 to the interior of the housing or to the metallic sleeve (if used) and isolated therefrom by an insulating film layer, or the (metallic body itself).
This arrangement allows the controller to detect the resistance presented by the switch to determine its state, as will be discussed below. It also insures that the switch is not serially connected in the loop with the primary current flow from the battery to the lamp, avoiding parasitic losses due to switch resistance.
The lamp 14 is preferably a light-emitting diode (LED), and may be a single lamp that operates efficiently over a wide range of input power to produce a wide range of possible light outputs. In alternative embodiments, there may be multiple light sources, either interconnected to provide a single, switchable (and dimmable) array, with all sources operating in the same manner. In other alternatives, there may be separate lamps or independently controllable lamp elements, so that color hue changes may be obtained by operating different color components in different combinations, or so that dimming control may be obtained by illuminating a different number of the components. The lamp may be an alternative light source, such as a tungsten halogen lamp or any other light source, although LED lamps are believed best suited to presently provide efficiency over a wide range of powers and brightness.
The dim level selector 20 may be of any type to provide the operator with the means to select a “dim” brightness level at any intermediate level within the range of the lamp's capability. The dim level selector is shown as connected directly to the controller 12, although in alternative embodiments the dim level selector may communicate with the controller by other means, including magnetic or radio frequency means. For instance, a rotatable ring may have one or more magnets, and the interior of the flashlight may contain a hall effect sensor connected to the controller to sense position or movement of the ring.
The dim level selector may have a selector element such as a dial or slider that establishes a dim level based on its position. Alternatively, the selector may establish a dim level by responding to the operator's duration (or magnitude) of pressure on a switch, such as by gradually rising in brightness in response to actuation until the selector is released. A dim level may be set by numerous alternative means, including by operation of the primary control switch 22, such as by its rotational position, by a series or sequence of impulses, or by any other means.
The flashlight 10 includes a conductive housing that is illustrated schematically in FIG. 1 by a ground bus line 24 extending between a battery electrode and switch lead, and the controller 12. As will be discussed below, the housing is a cylindrical tube defining a bore closely receiving one or more cylindrical batteries 16. Thus, it provides a single electrical path from the switch 22 at the rear end of the flashlight, and the controller 12 at the front end.
A second electrical path is provided over the length of the flashlight by the conductive sleeve element 26 shown schematically here, and detailed below. The sleeve is electrically isolated from the housing, and connects at its closed rear end to the rear of the battery 16 and to a contact from the switch 22, and at its open front edge to the lamp 14 and to the controller 12. The sleeve may be replaced in alternative embodiments by a single conductor wire or circuit element such as a flex circuit to provide the same function. Other alternatives include a conductive trace applied to the interior of the housing (isolated therefrom by an insulating film layer) and connected at each end to the appropriate components. The batteries themselves provide a third electrical path.
The second path provided by the sleeve allows the switch to connect directly with the controller over two paths, so that the controller may detect a resistance presented by the switch to determine its state, as will be discussed below. The second path further ensures that the switch is not serially connected in the loop with the primary current flow from the battery to the lamp, avoiding parasitic losses due to switch resistance.
FIG. 2 shows the physical structure of the preferred embodiment, with a lens 30 forward of the lamp 14. The housing is has several essentially cylindrical portions defining a chamber for containing the lens, lamp, controller 12, batteries, and switch 22. The dimmer level control 20 is shown in simplified form, and may take any form including a ring rotatable about the housing. The switch (shown in simplified form) is contained within a tail cap 32 having an elastomeric flexible dome 34 covering a switch actuator 36. The switch has a movable portion 40 having several contacts 42 each connected to the housing ground. The movable portion reciprocates axially with respect to a fixed switch portion 44 connected to the conductive sleeve 26.
As shown in FIG. 3, the contacts 42 of the movable portion 40 are leaf springs, each extending a different distance from a base panel that is connected to the housing ground. The switch show in FIGS. 2 and 3 is simplified for clarity of the principles of its operation. The actual switch of the preferred embodiment is configured like existing such switches that allow a bi-level operation. Such switches have the contacts arranged in arcs or annuluses to allow the switch to function when the tail cap is rotated through a range of positions. The preferred embodiment would have its contacts configured as such, although this would unduly complicate the illustrations, which are shown in schematic form.
All the leaf spring contacts are connected to each other. As the switch is depressed over its range of axial travel, the contacts contact the fixed element 44 in sequence. As shown in FIG. 4, the fixed element includes an array of pads 46, each positioned to be contacted by a respective end of a leaf spring contact 42. The pads are all connected to a node 50 that connects via a plated through-hole or other means to the opposite side of the element, which thereby connects to the sleeve 26. Each pad 46 connects to the node 50 with a different intervening resistance. Several resistors 52 are provided to intervene between the various pads and the node.
Before the switch button is depressed, the resistance between the fixed portion (and thereby the controller's connection to the sleeve) and the movable portion (and thereby the controller's connection to the housing ground) is infinite. When the button is slightly depressed, a first leaf spring contact makes contact with a pad associated with a resistor. The controller may thus determine by this resistance across these lines that the button has been pressed to an intermediate position. In the preferred embodiment, the controller then operates the lamp at the pre-selected dimmed illumination level.
When the button is further depressed, another leaf spring contacts a pad. In the simplest case, the switch has only two contacts (not the four illustrated), and the second contact would contact a pad having no resistor. This reflects a condition when the switch is fully depressed, and would cause the controller to provide full brightness illumination. In the more complex embodiment illustrated, there are five button states (including the released condition) determinable by the controller, so that various brightness levels or preselected dimmed or hue outputs might be provided based on the switch condition. The preferred embodiment requires at least two different contacts that make contact at different depression amounts of the button, and are connected to at least one resistor to provide a different output resistance depending on whether one, both, or neither are making contact. In the simple case, one extending spring contact may protrude, with the moving element panel 44 making direct contact in the fully actuated position.
By having an electronic controller connected to the switch, additional switching and control capabilities may be provided that are not provided by a conventional switch in line with the power loop. The illumination of the lamp need not correspond to the position of the switch. This enables a “click-on, click-off” switch mode in which a momentary actuation of the switch causes sustained illumination, and a second momentary actuation ceases illumination This function is provided in the absence of a conventional mechanical switch that switches between open and closed contact positions using springs and ratcheting mechanisms, in the manner of a ballpoint pen or other conventional on-off flashlight switches.
In the preferred embodiment, the tail cap 32 may be unscrewed from the housing a sufficient amount to prevent any switch contacts from making contact even when the button is fully pressed, providing a lockout position for storage to prevent inadvertent discharge of batteries or unwanted illumination during critical operations.
For normal operation, the tail cap is screwed tightly to the flashlight body to an “operational condition”. This differs from conventional flashlights that require the tail cap to be in an intermediate rotational position for selective operation (full screw-down providing constant-on operation in such lights.) This reduces potential operator error, and avoids the need for testing operational condition to ensure proper rotational position in advance of a critical operation, or after replacement of batteries.
When in the operational condition, displacement of the button to a first intermediate position (or intermediate pressure, for strain gauge buttons) causes the controller to provide power to the lamp for illumination at a pre-selected dimmed level, but only while the button is displaced. This provides momentary illumination, or a “dead man's” capability, so that the light turns off when pressure is ceased.
Displacement to a second intermediate position (such as when a second leaf spring makes contact in the switch, so that the controller detects a different resistance level) causes the controller to operate the lamp at the same pre-selected dimmed level, but with sustained operation upon release of the button. The switch may include a mechanical detent mechanism to provide tactile feedback to the operator to indicate that sustained illumination will be provided, or the rubber boot on the tail cap button may be designed with an over-center operation characteristic that provides a distinctive tactile feel when pressure beyond the required level to reach the second intermediate position is provided. In alternative embodiments, feedback devices may include electronic transducers in the flashlight connected to the controller, such as an audio annunciator that provides a “click” sound, or tactile transducers such as piezoelectric devices