JPH0246146Y2 - - Google Patents

Description

[Detailed description of the invention] <Technical field> The present invention utilizes the vertical blanking period of a television video signal to process character (multiplex) signals transmitted in data packets whose unit length is one horizontal scanning period. The present invention relates to a teletext receiver capable of receiving teletext broadcasts, and particularly relates to a reset circuit of a teletext decoder section.

<Background Art> Generally, a teletext receiver includes a television receiving section for receiving normal television broadcasts, and
The system is equipped with a teletext decoder unit for receiving the teletext multiplexed with the teletext broadcast, and the user can select and view the teletext screen and the teletext screen as desired. be able to.

Furthermore, at present, teletext is not multiplexed over all television broadcast channels, but only on specific broadcast channels.

Therefore, with conventional teletext receivers, during channel selection, especially when switching from teletext reception to a general television broadcast channel, the switching operation is not smooth, and the previous teletext screen remains. , there was a fear that general television broadcast screens would be blocked.

<Purpose> The present invention was devised in view of the above points, and its purpose is to prevent malfunctions during channel selection operations in a teletext receiver and to quickly perform switching operations.

<Example> Embodiments of the present invention will be described below.

The drawing shows a block diagram of an embodiment of the present invention, and the teletext receiver of this embodiment includes a television receiving section 1 for receiving ordinary television broadcasting, and a television receiving section 1 for multiplexing this television broadcasting. It has a teletext decoder section 2 for receiving teletext sent by the user. The television receiving section 1 includes a tuner 3, a channel selection circuit 4, an IF/detection circuit 5, an AFT circuit 6, a television signal processing circuit 7,
and a CRT (cathode ray tube) 8, and further switches between a television video signal obtained from the television signal processing circuit 7 and a character signal obtained from the teletext decoder section 2 and outputs the same to the CRT 8. It is equipped with 9.

On the other hand, the teletext decoder section 2 includes a character signal processing circuit 10 that extracts a character signal from the composite video signal obtained from the IF/detection circuit 5 of the television receiving section 1 and performs predetermined data processing, a buffer memory 11 that temporarily stores character signals from 10; a CPU (central processing unit) 12 that controls the entire operation of the decoder section B;
A program RAM (read-only memory) 13 in which a special program of No. 2 is pre-stored;
Furthermore, the working area used by the CPU 12 for operation
RAM (random access memory) 14.

The individual operations of the television receiving section 1 and the teletext decoder section 2, which are comprised of the above components, are not particularly different from those of conventional general teletext receivers, and detailed operations thereof will be omitted here.

Generally, a general-purpose channel selection IC is used in the channel selection circuit 4, but such a channel selection IC usually outputs a pulse of 50 to 200 msec each time a channel selection operation is performed, and these pulses are processed by AFT. It is designed to be used for release and voice muting.

Therefore, in the teletext receiver of this embodiment, a part of the AFT day pulse that is derived from the channel selection circuit 1 of the television receiver 1 for canceling the AFT and applied to the AFT circuit 6 during the channel selection operation is used for teletext transmission. It is also applied to the reset terminal of the CPU 12 of the decoder section 2, so that whenever the channel is switched, the CPU 1 of the teletext decoder section 2 is applied.
2 is reset.

With the above configuration, the CPU 12 of the teletext decoder section 2 is reset each time the channel switching operation of the television reception section 1 is performed, so that each memory such as the buffer memory 11 in the decoder section 2 is Each time, the system enters the initial state, and even if it has been in the teletext reception state until then, this reception state is canceled and it immediately shifts to the normal television broadcast reception state.
Note that if you select the same channel as before, the AFT day-to-day pulse will not be output from the channel selection circuit 4, so the teletext decoder section 2 will
The CPU 12 is not reset and continues to receive teletext.

<Effects> As described above, according to the teletext receiver of the present invention, the teletext decoder is reset to the initial state each time the reception channel is switched during the channel selection operation, so even if teletext was being received until then, the teletext decoder is reset to the initial state. Even in the event of a problem, the screen can be quickly switched to a normal television broadcast reception screen, and there is no risk of malfunction.

[Brief explanation of the drawing]

The drawing is a block diagram of an embodiment of the present invention. 1...Television receiver, 2...Teletext receiver, 4...Tuning selection circuit, 6...AFT circuit, 7...
...TV signal processing circuit, 9...TV/text signal switching circuit, 10...Text signal processing circuit, 12...
CPU.

Claims (1)

[Scope of utility model registration request] In a teletext receiver equipped with a television reception unit that receives general television broadcasts and a teletext decoder unit that receives teletext multiplexed with this television broadcast, television reception is performed during channel selection. Derived from the channel selection circuit of
A teletext receiver comprising a reset means for resetting a teletext decoder section to an initial state based on an AFT daily pulse.