Apparatus in a TV receiver for automatically detecting the type of keyboard attached thereto

A front panel keyboard of a television apparatus, comprising:

• first and second keys sharing a keyboard sense line coupled to a controller of the television apparatus for enabling the controller to detect that one of the first and second keys has been activated;
• an inverter to invert a key drive signal from the controller, wherein the controller sends the key drive signal to detect whether a key activation signal is coming from the first key or the second key;
• an AND gate for generating the key activation signal from the second key and the inverted key drive signal;
• and
• a light activatable by the controller for sending a light control signal through a light control line coupled to a switch in the front panel keyboard, wherein the switch is closed to activate the light in response to the light control signal.

A controller in a television apparatus including a front panel keyboard having first and second keys sharing a keyboard sense line, the controller comprising:

• a first input driver coupled to the keyboard sense line for receiving a key activation signal from the front panel keyboard to control the television apparatus according to the key activation signal;
• a first output driver for applying a keyboard operational voltage to the keyboard sense line;
• and
• a bidirectional driver for sending a light control signal to turn on a light in the front panel keyboard and for detecting if an identification voltage is applied from the front panel keyboard, wherein if the identification voltage is not applied, the controller, through the first output driver, applies the keyboard operational voltage to the keyboard sense line, and if the identification voltage is applied, the controller does not apply the keyboard operational voltage to the keyboard sense line.

A method for detecting a type of operational logic of a front panel keyboard of a television apparatus, the television apparatus including a controller for receiving a key activation signal from the front panel keyboard, the method comprising the steps of:

• detecting if an identification voltage is applied by the front panel keyboard to a first control line;
• if the identification voltage is applied, determining that the type of operational logic of the front panel keyboard is positive and applying no keyboard operational voltage to the front panel keyboard;
• if the identification voltage is not applied, determining that the type of operational logic of the front panel keyboard is negative and applying a keyboard operational voltage to the front panel keyboard;
• detecting the key activation signal from the front panel keyboard;
• and
• scanning the front panel keyboard to determine which key of the front panel keyboard has been activated.