Abstract:
A lighting apparatus capable of dimming lighting units using a discharge lamp in various ways. Each lighting unit includes a metal halide lamp and two spaced shutters arranged in front of the lamp on the optical path of the lamp. A shutter driver selectively opens or closes the shutters for mechanically dimming light issuing from the lamp. Six lighting units are cascaded in a single group. Ballast boxes each are assigned to a particular lighting unit and include a power supply section for feeding electric power to the lamp and a shutter controller for controlling a shutter driver. These structural elements are collectively controlled from a keyboard via a single control box. A command generating section included in the control box transforms a command input on the keyboard to a command for controlling the individual lighting unit. A selector also included in the control box distributes the command to five groups of lighting units. The apparatus allows the power supply and dimming of the individual lighting unit to be controlled via the keyboard.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to a lighting apparatus and more particularly to a profile spotlight or similar lighting apparatus capable of controllably dimming a lighting unit using a discharge lamp. 
     2. Description of the Background Art 
     A theater, hall, window display or similar cite is, in many cases, lighted by lighting units using halogen lamps. Metal halide lamps have a higher emission efficiency than halogen lamps and can emit a great quantity of light with small power while radiating a minimum of heat. However, metal halide lamps, which are discharge lamps, are difficult to electrically dim and are not suitable for profile spotlights required to dim a plurality of lighting units in various ways at the same time. 
     SUMMARY OF THE INVENTION 
     It is therefore an object of the present invention to provide a lighting apparatus capable of dimming a plurality of lighting units using discharge lamps in various ways. 
     In accordance with the present invention, a lighting apparatus includes a housing accommodating a removable discharge lamp. A shutter mechanism is positioned on the optical path of the discharge lamp in front of the lamp for p physically or mechanically opening or closing the optical path to thereby dim light issuing from the lamp. A lens converges the light passed through the shutter mechanism. A casing accommodates the housing, shutter mechanism and lens. A power supply section feeds electric power to the discharge lamp. A controller is operative in response to a control signal to control the power supply section for setting up or interrupting electric power feed from the power supply section to the discharge lamp, and control the shutter mechanism for dimming the light. 
     Also, in accordance with the present invention, a lighting apparatus includes a housing accommodating a removable discharge lamp. A first shutter mechanism is positioned on the optical path of the discharge lamp in front of the lamp for physically or mechanically opening or closing the optical path to thereby dim light issuing from the lamp. A lens converges the light passed through the first shutter mechanism. A second shutter mechanism is positioned on the optical path for physically or mechanically opening or closing an optical path on which the light converged by the lens is propagated to thereby dim the light. A casing accommodates the housing, first shutter mechanism, second shutter mechanism and lens. A power supply section feeds electric power to the discharge lamp. A controller is operative in response to a control signal to control the power supply section for setting up or interrupting electric power feed from the power supply section to the discharge lamp, and control at least one the first and second shutter mechanisms to thereby dim the light. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The objects and features of the present invention will become more apparent from the consideration of the following detailed description taken in conjunction with the accompanying drawings in which: 
     FIG. 1 is a schematic block diagram showing a lighting apparatus embodying the present invention; 
     FIG. 2 is a schematic block diagram showing a specific configuration of a lighting unit and a ballast box included in the illustrative embodiment; 
     FIG. 3 is a schematic block diagram showing an alternative embodiment of the present invention; and 
     FIG. 4 is a schematic block diagram showing a specific configuration of a lighting unit and a ballast box included in the alternative embodiment. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Referring to FIG. 1 of the drawings, a lighting apparatus embodying the present invention is implemented as a profile spotlight system by way of example. As shown, the lighting apparatus includes N lighting units  10  (# 1  through #N) and a keyboard  12 . It is to be noted that N is a natural number and may be “6” by way of example. The operator of the lighting apparatus is capable of controllably dimming the lighting units  10  via the keyboard  12 . The lighting units  10  can therefore play the role of high illumination, ellipsoidal spotlights. 
     Specifically, N ballast boxes  14  (# 1  through #N) are respectively connected to the N lighting units  10 . A single control box  16  is connected to the N ballast boxes  14  for controlling them collectively. 
     As shown in FIG. 2, each lighting unit  10  includes a reflector housing  18  and discharge lamp  20  removably accommodated in the housing  18 . The discharge lamp  20  should preferably be implemented by a high illumination, metal halide lamp. A rotatable barrel  24  and a lens tube  26  are arranged on the optical axis  22  of the discharge lamp  20 , as illustrated. The lens tube  26 , preferably including a convex lens and a plano-convex lens, is capable of converging light issuing from the discharge lamp  20  to a desired object to be lighted. The lighting unit  10  with such a configuration can be implemented if, e.g., a commercially available device Source-Four (trade name) is modified for use with a halogen lamp. 
     The barrel  24  is rotatable about the optical axis  22  while supporting a replaceable negative for a slide. In the illustrative embodiment, the barrel  24  should preferably support, e.g., a movable iris shutter  28  for following operation in its iris slot. Intervening between the lamp or light source  20  and the lens tube or converging lens  26 , the iris shutter  28  allows the light  22  to form a spot having a desired diameter and a sharp edge on a desired object. A douser shutter  29  for dimming, for example, is positioned on the optical axis  22  of the lens tube  26  in front of the lens tube  26  in addition to or in place of the iris shutter  28 . The douser shutter  29  should preferably be of the type having a pair of bladed plates, not shown, each being formed with sixteen slits in the form of saw-teeth. The bladed plates face each other on opposite sides of the optical path  22 . A drive motor, not shown, causes the bladed plates to move toward or away from each other for adjusting the size of the optical path  22 , i.e., the brightness of the light  22 . If desired, the two bladed plates may be replaced with four to sixteen bladed or slit plates, not shown, and arranged around the optical path to be movable toward and away from each other. 
     A shutter driver  30  controls the above movement of the shutters  28  and  29 . The shutter driver  30  includes a motor or a solenoid, not shown, for driving the shutters  28  and  29 , as schematically represented by arrows  72 . The ballast box  14  assigned to the lighting unit  10  includes a shutter controller  34  connected to the shutter driver  30  by a drive line  32 . The ballast box  14  additionally includes a power supply  38  connected to the discharge lamp  20  by a power supply line  36 . In the illustrative embodiment, the lighting unit  10  and associated ballast box  14  each are accommodated in a respective casing, as represented by a dotted line in FIG.  2 . The drive line  32  and power supply line  36  are removably connected to the lighting unit  10  and ballast box  14  via connectors not shown. Alternatively, the lighting unit  10  and ballast box  14  may be accommodated together in a single casing. 
     The power supply  38  included in the ballast box  14  includes a ballast and a no-fuse breaker, not shown, and plays the role of a power supply circuit for receiving electric power from, e.g., a commercially available 100 V power supply  40 , see FIG.  1 . For this purpose, the power supply  38  has its input side  42  connected to a feed line  46  via a power supply switch  44 . The feed line  46  is connected to the commercial electricity power supply  40 . The feed line  46  is connected to the other or output feed line  48  also. This feed line  48  is removably cascaded to the corresponding input feed line  46  of another ballast box  14 , as shown in FIG.  1 . 
     In the ballast box  14 , the shutter controller  34  has its input  50  connected to a control line  54  via a mode switch  52 . The control line  54  is connected to a control output  56  included in the control box  16 , see FIG.  1 . The mode switch  52  is a selector for allowing the operator to select either a local operation mode for operating the ballast box  14  within the operator&#39;s reach or a remote operation mode for operating it by remote control, as desired. The mode switch  52  sets up the local operation mode in the position shown in FIG. 2 or sets up the remote operation mode in the position opposite thereto. The input  50  of the shutter controller  34  should preferably have the USITT (United States Institute for Theatre Technology, Inc.) Standard, DMX-512 protocol and can be connected to, e.g., a general-purpose personal computer via an interface RS-412. 
     The shutter controller  34  has another control output  70  connected to the power supply  38 . The shutter controller  34  decodes a command, which will be described later, applied to its input  50  and decodes it. In accordance with the decoded command, the shutter controller  34  controls the electric power feed from the power supply  38  to the lamp  20  via the control line  70  in order to turn on, turn off or blink the lamp  20 , as desired. At the same time, the shutter controller  34  controls the motor and/or the solenoid of the shutter driver  30  for causing the shutters  28  and  29  to open or close. The shutter controller  34  additionally has an output control line  58  removably cascaded to the corresponding input control line  54  of another ballast box  14 , as shown in FIG.  1 . 
     Referring again to FIG. 1, the control box  16  has M output control lines  56 , M being a natural number. Therefore, in the illustrative embodiment, the control box  16  is capable of accommodating M groups of N pairs of lighting units  10  and ballast boxes  14 . It follows that the lighting apparatus allows N×M lighting units  10  at maximum to be arranged in, e.g., a theater, hall, window display or similar cite and collectively controlled via the keyboard  12  as to blinking and lightness/darkness. In the illustrative embodiment, there are provided a first group including control channels # 1  through # 6 , a second group including control channels # 7  through # 12 , and so forth; a fifth group includes channels # 25  through # 30 . 
     The control box  16  includes a selector  60  having M outputs # 1  through #M each being connected to particular one of the output control lines  56 . The selector  60  transfers a signal applied to its input  62  to one of the M output control lines  56  in accordance with the signal. The input  62  is connected to a command generation  64  having an input  66  thereof connected to the output  68  of the keyboard  12 . In response to a signal output from the keyboard  12 , the command generation  64  generates a command based on the DMX-512 protocol for controlling the individual lighting unit  10 . The control box  16  may advantageously be implemented by a microcomputer or similar processing system. In the illustrative embodiment, the control box  16  is accommodated in a casing independent of the keyboard  12  and ballast boxes  14 . 
     The keyboard  12  includes keys, not shown, to be operated by the operator of the lighting apparatus. When the operator operates any one of the keys, the keyboard  12  sends a corresponding signal to the control box  16  via the output  68 . The keys include selector switches for designating any one of the lighting units  10  and dim switches for turning on or dimming the designated lighting unit  10  and adjusting the blinking interval of the lighting unit  10 . The keyboard  12  may additionally include a display for displaying the conditions of the control box  16 . 
     In operation, the operator first turns on the power supply switches  44  of the ballast boxes  14  assigned to the lighting units  10  to be collectively controlled. In addition, the operator conditions the mode switch  52  for the remote operation mode. Subsequently, the operator inputs on the keyboard  12  a number, or channel, assigned to any one of the lighting units  10  to turn on, turn off, blink or control illumination. At the same time, the operator inputs whether to turn on the designated lighting unit  10  or to turn it off, a blinking interval, and illumination. Signals representative of such designated conditions are sent from the keyboard  12  to the command generation  64  via the line  68  and a line  66 . The command generation  64  transforms the input signals to a signal representative of the lighting unit  10  to be controlled and a command representative of the control conditions. The command is fed from the command generation  64  to the selector  60  via the output  62 . The selector  60  transfers the input command to the output  56  assigned to the group including the subject lighting unit  10  in accordance with the DMX-512 protocol. 
     The command output from the command generation  64  is sequentially transferred to the N cascaded ballast boxes  14 . In each ballast box  14 , the shutter controller  34  determines whether or not the above command includes a command meant for the lighting unit  10  associated with the ballast box  14 . If such a command is present, then the shutter controller  34  takes it in and decodes it. The shutter controller  34  controls, based on the decoded command, power feed from the power supply  38  to the lamp  20  via the control line  70  for thereby turning on or off the lamp  20 , or blinking it at desired intervals. In addition, the shutter controller  34  controls the motor and/or the solenoid of the shutter driver  30  in order to open or close each of the shutters  28  and  29  to a desired degree, thereby providing the light  22  with desired illumination. In this manner, the operator is capable of dimming each of the M groups of N lighting units  10  independently of the others via the keyboard  12 . 
     Referring now to FIGS. 3 and 4, an alternative embodiment of the lighting apparatus in accordance with the present invention is identical with the previous embodiments except for the following. As shown, the illustrative embodiment does not include the keyboard  12  or the control box  16 . Each ballast box  14  does not include the shutter controller  34 . Each lighting unit  10  includes a shutter operation  80  in place of the shutter driver  30 . With this configuration, the illustrative embodiment allows the operator to manually turn on or off, or blink the individual lighting unit  10  via the associated ballast box  14 . In FIGS. 3 and 4, structural elements like the structural elements of FIGS. 1 and 2 are designated by identical reference numerals and will not be described specifically in order to avoid redundancy. 
     As shown in FIG. 4, the operator is capable of turning on or turning off the power supply  38  of each ballast box  14  by operating the power supply switch  44  by hand. The shutters  28  and  29  of each lighting unit  10  may each be configured in the same manner as in FIG.  2 . In this embodiment, the shutters  28  and  29  are not electrically driven via the shutter driver  30 , but are operated by hand via the shutter operation  80 , as schematically represented by arrows  82 . Either the shutter  28  or the shutter  29  may be omitted, if desired. 
     In operation, the operator manually turns on the power supply switch  44  of the ballast box  14  assigned to the lighting unit  10  to be controlled and turns on, turns off or blinks the lighting unit  10 . In addition, the operator positions the mode switch  52 , FIG. 2, of the above ballast box  14  for the local operation mode (handy fader side). In this condition, the operator is capable of opening or closing the shutters  28  and  29  to a desired degree via the shutter operation  80  for a dimming purpose. 
     In summary, it will be seen that the present invention provides a lighting apparatus capable of allowing an operator to controllably dim a plurality of lighting units each including a discharge lamp in various ways. This unprecedented advantage is derived from the combination of a douser shutter, iris shutter or similar mechanical dimming device and a metal halide lamp or similar discharge lamp. 
     The entire disclosure of Japanese patent application No. 277494/1998 filed on Sep. 30, 1998 and including the specification, claims, accompanying drawings and abstract of the disclosure is incorporated herein by reference in its entirety. 
     While the present invention has been described with reference to the illustrative embodiments, it is not to be restricted by the embodiments. It is to be appreciated that those skilled in the art can change or modify the embodiments without departing from the scope and spirit of the present invention.