Safe broadcast monitoring method and monitoring device for broadcast television system

Abstract

The invention discloses a safe broadcast monitoring method and a safe broadcast monitoring device for a broadcast television system. The safe broadcast monitoring method comprises the following steps: detecting a plurality of continuous fault frames and a plurality of interval normal frames in a video signal; accumulating a plurality of continuous fault frame numbers to obtain a continuous fault frame number; and according to a comparison result of the continuous number of the fault frames and a reference threshold, whether an alarm signal is sent out is determined, and the plurality of continuous fault frames and the plurality of interval normal frames are alternately arranged in the video signal. According to the safe broadcast monitoring method, whether the broadcast fault occurs or not is judged according to the accumulated continuous number of the fault frames, so that the accuracy and the stability of broadcast fault detection are improved.

Description

Technical Field

[0001] The present invention relates to the technical field of broadcasting and television program playback control, and in particular to a safe broadcast monitoring method and a monitoring device for a broadcasting and television system. Background Art

[0002] In the broadcasting and television industry, the importance of safe broadcasting is self-evident. This is especially true for final-stage signal monitoring, where consistency comparison systems play a crucial role. The rapid development of digital television technology, coupled with the increasing number of channels, improved program quality, and enhanced video clarity, has placed higher demands on safe broadcasting. Traditional analog television technology is no longer able to meet the demands of modern viewers. The development of digital television has brought unprecedented change, but also new challenges. Against this backdrop, improving the accuracy of final-stage signal detection consistency comparison systems, particularly in identifying continuous, brief signal glitches, has become a key technological advancement.

[0003] In existing technical solutions, fault detection is usually carried out based on the type of fault, including black field, still frame, color field, color bars, silence, and too high or too low volume, etc. A fixed threshold is set for each fault type. When the duration of the fault reaches this threshold, the system will issue an alarm and automatically switch the signal after comprehensive judgment based on other conditions. However, this method has obvious limitations when facing continuous short-term faults. These faults may not be enough to trigger the preset threshold, or the system may not have time to respond during the duration of the fault. In addition, the setting of a fixed threshold may not be flexible enough when facing a complex and changing signal environment, and it is difficult to adapt to all types of signal anomalies. Furthermore, the existing technology may still require manual intervention in the process of signal comparison and fault handling, and it is impossible to achieve fully automated fault detection and handling.

[0004] Therefore, it is desirable to further improve the safe broadcast monitoring method of broadcasting and television systems to improve the accuracy and stability of identifying and responding to continuous short-term faults. Summary of the Invention

[0005] In view of this, the object of the present invention is to provide a safe broadcast monitoring method and monitoring device for a radio and television system, wherein multiple consecutive fault frame numbers are accumulated to obtain the number of fault frame durations, and broadcast faults are judged based on the number of fault frame durations, so as to improve the accuracy and stability of identifying and responding to continuous short-term faults.

[0006] According to one aspect of the present invention, there is provided a method for monitoring safe broadcasting of a radio and television system, comprising: detecting a plurality of consecutive fault frames and a plurality of interval normal frames in a video signal; accumulating the number of consecutive fault frames to obtain a duration number of fault frames; and determining whether to issue an alarm signal based on a comparison result of the duration number of fault frames with a reference threshold, wherein the plurality of consecutive fault frames and the plurality of interval normal frames are alternately arranged in the video signal.

[0007] Optionally, accumulating multiple consecutive fault frame numbers to obtain the fault frame duration number includes: if the frame number of one normal frame among the multiple normal frames is less than a first frame number threshold, accumulating the frame numbers of two adjacent consecutive fault frames of the one normal frame to obtain the fault frame duration number; if the frame number of one normal frame among the multiple normal frames is greater than or equal to the first frame number threshold, determining the frame numbers of two adjacent consecutive fault frames of the one normal frame as their respective fault frame duration numbers.

[0008] Optionally, the reference threshold is a second frame number threshold, and the comparison of the continuous number of faulty frames with the reference threshold includes: comparing the continuous number of faulty frames with the second frame number threshold, wherein when the continuous number of faulty frames is greater than or equal to the second frame number threshold, it is determined that a broadcast failure exists.

[0009] Optionally, the first frame number threshold is less than or equal to 10 frames, and the second frame number threshold is greater than or equal to 50 frames.

[0010] Optionally, the reference threshold is a proportion threshold, and the comparison of the continuous number of faulty frames with the reference threshold includes: calculating the proportion of faulty frames of the continuous number of faulty frames to the total number of frames; comparing the proportion of faulty frames with the proportion threshold, wherein, when the proportion of faulty frames is greater than or equal to the proportion threshold, it is determined that a broadcast failure exists.

[0011] Optionally, the proportion threshold is greater than or equal to 80%.

[0012] Optionally, when it is determined that a broadcast failure exists, the method further includes generating a switching control signal for selecting a correct signal source and / or signal channel for the broadcast signal.

[0013] Optionally, the fault types of the multiple consecutive fault frames include any one or more selected from the group consisting of black field, still frame, color field, color bar, silence, volume too high, and volume too low.

[0014] Optionally, a corresponding reference threshold is set according to the fault types of the multiple consecutive fault frames.

[0015] According to another aspect of the present invention, there is provided a safe broadcast monitoring device for a radio and television system, comprising: a fault detection module, which performs signal analysis on multiple source signals to detect whether there is a fault frame; a content comparison module, which compares the multiple source signals with the broadcast signal to detect whether there is any modification to the broadcast content; a controller, which generates a control signal based on the detection results of the fault detection module and the content comparison module; a real-time alarm module, which generates an alarm signal based on the control signal; and a switching control module, which generates a switching signal based on the control signal, wherein when the fault detection module detects the presence of a fault frame, the controller executes the above-mentioned control signal.

[0016] According to the safe broadcast monitoring method and safe monitoring device of the embodiments of the present invention, when detecting signal faults in multiple source signals, multiple consecutive fault frames and multiple interval normal frames in the video signal are detected, and the cumulative frame number of multiple consecutive fault frames of continuous short-term faults is compared with a reference threshold. Therefore, the safe broadcast monitoring method can accurately detect continuous short-term faults in the video signal, avoiding both missed signal faults of continuous short-term faults and false signal faults of occasional short-term faults, thereby improving the accuracy and stability of broadcast fault detection.

[0017] In a preferred embodiment, when the interval frame number is less than the interval frame number threshold, the accumulated frame number of multiple consecutive fault frames is compared with the fault frame number threshold, thereby accurately identifying continuous short-term faults with small intervals.

[0018] In a preferred embodiment, within a predetermined frame number range, the accumulated frame number of multiple consecutive fault frames is divided by the predetermined frame number range to obtain a fault frame ratio, thereby accurately identifying continuous short-term faults with a high ratio. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] The above and other objects, features and advantages of the present invention will become more apparent through the following description of the embodiments of the present invention with reference to the accompanying drawings, in which:

[0020] Figure 1 A schematic block diagram of a radio and television broadcasting system is shown;

[0021] Figure 2 A schematic block diagram of a safe broadcast monitoring device according to a first embodiment of the present invention is shown;

[0022] Figure 3 A schematic diagram of a video signal format illustrating a signal failure mode;

[0023] Figure 4 A flowchart showing a safe broadcast monitoring method according to a second embodiment of the present invention is shown;

[0024] Figure 5A schematic diagram of a video signal format illustrating another signal failure mode;

[0025] Figure 6 A flow chart of a safe broadcast monitoring method according to a third embodiment of the present invention is shown. DETAILED DESCRIPTION

[0026] Various embodiments of the present invention will be described in more detail below with reference to the accompanying drawings. In each of the accompanying drawings, identical elements are represented by identical or similar reference numerals. For the sake of clarity, the various parts in the accompanying drawings are not drawn to scale.

[0027] The specific implementation of the present invention is further described in detail below with reference to the accompanying drawings and examples.

[0028] Figure 1 The schematic block diagram of a broadcasting and television broadcasting system 100 is shown. The broadcasting and television broadcasting system 100 includes redundant multi-level multi-channel signal channels to cope with sudden broadcasting failures, thereby improving the continuity and reliability of program broadcasting.

[0029] The radio and television broadcasting system 100 includes a main video server 101 , a first backup video server 102 , a second backup video server 103 , a main broadcast switching device 104 , a backup broadcast switching device 105 , an automatic signal switching device 106 , and a safe broadcast monitoring device 110 .

[0030] The primary video server 101, the first backup video server 102, and the second backup video server 103 generate synchronized program content based on the same program list. In this embodiment, a redundant system of three video servers is used to generate three source video signals. In the event of a failure in any one or both of the video servers, at least one video server can immediately take over to avoid interruption of the source video signal, thereby ensuring the continuity of the broadcast. For example, the video server converts the received video signal in transport stream (TS) format received by the satellite ground station into a source video signal in serial digital interface (SDI) format, or decodes the video file in MPEG format on the storage server into an SDI source video signal, or decodes the SDI source video signal recorded by a camera at the scene of the program. SDI is a digital television and video transmission standard within broadcast television systems, used to transmit uncompressed digital video and audio signals.

[0031] The main broadcast switching device 104 and the backup broadcast switching device 105 are each connected to the main video server 101, the first backup video server 102, and the second backup video server 103, converting three source video signals into two broadcast signals. In this embodiment, a redundant system of two broadcast switching devices is used to generate two broadcast video signals. If either broadcast switching device fails, the other broadcast switching device can immediately take over to prevent interruption of the broadcast video signal, thereby ensuring broadcast continuity. The broadcast switching device is used to implement signal routing for multiple source video signals, rather than performing signal format conversion. Therefore, the video signal format of the source and destination ports of the broadcast switching device is SDI.

[0032] Automatic signal switching device 106 is connected to the destination ports of both primary broadcast switching device 104 and backup broadcast switching device 105, receiving both broadcast video signals. If a failure occurs in either signal channel, automatic signal switching device 106 immediately switches from one broadcast signal channel to the other, ensuring broadcast continuity. Automatic signal switching devices route multiple broadcast signals, not convert them. Therefore, the video signal format at both the source and destination ports of the automatic signal switching device is SDI.

[0033] Security monitoring device 110 is used to detect signal failures in multiple source signals and content consistency between multiple source signals and the broadcast signal. Upon detecting a signal failure or content modification, it provides a switching control signal to automatic signal switching device 106 to switch the broadcast signal channel. For example, security monitoring device 110 and automatic signal switching device 106 are connected to a local network via a network interface, and security monitoring device 110 transmits the switching control signal to automatic signal switching device 106 using the TCP / IP communication protocol.

[0034] In conventional broadcast and television broadcast systems, when detecting signal faults in multiple source signals, the safety monitoring device 110 determines whether a signal fault exists based on a comparison of the number of consecutive faulty frames with a reference threshold. If the number of consecutive faulty frames exceeds the reference threshold, a signal fault is determined to exist.

[0035] The inventors of this application have noted that continuous short-term faults exist in broadcast and television systems, severely impacting program quality. Using the aforementioned existing safe broadcast monitoring method, if the reference threshold is set too high, signal faults may be missed because the number of consecutive faulty frames does not reach the reference threshold. If the reference threshold is set too low, signal faults may be frequently falsely reported because the number of occasional short-term faults often reaches the reference threshold.

[0036] Figure 2A schematic block diagram of a safe broadcast monitoring device according to a first embodiment of the present invention is shown.

[0037] The safe broadcast device 110 includes a fault detection module 112, a content comparison module 113, a controller 111, a switching control module 114, and a real-time alarm module 115. The safe broadcast device 110 is used, for example, Figure 1 The radio and television broadcasting system shown is used to detect signal failures of multiple source signals and content consistency between the multiple source signals and the broadcast signals.

[0038] The fault detection module 112 receives multiple source video signals in SDI format, divides the multiple source video signals into single frame data, and then separates the screen image and audio signal from the frame data.

[0039] Furthermore, the fault detection module 112 uses an image processing algorithm, for example, based on key visual features such as color histogram and edge information, to analyze whether the screen image has errors such as black fields, color fields, color bars, and still frames. A black field refers to all pixels in the video screen being displayed as black, without any brightness or color information. This fault may be caused by a variety of reasons, such as camera signal loss, video processing equipment failure, or signal transmission interruption. Color fields and color bars are test signals used in video technology to adjust and calibrate equipment. During normal program broadcasts, test signals may appear due to signal source switching errors. Still frames refer to multiple consecutive frames in a video signal that are the same image, as if the video is "frozen" on a certain frame. This fault may be caused by output problems of the video source, signal processing errors, or playback equipment failures.

[0040] Furthermore, the fault detection module 112 uses an audio processing algorithm to analyze whether the audio signal has errors such as silence, excessive volume, or excessive volume based on the detected volume level and waveform.

[0041] The content comparison module 113 receives multiple source video signals and multiple broadcast signals in SDI format, uses an image processing algorithm to compare whether the picture images of the source signal and the broadcast signal are consistent, and uses an audio processing algorithm to compare whether the audio data of the source signal and the broadcast signal are consistent, to ensure that the broadcast content has not been accidentally modified or damaged during transmission or processing.

[0042] The controller 111 is used to execute the response strategy for broadcast safety monitoring. Based on the detection results of the fault detection module 112 and the content comparison module 113, the controller 111 generates a control signal. The control signal is used to activate at least one of the switching control module 114 and the real-time alarm module 115.

[0043] The switching control module 114 generates a switching signal based on the control signal, which is used to switch from one broadcast channel to another. The real-time alarm module 115 generates an alarm signal based on the control signal, which is used to send a prompt signal to the broadcast staff on duty and the leaders of the broadcast department. This can include displaying an alarm icon on the control terminal interface, sending an alarm message to a designated mobile terminal, and activating an audible and visual alarm device.

[0044] According to an embodiment of the present invention, when detecting signal faults in multiple source signals, the safety monitoring device 110 detects multiple consecutive fault frames and multiple interval normal frames in the video signal; accumulates the number of consecutive fault frames to obtain the number of fault frame durations; and determines whether to issue an alarm signal based on a comparison result of the number of fault frame durations with a reference threshold, wherein the multiple consecutive fault frames and the multiple interval normal frames are alternately arranged in the video signal.

[0045] The safety monitoring device 110 compares the accumulated frame number of multiple consecutive fault frames of the consecutive short fault with the reference threshold, thereby accurately detecting the consecutive short fault in the video signal to improve the accuracy and stability of broadcast fault detection.

[0046] Figure 3 A schematic diagram of a video signal format illustrating various signal failure modes. The first signal failure mode is characterized by continuous, short-duration failures at short intervals. In this example, the signal failure is a black field with an abnormal image. The reference threshold for determining consecutive failure frames as a failure signal is set to the failure frame count threshold, Nerror = 50 frames.

[0047] As shown in the figure, multiple consecutive faulty frames and multiple intervals of normal frames are arranged alternately in the video signal. The four consecutive faulty frames each have 16 frames, and the three intervals of normal frames each have 4 frames. The number of frames in each consecutive faulty frame does not exceed the faulty frame count threshold, Nerror. Therefore, the signal fault is not identified in the existing safe broadcast monitoring methods.

[0048] The safe broadcast monitoring method of the present invention further introduces a frame count threshold between normal frames, Ncorrect = 10 frames. Because the number of normal frames between four consecutive faulty frames is less than the frame count threshold Ncorrect, the cumulative number of the four consecutive faulty frames totals 64 frames, which exceeds the faulty frame count threshold Nerror. Therefore, the safe broadcast monitoring method of this embodiment of the present invention can identify continuous short-term faults.

[0049] Figure 4 FIG. 4 is a flow chart showing a method for monitoring safe broadcasting according to a second embodiment of the present invention. Figure 2 The safety broadcast device 110 shown executes each step of the safety broadcast monitoring method.

[0050] In step S01 , the controller 111 receives a fault detection signal sent by the fault detection module 112 .

[0051] Fault detection module 112 uses image and audio processing algorithms to identify image and / or audio errors frame by frame, thereby generating a faulty frame detection signal. Faulty frame fault types include any one or more selected from black frame, static frame, color field, color bars, silence, volume too high, and volume too low.

[0052] In step S02, it is determined whether the fault type is new. Different interval frame number thresholds Ncorrect can be set for different fault types. For example, compared with static frame faults, the interval frame number threshold for black field faults is set smaller to improve the sensitivity of black field fault detection.

[0053] If the detected fault frame is determined to be a new fault type, an additional step S03 is performed to reset the fault frame accumulator. In other words, since the original fault type fails to reach the reference threshold, the original fault type does not need to generate a fault alarm, and therefore, the accumulation of fault frames of the new fault type is restarted.

[0054] In step S04 , it is determined whether the interval number of frames before the faulty frame is less than the interval number threshold Ncorrect.

[0055] If it is determined that the detected interval frame number is greater than or equal to the interval frame number threshold Ncorrect, then additional step S05 is executed to reset the fault frame accumulator. That is, since the fault frame belongs to a large interval independent signal fault, the accumulation of the fault frame number of the independent signal fault is restarted.

[0056] In step S06, the number of consecutive fault frames is accumulated to obtain the number of fault duration frames.

[0057] In step S07 , it is determined whether the number of consecutive faulty frames is greater than a faulty frame number threshold Nerror.

[0058] If it is less than or equal to the fault frame number threshold, the process returns to step S01 to continue accumulating the fault frame number. If it is greater than the fault frame number threshold, the process proceeds to step S08 to identify it as a continuous short-term fault.

[0059] In the case of a continuous short-term fault, the controller 111 generates a control signal, the switching control module 114 generates a switching signal according to the control signal, and the real-time alarm module 115 generates an alarm signal according to the control signal.

[0060] Figure 5A schematic diagram of a video signal format illustrating another signal failure mode. The second signal failure mode is characterized by a high percentage of continuous short-duration failures. In this example, the signal failure is a black field with an abnormal image. The reference threshold for determining consecutive failure frames as a failure signal is set to a failure frame percentage threshold within a predetermined frame range, Rerror = 80%.

[0061] As shown in the figure, multiple consecutive faulty frames and multiple intervals of normal frames are arranged alternately in the video signal. The three consecutive faulty frames have a frame count of 20, 25, and 40, respectively, and the two intervals of normal frames have a frame count of 5. The number of frames in each consecutive faulty frame does not exceed the faulty frame count threshold Nerror, thus, no signal fault is identified in the existing safe broadcast monitoring methods.

[0062] In the safe broadcast monitoring method of the present invention, within the predetermined frame number range of Ntotal=100 frames, the cumulative number of three consecutive fault frames is equal to 85, and the cumulative proportion of three consecutive fault frames is equal to 85%, which has exceeded the above-mentioned fault frame proportion threshold Rerror. Therefore, continuous short-term faults can be identified in the safe broadcast monitoring method of an embodiment of the present invention.

[0063] Figure 6 FIG. 4 is a flowchart of a safe broadcast monitoring method according to a third embodiment of the present invention. Figure 2 The safety broadcast device 110 shown executes each step of the safety broadcast monitoring method.

[0064] In step S11 , the controller 111 receives a fault detection signal sent by the fault detection module 112 .

[0065] Fault detection module 112 uses image and audio processing algorithms to identify image and / or audio errors frame by frame, thereby generating a faulty frame detection signal. Faulty frame fault types include any one or more selected from black frame, static frame, color field, color bars, silence, volume too high, and volume too low.

[0066] In step S12, it is determined whether the fault type is new. Different fault frame ratio thresholds Rerror can be set for different fault types. For example, compared with static frame faults, the interval frame number threshold for black field faults is set smaller to improve the sensitivity of black field fault detection.

[0067] If the detected fault frame is determined to be a new fault type, an additional step S13 is performed to reset the frame counter and the fault frame accumulator. In other words, since the original fault type does not reach the reference threshold, the fault frame of the original fault type does not need to be alarmed. Therefore, the accumulation of the number of fault frames of the new fault type is restarted.

[0068] In step S14, the number of fault duration frames is accumulated to obtain the total number of fault frames.

[0069] In step S15 , the total number of faulty frames is divided by a predetermined frame number range corresponding to the fault type to obtain a faulty frame ratio.

[0070] In step S16, a determination is made as to whether the total number of frames counted is greater than the predetermined frame range Ntotal. If so, the process returns to step S13, resetting the frame counter and the fault frame accumulator. In other words, since the reference threshold is not reached within the predetermined frame range, no fault alarm is required for the fault frames within that range. Therefore, the accumulation of fault frames for the next predetermined frame range is restarted.

[0071] If the total is less than or equal to the predetermined frame number range Ntotal, step S17 is executed to determine whether the faulty frame ratio is greater than the faulty frame ratio threshold Rerror. If the total is less than or equal to the faulty frame ratio threshold Rerror, the process returns to step S11 and continues to accumulate the number of faulty frames. If the total is greater than the faulty frame ratio threshold, step S18 is executed to identify the fault as a continuous short-term failure.

[0072] In the case of a continuous short-term fault, the controller 111 generates a control signal, the switching control module 114 generates a switching signal according to the control signal, and the real-time alarm module 115 generates an alarm signal according to the control signal.

[0073] In the above embodiments, the cumulative number of consecutive faulty frames is compared with a faulty frame number threshold, or the cumulative frame number percentage of consecutive faulty frames is compared with a faulty frame ratio threshold to detect continuous short-term faults in the video signal. In a preferred embodiment, these two embodiments can be combined to calculate the cumulative number of consecutive faulty frames and the cumulative frame number percentage, respectively. When either the faulty frame number threshold or the faulty frame ratio threshold is reached, a signal fault is determined to exist.

[0074] While embodiments of the present invention have been described above, these embodiments do not exhaustively describe all details and do not limit the invention to the specific embodiments described. Obviously, many modifications and variations are possible based on the above description. These embodiments are selected and described in detail in this specification in order to better explain the principles and practical applications of the present invention, thereby enabling those skilled in the art to better utilize the present invention and its modifications. The present invention is limited only by the claims and their full scope and equivalents.

Claims

1. A method for monitoring safe broadcasting of a radio and television system, comprising: Detecting multiple consecutive fault frames and multiple interval normal frames in a video signal; Accumulate the number of consecutive fault frames to obtain the duration of fault frames; as well as According to the comparison result of the continuous number of fault frames and the reference threshold, it is determined whether to issue an alarm signal. The plurality of continuous fault frames and the plurality of interval normal frames are alternately arranged in the video signal.

2. The safe broadcast monitoring method according to claim 1, wherein: Accumulating the number of consecutive fault frames to obtain the number of fault frames in duration includes: If the number of frames of one of the plurality of normal frame intervals is less than the first frame number threshold, accumulating the numbers of two adjacent continuous fault frames of the one normal frame interval to obtain a continuous number of fault frames; If the number of frames of one normal frame interval among the multiple normal frames is greater than or equal to the first frame number threshold, the number of frames of two adjacent continuous fault frames of the one normal frame interval is respectively determined as the respective fault frame duration numbers.

3. The safe broadcast monitoring method according to claim 2, wherein: The reference threshold is a second frame number threshold, and the comparison between the continuous number of fault frames and the reference threshold includes: Compare the duration of the faulty frames with the second frame number threshold, When the continuous number of faulty frames is greater than or equal to the second frame number threshold, it is determined that a broadcast fault exists.

4. The safe broadcast monitoring method according to claim 3, wherein: The first frame number threshold is less than or equal to 10 frames, and the second frame number threshold is greater than or equal to 50 frames.

5. The safe broadcast monitoring method according to claim 2 or 3, wherein: The reference threshold is a percentage threshold, and the comparison between the continuous number of fault frames and the reference threshold includes: Calculate the ratio of the duration of the faulty frames to the total number of frames; Compare the fault frame ratio with the ratio threshold, When the proportion of the faulty frames is greater than or equal to the proportion threshold, it is determined that a broadcast failure exists.

6. The safe broadcast monitoring method according to claim 5, wherein: The proportion threshold is greater than or equal to 80%.

7. The safe broadcast monitoring method according to claim 1 further includes generating a switching control signal to select the correct signal source and / or signal channel for the broadcast signal when it is determined that a broadcast failure exists.

8. The safe broadcast monitoring method according to claim 1, wherein: The fault types of the multiple consecutive fault frames include any one or more selected from black field, static frame, color field, color bar, silence, volume too high, and volume too low.

9. The safety monitoring method according to claim 8, wherein: A corresponding reference threshold is set according to the fault types of the multiple consecutive fault frames.

10. A safe broadcast monitoring device for a radio and television system, comprising: A fault detection module performs signal analysis on multiple source signals to detect whether there is a fault frame; a content comparison module, which compares the multiple source signals with the broadcast signal to detect whether the broadcast content has been modified; a controller, generating a control signal according to the detection results of the fault detection module and the content comparison module; A real-time alarm module generates an alarm signal according to the control signal; as well as The switching control module generates a switching signal according to the control signal. Wherein, when the fault detection module detects the presence of a fault frame, the controller executes the safety monitoring method according to any one of claims 1 to 9 and generates the control signal according to the detection result.

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