The Kailh White Jasmine low-profile switch introduces a key structural integration: a dedicated light-guiding column is built directly into the switch housing, forming an “integrated lens component.” This design addresses a fundamental structural challenge inherent to low-profile switch backlighting. Because the total height of these switches is significantly reduced—leaving minimal vertical space for the stem and housing—the traditional approach (relying on slots in the switch housing to channel light into the keycap) often fails to produce uniform illumination. By incorporating a lens, the optical path is transformed from “scattered diffusion” into “directional projection,” ensuring high-quality RGB lighting effects without increasing the overall thickness of the keyboard.
I. The Structural Dilemma of Low-Profile Switch Backlighting
Standard mechanical switches typically have a total height of 12–14 mm, providing ample internal space for light-guiding structures. Furthermore, the keycaps used with these switches are tall enough to allow light to diffuse internally before passing through the legends (characters). In contrast, low-profile switches compress the total height to approximately 8 mm, drastically reducing the space between the switch top housing and the keycap.
Consequently, if a low-profile switch were to follow the same backlighting logic as a standard switch, the light would either leak directly through the gaps in the switch housing—creating harsh, glaring hotspots—or be obstructed by the cramped interior of the keycap, resulting in dim, poorly illuminated legends. The Kailh “White Jasmine” switch solves this by integrating a lens component, effectively shifting the responsibility for “optical path management” away from the keycaps and keyboard structure and bringing it inside the switch itself.
II. The Optical Logic of the Integrated Lens
Structurally, the integrated lens component is positioned within the top housing of the switch, serving as an optical intermediary between the LED and the keycap. Its function can be understood in two ways.
The first is collimation and directional control. Light emitted from an LED is typically divergent; if it were directed straight toward the underside of a keycap, most of it would undergo diffuse reflection against the plastic walls of the keycap’s interior, leaving only a limited amount of light to pass through the legends. The lens uses a refractive surface to gather divergent light into a more concentrated beam, directing a greater amount of light upward along the axis.
The second function is homogenization. Keycaps for low-profile switches are typically thinner with shallower internal cavities, leaving little room for light to diffuse once it enters. The lens pre-processes the light spot for uniformity before it reaches the keycap, mitigating the “hotspot” effect—where the center appears bright while the edges remain dim. This is particularly crucial for low-profile keycaps featuring side-printed or translucent legends, as uneven light distribution would otherwise lead to inconsistent brightness across the characters.
III. Specifications of the White Jasmine Low-Profile Switch and the Role of the Lens
The White Jasmine low-profile switch is a linear switch with a total travel of 2.8 ± 0.25 mm, an actuation travel of 1.3 ± 0.30 mm, an operating force of 40 ± 10 gf, and a return force of ≥ 15 gf. These specifications position it as a low-profile switch designed for light actuation and rapid response—well-suited for office work and casual gaming.
The inclusion of a lens component strikes a balance between a “slim” profile and high brightness. The “WEEK” series of keyboards from Black Canyon (He Xia Gu), which utilize these switches, highlight their RGB backlighting and side-lighting capabilities; the lens serves as the essential hardware foundation for delivering these lighting effects. Without the lens, the RGB light from a low-profile switch would likely manifest merely as “light leakage” through the gaps between switches, rather than illuminating the keycap legends or creating an ambient glow.
IV. Comparison with Conventional Low-Profile Backlighting Solutions
In Kailh’s own “Choc” series of low-profile switches, some models enhance light transmission via a “light-slot” design—essentially an aperture in the switch housing that allows light to escape from the sides or the top. This approach relies on “opening a path” for the light; while the structure is simple, it offers limited control over the light path.
In contrast, the integrated lens in the “White Jasmine” switch represents a more proactive optical design. Rather than simply providing a route for the light to escape, it actively dictates the path the light must take and the form in which it is projected. The trade-off involves a more complex internal structure for the switch and a requirement for higher-precision molds; the benefit is greater predictability in backlighting, eliminating the need for supplementary light-guiding structures within the keycaps or the keyboard base.
V. Scope and Use Cases
The value of an integrated lens design in White Jasmine low-profile switches depends heavily on the specific use case.
For keyboards with no backlighting or weak backlighting, the lens component offers no tangible benefit; instead, it merely increases the switch’s structural complexity and cost. For low-profile keyboards designed for RGB aesthetics, the lens is the critical element that elevates lighting effects from merely “functional” to “visually appealing.” In office environments where high legibility of keycap legends is required, the lens’s ability to diffuse and even out light helps reduce visual fatigue caused by uneven brightness across the characters.
It should be noted that the optical path of the lens is precisely calibrated to the switch height, the position of the LED, and the internal cavity shape of the keycaps. When replacing the stock keycaps, if the depth of the internal cavity or the light-transmitting area does not align with the lens’s light-emission angle, the quality of the lighting effects may be compromised. This is an inherent constraint of integrated optical design: while the switch manufacturer optimizes the optical path, they also tether the consistency of that path to a specific ecosystem of compatible keycaps.
