US3541324A

US3541324A - Ventilated light unit with roller curtain shutter

Info

Publication number: US3541324A
Application number: US691357A
Authority: US
Inventors: Maksymilian A Michalski; Peter Promuto
Original assignee: Berkey Photo Inc
Current assignee: Bank of America Illinois; Prudential Insurance Company of America; First National Bank of Minneapolis; Wells Fargo Bank Minnesota NA
Priority date: 1967-12-18
Filing date: 1967-12-18
Publication date: 1970-11-17
Anticipated expiration: 1987-11-17
Also published as: FR1598421A; DE1815491A1; GB1242434A

Description

Nov. 17, 1970 MlCHALSKl EIAL 3,541,324

VENTILATED LIGHT UNIT WITH ROLLER CURTAIN SHUTTER Filed Dec. 18, 1967 2 Sheets-Sheet l ATTORNEY Nov. 17, 1970 MlCHALSK] ETAL 3,541,324

VENTILATED LIGHT UNIT WITH ROLLER CURTAIN SHUTTER 2 Sheets-Sheet 2 Filed Dec.

"f-L S H o u o o o u U.S. Cl. 24046.17 Claims ABSTRACT OF THE DISCLOSURE A light unit assembly includes a housing which supports and encloses the operating parts. A lamp is positioned within the housing in front of the main reflector, air passage means being provided through the reflector behind the lamp. Blower means is supported by the housing and operative to pass cooling air past the lamp. A shutter means is provided including a generally rectangularly shaped frame which supports a pair of rollers carrying a flexible curtain. Flexible means is provided for the simultaneous rotation of both roller shafts, the curtain being attached at both ends to the rollers so that as either of the rollers are rotated the curtain is moved past the reflector alternatively blocking and passing light from the lamp outwardly. Limit switch means is provided and operated by means carried for movement with the curtain so that the curtain operating motor is disconnected at both the upper and lower positions of the curtain. The motor for operation of the curtain is supported and enclosed within the housing and positioned outside the main reflector spaced from the curtain.

The present invention relates to a light unit assembly such as for illuminating copy in the graphic arts field, the assembly being particularly suitable for incorporating a metal-additive type lamp.

The metal-additive type lamps are gas discharge lamps metal additive such as a halide, which affect the spectral emission of the lamp.

Because of the use of mercury in these lamps a warming up period is required generally of the order of several seconds to a few minutes, during which time the lamp is in operation and the current passing therethrough provides heat for vaporizing the mercury until a steady state of operation is achieved. During the warm up period the light is weak and varying in intensity. Thus the warm up time is wasted time on the part of the operator.

Several devices have been provided to reduce the time required for the warming up of the lamp. However, such devices have added to the complexity and cost of the installation.

The present invention aims to overcome the difliculties and disadvantages of the use of such devices by providing a shuttered light box in which a metal-additive type lamp is incorporated behind a roller type shutter. The shutter is opened and closed for repetitive exposures. Thus the lamp is not shut off between exposures with the attendant waiting time for the lamp to cool before starting it up again for another exposure and waiting for it to reach operating temperature. In accordance with the invention a shuttered box light is provided comprising a housing to receive the lamp, and shutter means so that the light may be blocked off by closing the shutter. The operating time of the shutter is approximately one half second but this operating time may be decreased if desired.

Objects and advantages of the invention will be apparent from the following description and from the ac- United States Patent 0 ice companying drawings which show by way of example an embodiment of the invention.

In the drawings:

FIG. 1 is a perspective view of a light unit assembly in accordance with the invention shown without its removable hood reflector.

FIG. 2 is a vertical sectional view of the light unit asembly taken along the line 22 of FIG. 1 and showing the removable hood reflector.

FIG. 3 is a top view of the light unit assembly.

FIG. 4 is a front view of the light unit assembly.

Referring to the drawings there is shown in FIG. 1 a light unit assembly 10 comprising a housing '11 with main reflector means 12 positioned within the housing 11. Also positioned in the housing 11 in front of the main reflector means 12 is a lamp 14 preferably of the metal additive type. In order to maintain the operating temperature at a desired low temperature blower means 15 is operative to pass cooling air through the housing 11. In order that the lamp 14 may be continuously operated between successive exposures shutter control means 16 is provided to operate shutter means 17 alternatively to pass lamp light from the housing 11 or to block the lamp light from leaving the housing 11.

If desired a removable hood reflector 19 may be attached to the front of the housing 11 when the assembly is used for exposure of open-type vacuum frames. The blower means 15 is attached to the rear of the housing 1-1 on the outward surface thereof to pass air through an opening in the rear of the housing and through an opening 20 in the main reflector means 12 so that cooling air is passed over the lamp 14. A thermostat 21 is positioned attached to the reflector means 12 to control the blower means in a manner well known in the art. A deflector 24 may be positioned within the housing behind the lamp 14 and ahead of the opening 20 in the main reflector 12. The deflector 24 prevents direct cooling of the lamp 14 under its standby operation when the lamp is operated at about forty percent of rated power. Excessive cooling of the lamp under reduced power may cause it to become deionized and extinguishd. The deflector 24 also causes cooling air to bedirected against the center of a Pyrex glass shield 25 which may be positioned in the front of the shutter means 17 which might otherwise break because of the concentrated heat from the light beam.

The housing 11 is of generally rectangular shape of sheet metal with a top surface 29, a bottom surface 30, a rear wall 31, and an open front 32. On the top surface 29 may be positioned a vent hood 34 apertured as indicated at 35 for the passage of cooling air.

Within the housing 11 may be positioned a partition 36 carrying a blower motor capacitor compartment 37 and an arc suppression capacitor compartment 39. A relay 40 of the shutter control means 16 may be supported by the partition 36. The shutter control means *16 includes a shutter control motor 41 which is mounted inside the bottom surface 30.

The main reflector means 12 may be made of any suitable material such as aluminum and formed wtih a spe cific curvature designed for optimum eificiency in projecting light on a flat surface as is well known in the art. The reflector 12 is made with the cooling air opening 20 at its rear end 42. Front end 44 of the reflector 12 is provided with a flange 45. The reflector 12 is supported by partition 46 attached to the walls of the housing 11. A space 47 is provided for the passage of cooling air.

The lamp 14 is generally of tubular shape supported at its ends in a socket 49 provided with the usual means for connection to a source of electric power.

At the rear of the housing 11 is the blower means 15, which may be electrically powered, the blower means having an inlet 50 and an outlet 51. Preferably the blower is arranged to blow cooling air into the housing. However, an alternative construction might be used in which the blower means is used to evacuate heated air from the housing. A supply wire 52 for the-blower and a main power cable 54 are shown broken away. Baffle means 53 is provided to prevent light from leaking from the housing 11 through the blower means 15.

The electrical circuit for the light unitassembly may. be conventional or it may be as shown in copending U.S. patent applications of Maksymilian A. Michalski, one of the applicants herein, Ser. No. 655,954, now Pat. No. 3,465,204, titled Electric System and, and Ser. No. 65,956, now Pat. No. 3,470,415, titled System Cooling for a Discharge Lamp.

The first mentioned application, Ser. No. 655,954 discloses an electric system which includes first and second capacitor means adapted to be switched into the circuit in series with the lamp 14 for variation in the power output thereof. The circuit means includes switching means so that upon energization of the lamp both capacitors are connected in parallel whereby the lamp 14 is fully loaded upon ignition in order that it will arrive at operating terncapacitor is switched into the circuit to make the full.

light output of the lamp available. Upon termination of the exposure the switching means causesthe second capacitor to be disconnected and the shutter to be closed.

ApplicationSer. No. 655,956 concerns a system whereby the blower means 15 is adapted to be operated at two speeds, a lower speed on partial voltage and a higher speed on full voltage. Switching means is provided so that upon the start up of the light unit assembly the blower is not energized so that there is no cooling, thus allowing the lamp 14 to reach operating temperature at a rapid rate. Timing means is provided so that after the lamp 14 has been in operation for a predetermined time switching means is actuated causing the blower means to operate under partial voltage. Upon deenergization of the main circuit for the light unit assembly the lamp 14 is turned off and hold over delay means is actuated so that the blower motor is operated for a predetermined length of time after the lamp is turned off, this phase of blower operation being at full voltage so that the lamp 14 is cooled rapidly so as to be ready for subsequent operation.

The shutter means 17 includes a unitized removable assembly which includes aframe 55 generally L-shaped in cross-section. The frame 55 extends around the inner surface of the housing 11 at the front end 30 thereof and may be secured in position by leg mounts 56. Attached to the inner surface of the frame 55 at the sides thereof are rail guides 57, which have cut away portions at the top and bottom ends thereof as indicated at 59 to provide space for the pulleys 60. These pulleys are respectively carried by upper supporting shaft 61 and by lower supporting shaft 62, bothof which are journalled in openings in the rail guide 57 with hearing members. A gear type drive belt 64 connects the pulleys 60 so that the

shafts

61 and 62 rotate at the same speed.

The curtain 65 is attached at its upper end to the shaft 61 by one or more spring curtain clips 66. The curtain 65 may be made of silicon rubber coated fiberglass fabric about .015 inch in thickness aluminized on its inner surface and dyed black on its outersurface. The lower edge of the curtain 65 is provided with a curtain bar 67 to stiifen the bottom edgeof the curtain and to provide supporting means for gliders 69 which may be Teflon coated and which contact the rail guides 57. Also carried by the curtain bar 67 is a tab 70 for contacting upper limit switch 71 and lower limit switch 72. At the lower and upper ends of the rail guides 57 are curtain stops 73 and 74 to limit the upper movement of the curtain 65 if con tacted by the tab 70. Attached to the curtain bar 67 is a pair of curtain straps 75 made of Teflon-filled fiberglass fabric, about .010 inch in thickness, and wound about pulleys 76 carried by the shaft 62; The straps 75 are attached to the pulley hubs by spring clips or the like, the diameter of the pulley hubs being such that upon the rotation of the

shafts

61 and 62 the curtain 65 is moved while being held taut and guided by the curtain straps 75 so that a smooth action is had evenat high speed as the curtain is alternatively raised and lowered.

The shaft 62 is rotated by a motor pulley 77 engaged by a motor drive belt 79 and driven by a motor pulley 80 on the shaft of the motor 41. A solenoid brake 81 is attached to motor 41 so that its rotation is stopped practically instantaneously upon the actuation of the limit switches 71 or 72..

The light unit assembly 10 is suitable for use in the graphic arts field in which a high intensity lamp is used to expose photosensitive materials. Because of the small size and weight of the light assembly it may be used in step and repeat machines, among other purposes. The light unit is particularly suitable for short exposures, although it works equally well for long exposures. The light assembly may be wired in any manner well known in the art or it may incorporate the circuits of the aforesaid Michalski applications.

In using the light assembly switching means are actuated to energize the lamp and bring it up to operating temperature without operation of the blower and with the curtain closed, which of course allows retention of heat providing for a more rapid rise to operating temperature. An exposure of predetermined length of time is made by actuating switching means to open the shutter by energizing the motor 41 which moves the belt 79 and rotates the

shafts

61 and 62 in the direction to raise the shutter. The limit switch 71 causes the motor to be disconnected whenthe shutter is fully opened. At the end of the exposure appropriate switching means is actuated causing the motor 41 to operate in the opposite direction so that the belt 79 rotates shaft 62 and through belt 64 operates shaft 61. The light assembly is capable of heavy duty with a minimum of repair.

While the invention has been disclosed and illustrated with reference to a specific embodiment thereof it will be understood that other. embodiments; may be resorted to without departing from the invention. Therefore, the form of the invention set out above should be considered as illustrative and not as the scope of the following claims.

We claim:

1. A light unit assemblycomprising housing supporting means, a main reflector carried and enclosed by the housing supporting means, a lamp positioned in front of the main reflector, means defining an air passage through the reflector behind the lamp, blower means supported by the housing supporting means and operative to pass cooling air past the lamp, shutter control means, and shutter means positioned in front of thelamp, the shutter control means operative to actuate the shutter means between open and closed positions alternatively to pass lamp light from the reflector or to block lamp light from leaving the reflector, the shutter means including a generally rectangularly shaped frame, a pair of roller shafts, journal means for the roller shafts carried by the frame, flexible means for the simultaneous rotation of both roller shafts, a flexible curtain, attachment means for the curtain fixed at one end to one of the roller shafts and fixed at the other end of the curtain to the other of the roller shafts, limit switch means, and operating means for the limitswitch means carried for movement with said curtain, the shutter control means including a motor,

a motor drive belt operative for the drive of one of the roller shafts, and switching means for the motor, the motor supported and enclosed by the housing and positioned outside the main reflector spaced from the curtain.

2. A light unit assembly according to claim 1 in which a removable hood reflector is attached to said supporting means.

3. A light unit assembly according to claim 1 in which a thermostat is carried by said main reflector.

4. A light unit assembly according to claim 1 in which a transparent shield is positioned at the front of said supporting means ahead of said lamp.

5. A light unit assembly according to claim 4 in which a deflector is positioned between said lamp and said main 15 reflector so that cooling air is directed against the center of said transparent shield.

6 References Cited UNITED STATES PATENTS 12/1921 Ewing 24046.17 6/1934 Adams et a1 24047 11/ 1952 Foulds 24047 8/1958 Burns 24047 8/ 195 8 Lipscomb 24011.4 8/1966 Meckler 24047 FOREIGN PATENTS 11/ 1962 France.

U.S. C1. X.R.

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patentbm. 3,541,324 Dated November 17, 1970 uo Maksymilian A. Michalski and Peter Promuto It Is certified Lhat error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

Column 1, line 40, after lamps insert --which contain one or more gases, mercury, and a--.

Column 2, line 8, change "asembly" to --assembly--.

Column 2, line 42, change 'estzinguishd" to -extinguish Column 3, line 14, change "65,956" to --655,956--.

smmaa AME Edw mun. W, H om 00-15 new of Patent: