actuated to energize sound projection equipment No. 2, the interlocking relay il is in the position indicated in the drawing with Contact 63 closed and contact B open. Furthermore, contact 'ifi is closed, shorting out the output from soundhead No. l and Contact 'il is open to permit the output from soundhead No. 2 to belfimpressed on the speakers. Also, contact 8l in conductors 84 is open to permit energization oi" indicator lamp I6 for projector No. 2 and contact 82 in conductors 85 (one Two rectifiers for the accorse conductor being common) is closed to short out indicator lamp i for projector No. 1.
Now,'the procedure for changing the operation from projection equipment No. 2 to projection equipment No. 1, will be explained. The rst step is to thread the iilm through the projector and soundhead Il. or No. l. If the threading of the film does not bring the start marks at the proper points, the operator may jog the motor in soundhead No. 1 simply by operating the motor switch in control box No. l to the left so that contacts 44 and 45 are closed, thus completing a circuit over conductor 3i, contacts I4 and 45 in parallel, conductor 4l, the driving motor in box il, and conductor 33. Since the motor switch has a spring return, it immediately returns to o3 position. The operator now watches for the motor cue on the iilm being projected by equipment No. 2, and when the cue appears, he throws the motor switch in control box No. 1 to the right to the "run position. This closes contacts 50, 5|, and 52, and the motor circuit is the same as the one just traced. The closing of contact 52 energizes exciter lamp supply 23` over a circuit including conductor 36, conductor 31, closed contact 52, conductor 54, and conductor 40, the output of the exciter lamp supply being fed to the exciter lamp in soundhead Il over conductors 55.
The operator now watches for the changeover cue on the lm being screened, and when this appears, the operator presses the sound and picture momentary changeover switch 51. The closing of this switch completes a circuit over conductor 3l, left-hand contacts of switch 51, conductor 58, conductor 59, coil A for projector No. l, and conductor 40. A parallel circuit is also made from conductor 59 over conductor 5I, dowser coll D of projection equipment No. 2, and conductor 40. Simultaneously, another parallel circuit is made from conductor 58 over conductor 52, closed contact 63, conductor 65, coil E of interlocking relay I1, conductor 6'6, conductor 61, righthand closed contacts of switch 6B, conductor 69, right-hand closed contacts of switch 10, and conductor li. This operation removes the dowser from the light beam of projector No. l, places the dowser in the light beam of projector No. 2, and actuates the left-hand armature of interlocking relay Il, the latter opening contact 14, which removes the short across conductors le in the output of soundhead No. 1 and closes contact il?, which places a short across conductors l@ (one conductor being common) in the output of soundhead No. 2. Simultaneously, contact 89 is made and contact et is broken, which closes contact 9|, shorting out indicator lamp i6, and opens contact 32, which permits the energization of indicator lamp i 5 over respective pairs of conductors at and 85, as mentioned above. The changeover has now been completed from the projection equipment No.2 to projection equipment No. i, and the operator opens motor switch in control box Q. If it is now desired to vary the volume, the'switch Si may be actuated either to the left or to the right, which increases and decreases, respectively, the volume of the output from equipment No. l 'by actuating the stepped relay 2@ over a circuit from conductor 31, conductor 88, and either conductors 89 and 9| or conductors 9E and 92 to conductor 40. Similarly, the volume from soundhead No. 2 may be varied by operation of the switch 9d in a similar manner. VThis type of volume control permits whatever type attenuator is used to be located on the amplifier rack or other convenient place.
As above explained, picture and sound changeover was accomplished simultaneously by the inomentary closing oi switch el. Should it m desired to change over the picture only, then switch 98 instead of switch 53 is momentarily closed. and this operation will then operate only-the dowsers in the manner just indicated when the switch 5i is closed. The interlocking relay il, however, will not be operated, since the switch $8 will have broken its right-hand contacts, thus breaking the interlocking relay energizing circuit as traced above. 1i the sound is to be subsequently changed over, then it is only necessary to actuate switch 5l which will energize the coll E of relay il and make the necessary circuit changes as indicated above. When it is again necessary to change from equipment No. l to equipment No. 2, the motor and changeover switches in control box No. 2 will then operate in the same manner as just described for switching from equipment No. 2 to equipment No. l, dowser coils B and C and relay coil F being energized.
It will be noted that as above described two sound reproducing elements of each equipment are aiected in changing over from one equipment to the other. That is, the exciter lamps are alternately energized and de-energized. and the outputs of the sound reproducers are switched. By switching the outputs of the soundheads, the exciter lamps may remain energized continuously. However, the switching circuits for the out- Duts may be eliminated entirely and only the energization and de-energization of the exciter lamps constitute the sole means of changing over the sound.- This may be accomplished by eliminating contacts 52 and 29, closing switches 24 and 25, disconnecting conductors l5 and 18 from the outputs of the soundheads and connecting contacts 'le and 'H to conductors 35 and 55 feeding the exciter lamps.
With the above all-electric changeover system, the operator need only close the proper switches to energize the motors for the respective picture and sound head mechanisms, to change over the projector lights, and to energize the soundheads and transfer the sound outputs. With this arrangement, the projectors may be positioned in any arrangement, such as opposite sides of a room. `With. mechanical interlinkage systems, a line arrangement is practically required.
l claim:
i. A motion picture changeover system comprising a plurality of light sources for illuminating respective picture ninos, a plurality of light sources for scanning respective sound records on said ninas, one of each of said light picture iliuml= nating and scanning light sources being operative at the same time, and a plurality of control boxes for changing from one liuminating iight source to another and from one sound scanning iight source to another, each of said control boxes containing means for individuaily changing from one illuminating light source to another illuminating light source and subsequently from one scanning light source to another scanning light source, the actuation of one of said means pro= vlding simultaneous changeover from one `of said picture illuminating sources to another and from one of said scanning light sources to another.
2. .el changeover system in accordance with claim l, in which means are provided in said control boxes for energizing respective motors both momentarily and continuously.
3. in a system for switching from one soun motion picture projection and sound reproducing equipment to another sound motion picture projection and sound reproducing equipment comprising a picture projection light beam in each of said equipments, a sound record scanning light beam in each of said equipments, a motor for aclvancing lm through each of said equipments. a volume control for each of said equipments, a control box for each of said equipments, and a plurality of interconnecting circuits between said control boxes and equipments adapted to remotely change from one projection light beam to another,` for energizing a respective motor for each of said equipments, for changing over from one of said scanning light beams to another, for simultaneously changing over from one of said projection light beams to another, and from one of said scanning light beams to another, and for remotely varying the volume of said sound reproducing equipments.
4. A system for remotely controlling theV changeover from one motion picture projection and sound reproducing equipment to another motion picture projection and sound reproducing equipment comprising a projection light beam in each of said equipments, a sound scanning light beam in each of said equipments, a film advancing motor in each of said equipments, a volume control device for each of said equipments, and a control box for each said equipments, said control boxes including a switch for momentarily and continuously energizing the motors in each ot said equipments, a momentary switch for simultaneously changing over` from one light projection beam to another, and from one sound scanning light beam to another, a switch for remotely controlling the volume control device in each of said equipments, and a momentary switch for shitting solely from the projecting iight beam oi' one equipment to the projecting light beam of another equipment.
5. A system in accordance with claim 4, in which an interlocking relay is provided in the switch circuit of said sound changeover, said interlocking relay being under control of only said iirst mentioned momentary switch.
6. A system in accordance with claim 4, in which an interlocking relay is provided, said energizing'relay circuit including the closed position of all said last mentioned momentary switches.
'i'. A system in accordance with claim 4, in which an interlocking relay is provided for controlling the output circuits of said reproducing equipments.
8. A system in accordance with claim 4, in which energizing means are provided for said scanning light beams, saidv first mentioned switches controlling said energizing means.
9. A motion picture changeover system comprising a pair of dowsers, a pair oi' exciter lamps, a pair of motors, a pair of output circuits. a Pair of volume control devices, a pair ot control boxes, one oi' each of said pairs being associated as a sound motion picture projection equipment, said control boxes 4including a motor and exciter lamp energizing switch, s. dowser changeover switch, a combination dowser and output circuit changeover switch, and a switch for varying said volume control device.
110. A motion picture changeover system in vaccordance with claim 9, in which an interlocking relay is provided and energized by said third mentioned switch.
11. A motion picture changeover system comprising a pair of picture projection units. a pair oi sound reproducing units, a pair of motors for advancing iilm through said units, a pair of control boxes, one of each of said pairs being associated together as a sound motion picture projection equipment, said control boxes including a switch for energizing and deenergizing said motors, a switch for simultaneously switching from one picture projection unit to the other and switching sound from one of said reproducing units to the other, a switch for changing over from one picture projection unit to the other only, and a switch for varying the volume output of each of said reproducing equipments.
12. A motion picture changeover system in accordance with claim 11, in which an interlocking relay is provided, said relay being under control of said switch for simultaneously changing over said picture projection units and said sound reproducing units.
13. A motion picture changeover system in accordance with claim 11, in which an interlocking relay is provided under control of said second mentioned switch, said interlocking relay controlling the changeover of said reproducing units.
14. A motion picture changeover system in accordance with claim 1l, in which an interlocking relay is provided together with an energizing circuit therefor, said energizing circuit being under control of said second mentioned switch through the closed contacts of said third mentioned switch.
l5. A motion picture changeover system for motion picture projection and sound reproducing equipments comprising a plurality of units each ofA which includes a motion picture projector, a dowser therefor, a sound record scanning system, a film advancing motor and a changeover control box, an interlocking relay common to said units energizable from said changeover control box for changing over from one of said projectors to another, and from one of said sound record scanning systems to another, said relay also switching between the output circuits of said sound record scanning systems, and a sound volume control for said units, the volume being control-led from said control boxes.
JAMES D. PHYFE.
REFERENCES CITED The following references are oi record in the nie of this patent:
UNITED STATES rA'rEN'rs
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US674762A US2440184A (en) | 1946-06-06 | 1946-06-06 | Electric change-over system |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US674762A US2440184A (en) | 1946-06-06 | 1946-06-06 | Electric change-over system |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| US2440184A true US2440184A (en) | 1948-04-20 |
Family
ID=24707787
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| US674762A Expired - Lifetime US2440184A (en) | 1946-06-06 | 1946-06-06 | Electric change-over system |
Country Status (1)
| Country | Link |
|---|---|
| US (1) | US2440184A (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE1039761B (en) * | 1955-09-21 | 1958-09-25 | Kinowerke Dresden Veb | Image sound projectors with optional light or magnetic sound scanning |
Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US1960817A (en) * | 1932-02-03 | 1934-05-29 | William F Kemp | Automatic change-over apparatus for motion picture projectors |
| US1973588A (en) * | 1933-08-24 | 1934-09-11 | Walker Albert Harrison | Change-over apparatus |
| US2343046A (en) * | 1942-02-02 | 1944-02-29 | Stefano Thomas Di | Automatic motor starting changeover device for use with two or more motion-picture projectors |
-
1946
- 1946-06-06 US US674762A patent/US2440184A/en not_active Expired - Lifetime
Patent Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US1960817A (en) * | 1932-02-03 | 1934-05-29 | William F Kemp | Automatic change-over apparatus for motion picture projectors |
| US1973588A (en) * | 1933-08-24 | 1934-09-11 | Walker Albert Harrison | Change-over apparatus |
| US2343046A (en) * | 1942-02-02 | 1944-02-29 | Stefano Thomas Di | Automatic motor starting changeover device for use with two or more motion-picture projectors |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE1039761B (en) * | 1955-09-21 | 1958-09-25 | Kinowerke Dresden Veb | Image sound projectors with optional light or magnetic sound scanning |
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