Touchscreens

Hardware checkpoint 1.3

Provide an alternative input method for touchscreens or touch-operated controls.

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Rationale

Touchscreens or contact-sensitive controls provide no tactile cues so they require the user to be able to see the areas of the screen in order to activate a touch control. Blind users cannot locate the areas of the touchscreen to activate the controls. Touch-operated controls often require physical body contact. Someone with a physical disability who may have an artificial limb would not be able to activate the control.

Development techniques

When touchscreens are used, provide a redundant set of controls that complies with the following in order to meet Checkpoint 1.3 from the IBM Hardware Accessibility Checklist. These requirements apply to the redundant set of controls when a touchscreen is used:

Provide controls and keys which are tactilely discernible without activating the controls.
Provide controls and keys which can be operated with one hand and which do not require tight grasping pinching or twisting of the wrist. The force required to activate controls and keys shall be a maximum of 5 pounds (22.2 N).
If key repeat is supported provide an option to adjust the keyboard repeat rate to at least 2 seconds. The key repeat rate should be adjustable to 2 seconds per character.
Provide the status of all locking or toggle keys visually and either through touch or sound.

The above techniques are required; the following technique is recommended to enhance accessibility.

Provide audible feedback when a user pauses over a section of a visible keyboard.

Testing techniques

Test the hardware to ensure that it complies with accessibility requirements. These requirements apply to the redundant set of controls when a touchscreen is used.

Tools

Force or torque gauge.

Techniques

*The following techniques are **required** to verify this checkpoint:*
	Action	Result
1	Check each control or each key to determine that it can be identified uniquely without activating it. This can be accomplished by touching or viewing each control or key and perceiving the distinctions as to its physical configuration or location in regard to other controls or keys.	Pass: Each control or key can be uniquely identified either by touch or visual observation without activating it. Fail: A control or key can not be uniquely identified either by touch or visual observation. A control or key can be uniquely identified by either touch or visual observation, but not without activation.
2	Check that each control can be activated with only one hand, requires no tight grasping, pinching, no twisting of the wrist, and requires no more than 5lbs of force to activate. Use a force or torque gauge to measure the force required to activate the control.	Pass: All controls can be activated with one hand, needs no constricted tight grasping, no squeezing between the thumb and finger, no rotating or revolving of the wrist. A control requires no greater than 5 lbs of force to activate. Fail: A control cannot be activated with one hand. A control requires constricted grasping to activate. A control requires squeezing between the thumb and finger to activate. A control requires rotating or revolving of the wrist. A control requires greater than 5 lbs. of force to activate.
3	If key repeat is supported: Verify that the repeat rate can be set to at least 2 seconds.	Pass: Repeat rate can be set to at least 2 seconds. Fail: Repeat rate can not be set to at least 2 seconds.
4	Verify the status of locking and toggle keys is visible. Verify the status is available through touch or sound.	Pass: Status of locking or toggle key can be visually ascertained, and Status of locking or toggle key can be either ascertained through touch or ascertained through sound. Fail: Status of locking or toggle key can not be visually ascertained. Status of locking or toggle key can be visually ascertained, but cannot be ascertained through touch and sound.

Last updated February 22, 2008.

Checklist