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Screenkey Selection FAQs

1. What is soft-touch? What is tactile?

ScreenKeys are offered with two different switch actions, soft-touch and tactile

Many users like to receive "feedback" from the ScreenKey when pressed. This “feedback” is the sensation of the ScreenKey resisting the downward motion of pressing the key. There is a feeling of bounce-back at the bottom of the key press. This bounce, or feedback, is what is referred to as "tactile feedback."

Some users prefer not to have tactile feedback and instead prefer more of a cushioning sensation at the bottom of the key press. This “soft-touch” effect is registered by a soft thud when the ScreenKey movement reaches the bottom of the key press.

2. What IP rating have ScreenKeys got?

ScreenKeys are not IP rated. Some ScreenKey users have used silicon screens in hostile environments.

3. Are ScreenKeys ROHS compliant?

All ScreenKeys are RoHS compliant. There is no special marking or order code to request RoHS compliant.

4. What approvals does ScreenKeys have?

SK Interfaces POS consoles that incorporate ScreenKeys have been fully approved and certified with the “CE” and “CSA (NRTL/C)” mark for Europe and the USA.

ScreenKeys only use UL approved materials (see appropriate datasheets).

ScreenKey manufacturing is conducted in an ISO9002 certified facility in a class 100k cleanroom environment.

5. Have ScreenKeys undergone ESD testing?

Screenkeys have been tested for Electrostatic Discharges(ESD) up to 8 Kvolts.

Recommendations to combat the effects of ESD are:

• Refresh Frequency register (0xEE) and the MUX register (0xEE) regularly (e.g. every 60 seconds)
• Clock signal should be driven for groups of maximum 8 switches
• Clock and data lines should be as short as possible
• Place pull ups in clock and data line
• Use of slow clock frequency is helpful for EMV
• Use ground planes as big as possible around the switches

6. What different configuration options are available? How do I specify my requirements?

ScreenKeys are available with several different configurations and options:

LC | RGB              16 | 24              T | (no designation)

LC/RGB refers to the base backlighting LED colors:
LC = two base color backlighting - Red and Green
RGB = three base color backlighting – Red, Green and Blue

16/24 refers to the LCD resolution:
16 = 32 pixels horizontally and 16 pixels vertically
24 = 36 pixels horizontally and 24 pixels vertically

T/(no designation) refers to the switch mechanism:
T = tactile feedback switch action
(no designation) = soft-touch switch action

Examples:

LC24: refers to Red-Green backlighting, 36x24 resolution, soft-touch.
RGB16T: refers to Red-Green-Blue backlighting, 32x16 resolution, tactile.

7. Can ScreenKeys be used in sunlight?

ScreenKeys use transflective LCD technology which enables them to be used outdoors in direct sunlight but with limited functionality.

Transflective LCD technology uses a rear polariser mirror that allows the transmission of the LED backlighting but that also bounces back a portion of the ambient light. The net effect is that indoors the LED backlight is dominant and easily viewed. However, outdoors in direct sunlight the ambient light levels are mostly too strong and overwhelm the LED backlighting. The result is that the pixel pattern is easily viewed on the LCD but the LED backlighting is ineffective and may not be easily seen.

8. What is the lifetime of a ScreenKey?

ScreenKey lifetime is primarily determined by the switch mechanism. Soft-touch mechanisms are rated for 1million+ operations and tactile mechanisms are rated for 3million+ operations. However, testing and end-user field feedback has empirically shown that the true lifetime is considerably higher and likely to be closer to 10million operations.

9. What is the operating temperature range for ScreenKeys?

The primary factor that limits the storage and operating temperature of ScreenKEys is the LCD display. ScreenKeys use enhanced LCD displays with wide storage and operating temperature ranges:

• Storage: -20C to +80C
• Operating: -10C to +70C

10. How many backlight colors can ScreenKeys produce?

The number of distinct colors that a ScreenKey can produce depends on the number of available base colors.

The LC Series have two base colors (red and green) that can be individually turned on a half or full brightness. This allows 3 distinct colors to be produced in either bright or dark:

• Red (Dark / Bright)
• Green (Dark / Bright)
• Orange (Dark / Bright)

The RGB Series have three base colors (red, green and blue) that can also be individually turned on a half or full brightness. This allows 8 distinct colors to be produced, some of which can be further adjusted to dark or bright levels:

• Red (Dark / Bright)
• Green (Dark / Bright)
• Blue (Dark / Bright)
• Yellow
• Purple (Dark / Bright)
• Pink
• Torquoise
• White