JPS62196980A - Display device for channel selection index of on-vehicle television - Google Patents

Abstract

PURPOSE:To facilitate channel selection by displaying with an index the propriety for reception of a preset channel on a screen. CONSTITUTION:A VIF circuit 5 applies AGC voltage, for example, to the input at one side of a comparator 4 as a signal showing the IF level. While the reference voltage REF is supplied to the other input of the comparator 4. Then the comparator 4 compares successively the AGC voltage of preset channels with the voltage REF and decides the propriety for reception of pictures according to the field intensity level higher or lower than a reference level. The result of this decision is supplied to a channel selection control circuit 2 and this circuit 2 produces an index signal according to said result of decision to supply it to the picture receiver side via an adder 6. Video signals subjected to wave detection through the circuit 5 are supplied to the adder 6. Then the pulse voltage is superposed on said video signals as the index signal. Then the result of decision is displayed on a screen and therefore the quality of pictures is manifest quickly for the preset channel. Thus a channel of high picture quality can be easily selected.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to a television receiver (
In-vehicle television)'s channel selection index.

[Summary of the invention]

The present invention facilitates channel selection in a vehicle-mounted television by displaying an index on the screen indicating whether or not nine preset channels can be received.

[Conventional technology]

In the case of a normal home television receiver, to check the quality of each channel, it is normal to manually change the channels one by one (up and down) and look at the image. This also applies when the tuner is preset. However, in this case, since the receiver is fixed, the appearance of each channel is generally constant.

Therefore, in a home-use receiver, there is no need to display a list on the screen of which channels are the best.

[Problem that the invention seeks to solve]

However, in a car-mounted television, the receiver moves as the car moves, so even on the same channel, the quality of the picture changes and the channels that can be received also change, so it is necessary to find out which channels are most visible. However, for in-vehicle televisions, a channel selection index display device that displays channels with good quality on the screen has not yet appeared. Although some in-vehicle radio receivers display the electric field strength of each broadcasting station (for example, see Japanese Patent Publication No. 13767/1983), it has the drawback that it is difficult to determine whether reception is possible or not.

[Ninth way to solve the problem]

The present invention utilizes a preset memory group used to preset the tuner of an in-vehicle television, and searches for a preset memory position (preset position) t in this memory group to correspond to that position. It is determined whether the electric field strength of the channel (precent channel) is higher or lower than a reference value, and the determination result is displayed on the picture tube surface. Then, by simply pressing the channel selection index button, the channel selection control circuit is made to perform this operation.9 [Operation] By displaying the judgment result on the screen, it becomes clear at a glance whether the image is good or bad for the preset channel. It becomes possible to easily select an image channel.

〔Example〕

FIG. 1 is a block diagram illustrating a preferred embodiment of the present invention. In this figure, (1) is a precent memory group that stores the channel frequency at which each memory is reset, for example, in the form of a division ratio of the local oscillation frequency, and (2) is a memory group for writing/continuing to memory group (1). (3) is a control panel (key node) that gives commands to the control circuit (2); (4) is a comparator as a determination means. , (5) is a video intermediate frequency (VIP) circuit, (6) is an adder, and (7) is a tuner circuit (pack).

Fig. 2 is a plan view showing an example of the operation panel (3) in Fig. 1. In this figure, (to) is a preset button, 01)
is the enter button, 0 is the channel input button, 0
The key is the index button, and the other 10 buttons are the numeric keypad. Numerals from 0 to 9t are displayed on the numeric keypad (b), and alphabetical characters (for example, A-H) are displayed on the keys that are also used for selecting preset positions. To reset the tuner, for example, press the preset button (1), enter button 0, and numeric keypad (A-H, O).
~9] (b). Once preset,
Of the memory group (1), preset channels corresponding to the positions of the pressed numeric keypad, for example A, B, C, . . . ... is memorized. Specifically, data representing the division ratio of the local oscillation frequency is stored, and this data is used to control a variable divider (not shown) when selecting a channel.

Index button 03 displays the channel selection index on the screen (
Preset CH JP corresponding to the grisset position -/
+ A-/r'+ 84(h/rI E
T FJ5 ; ÷ 16 −! j to λ Boolean θ) There are 401 tastes. If you press the index button υ while receiving a channel, the channel selection control circuit (2)
detects this, searches the memory group (1) for the preset position, reads out the preset channel, and controls the tuner circuit (7), which in turn controls the VIP circuit (
5) The tuning frequency of the preset channels is supplied to the preset positions, for example, in the order of A, B, C, . . . . VIP
The circuit (5) applies, for example, AGC pressure to one input of the comparator (4) as a signal representative of these IF levels. A reference voltage REF is supplied to the other input of the comparator (4), and the comparator (4) sequentially compares the AGC voltage of each preset channel with the reference voltage REF, and determines that the electric field strength is higher than the reference value. It is determined whether or not the image can be received based on whether the image quality is low or not. The determination result is input to the tuning control circuit (2), which creates an index signal according to the determination result and supplies it to the picture tube side via the adder (6). The adder (6) is supplied with the detected video signal from the VIP circuit (5), and a pulse voltage as described later is superimposed thereon as an index signal.

Figure 3 shows an example of the channel selection index display screen.
A list of preset positions is displayed at the top right of the screen.

In the figure, positions D and G among the preset positions appear black on the screen, which indicates that the electric field strength of the channel preset at that position is below the reference level and the image is defective. In order to display such a tuning index, the control circuit (2) generates short white level nodes that display these characters at the positions of A, B, C, E, F, and H for each scanning line, for example. It is sufficient to output 4 pulses, and output slightly long pulses at the black level that make a black square appear at the D and G positions. Since such a display technique can be easily designed by a person skilled in the art, a detailed description thereof will be omitted.

FIG. 4 is a flowchart showing an example of a program when a microcomputer is used for the 1-channel selection control circuit (2). This program writes 1 judgment result to memory,
Although the case where the memory groups are read out all at once after the end of the search has been shown, the present invention can also be applied to a case where there are two or more memory groups of the same type and they are used by switching between them.

〔Effect of the invention〕

As explained above, according to the present invention, even if the field intensity of each channel changes due to the movement of the car, in a car-mounted television, the preset level IIL (A, B) can be adjusted by simply operating a single button. , C, etc.) can be displayed in a list on the picture tube surface, so there is no need to go up and down the channels and look at each image one by one to judge whether the image is acceptable or not. It is very convenient to understand.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing a preferred embodiment of the present invention, FIG.
Figure 3 is a plan view showing an example of a control panel used in the present invention, Figure 3 is a front view showing an example of a channel selection index display screen according to the present invention, and Figure 4 is an example of a program when a microcomputer is used in the present invention. FIG. (1) Preset memory group, (2) Tuning control circuit, (3) Tuning operation panel, Index button,
(4)...Judgment means.

Claims (1)

[Scope of Claim] In a vehicle-mounted television having a preset memory group, a tuning control circuit, and a tuning operation panel, the operation panel is provided with an index button, and the tuning control circuit has an electric field strength that is lower than a reference value. A means for determining whether the channel is high or low is provided, and when the index button is operated, the channel selection control circuit searches the preset memory and causes the determination means to determine the electric field strength of the preset channel. An in-vehicle television channel selection index display device that displays the results on the picture tube surface.