JPH0673934U - Tuner circuit - Google Patents

Abstract

(57) [Summary] [Object] It is an object of the present invention to provide a tuner circuit capable of promptly performing channel switching irrespective of a difference between channels when switching channels. In a tuner circuit 10 with a PLL circuit for switching channels based on a step frequency,
A step select terminal 11 for switching the step frequency is provided, and the tuner circuit 10 is configured so that the step frequency can be switched based on a selection signal input to the step select terminal.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to a tuner circuit with a PLL circuit, and more particularly to a synchronization method when switching channels.

[0002]

[Prior art]

 Conventionally, a tuner device is configured, for example, as shown in FIG. That is, in FIG. 4, the tuner device 1 includes a tuner circuit 2, a control circuit 3 including a microcomputer for controlling the tuner circuit 2, and a channel selection button for selecting a channel to be received. And a channel selection device 4 for sending channel data to the control circuit.

The tuner circuit 2 is configured as shown in FIG. 5, so that the PLL circuit is connected to the PLL terminal and the tuning voltage from the PLL circuit is applied to the VT terminal. The tuning operation is performed based on a constant step frequency.

According to the tuner device 1 having such a configuration, when a channel is selected by the tuning device 4, the channel data is sent from the tuning device 4 to the control circuit 3. As a result, the control circuit 3 sends the channel switching data to the tuner circuit 2. Therefore, the tuner circuit 2 changes the channel based on this data by the PLL circuit based on a constant step frequency.

[0005]

[Problems to be Solved by the Invention]

 However, in the tuner device 1 thus configured, since the step frequency of the PLL circuit is fixed, if the step frequency is reduced when switching from a low channel to a high channel, As shown in Fig. 6, when the difference between the channels is small, the desired channel is switched relatively quickly as shown in Fig. 6 (A). As shown in (B), it takes time to reach the desired channel.

Further, when the step frequency is increased, as shown in FIG. 7, when the difference between the channels is large, the desired channel is switched relatively quickly as shown in FIG. 7B. When the difference between channels is small, as shown in FIG. 7 (A), so-called overshoot occurs over the desired channel, and it takes time to switch to the desired channel. It will be. For this reason, in the tuner device 1, the step frequency is increased, and a low-pass filter is attached to the VT terminal so that the response characteristic is blurred so that overshoot does not occur even when the channel difference is small. However, setting this low-pass filter was difficult.

In view of the above points, the present invention is to provide a tuner circuit and a tuner device that enable quick channel switching regardless of the difference between channels when switching channels. Has an aim.

[0008]

[Means for Solving the Problems]

 According to the present invention, a tuner circuit with a PLL circuit for switching channels based on a step frequency is provided with a step select terminal for switching the step frequency, and an input signal is input to the step select terminal. This is achieved by a tuner circuit characterized in that the step frequency is switched based on the selected signal.

Further, according to the present invention, the tuner circuit, a control circuit such as a microcomputer for controlling the tuner circuit, a tuning circuit for sending channel data to the control circuit, A channel that is inserted between the tuning circuit and the control circuit, detects the difference between channels when switching channels, and outputs a step select signal to the step select terminal of the tuner circuit based on the difference between channels. It is achieved by a tuner device, characterized in that it includes a discrimination circuit.

[0010]

[Action]

 According to the above configuration, since the tuner circuit has the step select terminal, it is possible to switch to an appropriate step frequency by inputting a step select signal from the outside to the step select terminal. , An appropriate step frequency can be selected according to the difference between channels when switching channels. Therefore, it is possible to switch channels quickly regardless of whether the difference between channels is large or small.

[0011]

【Example】

 Hereinafter, the present invention will be described in detail based on the embodiments shown in the drawings. FIG. 1 shows an embodiment of a tuner circuit according to the present invention. The tuner circuit 10 is similar to the conventional tuner circuit shown in FIG. The tuning voltage from the PLL circuit is applied to the terminal, and the tuning operation is performed based on the step frequency.

The above-mentioned configuration is similar to the conventional tuner circuit 2 shown in FIG. 5, but the tuner circuit 10 according to the present invention further includes a step select terminal 11, and the step select terminal 11 is provided. The step frequency can be switched to the step frequency corresponding to the step select signal by inputting the step select signal from 11 to the outside.

The tuner circuit 10 according to the present invention is configured as described above, and can be used by being incorporated in the tuner device 20 as shown in FIG. That is, in FIG. 2, the tuner device 20 includes the tuner circuit 10, a control circuit 21 such as a microcomputer for controlling the tuner circuit 10, a tuning button for selecting a channel to be received, and the like. Further, it comprises a channel selection circuit 22 for transmitting channel data to the control circuit 21, and a channel discrimination circuit 23 inserted between the channel selection circuit 22 and the control circuit 21.

Here, the channel discrimination circuit 23 detects a difference between the channels from the channel data from the channel selection circuit 22 at the time of switching the channel, and based on the difference between the channels, a step select signal. Is output to the step select terminal of the tuner circuit.

In the tuner device 20 thus configured, when a channel is selected by the channel selection device 22, channel data is transmitted from the channel selection device 22 to the control circuit 21 via the channel determination circuit 23. Sent out. As a result, the control circuit 21 sends the channel switching data to the tuner circuit 10. Thus, the tuner circuit 10 changes the channel based on this data by the PLL circuit based on a constant step frequency.

At this time, the channel discrimination circuit 23 operates as shown in the flowchart of FIG. That is, in FIG. 3, the channel discrimination circuit 23 stores the channel previously selected by the channel selection circuit 22. When a new channel is selected, it is detected and the previous channel is selected. And calculate a new channel difference.

When the channel difference calculated in this way is smaller than, for example, 10 channels, one step select signal, for example, an L0 level step select signal is supplied to the tuner circuit via the control circuit 22. It is sent to the step select terminal 11 of 10. When the channel difference is, for example, 10 channels or more, a different step select signal, for example, a Hi level step select signal is sent to the step select terminal 11 of the tuner circuit 10 via the control circuit 22. To send.

Thus, when the channel difference between the channel selected by the channel selection circuit 22 and the previous channel is 10 or more, the tuner circuit 10 is relatively high because the step select signal is at the Hi level. Set to a large step frequency. This allows the selected channel to be switched quickly.

Further, when the channel difference between the channel selected by the channel selection circuit 22 and the previous channel is smaller than 10, the tuner circuit 10 has a relatively small value because the step select signal is at the L0 level. Set to the step frequency. This allows the selected channels to be quickly switched without overshoot occurring.

[0020]

【The invention's effect】

 As described above, according to the present invention, there is provided an extremely excellent tuner circuit and tuner device that can perform channel switching quickly regardless of the difference between channels when switching channels. You will get it.

[Brief description of drawings]

FIG. 1 is a schematic diagram showing an embodiment of a tuner circuit according to the present invention.

FIG. 2 is a block diagram showing an embodiment of a tuner device incorporating the tuner circuit of FIG.

FIG. 3 is a flowchart showing an operation of the tuner device of FIG.

FIG. 4 is a block diagram showing a configuration of an example of a conventional tuner device.

5 is a schematic diagram showing an example of a tuner circuit used in the tuner device of FIG. 4. FIG.

6 is a graph showing channel switching states when the step frequency is small in the tuner circuit of FIG. 5, (A) shows a small difference between channels and (B) shows a small difference between channels. .

7A and 7B are graphs showing channel switching states when the step frequency is large in the tuner circuit of FIG. 5A, when the difference between channels is small, and FIG. 7B when the difference between channels is small.

[Explanation of symbols]

 10 tuner circuit 11 step select terminal 20 tuner device 21 control circuit 22 channel selection circuit 23 channel discrimination circuit

Claims (2)

[Scope of utility model registration request] 1. A tuner circuit with a PLL circuit for switching channels based on a step frequency is provided with a step select terminal for switching the step frequency, and a select signal input to the step select terminal is provided. A tuner circuit, wherein the step frequency is switched based on the tuner circuit. 2. The tuner circuit according to claim 1, a control circuit such as a microcomputer for controlling the tuner circuit, a tuning circuit for sending channel data to the control circuit, and the tuning circuit. Inserted between the control circuit,
Detects the difference between channels when switching channels,
A tuner device, comprising: a channel determination circuit that outputs a step select signal to a step select terminal of a tuner circuit based on a difference between channels.