JPH02274011A - Channel selector - Google Patents

Abstract

PURPOSE:To facilitate the switching of a first mode and a second mode (manual channel search mode) by providing a manual search stop switch means for stopping the sweep of a tuning voltage. CONSTITUTION:A down-search start switch 14a and an up-search start switch 14b are provided as an auto search start switch (auto search start switching means), and also, a volume-up switch 16a and a volume-down switch 16b a provided as a sound volume variable switch. In such a state, these sound volume variable switches 16a, 16b operate as a manual search stop means for stopping this auto search in the course of an auto search mode. That is, by the manual search stop switches 16a, 16b, the sweep of a tuning voltage Tu can be stopped. In such a way, the auto search can be stopped freely, and a user can set freely the tuning voltage without setting a manual channel search mode.

Description

DETAILED DESCRIPTION OF THE INVENTION (A) Field of Industrial Application The present invention relates to a channel selection device, and particularly to a channel selection device for a portable liquid crystal television.

(b) Conventional Technology As is well known, a typical home television receiver is provided with about ten channel buttons corresponding to the selected channels. In addition, some devices are equipped with an automatic search function to facilitate the operation of presetting tuning voltage data corresponding to the 10 or more channel buttons. This auto search function
A tuning detection circuit detects the tuning state based on the T voltage and the horizontal or vertical synchronizing signal and stops the sweeping of the tuning voltage.

A channel selection circuit that performs such a thing is, for example, published in Japanese Patent Application Laid-open No. 55-1
It is also shown in No. 65021 (HO3J5100).

By the way, the stations that a portable liquid crystal television can receive differ depending on conditions such as the location at the time of use. For this reason, rather than the function of setting tuning voltage data of stations that can be received in advance,
An auto-search function that searches for receivable channels on the spot is often used.

However, when receiving a weak electric field, detection of the tuning state by the electrical tuning detection circuit becomes inaccurate. Furthermore, in the case of a channel with a very weak electric field and a lot of noise, the determination of whether the channel is "receivable or not" differs depending on the user.

For this reason, portable LCD TVs have a changeover switch that allows
The first mode is auto search mode when searching for a station, and the second mode is where the tuning voltage value is manually set when searching for a station.
mode (manual station search mode).

Incidentally, such a circuit is disclosed in Japanese Patent Application Laid-open No. 60-235593 (HO
4N5/44) is well known.

(c) Problems to be Solved by the Invention However, switching between the first mode and the second mode (manual station search mode) is troublesome. Furthermore, if only the first mode is used, malfunctions occur when weak electric fields are received, and station searching is troublesome if only the second mode (manual station search mode) is used. (d) Means for Solving the Problems The present invention provides a microcomputer (3) that cooperates to output a tuning voltage (Tu) to a tuner (20).
2), a tuning voltage output circuit (34), and a display panel (1) that displays the video signal from this tuner.
0), an auto search start switch (14a, 14b) that sets the microcomputer etc. (32) (34) to auto search mode and sweeps the tuning voltage (Tu), and an AFT.
the microcomputer (32) inputting a voltage signal and a synchronization presence/no-synchronization signal, detecting the tuning state of the tuner (20) using a built-in tuning state detection program, and stopping the sweeping of the tuning voltage (Tu); The channel selection device includes a manual search stop switch (16a, 16b) for stopping the tuning voltage sweep.

(E) Function According to the present invention, the manual search stop switch (16a,
16b) allows the sweeping of the tuning voltage (Tu) to be stopped. In other words, there is no need to separately provide a switch for starting the tuning voltage sweep for manual search.

(F) Embodiment An embodiment of the present invention will be described with reference to FIGS. 1 to 4.

FIG. 1 is a diagram of a liquid crystal television, where (10) is a liquid crystal panel (display element) and (12) is an antenna. (14
a) (14b) Auto search start switch (auto search start switch means), (14a) is a down search start switch, and (14b) is an up search start switch. (16a) and (16b) are volume variable switches; (16a) is a volume up switch;
b) is a volume down switch.

The feature of this embodiment is this volume variable switch (16a) (
16b) acts as a manual search stop means for stopping the auto search in the auto search mode.

Figure 1 shows the auto search in progress, and the LCD panel (10
) displays the received image (during the search, the background received image is naturally a noise image), and also displays the current tuning voltage value using the built-in character generator. . In Figure 1 (
Sl) is the channel-corresponding comparison scale for this purpose, (S,)
is a scale representing the current tuning voltage value. (
S, ) is the scale reference graduation.

The operation of this embodiment will be explained.

When one of the auto search start switches (14a) and (14b), for example, the up search start switch (14b) is pressed, the auto search mode is activated, and the tuning voltage is swept in the up direction, and the liquid crystal panel (
10) is also as shown in the figure. Correspondingly, the LCD panel (1
The tuning voltage value scale (S, ) of 0) also increases. When the tuning detection circuit (not shown) detects tuning (stationed), it automatically stops the search, cancels the auto search mode, and stops superimposing the character generator on the liquid crystal display panel (10). The screen will become normal.

By the way, the auto search can be stopped by pressing the volume up or down switch (16a, 16b) during this auto search mode.

After the auto search mode is canceled by operating these switches (16a, 16b),
6b) acts as a switch for volume up/down operation as usual, and changes the volume depending on the pressing time.

It is believed that the gist of the present invention has been understood from the above explanation.

As a precaution, the channel selection circuit employing the present invention will be explained again with reference to circuit diagrams and the like.

In FIG. 2, (20) is a tuner circuit, (22) is an IF circuit, (24) is a video processing circuit, (26) is a liquid crystal control circuit, and (10) is a liquid crystal panel.

(32) is a search operation circuit consisting of a channel selection microcomputer. (34) is the tuner (2
This is a tuning voltage output circuit that outputs a tuning voltage (Tu) to 0). This tuning voltage output circuit (
34) is controlled by a signal from the microcomputer (32). The AFTt pressure signal from the IF circuit (22) is sent to the microcomputer (
32) to control the tuning voltage output circuit (34) to correct the tuning voltage.

(36) is a key operation section.

(38) is a nonvolatile memory made of EEROM or the like. (40) is a memory control circuit.

Incidentally, as shown in the above-mentioned known example, the microcomputer (32) detects the synchronization state based on the AFT signal from the IF circuit (22) and the synchronization presence/absence determination signal from the video processing circuit (24). Stop the auto search and write the band data and tuning voltage data at this time to the memory (38).

Alternatively, even if the switch (16a) or (16b) of the key operation unit (36) is pressed during auto search, the auto search is similarly stopped and the data is written in the memory (38).

The operation of the above circuit will be explained with reference to FIG. In addition, the reception condition at this time is that the signal of channel 2, -1.6 can be received, but the reception condition of channel 4 is very poor and the image is unbearable to view. However, the tuning state detection program (tuning state detection means) of the microcomputer (32) determines that there is no station.

Suppose that the TV is currently receiving channel 2.

a. Press the up search start switch (14b).

b. The microcomputer (32) starts a search. At the tuning voltage corresponding to channel 4, although the screen is visible, the search is not completed, and the tuning state detection means operates in channel 6, and the auto search is completed.

If the C9 user wants to watch channel 4, he or she presses the down search start switch (14a).

d. The device enters auto search mode, the tuning voltage changes, and the channel 4 reception state approaches, and the channel 4 image appears on the screen.

e. When the screen of channel 4 is displayed on the liquid crystal panel (10), the user presses the switch (16a) to stop the auto search mode.

f. Write tuning data to memory (38).

Incidentally, FIG. 4 shows a flowchart of the operation which is a feature of the present invention.

In the above embodiment, the volume switch (16a
, 16b) was used as a manual search stop switch means,
This is because during auto search, the sound is muted and there is no need to control the volume, so volume control using this switch is essentially useless during auto search.

Further, in this embodiment, auto search is stopped by pressing either of the switches (16a, 16b), but it may be stopped by pressing both at the same time.

(G) Effects of the Invention As described above, according to the present invention, automatic search can be stopped freely. Therefore, the user can freely set the tuning voltage without having to enter the manual search mode.

[Brief explanation of drawings]

Fig. 1 is a diagram of a liquid crystal television incorporating a channel selection device according to an embodiment of the present invention, Fig. 2 is its circuit diagram, Fig. 3 is a diagram for explaining the operation, and Fig. 4 is a diagram showing a flowchart. It is. (20)...Tuner, (Tu)...Tuning voltage, (32)...Microcomputer (tuning voltage output means) (
34)...Tuning voltage output circuit (tuning voltage output means), (10)...Liquid crystal panel (display element), (14a) (
14b)...Auto search start switch (auto search start switch means), (32)...Microcomputer with built-in tuning state detection program (tuning state detection means), (16a) (16b)...Volume variable switch ( manual search stop switch means). Figure 1 Figure 3

Claims (2)

[Claims] (1) Tuning voltage output means (32) (34) that outputs a tuning voltage (Tu) to the tuner (20), and a display element (1) that displays the video signal from the tuner.
0), and the tuning voltage output means (32) and (34) are set to auto search mode, and the tuning voltage (Tu) is set to auto search mode.
auto search start switch means (14a,
14b); and tuning state detection means (32) for detecting the tuning state of the tuner (20) and stopping the sweeping of the tuning voltage (Tu). A channel selection device comprising manual search stop switch means (16a, 16b) for stopping the search. (2) The manual search stop switch means (16a, 16
2. The channel selection device according to claim 1, wherein b) outputs a signal for stopping the sweep when in the auto search mode, and acts as a switch means for other functions when in a mode other than the auto search mode.