On-screen display apparatus

• US 20020075410A1
• Filed: 12/20/2001
• Published: 06/20/2002
• Est. Priority Date: 12/20/2000
• Status: Active Grant

• Current Assignee: Godo Kaisha IP Bridge 1 (IP Bridge, Inc.)
• Original Assignee: Matsushita Electric Industrial Company Limited (Panasonic Holdings Corporation)
• Inventors: Okuno, Tomohiro, Tomikawa, Yasuhiko
• Granted Patent: US 7,184,097 B2
• Time in Patent Office: Days
• US Class Current: 348/569
• CPC Class Codes: H04N 9/641 Multi-purpose receivers, e.g. for auxiliary information H04N9/642 takes precedence

Abstract

The present invention provides an on-screen display apparatus which can eliminate variations in the DC level at a time when an input chroma signal and an OSD chroma signal are switched, and prevent an erroneous display of color. The on-screen display apparatus of the present invention comprises a voltage holder which holds a voltage value at a time when the input chroma signal is a null signal, and an output switch which outputs the voltage value held by the voltage holder in an OSD period and outputs the input chroma signal other than the OSD period.

Claims

1. An on-screen display apparatus which holds a voltage value at a time when an input chroma signal is a null signal and outputs the voltage value during an on-screen display period.

2. An on-screen display apparatus which holds a voltage value at a time when an input chroma signal is a null signal and outputs a chroma signal generated on the basis of the voltage value during an on-screen display period.

3. An on-screen display apparatus comprising:

a voltage holding means for holding a voltage value at a time when an input chroma signal is a null signal; and

an output switch for outputting the voltage value held by the voltage holding means during an on-screen display period and outputting the input chroma signal other than the on-screen display period.

5. The on-screen display apparatus of claim 3 wherein

the voltage holding means has a capacitor for holding a voltage value.

6. The on-screen display apparatus of claim 5 wherein

the voltage holding means further has a resistor placed on a chroma signal input side of the capacitor.

7. The on-screen display apparatus of claim 6 wherein

the voltage holding means is placed on a chroma signal input side of the resistor, and further has a hold timing switch that is brought into conduction when the input chroma signal is a null signal.

8. The on-screen display apparatus of claim 6 wherein

the voltage holding means is placed between the capacitor and the resistor, and further has a hold timing switch that is brought into conduction when the input chroma signal is a null signal.

9. The on-screen display apparatus of claim 3 wherein

the voltage holding means comprises:

an AD converter for converting an input chroma signal into a digital signal when the input chroma signal is a null signal;

a storage means for storing a voltage value at the time when the input chroma signal is a null signal, which has been converted into a digital signal by the AD converter; and

a DA converter for converting the voltage value stored in the storage means into an analog signal.

10. The on-screen display apparatus of claim 3 wherein

the voltage holding means holds the voltage value during a horizontal sync period in which the input chroma signal is a null signal.

11. The on-screen display apparatus of claim 3 wherein

the voltage holding means holds the voltage value during a vertical sync period in which the input chroma signal is a null signal.

4. An on-screen display apparatus comprising:

a voltage holding means for holding a voltage value at a time when an input chroma signal is a null signal;

an AC component generation means for generating AC components of the chroma signal;

an adder for adding the voltage value held by the voltage holding means and the AC components of the chroma signal which are generated by the AC component generation means; and

an output switch for outputting the signal added by the adder during an on-screen display period and outputting the input chroma signal other than the on-screen display period.