JPH0727356B2 - Auto tracking circuit - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of application] The present invention relates to an input signal frequency in a video display device,
The present invention relates to an auto-tracking circuit that controls so that the horizontal oscillation frequency and the vertical oscillation frequency automatically follow each other.

[Conventional technology]

FIG. 9 is a circuit diagram showing a conventional auto-tracking circuit disclosed in, for example, Japanese Unexamined Patent Publication No. Sho 56-132826. In FIG. 9, 1 is an RO for storing a data conversion table and the like described later.
Microcomputer with built-in M, calculation RAM, counter, etc., 3 is an output port of this microcomputer 1.
A D / A converter as D / A conversion means connected to B _{0 to} B _n , 4 is an output port C _{0 of the} microcomputer 1 as well.
~ D / A converter as D / A conversion means connected to C _n ,
Reference numeral 5 designates oscillator connection terminals OSC1 and OS of the microcomputer 1.
An oscillator connected between C2, and 6 and 7 are capacitors connected to both terminals of the oscillator 5, respectively.

Next, the operation will be described. FIG. 10 is a flowchart showing the operation of this auto-tracking circuit, which will be described below with reference to the drawing. First, in the process of step ST1, the number of pulses of the horizontal synchronizing signal Hsync input to the input port HS of the microcomputer 1 is counted for a certain period within the vertical cycle. Next, based on the count result, the address of the count result-to-horizontal oscillation frequency control data conversion table in the ROM built in the microcomputer 1 is determined, and the address of the designated address in the ROM is determined. The horizontal oscillation frequency control data is obtained from the conversion table. The above is the process of step ST2.

Next, in steps ST3 and ST4, vertical oscillation frequency control data is similarly obtained. That is, the microcomputer 1
The number of pulses of the vertical synchronizing signal Vsync input to the input port VS of is counted for a certain period. Similarly, the address of the counting result-vertical oscillation frequency control data conversion table is determined from the counting result, and the vertical oscillation frequency control data is obtained from the ROM data at the specified address.

Next, in step ST5, the horizontal oscillation frequency control data obtained by the above processing is output to the D / A converter 3, and the DC voltage for horizontal oscillation frequency control is output from the output terminal HO of the D / A converter 3. Output H-OSC. Similarly, in step ST6, the vertical oscillation frequency control data is output to the D / A converter 4, and the DC voltage V-OSC for controlling the vertical oscillation frequency is output from the output terminal VO of the D / A converter 4. By repeating the above operation, the circuit of FIG. 9 can perform the auto-tracking operation.

[Problems to be Solved by the Invention]

Since the conventional auto-tracking circuit is configured as described above, the oscillation frequency control data with respect to the input signal frequency has a fixed value. Therefore, variations in the oscillation frequency occur due to variations in the constants of the horizontal and vertical oscillation circuits to which this auto-tracking circuit is connected. Therefore, it is necessary to specially provide an adjustment circuit for each oscillation frequency and perform correction by the adjustment circuit. There was a problem.

In addition, as an approximation technique, in addition to those disclosed in JP-A-55-44209,
JP-A-55-67225, JP-A-61-170116, JP-A-62-8
8415, JP-A-61-216510, JP-A-62-137910, JP-A-62-143572, and JP-A-61-32274.

The present invention has been made to solve the above problems, and adjusts the value of the oscillation frequency control data for the input frequency in all ranges of the auto-tracking operating frequency manually or by an external measurement control device, Accordingly, it is an object of the present invention to obtain an auto-tracking circuit that can correct and adjust variations in the oscillation frequency due to variations in the circuit constants of the oscillation circuit.

[Means for Solving the Problems]

The auto-tracking circuit according to the present invention includes storage means for storing maximum and minimum frequencies of horizontal and vertical oscillation frequency control reference data set by the setting means, and maximum and minimum frequencies of the oscillation frequency control reference data. A micro that calculates horizontal and vertical oscillation frequency control data by linear approximation from the input frequency based on the frequency, the horizontal frequency value based on the conversion table, the maximum and minimum values of the vertical frequency value, and the count values of the horizontal sync signal and the vertical sync signal. It has a computer and D / A conversion means for performing D / A conversion of horizontal and vertical oscillation frequency control data calculated by this microcomputer.

[Action]

The microcomputer according to the present invention inputs the oscillation frequency control reference data arbitrarily set in the storage means by the setting means, that is, based on the maximum value and the minimum value of the oscillation frequency control data in the auto-tracking operation frequency range. Oscillation frequency control data corresponding to the frequency is calculated by a linear approximation method and output to the D / A conversion means.

〔Example〕

An embodiment of the present invention will be described below with reference to the drawings. 2 non-volatile memory as a storage means connected to the input and output ports E ₀ to E _n of the microcomputer 1, 8, 9 and 10 input ports KeyA of the microcomputer 1, KeyB, husband KeyC s connected setting device , A rotary switch 11 as a setting means connected to the input ports A _{0 to} A ₃ of the microcomputer 1, 12 is an input port A _{0 to} A ₃ of the microcomputer 1, KeyA, KeyB, KeyC and output Collectors connected to ports D ₀ and D ₁ , 13, 14 and 15 are pull-up resistors connected to 1 input ports KeyA, KeyB and KeyC, 1
Reference numerals 6, 17, 18, and 19 are pull-up resistors connected to one input port A ₀ , A ₁ , A ₂ , and A ₃ .

Next, the operation of the above embodiment will be described. FIG. 2 is a flow chart showing the operation of the auto-tracking circuit of FIG. Description will be given below with reference to the drawings.

First, the horizontal and vertical oscillation frequency control data HOSC and VOSC in the RAM of the microcomputer 1 are initialized in step ST11, and then the oscillation frequency control reference data is stored in the nonvolatile memory 2 in step ST12. , HOSCL, HOSCH, VOSCL, VOSCH are read. Where HOSCL is the horizontal oscillation frequency control data at the lowest frequency in the horizontal auto-tracking frequency range, HOSCH is the horizontal oscillation frequency control data at the highest frequency in the same frequency range, and VO
SCL is vertical oscillation frequency control data at the lowest frequency in the vertical auto-tracking frequency range, and VOSCH is vertical oscillation frequency control data at the highest frequency in the same frequency range.

Next, in step ST13, the contents of the input ports A _{0 to} A ₃ connected to the rotary switch 11 are read by the microcomputer.
Read in RAM. This is PA. Next, in step ST14, it is determined whether or not PA = $ F. Here, PA = $ F means that the rotary switch 11 is set to the zero position,
But when PA = $ F, HOSCL, HOSCH, VOSCL, VO
The operation of outputting the oscillation frequency control data HOSC, VOSC is performed based on the value of SCH and the counting result of the input horizontal and vertical frequencies. Hereinafter, the operation at this time, step ST31 ~
ST39 will be described.

First, in step ST31, the horizontal synchronizing signal Hsync input to the input port HS of the microcomputer 1 is counted for a certain period of the vertical synchronizing signal period. Let this value be HCOUNT.
Next, in step ST32, pulses having a constant period during the vertical synchronization signal period are counted. This value is VCOUNT. Here, the counted pulse is obtained by dividing the system clock of the microcomputer 1 by the internal frequency divider. Next, referring to the HCOUNT-to-horizontal frequency value conversion table stored in the ROM of the microcomputer 1 shown in FIG. 7 from the HCOUNT obtained by the above method, the horizontal frequency value HF
Ask for RQ. That is, the address of the conversion table in ROM is obtained from the value of HCOUNT, and the ROM of the obtained address
The data written in is set to HFRQ (step ST3
3). Similarly, in step ST34, the vertical frequency value VFRQ is obtained from VCOUNT. Next, in step ST35,
Judge whether both HFRQ and VFRQ are different from the previously counted value. Here, when the processing of steps ST31 to ST35 is executed for the first time after the power is turned on, it is determined that the frequency is different from the previous frequency. Then, if it is determined that the same as the previous time, steps ST36, ST37 are skipped, step ST38
Move to. On the other hand, when it is determined that it is different from the previous time, the process proceeds to step ST36. FIG. 6 shows a flow chart of the contents of the processing in step ST36. Further, FIG. 5 is a schematic diagram showing the processing contents in step ST36. here
HFRQL is the lowest frequency value in the horizontal auto-tracking frequency range, and HFRQH is the highest frequency value in the same frequency range. In step ST36-1, first, the difference (HOSCH-HOSCL) is calculated and set as D01, and then the difference (HFR
QH-HFRQL) is calculated as DF1 (ST36-2), then the difference (HFRQ-HFRQL) is calculated as DF2 (ST36-3), then DO1 x DF2 is calculated as DM1 (ST36- 4), then DM1
Find / DF1 and use this as DD1 (ST36-5), then HOSCL + DD
Obtain 1 and use this as HOSC (ST36-6). In other words, here, HOSC is calculated according to the following calculation formula (1).

The equation (1) will be explained with reference to FIG.
The values of HFRQL and HFRQH set in the table and the corresponding reference data for oscillation frequency control, HOSCL and HOSCH.
From this value, the oscillation frequency control data HOSC corresponding to the input horizontal frequency value (horizontal synchronizing signal frequency) HFRQ is obtained by the linear approximation formula.

Next, in step ST37, as in step ST36, VFRQ, VOS
Obtain the oscillation frequency control data VOSC from CL and VOSCH.

Next, the HOSC is output from the output ports B _{0 to} B _{n of} the microcomputer 1 and input to the D / A converter 3,
A DC voltage H-OSC for controlling the horizontal oscillation frequency is output from the output terminal HO of the / A converter 3 and added to the horizontal oscillation circuit (ST38).

Next, the VOSC is output from the output ports C _{0 to} C _{n of the} microcomputer 1 and input to the D / A converter 4, and the D / A
The DC voltage V-OSC for controlling the vertical oscillation frequency is output from the output terminal VO of the converter 4 and is applied to the vertical oscillation circuit (ST39). Finally, the process returns to step ST13 and the above operation is repeated.

On the other hand, the operation when PA is not equal to $ F in step ST14 (ST
15 to ST30) will be described below. Here, reference data HOSCL, HOSCH, VO for controlling the oscillation frequency in the nonvolatile memory 2 is used.
Change SCL and VOSCH. Therefore, the increase / decrease of the data is the HOSCL and HOSC read from the nonvolatile memory 2 into the RAM.
It is performed for the values of H, VOSCL, and VOSCH, and is stored in the nonvolatile memory 2 by an external command, and the data in the nonvolatile memory 2 is changed. And the command to increase / decrease the data is input port KeyA, KeyB of the microcomputer 1.
Through the RAM in the microcomputer 1 to the nonvolatile memory 2 through the input port KeyC. The selection of which of the horizontal and vertical oscillation frequency control reference data HOSCL, HOSCH, VOSCL, VOSCH is to be changed is selected from the input ports A _{0 to} A ₃ of the microcomputer 1.
It is judged by the input value PA of.

First, in steps ST15 and ST16, the rotary switch 11
Refer to the table in ROM from the value of PA which is the content of
Determine the address of RAM to access. Next input port Key
It is determined whether or not the value of A is Low (ST17), and if it is Low, the data increment process of step ST18 is performed. Here, FIG. 3 shows a flowchart of the processing contents of step ST18. First, in step ST18-1, the contents of the RAM to be accessed are checked, and it is determined whether the value is smaller than the data upper limit preset in ROM (ST18-2). If it is determined that the value is smaller than the upper limit, Proceed to Step ST18-3, reset the D ₀ port, and set the access destination RAM contents to 1
Increase (ST18-5). On the other hand, if it is determined in step ST18-2 that the upper limit is reached, step ST18
-4, set the D ₀ port and finish the process.

On the other hand, when it is determined in step ST17 that the value of the input port KeyA is not Low, the process proceeds to step ST19, in which it is determined whether the input port KeyB is Low. If the input port KeyB is Low here, the process proceeds to step ST20, and the decrement process of the data in RAM is performed. Fig. 4 shows this step ST
It is a flow chart which shows the contents of processing of 20. First, in step ST20-1, the contents of the RAM to be accessed are checked, and in step ST20-2 it is compared with the data lower limit set in advance in ROM to determine whether it is greater than the lower limit,
If it is determined to be larger, the process proceeds to step ST20-3, and if it is determined that the lower limit value is reached, the process proceeds to ST20-4. Thus is in step ST20-3 to reset the D ₁ port, then proceeds to step ST20-5, the process is finished is reduced by one the contents of the access destination RAM. Step ST20-4
In, reset the D ₁ port and finish the process.

If it is determined in step ST19 that the input of the input port KeyB is not Low, the process proceeds to step ST21, where it is determined whether the input of the input port KeyC is Low, and if it is Low, the process proceeds to step ST22, If not, the process proceeds to step ST23. Then, in step ST22, H in RAM is
The four oscillation frequency control reference data of OSCL, HOSCH, VOSCL, and VOSCH are stored in the nonvolatile memory 2.

In step ST23, if the value of PA is $ E, step ST23
If not, the process proceeds to step ST25. Further, in step ST24, the value of VOSC is made equal to the value of VOSCL to output the data of VOSCL to the D / A converter 4, and the vertical oscillation frequency is determined by the value of the reference data VOSCL for oscillation frequency control. To do. In step ST25, if the value of PA is $ D, the process proceeds to step ST26, and if not, the process proceeds to step ST27. In step ST26, the VOSC value is set to be the same as the VOSCH value so that the VOSCH data is output to the D / A converter 4. And ST27
Then, if the value of PA is $ C, the process proceeds to step ST28, and if not, the process proceeds to step ST29. In step ST28, the value of HOSC is made the same as the value of HOSCL, so that the data of HOSCL is
Output to the D / A converter 3 so that the horizontal oscillation frequency is determined by the value of the oscillation frequency control reference data HOSCL. In step ST29, if the value of PA is $ B, step
If not, proceed to ST30. In step ST30, the value of HOSC is made equal to the value of HOSCH, so that the data of HOSCH is output to the D / A converter 3. After completing steps ST24, ST26, ST28, ST30, the process proceeds to steps ST38, ST39, and further steps ST13.
Return to.

In the above embodiment, the nonvolatile memory 2 is connected to the microcomputer 1, but the nonvolatile memory may be built in the microcomputer 1.

Further, although the rotary switch 11 and the tact switches 8, 9 and 10 are used in the above-described embodiment, a dip switch or another switch may be used, and the same effect as above can be obtained.

Further, the connector 12 is not always necessary and can be omitted in the case of only manual adjustment.

〔The invention's effect〕

As described above, according to the present invention, the value of the oscillation frequency control data with respect to the input signal frequency can be arbitrarily set in the storage means manually or by the setting means by the external measurement control device, whereby the circuit constant of the oscillation circuit is set. The variation of the oscillation frequency of the auto-tracking operation due to the variation of (3) can be corrected, and the variation can be easily adjusted. Therefore, an auto-tracking circuit having a stable oscillation frequency of the auto-tracking operation can be obtained.

[Brief description of drawings]

FIG. 1 is a circuit diagram showing an auto-tracking circuit according to an embodiment of the present invention, FIG. 2 is a flow chart showing the operation of the circuit shown in FIG. 1, FIG. 3 is a flow chart showing a data increasing process, and FIG. FIG. 5 is a flow chart showing data reduction processing, FIG. 5 is a schematic diagram showing means for obtaining horizontal oscillation frequency control data with respect to an input horizontal frequency, and FIG. 6 is a flow chart showing means for obtaining horizontal oscillation frequency control data. Is a schematic diagram showing a conversion table of input horizontal frequency counting results versus horizontal frequency values, FIG. 8 is a schematic diagram showing a conversion table of input horizontal frequency counting results versus horizontal frequency control data, and FIG. 9 is a conventional auto table. FIG. 10 is a circuit diagram showing the tracking circuit, and FIG. 10 is a flow chart showing the operation of FIG. 1 is a microcomputer, 2 is a non-volatile memory (storage means), 3 and 4 are D / A converters (D / A conversion means), 8, 9 and 10
Is a tact switch (setting means), 11 is a rotary switch (setting means). In the drawings, the same reference numerals indicate the same or corresponding parts.

Claims (1)

[Claims] 1. Storage means for respectively storing a maximum frequency and a minimum frequency of horizontal oscillation frequency control reference data and a maximum frequency and a minimum frequency of vertical oscillation frequency control reference data, and the storage means for storing the horizontal oscillation frequency control. Setting means for setting the maximum frequency, the minimum frequency of the reference data and the maximum frequency, the minimum frequency of the reference data for controlling the vertical oscillation frequency, a counter for counting the horizontal synchronizing signal and the vertical synchronizing signal, and a horizontal frequency for the count value of this counter value,
It has a ROM for storing each conversion table of vertical frequency values and a calculation RAM, and also has the maximum frequency, the minimum frequency of the horizontal oscillation frequency control reference data and the maximum frequency, the minimum frequency of the vertical oscillation frequency control reference data, and the conversion. A horizontal frequency value of the table, a maximum value of the vertical frequency value, a minimum value, and a microcomputer for calculating the horizontal and vertical oscillation frequency control data for the input frequency using the value of the input frequency by the linear approximation, An auto-tracking circuit comprising: D / A conversion means for D / A converting the horizontal and vertical oscillation frequency control data calculated by the microcomputer.