Abstract:
A signal detection method is provided. The signal detection method for an electronic device having a plurality of terminals to receive signals from a plurality of sources corresponding to the terminals, includes the following steps: providing a sequence index for each terminal; providing a plurality of weighting numbers for the electronic device; comparing the sequence indexes of the terminals to determine a terminal detection sequence when the electronic device is turned on or the signal source changes; detecting the terminals according to the detection sequence; adding one of the weighting number to the sequence index of the terminal with signal traffic. The detection sequence begins at the terminal with a largest sequence index and ends at the terminal with a smallest sequence index.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The invention relates to a signal detection method, and more particularly to a method of determining the sequence of detected signals. 
     2. Description of the Related Art 
     A liquid crystal display may have many signal sources, such as analog signals (D-SUB), digital signals, video signals and various other signals. A conventional liquid crystal display must detect terminals for different signal sources one-by-one to determine which terminal is conducting signals and for receiving the signals when the liquid crystal display is turned on. The signal detection is performed manually or automatically in the conventional liquid crystal display. 
     A conventional manual signal detection method is shown in  FIG. 1 . When the liquid crystal display is turned on, the liquid crystal display is manually switched to a desired terminal, for example to a D-SUB terminal as shown in step  101  of  FIG. 1 , to a DVI terminal as shown in step  102 , or to an S-video terminal as shown in Step  103 . Steps  104  and  105  of  FIG. 1  show the manual switch to other two terminals. In spite of the fast and direct operation of the manual switch, human intervention is required. 
     A conventional automatic signal detection method is shown in  FIG. 2 . When the liquid crystal display is turned on, the terminals of the liquid crystal display are detected automatically one-by-one to determine the terminal conducting signals as shown in step  201  of  FIG. 2 . When signals at one terminal are detected, the liquid crystal display is switched automatically to the terminal, for example to the D-SUB terminal as shown in step  202 . Note that when the detected signals are unstable, the liquid crystal display detects the terminal with signal traffic periodically as shown in step  203  until the signals are stable. When the signals are interrupted, the automatic detection is resumed. Although automatic detection is convenient, detecting terminals one-by-one is time consuming. 
     BRIEF SUMMARY OF INVENTION 
     A signal detection method for an electronic device is provided. An exemplary embodiment of an electronic device comprises a plurality of terminals receiving signals from a plurality of sources corresponding to the terminals. An exemplary embodiment of the signal detection method for an electronic device comprises: providing a sequence index for each terminal; providing a plurality of weighting numbers for the electronic device; comparing the sequence indexes of the terminals to determine a terminal detection sequence when the electronic device is turned on or the signal source changes; detecting the terminals according the detection sequence; adding one of the weighting numbers to the sequence index of the terminal with signal traffic. The detection sequence begins at the terminal with the largest sequence index and ends at the terminal with the smallest sequence index. 
     The weighting numbers comprise a first weighting number, a second weighting number and a third weighting number. The first weighting number is added to the sequence index of the terminal with signal traffic. The second weighting number is added to the sequence index of the terminal without signal traffic but connected to a corresponding source. The third weighting number is added to the sequence index of the terminal not connected to a corresponding source. When the electronic device is turned on or the signal source changes, the electronic device detects the terminals connected or not connected corresponding sources to add the second weighting number or the third weighting number to the sequence index. 
     The signal detection method of the invention further comprises the following steps: comparing all sequence indexes to determine whether all sequence indexes are identical; selecting one of the terminals arbitrarily to begin detection when all sequence indexes of the terminals are identical. 
     The signal detection method of the invention further comprises the following steps: selecting manual or automatic addition of the weighting numbers to the sequence index when the electronic device is turned on or the signal source changes; determining the detection sequence according the sequence indexes when manual addition is selected. 
     The signal detection method of the invention further comprises the following steps: determining whether one of the terminals is selected directly and providing signals to the selected terminal when the electronic device is turned on or the signal source changes; determining whether manual or automatic addition of the weighting numbers to the sequence index of the selected terminal is selected when one terminal is selected; adding the weighting numbers to the sequence indexes of the terminals automatically when automatic addition is selected. 
     The signal detection method of the invention further comprises the following steps: determining whether manual or automatic addition of the weighting numbers to the sequence index of the terminals is selected when no terminal is selected; determining the detection sequence according the sequence indexes when manual addition is selected. 
     The terminals comprise an analog signal terminal, a digital signal terminal and a video signal terminal. 
     A detailed description is given in the following embodiments with reference to the accompanying drawings. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
       The invention can be more fully understood by reading the subsequent detailed description and examples with references made to the accompanying drawings, wherein: 
         FIG. 1  is a flow chart of a conventional manual signal detection method; 
         FIG. 2  is a flow chart of a conventional automatic signal detection method; and 
         FIG. 3  is a flow chart of a signal detection method of the invention. 
     
    
    
     DETAILED DESCRIPTION OF INVENTION 
     The invention provides a signal detection method determining the detection sequence of terminals of an electronic device, such as D-SUB, DVI, S-Video terminals and similar. A liquid crystal display is described the following, but the electronic device is not limited to a liquid crystal display. The invention is also applicable to other electronic devices with multiple terminals. Several weighting numbers determine the detection sequence. In general, the most frequently used terminal is detected prior to the least used terminal, thus detection time is reduced. The weighting numbers, therefore, represent the frequency of usage. Certainly, the detection sequence may be determined by certain factors other than the frequency of usage, depending on requirements. 
     There are three possible detection results for a terminal. The terminal is connected to a source by a wired or wireless connection for receiving signal. The terminal is connected to a source by a wired or wireless connection but receives no signals. The terminal is not connected to a source. The weighting numbers are defined according to the three possible detection results. 
     The weighting numbers comprise a first weighting number D 1 , a second weighting number D 2  and a third weighting number D 3 . The first weighting number D 1  indicates that a terminal is connected to a source by a wired or wireless connection and receives signals. The second weighting number D 2  indicates that a terminal is connected to a source by a wired or wireless connection but receives no signal. The third weighting number D 3  indicates that a terminal is not connected to a source. Because the most frequently used terminal is detected prior to the least used terminal, the first weighting number is greater than the second weighting number and the second weighting number is greater than the third weighting number, D 1 &gt;D 2 &gt;D 3 . 
     Although three terminals, a first terminal, a second terminal and a third terminal, are described in the embodiment, the invention is not limited to three terminals. The invention is also applicable to an electronic device with more than three terminals. 
     Each terminal is provided with a sequence index by the electronic device. The sequence index of the first terminal, the second terminal and the third terminal is W 1 , W 2  and W 3 . 
     When the electronic device is turned on, each terminal is detected to determine whether the terminal is connected to a source to determine if the first weighting number D 1 , the second weighting number D 2  or the third weighting number D 3  is added to the sequence indexes W 1 , W 2  and W 3 . For example, when it is detected that the second terminal is connected to a source and receives signals, the first weighting number D 1  is added to the sequence index of the second terminal W 2 . Thus, the weighting numbers D 1 , D 2  and D 3  are added to the sequence index of each terminal respectively according to the detection result. When the electronic device turns off and on again or is turned on, the sequence indexes W 1 , W 2  and W 3  may be different. 
     When the electronic device is turned on, the sequence indexes are compared with one another to determine the detection sequence. The larger the sequence index is, the earlier the corresponding terminal is detected. For example, the sequence indexes of the first, second and third terminals are compared. If the sequence indexes are identical, i.e., W 1 =W 2 =W 3 , the electronic device selects one of the terminals arbitrarily to begin the detection. If the sequence indexes are not identical, such as W 1 &gt;W 2 &gt;W 3 , the electronic device detects the first terminal, then the second terminal and finally the third terminal. 
     When the electronic device detects signals at a terminal, the first weighting number D 1  is added to the sequence index of the terminal receiving signals. For example, when signals are detected at the second terminal, the first weighting number D 1  is added to the sequence index W 2 . When the electronic device turns off and on again, the updated sequence index W 2  is compared with the other sequence indexes. 
     In addition to the weighting numbers automatically being added to the sequence indexes according to the detection results (referred to in the following as auto-weighting), the weighting numbers can also be added to the sequence indexes manually (referred to in the following as manual weighting). The signal detection method of the invention is described with reference to the accompanying flow chart. 
       FIG. 3  is a flow chart of the signal detection method of the invention. For brevity, the entire procedure is divided into procedure A and procedure B. Procedure A is executed prior to detection. Procedure B is the signal detection procedure according to sequence index after turning off and on of the electronic device or signal interruption. In step  301 , the auto-weighting function is selected. If the auto-weighting function is not selected, step  302  where the manual weighting is selected proceeds. If manual weighting is not selected, one of the conventional signal detection methods (the automatic or manual methods as shown in  FIGS. 1 and 2 ) is executed, as shown in step  303 . If the manual weighting is selected, step  304  proceeds for manual weighting, and procedure B where the terminal with the largest sequence index is detected first as shown in step  3071  proceeds. If signal traffic is present at the terminal, step  3072  proceeds, wherein the electronic device switches to the terminal and adds the first weighting number D 1  to the sequence index of the terminal. When signals are detected but unstable, the electronic device periodically redetects the terminal until a stable signal is detected, as shown in step  3073 ′, but the weighting number is not added to the sequence index. If the signals are interrupted, method returns to procedure A. 
     In step  301 , if auto-weighting is selected, step  305  proceeds, wherein the second weighting number or the third weighting number is added by the electronic device to the sequence index according to the source connection of the terminal. When the connection is detected, the third weighting number D 3  is added to the sequence index. When no connection is detected, the second weighting number D 2  is added to the sequence index. 
     In step  306 , the sequence indexes of all terminals are compared. If all of the sequence indexes are identical, step  3061  proceeds, wherein one terminal is selected arbitrarily to begin detection. In this embodiment, the liquid crystal display first detects the D-SUB terminal. If signal traffic is present at the D-SUB terminal, step  3062  proceeds, wherein the liquid crystal display is switched to the D-SUB terminal to receive signals, and the difference of the first weighting number and the second weighting number (D 1 -D 2 ) are added to the sequence index. Because step  3062  is the same as step  3072 , the description of step  3062  is omitted. If no signal traffic is present at the D-SUB terminal, step  3064  proceeds, wherein the terminal (DVI terminal) is detected. If signal traffic is present at the DVI terminal, step  3065  proceeds, wherein the liquid crystal display switches to the DVI terminal and the difference of the first weighting number and the second weighting number (D 1 -D 2 ) is added to the sequence index. Because step  3066  is the same as step  3063 , further description is omitted. Similarly, if no signal is detected at the DVI terminal, step  3067  proceeds, wherein the terminal (S-Video terminal) is detected. If signals are detected at the terminal S-Video, step  3068  proceeds, wherein the electronic device switches to the S-Video terminal and the sequence index of the S-Video terminal is added by difference of the first weighting number and the second weighting number (D 1 -D 2 ). Because step  3069  is the same as step  3063 , the description is omitted. 
     If the sequence indexes of the terminals are not identical, step  307  proceeds, wherein the detection sequence is determined by the value of the sequence index. Procedure B is then executed. The terminal with the largest sequence index is detected, as shown in step  3071 . If signals are detected at the terminal, step  3072  proceeds, wherein the electronic device switches to the terminal and the difference of the first and second weighting numbers (D 1 -D 2 ) is added to the sequence index. If no signals are detected at the terminal with the largest sequence index, then the terminal with the next largest sequence index is detected, as shown in step  3074 . If signals are detected at the terminal with the next largest sequence index, then the electronic device switches to the terminal and the difference of the first and second weighting numbers (D 1 -D 2 ) is added to the sequence index, as shown in step  3075 . Step  3076  is the same as step  3073 . In step  3077 , the terminal with the third largest sequence index is detected. If signals are detected at the terminal, step  3078  proceeds, wherein the difference of the first and second weighting numbers (D 1 -D 2 ) is added to the sequence index. Step  3079  is the same as step  3073 . 
     Prior to procedure A, a function allowing a terminal to be user pre-selected is added, as shown in step  10 . The function can be selected from on an screen display (OSD) menu. If the function is not selected, procedure A is entered directly. If users select the function, step  11  proceeds to determine whether the first weighting number D 1  is added to the sequence index of the selected terminal. If no weighting number is to be added to the sequence index of the selected terminal, procedure A is entered directly. If a weighting number is to be added to the sequence index of the selected terminal, step  12  proceeds, wherein the first weighting number is added to the sequence index of the selected terminal, procedure A then proceeds. 
     In the invention, the weighting numbers D 1 , D 2  and D 3  are applied to all terminals. In some embodiments, each terminal has its own weighting number different from the other terminals. Two terminals, a first terminal and a second terminal, are described here as an example, but the invention is not limited to two terminals. The sequence index of the first terminal is W 1 , and the sequence index of the second terminal is W 2 . The weighting numbers applied to the first terminal comprise a first weighting number C 1 , a second weighting number C 2 , a fifth weighting number C 5  and a seventh weighting number C 7 . The weighting numbers applied to the second terminal comprise a third weighting number C 3 , a fourth weighting number C 4 , a sixth weighting number C 6  and a eighth weighting number C 8 . The first weighting number C 1  indicates that the first terminal is connected to a first source and signals are detected at the first terminal. The second weighting number C 2  indicates that no signals are detected at the first terminal. The third weighting number C 3  indicates that the second terminal is connected to a second source and signals are detected at the second terminal. The fourth weighting number C 4  indicates that no signal is detected at the second terminal. If no signal is detected at the first or second terminal, two conditions are possible: the terminal is connected to a source and receives no signal, or the terminal is not connected to a source. The fifth weighting number C 5  indicates that the first terminal is connected to the first source and receives no signal. The sixth weighting number C 6  indicates that the second terminal is connected to the second source and receives no signal. The seventh weighting number C 7  indicates that the first terminal is not connected to the first source. The eighth weighting number C 8  indicates that the second terminal is not connected to the second source. In this embodiment, C 1 &gt;C 2 , C 1 &gt;C 4 , C 3 &gt;C 2 , C 3 &gt;C 4 . 
     When signals are detected at the first terminal, the first weighting number C 1  is added to W 1 . When the first terminal is connected to the first source but and receives no signal, the fifth weighting number C 5  is added to W 1 . When the first terminal is not connected to the first source, the seventh weighting number C 7  is added to W 1 . 
     When signals are detected at the second terminal, the third weighting number C 3  is added to W 2 . When the second terminal is connected to the second source and receives no signal, the sixth weighting number C 6  is added to W 2 . When the second terminal is not connected to the second source, the eighth weighting number C 8  is added to W 2 . 
     When signals are detected at the second terminal, the third weighting number C 3  is added to W 2 . When the second terminal is connected to the second source but receives no signals, the sixth weighting number C 6  is added to W 2 . When the second terminal is not connected to the second source, the eighth weighting number C 8  is added to W 2 . 
     As described, the first terminal has weighting numbers different from the second terminal. The weighting numbers of the first terminal are greater than the weighting numbers of the second terminal, such as C 1 &gt;C 3 , C 1 =15, C 3 =10. The value added to W 2  three times by the third weighting number C 3  is equal to the value added to W 1  twice by the first weighting number C 1 , which means the first terminal is more advantageous than the second terminal. 
     Except for the weighting numbers for each terminal, other procedures are identical to procedures as previously described. The terminals are detected according to the value of the sequence index. 
     While the invention has been described by way of example and in terms of preferred embodiment, it is to be understood that the invention is not limited thereto. To the contrary, it is intended to cover various modifications and similar arrangements (as would be apparent to those skilled in the art). Therefore, the scope of the appended claims should be accorded the broadest interpretation so as to encompass all such modifications and similar arrangements.