JP2000305544A - Input signal automatic discrimination device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To discriminate automatically the kind of an input image signal. SOLUTION: A vertical counting part 2 counts the number of lines per one vertical scanning relative to an input image signal Vin, and a horizontal counting part 4 counts the number of clocks per one horizontal scanning. A vertical value register 5 houses the counted value of the vertical counting part 2, and a horizontal value register 6 houses the counted value of the horizontal counting part 4. A CPU 7 discriminates the kind of the input image signal Vin, based on the vertical counted value housed in the vertical value register 5 and the horizontal counted value housed in the horizontal value register 6.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an input signal automatic discrimination device for automatically discriminating the type of an input video signal.

[0002]

2. Description of the Related Art A projection display device such as a liquid crystal projector for enlarging and projecting a computer image, a video image or the like on a screen has been known. The projection display device is
Although connected to various devices such as a computer, a video device, or a TV camera, the standards (pixel clock frequency, number of display pixels, horizontal frequency, vertical frequency) of a video signal output by these devices vary depending on the device.

[0003]

As described above, in the projection type display device, since the standard of the input video signal is not standardized, the system setting is changed according to each input video signal, and from the data processing to the projection. However, for this purpose, the type of the input video signal must be determined. As a method for dealing with such a problem, there is a method in which a user switches a switch or the like according to the type of an input video signal. However, in this case, the operation of the user becomes complicated and the user may make a mistake in setting. was there. SUMMARY An advantage of some aspects of the invention is to provide an input signal automatic determination device that can automatically determine the type of an input video signal.

[0004]

A vertical counting unit (2) for counting the number of lines per vertical scanning for an input video signal (Vin) according to the present invention.
A horizontal count unit (4) for counting the number of clocks per horizontal scan for the input video signal, a vertical value register (5) for storing the count value of the vertical count unit,
A horizontal value register (6) for storing the count value of the horizontal count unit; and a determination for determining the type of the input video signal based on the vertical count value stored in the vertical value register and the horizontal count value stored in the horizontal value register. (7). Further, one configuration example of the above-described automatic input signal determination device includes a line detection unit (3) that detects whether the count value output from the vertical count unit has reached a predetermined number of lines. The horizontal counting section (4) counts the number of clocks when a predetermined number of lines is reached.

[0005] One example of the configuration of the discriminating section (7) is as follows.
A discrimination table in which the vertical count value and the horizontal count value are associated with the input video signal; and by comparing the vertical count value stored in the vertical value register and the horizontal count value stored in the horizontal value register with the discrimination table. ,
This is to determine the type of the input video signal. In addition, when the counting of the number of lines per vertical scanning is not completed, the vertical counting unit (2) adds a determination bit indicating that the counting period is being performed to the vertical count value output by itself. When the horizontal counting unit (4) has not finished counting the number of clocks per horizontal scan, it adds a determination bit indicating that the counting period is being performed to the horizontal count value output by itself. Then, the determination unit (7) determines that the vertical count value and the horizontal count value to which the determination bit has been added are invalid, and does not use the count values for determining the input video signal.

[0006]

Next, embodiments of the present invention will be described in detail with reference to the drawings. FIG. 1 is a block diagram showing a configuration of an input signal automatic discrimination device according to an embodiment of the present invention. First, the synchronization separation unit 1 converts a vertical synchronization signal VSYN from an input video signal (composite video signal) Vin input from an external device (video device) (not shown).
C, the horizontal synchronization signal HSYNC is separated.

The input video signal Vin input to the liquid crystal projector includes a signal input from a video device as described above, and also includes a signal input from a computer. Then, an external device such as a computer outputs the vertical synchronization signal VSYNC and the horizontal synchronization signal HSYNC independently. Therefore, whether the vertical synchronization signal VSYNC and the horizontal synchronization signal HSYNC output from the synchronization separation unit 1 are used or whether the vertical synchronization signal VSYNC and the horizontal synchronization signal HSYNC output directly from the external device are used is determined for the external device to be connected. You need to make a selection accordingly.

[0008] The selector 9 selects either the output of the sync separation unit 1 or the direct output from an external device in accordance with an input selection signal input from the outside. Thus, the selector 9
Is a vertical synchronization signal VSY output from the synchronization separation unit 1 if the external device is a video device that outputs a composite synchronization signal.
In the case of a computer or the like that selects and outputs the NC and the horizontal synchronization signal HSYNC and the external device outputs an independent synchronization signal, the vertical synchronization signal VSYNC output from the external device is used.
C and the horizontal synchronization signal HSYNC are selected and output.

Next, the vertical counting section 2 counts the number of lines per one vertical scan for the input video signal Vin. In order to count the number of lines per vertical scan, the horizontal synchronization signal HSYNC may be counted from an arbitrary vertical synchronization signal VSYNC to the next vertical synchronization signal VSYNC. Therefore, the count value of the vertical counting unit 2 is
It becomes 0 each time the vertical synchronization signal VSYNC is detected.

The 128 line detector 3 detects whether or not the count value output from the vertical counter 2 has reached 128 lines. The horizontal counting section 4 counts the number of clocks per horizontal scan when the output of the 128 line detection section 3 indicates that the output is the 128th line.

In order to count the number of clocks per horizontal scan, the clocks may be counted from an arbitrary horizontal synchronization signal HSYNC to the next horizontal synchronization signal HSYNC. Therefore, the count value of the horizontal count unit 4 becomes 0 every time the horizontal synchronization signal HSYNC is detected. The clock counted by the horizontal counting unit 4 is a horizontal synchronization signal HSY.
A clock of a fixed frequency that is asynchronous with the NC may be used.

The line for counting is set to the 128th line because the horizontal period may be unstable during the period before and after the vertical synchronization signal VSYNC. By counting the number of clocks when the horizontal cycle is stable,
The number of clocks per horizontal scan can be correctly counted.

Next, the vertical value register 5 takes in the count value of the vertical count unit 2 after the vertical count unit 2 has finished counting the number of lines per vertical scan. To capture the value after the count is completed, the vertical synchronization signal VSYNC is used.
It is sufficient to take in the count value when is detected. Then, the vertical value register 5 holds the fetched value at the time of the next update, that is, until the next VSYNC is detected.

As described above, the count value of the vertical counting unit 2 becomes 0 every time the vertical synchronization signal VSYNC is detected. However, in order to enable the vertical value register 5 to capture the count value, the vertical count unit 2 sets the vertical synchronization signal VSYNC not immediately after the detection of the vertical synchronization signal VSYNC.
The count value is set to 0 after a lapse of a predetermined time from the detection of NC.

On the other hand, the horizontal value register 6 takes in the count value of the horizontal count unit 4 after the horizontal count unit 4 has finished counting the number of clocks per horizontal scan. To take in the value after the count is completed, the horizontal synchronization signal HSYN
What is necessary is just to take in a count value when C is detected. Then, the horizontal value register 6 holds the fetched value at the next update, that is, until the next HSYNC detection.

In order to enable the horizontal value register 6 to take in the count value, the horizontal count unit 4 sets the horizontal synchronization signal HSY not immediately after the detection of the horizontal synchronization signal HSYNC.
The count value is set to 0 after a lapse of a predetermined time from the detection of NC.

Next, the CPU 7 serving as a determination unit fetches the vertical count value stored in the vertical value register 5 and the horizontal count value stored in the horizontal value register 6 via the CPU bus 8. This fetch timing is arbitrary. Subsequently, the CPU 7 determines the type of the input video signal Vin by comparing the vertical count value and the horizontal count value with an input video signal determination table created in advance.

The discrimination table provided in the CPU 7 is as follows.
Vertical count value and horizontal count value, and input video signal Vi
n. That is, the CPU 7 acquires the standard of the input video signal Vin corresponding to the vertical count value and the horizontal count value from the determination table.

Then, the CPU 7 outputs the input video signal Vin
Changes the internal settings of the system according to the result of the determination.
For example, if the system incorporating the input signal automatic discrimination device of FIG. 1 is a liquid crystal projector, it is necessary to convert the resolution of the input video signal Vin to the resolution of the liquid crystal panel in the projector and display it. Therefore, the CPU 7 changes the enlargement / reduction ratio in the resolution conversion processing (enlargement or reduction processing) of the input video signal Vin according to the above determination result.
Thus, display corresponding to various input video signals Vin can be performed.

When the number of lines per vertical scan has not been counted, the vertical counting section 2 adds a determination bit indicating that the counting period is being performed to the vertical count value output by itself. Similarly, the horizontal counting unit 4
Adds the determination bit indicating that the counting period is in progress to the horizontal count value output by itself when the number of clocks per horizontal scan has not been counted.

As described above, the vertical value register 5 takes in the count value of the vertical count unit 2 after the vertical count unit 2 finishes counting the number of lines per vertical scan, and the horizontal value register 6 After the counting unit 4 finishes counting the number of clocks per horizontal scan, the count value of the horizontal counting unit 4 is fetched. Therefore, it is generally impossible for the value being counted to be taken into the vertical value register 5 or the horizontal value register 6. However, it is conceivable that the value being counted is taken into the vertical value register 5 or the horizontal value register 6 due to malfunction due to noise or the like.

Therefore, the CPU 7 determines that the vertical count value and the horizontal count value to which the determination bit indicating that the counting period is being performed are invalid, and does not use the count values for determining the input video signal Vin. Thus, the validity / invalidity determination of the count value based on the determination bit enables
It is possible to prevent an invalid count value from being used for determining the input video signal Vin, and to use only a valid count value for determination.

As a process for preventing erroneous determination, the CPU 7
Alternatively, a vertical count value and a horizontal count value may be fetched a plurality of times, an average value of each value may be obtained, and comparison with the discrimination table may be performed. As a result, it is possible to reduce the influence of variations in count values and noise. In the present embodiment, a liquid crystal projector has been described as an example of a system having a built-in input signal automatic determination device, but it is needless to say that the present invention can be applied to other systems.

[0024]

According to the present invention, an input signal automatic discrimination device is constituted by a vertical count section, a horizontal count section, a vertical value register, a horizontal value register, and a discrimination section.
The type of the input video signal can be automatically determined without the user's particular awareness.

Further, a line detecting section is provided, and the horizontal counting section counts the number of clocks when a predetermined number of lines is reached, so that the number of clocks per horizontal scanning can be reliably counted. As a result, erroneous determination of the input video signal due to an incorrect horizontal count value can be prevented.

Further, by providing the discrimination table in the discrimination section, the discrimination of the input video signal can be easily realized.

Further, by determining whether the count value is valid or invalid based on the determination bit, it is possible to prevent an invalid count value from being used for determining an input video signal and to use only a valid count value for determination. Can be.

[Brief description of the drawings]

FIG. 1 is a block diagram illustrating a configuration of an input signal automatic discrimination device according to an embodiment of the present invention.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Synchronization separation part, 2 ... Vertical count part, 3 ... 128 line detection part, 4 ... Horizontal count part, 5 ... Vertical value register,
6 horizontal value register, 7 CPU, 8 CPU bus, 9
…selector.

Claims (4)

[Claims] 1. An input signal automatic discrimination device for discriminating a type of an input video signal, comprising: a vertical counting section for counting the number of lines per one vertical scan for the input video signal; and one horizontal scan for the input video signal. A horizontal count unit that counts the number of clocks per clock, a vertical value register that stores the count value of the vertical count unit, a horizontal value register that stores the count value of the horizontal count unit, and a vertical count value that is stored in the vertical value register A determination unit for determining the type of the input video signal based on the horizontal count value stored in the horizontal value register. 2. The input signal automatic discrimination device according to claim 1, further comprising: a line detection unit that detects whether a count value output from the vertical count unit has reached a predetermined number of lines, When the count reaches a predetermined number of lines,
An automatic input signal discriminating apparatus for counting the number of clocks. 3. The input signal automatic discrimination device according to claim 1, wherein the discrimination unit includes a discrimination table in which the vertical count value and the horizontal count value are associated with an input video signal, and is stored in a vertical value register. An automatic input signal discriminating apparatus for discriminating a type of an input video signal by comparing a vertical count value and a horizontal count value stored in a horizontal value register with a discrimination table. 4. The input signal automatic discrimination device according to claim 1, wherein the vertical counting unit sets a determination bit indicating that the counting period is in progress when the number of lines per vertical scanning has not been counted. The horizontal count unit adds to a vertical count value output by itself, and the horizontal count unit outputs a determination bit indicating that a count period is in progress when the count of clocks per horizontal scan has not been completed. Input, wherein the determination unit determines that the vertical count value and the horizontal count value to which the determination bit has been added are invalid, and does not use the count values for the determination of the input video signal. Automatic signal discriminator.