Lighting devices are commonly used in modern dental practice, as well as in medical, veterinary and like fields, to provide a desired pattern of illumination on an area under study or examination. The quality of the light provided is of critical importance to a user of such lighting devices, particularly when the illumination provided impacts the quality of diagnostic and treatment procedures performed on a human or animal subject. It is highly desirable to have a lighting device that provides and mimics pure white light at an acceptable and useful color temperature.
Dental operatory lights are well known in the prior art, many of which utilize a high intensity gas-filled bulb such as a halogen or xenon bulb to produce a light of acceptable quality. Many of these lights utilize a reflector of a predetermined shape to produce the desired pattern of illumination. The reflector typically incorporated into these lights is oftentimes formed of glass with a selective coating on the reflector surface that acts to filter out UV, infrared and other undesirable light energy from the light spectrum produced from the light bulb, and allows for the reflected light to be cooler for minimization of subject desiccation and discomfort. The filtered light energy is absorbed by or passes through the reflector. Therefore, these high intensity bulbs and reflectors, allowing a certain portion of light energy to pass through, work together to produce the required color of acceptable quality. A typical high intensity bulb with a reflector can produce a 5,000 degree Kelvin color temperature and a 25,000 lux light output that requires approximately 90 watts of power.
Dental operatory lights of this type commonly have a lamp head assembly having a housing containing a light emitting bulb, the bulb usually being retained in a bulb socket, a reflector, a lens covering the bulb and reflector, and electrical wiring for providing electrical current to the bulb. It is desirable that the lamp head assembly be maximally positionable and adjustable for directing the light pattern to a focal point on a particular subject. Handles are commonly used in the prior art to facilitate manipulation of the lamp head by a user, however, the handles are commonly attached as separate pieces to the lamp head housing.
Because the higher intensity bulbs in these lights produce higher amounts of heat, including that produced by the light energy absorbed by and passing through the reflector, various means of eliminating the heat have been provided in the prior art. Some lighting devices utilize motorized cooling fans while others allow for self-ventilation. A problem remains in that heat typically radiates through all portions of the lamp head assembly, including the handles, which can get uncomfortably hot for a user. It is therefore desirable to have handles for a dental operatory light that can provide a comfortable grip in the presence of high temperatures which are simple and economical to manufacture.
Many dental lights of the prior art include a system of articulating arms or booms attached to the lamp head to enable multi-axial positioning of the light pattern onto a desired location. Knuckles with limited motion are commonly provided for coupling a lamp head assembly to an arm member, and for coupling arm members end-to-end, thereby enabling the lamp head assembly to be raised, lowered, swiveled, tilted, rotated, and moved closer to or further from the subject. Dental light arms and booms of the prior art often require a complex structural framework in order to temporarily and stably fix the lamp head in a desired position and to withstand the weight of the lamp light assembly once it has been adjusted on a focal point of the subject. Friction discs, gears, springs and screw-type tensioners have been used to fix the various pivot points. Larger lamp heads require more substantial arms and booms to support and maintain positioning of the added weight and are cumbersome for swift handling.
A problem exists in that heat from the lamp head radiates through the lamp head housing, consequently into adjoining knuckle and arm members. Temperatures can rise dramatically when the light is turned on and the bulb is energized, and drop back down to an ambient temperature when the light is turned off and the bulb is de-energized. Temperature extremes are well known to cause structural changes in previously known knuckle couplers, resulting in fatigue. The repeated fatigue from extreme temperature changes ultimately results in failure in ability to maintain sufficient friction and sustain functionality between moving parts that would otherwise keep the lamp head in a desired position. This problem is exacerbated when temperature extremes are combined with usual wear and tear associated with routine manipulation and repeated adjustment of the lamp head, and knuckle and arm members.
Ball and socket joints are well known in the prior art, and are capable of providing multi-axial movement of a ball member relative to a socket member. A ball and socket joint has not been adopted into lighting devices, particularly dental or medical operatory lighting. A ball and socket joint in conjunction with an optional, additional joint for infinite positioning and manipulation of the lamp head is necessary to allow maximum freedom of light adjustment and overcoming the previous problems inherently caused by high intensity lighting. Combining a ball and socket joint, with optionally at least a second joint, for infinite positioning of the lamp head, is desirable to facilitate repetitive lamp head assembly use for diagnostic and treatment procedures. Repeated movement of the light with wiring passing through the interior space of the mounting system results in shearing or internal breakdown of conductors within the wire of electrical cables which can render the light inoperable and also present a fire hazard. It is therefore desirable to have a rotational stop for a ball and socket joint within the mounting system that would prevent damage to internal wiring without requiring added bulk and weight of associated lamp arms and knuckles, while providing means for maximal and repetitive adjustment of the light over an extended period of use.