JPS62196982A - Display device for channel selection index of on-vehicle television - Google Patents

Abstract

PURPOSE:To choose quickly a preset channel having good picture quality among plural channels and at the same time to make undesirable pictures under searching invisible to user's eyes, by displaying a channel selection index on a screen. CONSTITUTION:A channel selection index is displayed after the preset position of a memory group 1 is searched. In a search mode, the pictures of each preset channel are projected sequentially and the screens are switched rapidly. Thus it is desirable to make those switching screens invisible to user's eyes. For this purpose, a frame memory 8 is provided and the writing/reading operations of the memory 8 are controlled by a channel selection control circuit 2. When an index button 33 is pushed, the memory 8 is set under a writable state and stores picture reception signals by an amount equal to a single frame. When the writing operation is finished in the memory 8, the memory 8 is set under a reading state. Thus the picture reception signals equivalent to a single frame are supplied to a picture tube 10 and the still pictures are projected after a switch 9 is changed to the side of the memory 8. At the same time, the index signal is supplied to the tube 10 and the channel selection index is displayed on the screen.

Description

[Detailed Description of the Invention] The present invention provides a ten vision receiver for use in a car.
This invention relates to a channel selection index display device for a vehicle-mounted television.

[Summary of the invention]

The present invention provides preset and
In addition to displaying an index on the screen to indicate whether or not a channel can be received, the image that is disturbed when searching for a preset memory location for index display is made into a still image so that the user cannot see it.

[Conventional technology]

In the case of a normal home television receiver, to check the image 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, 1. Since the receiver is fixed, the appearance of each channel is generally constant. Therefore, in home-use receivers, there is little need to display on the screen which channel looks good.

[Problem that the invention seeks to solve]

However, in a car-mounted television, the receiver moves as the car moves, so the quality of the display changes even for the same channel, and the channels that can be received also change (therefore, it is necessary to check which channels are displayed well). Therefore, in a car-mounted television, there is a long-awaited device for displaying a channel selection index on a highly visible channel/I/input screen to indicate whether or not a channel is available.

[An unsuccessful means to solve the problem] The present invention utilizes a preset memory group used to preset the tuner of a car-mounted television, and simply presses the tuning index button provided on the tuning operation panel. , the channel selection control circuit searches for a preset memory position (preset position) ya' and compares the signal voltage representing the electric field strength of the channel corresponding to that position (preset channel) with the reference voltage to generate an image. The quality of the TV is judged and the result of the judgment is displayed on the reception screen as a channel selection index. At this time, since a distorted image appears during the search, a frame memory for storing 17V of the received signal was provided in order to make it a still image so as not to show it to the user.

[Effect]

Since the channel selection index is displayed on the screen, you can see at a glance which of the preset channels has a good image, and you can instantly select the desired channel. Moreover, undesirable images being searched are not visible to the user.

〔Example〕

FIG. 1 is a block diagram illustrating a preferred embodiment of the present invention. In this figure, (1) is a preset memory group that records the frequency of the channel to be preset, for example, in the form of division ratio data of a local oscillation frequency, and (2) is a read/write function for the memory group +1). (3) is an operation 111 (keyboard) that gives commands to the channel selection control circuit (2), and (4) is a determination means. comparator, <51 is a video intermediate frequency (VIP) circuit,
(6) is an adder, (7) is a tuner circuit (back), (
Is 8) a received signal? : Frame memory that stores only one frame; (9) is a changeover switch; (IO indicates a picture tube).

FIG. 2 is a plan view showing an example of operation *13) in FIG. 1. In this figure, ■ is a preset button, 6η is an enter button, O is a channel up/down button, 间 is an index button, and the other 10 button diagrams are a numeric keypad. Numbers from 0 to 9 are displayed on the numeric keypad, and among these numeric keys (b), the ones used in common to select the memory location to be preset (preset position) display alphabetic characters (for example, A-). H) is displayed.

Tuner presets can be set using, for example, the preset button (to),
Enter button 6υ and numeric keypad (A-H, Qゝ゛~9) (
(4). When preset, the preset memory location in memory group (1), for example A.

For example, channels 1, 4, 6, etc. are preset in the numeric keypad diagram corresponding to B, C, . . . ...
... is memorized. Specifically, as mentioned above, data representing the division ratio of the oscillation frequency of the local oscillator (not shown) is stored, and when leaving the station, this data is read out to control the variable division divider (not shown). It's Nishide.

The index button (to) is a button for displaying a channel selection index on the screen (displaying a list of whether or not the preset channel corresponding to the preset position can be received). When you press the index button while receiving a channel, the channel selection control circuit (2) detects this and stores the memory group (1).
), the tuner circuit (7) is controlled by searching for a preset position and outputting preset channels one after another, and the VIP circuit (5) is given a preset position, for example, A, B, C, etc.
・The tuning frequency of the preset channel is supplied in this order. The VIP circuit (5) applies, for example, an AGC voltage to one input of the comparator (4) as a signal representing these IF levels. A reference voltage REF is supplied to the other input of the comparator (4), and the comparator (4) compares the AGC voltage of each preset channel with the reference voltage REF and determines whether the electric field strength is higher than the reference value. It is determined whether or not the image can be received depending on whether the image is low.

The determination results are sequentially input to the tuning control circuit (2), and the tuning control circuit (2) creates an index signal according to the determination result and supplies it to the picture tube ucjI via the adder (6). , change the switch (9) from the position shown in the figure to the frame memory (8) side. Before pressing the index button, the switch (9) is connected to the VIP circuit (5), and the adder (6) is supplied with the detected video signal. The index signal is input to the adder (6) in the form of a pulse voltage as described below.

FIG. 3 shows an example of a channel selection index display screen, in which a list of preset positions is displayed at the upper right of the screen. In the same figure, positions D and G of preset positions A-H appear black on the screen, which means that the electric field strength of the channel preset at that position is below the standard novel and the image is defective. show. In order to display such a display, for example, the tuning control circuit (2) sends the following information to each scanning line.
A, B.

It is sufficient to output short pulses at the white level that make these characters appear at the positions C, E, F, and H, and output slightly longer pulses at the black level that make the black square appear at the positions D and G. These five display techniques can be easily designed by those skilled in the art, so detailed explanations will be omitted.

The above-mentioned channel selection index is displayed after searching the preset position in memory group tll, but during the search, the images of each preset channel are displayed one after another and the screen changes rapidly, so the user cannot see it. It's better not to have it. The frame memory (8) is provided to prevent this, and its writing and subsequent output are controlled by the channel selection control circuit (2). When the index button made of lead is pressed, the frame memory (8) becomes ready for writing, and one frame of the received image signal is stored. Immediately after writing is completed, frame memory f8)? :1! ! Put it out. Therefore, when the switch (9) is switched to the frame memory (8) side, one frame of image reception signal is supplied to the picture tube (1(l) and a still image is displayed. At the same time, the index signal is supplied to the picture tube αC. , the channel selection index will be displayed on the screen.Therefore, after pressing the index button, the screen will show a still image instead of the distorted image being searched.

After completing the search for the preset position, press the switch (91?i-
Undo. The channel selection index display is automatically erased after a certain period of time by, for example, a timer, but the switch (9) may be returned to its original state at the same time. switch(
9) is restored, the device returns to the state before index button qv was pressed.

FIG. 4 is a flowchart showing an example of a channel selection index display program when a microcomputer is used as the channel selection control circuit (2). Since the procedure according to this program is the same as the procedure described above, repeated explanation will be omitted. Note that the flow related to the frame memory is also omitted because it is the same.

In addition, in the above example, the preset memory group (bank)
Although only one memory group has been shown, the present invention can also be applied to a system in which there are two or more identical memory groups and these are used selectively.

〔Effect of the invention〕

As explained above, according to the present invention, even if the electric field strength of a channel changes due to the movement of the car, in a car-mounted television, a preset position (person, B, C, etc.) can be set by simply pressing a single button. ) can easily display an index on the picture tube surface to indicate the quality of the image of the corresponding channel.
It is extremely convenient to select a channel because you can instantly know whether the image is being received or not. Furthermore, since the disturbed image that appears before the index display is made into a still image, there is an effect that the user does not feel uncomfortable.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing a preferred embodiment of the present invention, FIG.
The figure is a plan view showing an example of the channel selection operation panel used in the present invention.
FIG. 4 is a front view showing an example of a channel selection index display screen according to the present invention, and FIG. 4 is a flowchart showing an example of a channel selection index display program when a microcomputer is used in the present invention. (IJ... preset memory group, (2)...
...Tuning control circuit, (3)...Tuning selection operation panel, link...Index button, (4)...
Judgment means, (8)...Flame memory, αe・
... Picture tube.

Claims (1)

[Claims] In a vehicle-mounted television having a preset memory group, a channel selection control circuit, and a channel selection operation panel, the operation panel is provided with an index button, and it is determined whether the electric field strength is higher or lower than a reference value. A frame memory for storing one frame of the received image signal is disposed in the tuning control circuit, and when the index button is operated, the tuning control circuit searches for a preset memory position and responds to the preset memory position. An on-vehicle device that causes the determination means to determine the electric field strength of the channel, displays the determination result on the picture tube surface, writes and reads the frame memory, and supplies one frame of still image signal to the picture tube. TV channel selection index display device.