JP2001326950A - Line time difference measuring device and signal generator for line time difference measuring device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To measure reliably and easily an arrival time difference between a sound signal and a video signal transmitted in the line and their sequential relation. SOLUTION: In the measuring device to detect the change of a video and a sound synchronized and generated in the sending side of the line from a video and a sound reaching a receiving side, the arrival time difference between a sound signal and a video signal transmitted in the line and their sequential relation are measured by detecting the intensity change of a video P displayed on a display D of the receiving side by the detecting part of a portable probe 50 separated from the display and a measuring device main body 1 and then by detecting the sound volume change of the sound signal of the receiving side.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a transmission / reception of a television signal which simultaneously handles video and audio, a broadcasting / editing / computer graphic, and other problems. The present invention relates to a measuring device for measuring and a signal generator used for the measurement.

[0002]

2. Description of the Related Art For example, when video and audio are handled simultaneously as in a television, it is needless to say that the timing of the video and audio must match. However, for example, in relaying a television signal, when transmitting these video signals and audio signals using different transmission paths such as a satellite line and a terrestrial line, or when compressing and transmitting a digitized video signal, A difference in arrival time between the video signal and the audio signal occurs on the receiving side, and a problem arises in that the video and the audio whose timings match on the transmitting side are shifted. In most cases, the video is delayed from the audio,
This results in a very strange impression for a person who knows only that the sound is delayed with respect to the image, such as a lightning strike or fireworks in the natural world, and it is necessary to correct it.

[0003] In order to solve the above problems, conventionally, a human monitors video and audio, grasps a time difference for correction by visual and auditory senses, and controls a delay of a video signal or an audio signal based on the difference. Was. However, this method does not require special equipment, but requires skill and intuition for adjustment.
There was a problem that it was not possible to obtain specific numerical data by measuring immediately, and that the results varied depending on the person.

Therefore, a method has been proposed in which a detection signal is inserted into a video signal and an audio signal to be transmitted, respectively, and the reception side detects the signal and measures a difference in arrival time (for example, Japanese Patent Laid-Open No. 5-236513). No.). However, this method requires a signal source to be connected to the transmission terminal of the line, and a measuring device to be connected to the reception terminal, and must be used as a set. In addition, both methods are large-scale, are not portable, and are difficult to use. In addition, there is a problem that usable television systems are limited.

On the other hand, as a method of electrically measuring the arrival time difference, a detection signal is not directly inserted into a video signal and an audio signal to be transmitted, but a signal based on an actual video and audio generated on the transmission side is received. A method of detecting on the side has also been proposed. This method is disclosed in JP-A-5-21.
No. 9449, which discloses that "on the transmitting side, a plurality of light-emitting points that repeat blinking scanning in synchronization with a reference signal, and blinking of a specific light-emitting point among the plurality of light-emitting points. A video / audio generation source having a speaker that repeatedly generates audio of a predetermined frequency in synchronization with the video, an image of a flashing light emitting point of the generation source and an audio of a predetermined frequency are captured by an imaging device separately provided, While collecting and transmitting the sound, the receiving side measures the time lag between the transmitted image of the blinking light emitting point and the sound of the predetermined frequency, which is caused by the transmission system. Video and audio, wherein a delay amount of an audio delay unit provided in a reception audio system and / or a delay amount of a video delay unit provided in a reception video system are set so as to correct the measured time lag. How to sync . "It is disclosed. In this known invention, a device having a plurality of light-emitting points that repeat blinking scanning on a sending side and a sound source generated at a specific light-emitting point is prepared, and the video is photographed by a television camera, and the sound is recorded by a microphone. The sound is picked up and transmitted as a video signal and an audio signal, respectively. At the time when the audio is detected on the receiving side, the transmitted video signal is stopped and displayed on a display. The delay amount is measured by visually recognizing the positional relationship with a specific light emitting point that coincides with.

[0006] Similarly, a method for detecting a real video and audio signal generated on the transmitting side on the receiving side instead of directly inserting a detection signal into the transmitted video signal and audio signal is disclosed in Japanese Patent Laid-Open No. 10-285483. It is also known in the gazette. Here, a device that simultaneously performs the change in luminance due to light emission and the generation of audio on the sending side is prepared, and this video is captured by a television camera, and the audio is collected by a microphone to generate a video signal and an audio signal, respectively. At the receiving end, the video signal is displayed on the display as a video on the receiving side, and the audio signal is reproduced from the speaker, the change in luminance and the audio are detected, and a pulse signal is generated at that time. The method is characterized in that a delay amount is measured.

[0007]

Among the prior arts described above, the invention disclosed in Japanese Patent Application Laid-Open No. Hei 5-219559 is characterized in that the measurement unit of the delay amount is determined in detail because the unit of measurement is determined by the interval between the specified light emitting points. There was a problem that results could not be obtained. In addition, since the measurement is performed by visual recognition of the relationship between the position of the light emitting point of the still image on the display and the position of the specific light emitting point coincident with the sound,
There was a problem that the measurement result could not be output as data due to automation of the delay control of the video signal or the audio signal.

On the other hand, in the invention disclosed in Japanese Patent Application Laid-Open No. 10-285483, although the above-mentioned problem has been solved, there is no recognition of the problem of accurately and easily detecting a change in luminance on a display. There was no disclosure of the means for that. Therefore, on the receiving side, the detection part and the measurement / display part are actually integrated with the measuring device body close to the display, and on the transmission side, the part where the change in luminance occurs is accurately positioned in the center of the screen. And there was a problem in practicality.

Further, a problem common to the above two known inventions is that a dedicated video / audio generation source paired with the measuring device (in the former invention, a plurality of light emitting points that repeat blinking scanning and a specific light emitting point). A device having a sound source generated in the above, a clapperboard or the like having a light emitting device in the latter case), and a case where an audio signal is only a line signal, or a reproduced sound from a speaker cannot be used. There was a problem that could not be dealt with in the situation.

[0010]

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems of the prior art, and measures the arrival time difference between the transmitted video signal and the audio signal on the receiving side. The invention comprises a line time difference measuring device and a signal generator optimal for the measuring device.

That is, the line time difference measuring device of the present invention comprises:
In a measuring device for detecting changes in video and audio synchronously generated on a transmission side of a line from video and audio arriving at a receiving side, a luminance change of a video displayed on a display on the receiving side is measured by a display and a measuring device main body. While being detected by the detection unit of the handheld probe separated from
By detecting a change in the volume of the audio signal on the receiving side, the mutual arrival time difference and the context of the audio signal and the video signal transmitted on the line are measured.

Further, the signal generator of the present invention emits light at the transmission side for a measuring device which detects changes in video and audio synchronously generated at the transmission side of the line from the video and audio arriving at the reception side. A signal generator for synchronizing the sound and the sound with a means for outputting the sound as an electric signal to the outside.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 shows an overall system for measuring the mutual arrival time difference and the context of an audio signal and a video signal transmitted on a line using the line time difference measuring apparatus and signal generator of the present invention. FIG. The outline of the present invention will be described first with reference to FIG.

In the line time difference measuring apparatus according to the present invention, regarding a video signal transmitted on a line, a received image P actually displayed on a display D on a receiving side is measured, and a change in luminance in the image is measured. Is detected. Similarly, with respect to the audio signal, the reproduced audio or the electric signal on the line is measured, and a change in the volume is detected.

In FIG. 1, reference numeral 60 denotes a signal generator according to the present invention, which is a signal (video and audio) generation source on the transmitting side. The signal generator 60 has a function of emitting light from the light emitting section 68 and simultaneously outputting a sound such as a dial tone to the outside or outputting it as an electric signal. On the transmitting side, the television camera C
And outputs a video signal to the video line VL, sends the video signal to the receiving side via the transmission line N, and simultaneously outputs the sound emitted from the signal generator 60 as an audio signal to the audio line AL. To the receiving side via.

Similarly, reference numeral T in the figure denotes a line time difference measuring apparatus according to the present invention. In this measuring device, a hand-held probe 50 separated from the measuring device main body 1 has a signal cable 5.
1, and the detection window at the tip of the probe 50 is brought into close contact with the light-emitting portion of the reception image P of the subject (the signal generator 60) displayed on the display D on the receiving side, so that the luminance depending on the presence or absence of light emission Has the function of detecting a change in the measurement result and outputting it to the measuring device main body 1 as an electric signal. Similarly, regarding the audio signal, the audio reproduced from the speaker S is input through the microphone M or the audio line AL.
It has a function of detecting a change in volume by directly inputting the above electric signal from the line L. Then, by comparing the detection points of each change of the video and audio, the mutual arrival time difference and the context of the audio signal and the video signal transmitted on the line are measured, and this is displayed on the display unit, or together with the display. It has the function of outputting it to the outside as data.

Hereinafter, specific embodiments of each device will be described with reference to the accompanying drawings. FIG. 2 is an external view of the line time difference measuring device T of the present invention, and FIG. 3 is a diagram showing an electric circuit. The measuring device T includes a power supply (battery) 2 and a measuring circuit, is provided with a main operation unit and a display unit outside, and further has an external connection terminal 15 for outputting data and the like. It comprises a probe 50 which is configured separately from the main body 1 and connected to the apparatus main body via a signal cable 51.

The measuring apparatus main body 1 has a video input terminal 20 for an electric signal (hereinafter referred to as "bright and dark signal V" for convenience) to which the signal cable 51 of the probe 50 is connected, and an audio input terminal for an audio signal. Is provided with two systems of an audio input terminal 30 for the audio signal A1 and an audio input terminal 40 for the audio signal A2 so as to be simultaneously connected to two audio lines, and detects a change in the volume of the audio transmitted through each audio line. It is possible. In the operation of actual television broadcasting, the audio signal is transmitted through a separate protection line in addition to the main line in case of a line accident or the like. Since the delay with respect to the signal can always be measured, there is an advantage that even when the voice line is suddenly switched, it can be dealt with immediately. Also, since the delay of the audio signal between the audio lines can be measured, the measuring device can be used for various purposes other than video.

The light / dark signal V input from the video input terminal 20 is adjusted in signal level by the DC amplifier 21 and then adjusted.
The detection sensitivity is adjusted by the variable gain amplifier 23. Reference numeral 22 in the figure denotes a volume for adjusting the sensitivity by the measurer in this case. The light / dark signal whose detection sensitivity has been adjusted drives the video light / dark indicator 11 which indicates the degree of light / dark detected by the lighting amounts of the plurality of LEDs, and crosses a threshold set in advance by the DC voltage detection amplifier 25. At this time, the signal is changed to a signal for the central processing circuit and sent to the central processing circuit 3. Reference numeral 24 in the figure is a volume for adjusting the threshold value by the operator in this case. In the present invention, a signal having a level equal to or higher than the threshold value is determined to be in the "bright" state. However, since the signal for the central processing circuit is generated when the signal crosses the threshold value as described above, The detection target extends from dark to bright as well as from light to dark, and as a result of the combination of the action of the probe peculiar to the present invention, as described later, it is possible to support a wide range of signal sources as well as a dedicated signal generator. Becomes While the brightness is in the "bright" state, the video "bright" detection indicator 26 for notifying the state is turned on.

The audio input terminal 30 can be connected to a microphone M for collecting reproduced audio or a line of an audio line, and a level switch 31 is provided to adjust an input level difference in these cases. After the input audio signal A 1 is adjusted in signal level by the audio amplifier 32, the unnecessary band is reduced by the band-pass filter 33. The audio signal in which the unnecessary band has been reduced changes to a signal for the central processing circuit when the audio signal detection amplifier 35 exceeds a preset threshold value, and is sent to the central processing circuit 3. Reference numeral 34 in the figure denotes a volume for adjusting the threshold value by the measurer in this case. In this case, the sound detection indicator 36 that has detected the sound signal is turned on. The audio signal is amplified by the audio amplifier 12 by selecting the audio signal by the audio circuit selection switch 14 and
Thus, it is possible for the measurer to listen to the detected sound as intended.

The audio input terminal 30 can be connected to a microphone M or a line of an audio line for collecting reproduced audio, and a level switch 41 is provided to adjust an input level difference in these cases. After the input audio signal A2 is adjusted in signal level by the audio amplifier 42, the unnecessary band is reduced by the bandpass filter 43. The audio signal from which the unnecessary band has been reduced changes to a signal for the central processing circuit when the audio signal detection amplifier 45 exceeds a preset threshold value, and is sent to the central processing circuit 3. Reference numeral 44 in the figure is a volume for adjusting the threshold value by the measurer in this case. In this case, the sound detection indicator 46 that has detected the sound signal is turned on. The audio signal is amplified by the audio amplifier 12 by selecting the audio signal by the audio circuit selection switch 14 and
Thus, it is possible for the measurer to listen to the detected sound as intended.

The central processing circuit 3 compares and judges the signals emitted from the light / dark detection circuit and the sound detection circuit, and measures the time difference of arrival time between each signal and the order (arrival order).
The result is displayed on the display unit as visible information or output to the outside as data. In the measurement result, the time difference between the arrival times of the respective signals is displayed by the measured value display unit 4A, and similarly the context of each signal is displayed by the data display indicator 5. The selection of each signal to be displayed can be sequentially selected by the data selection switch 7, and the type of each signal currently selected is displayed by the data display indicator 5 at that time. The display unit can be selected from a time (millisecond) unit and a frame unit by the display unit selection switch 8, and the display unit currently selected is displayed by the display unit indicator 4B. Incidentally, reference numeral 10 in the figure denotes a preset switch for automatically setting the sensitivity and threshold value of each signal described above to a preset standard value.
Similarly, reference numeral 9 denotes a manual switch for enabling these to be set by a measurer.

The probe 50 connected to the measuring apparatus main body 1 is a rod-shaped main body 52A that can be held by a measurer.
, A detection window 52B for detecting a change in luminance by being brought into close contact with the display D on the receiving side. The light entering through the detection window 52B is guided to the photoelectric conversion unit 53 by the lens, and is converted into the above-described electric signal (bright and dark signal V). In this embodiment, a silicon photodiode is employed as a detection element of the photoelectric conversion unit 53, thereby reducing measurement errors when performing continuous measurement of a high-luminance screen and variations in measured values due to differences in screen luminance. . The probe 50 is provided with a video "bright" detection indicator 55 for notifying that a luminance change of an image has been detected, and a measurement start switch 54 for instructing start of measurement. Note that the measurement start switch is also provided in the measurement device main body 1 (reference numeral 6 in the figure).

The operation of the line time difference measuring apparatus T according to the present invention having the above configuration will be described below with reference to the flowcharts of FIGS. Start measurement After selecting whether to connect each input terminal and set the sensitivity and threshold of each signal to the standard setting or to set manually, press the measurement start switch on the measuring device or probe to wait for the signal. (Waiting for 1st signal) (procedures S1 to S4). Display of measurement result 1 The time difference counting operation starts at the same time as signal detection. Upon detection of the first (1st) signal, the display of the corresponding signal is turned on in the 1st column of the data display indicator.
At the same time as detecting the next (2nd) signal, the display of the corresponding signal is turned on in the 2nd column of the data display indicator, and the time difference between 1st and 2nd is displayed numerically (steps S5 to S11). Even in this state, the time difference counting operation is continued. At the same time that the last (3rd) signal is detected, the time difference between 2nd and 3rd is stored internally, and the time difference counting operation ends (steps S15 to S20). Measurement result display 2 When the time less than 6 seconds is measured between 1st and 2nd and between 2nd and 3rd, 1 is displayed every time the data selection switch is pressed.
between st2nd → between 2nd3rd → between 1st3rd → 1s
The numerical value display data is sequentially switched and displayed, for example, from t2nd to (hereinafter, repeated) (steps S21 to S22). Display of measurement result 3 If the measured time difference exceeds 6 seconds, it is recognized as time over and the measurement is terminated. In this case, no data is displayed (steps S9 to S13, steps S17 to S2).
0). When the measurement start switch is pressed after the measurement is completed or during the measurement, the process returns to the signal waiting state (waiting for the first signal) (step S7, step S15, and step S27).

Next, a specific embodiment of the signal generator of the present invention will be described. 6 and 7 are views showing the appearance of the signal generator 60. FIG. The signal generator 60 has a box-shaped main body 75 having a screw hole 78 provided on the bottom for supporting by a tripod or the like.
A light emitting surface 68 made of a high-luminance white LED or the like is arranged in front of the device, and a power supply (battery) 61 and a sound generating device are built therein.

In the signal generator 60, the sound can be generated as an audible sound and can be output from the output terminal 74 as an electric signal to the outside. The sound generation of the sound and the light emission of the light emitting surface are performed at the same time, and the shift between the audio signal and the video signal is detected by detecting the shift by the receiving side. In the above-mentioned prior art, the sound was picked up by the microphone on the transmitting side, but in a noisy environment, there was a possibility that noise other than the signal to be detected might be picked up. According to the method, the sound can be transmitted as it is to the voice line as an electric signal, so that such a problem is solved. Further, if this signal generator is used in combination with the above-mentioned measuring device which can directly input a sound from a line without passing through a microphone, it is possible to more reliably detect a sound signal.

On the other hand, in the signal generator 60 according to the present invention, it is erroneously recognized that the light emitting surface emits light on the receiving side due to the reflection of external light or the like in a sunny day or in a studio or the like provided with a high illuminance light, or the luminance changes. In order to prevent a situation in which recognition is difficult, the light emitting surface 68 is first inclined with respect to the front of the signal generator (see FIG. 7). Next, hoods 77, 77 for shielding light in the horizontal direction and 76, 76 for shielding light in the vertical direction are provided on the four circumferences of the light-emitting surface. Effective light shielding according to the direction is realized. In addition, a marker 79 made of a high-brightness color (here, white) is provided around the light emitting surface 68 in order to suggest an optimal aperture setting of the television camera when the signal generator is used as a subject. In this case, it is possible to reliably detect a change in luminance by narrowing the aperture of the television camera so that the marker 79 is slightly visible on the display on the receiving side.

Further, in this embodiment, a countdown indicator 70 composed of a plurality of (three in this case) LEDs is arranged adjacent to the light emitting surface 68, and this indicator is turned on all the lights a predetermined time before the light emission of the light emitting surface. After that, the countdown display is performed by sequentially turning off the lights one by one, thereby facilitating the measurement timing. A mode switch 65 switches between an auto mode in which light emission and transmission of a voice signal are repeated at regular intervals and a manual mode in which a one-shot button switch 64 allows free transmission.
Can be selected. FIG. 8 is a diagram showing an electric circuit of the signal generator 60 of the present invention for realizing the above functions. In the figure, reference numeral 62 denotes a reference clock generator, 63 denotes a frequency divider for main transmission, and 66 denotes a one-shot. Circuit, 67 is a constant current circuit, 69 is a frequency divider for countdown, 71 is a tone oscillator, 72 is an output transformer, and 73 is an audio output level switch. FIG. 9 is a flowchart of the above operation, and reference numerals TC1, TC2, TC3
Indicates each LED of the countdown indicator 70.

[0029]

The present invention having the above configuration has the following specific effects. In the line time difference measuring apparatus of the present invention, since the detection unit for detecting the luminance of the image displayed on the display is provided on the main body of the measuring apparatus or the hand-held probe separated from the display, the position of the part where the luminance changes may be changed. Even if it changes on the display, it becomes possible to catch the change. As a result, it is necessary to take an image so that the signal generator that causes a change in luminance is positioned exactly at the center of the screen as in the prior art in which the detection device and the measurement / display portion are integrated with the measurement device body close to the display. Further, a dedicated signal generator is not necessarily required, and for example, as shown in FIG. 10, the arrival time difference between the video signal and the audio signal is detected by detecting the voice of the human H and the movement of the lips collected by the microphone M1. It becomes possible to detect. In the above case, the probe is provided with a video "bright" detection indicator that indicates that a change in the image brightness has been detected, and a measurement start switch that indicates the start of measurement. However, it becomes possible to perform measurement work flexibly. By adopting a configuration in which the sound can be directly input from the audio line without passing through the reproduced sound, reliable measurement can be performed without noise due to noise even in a noisy environment. Since the reproduced audio signal can be reproduced by the speaker, it is also possible for the measurer to listen to the detected audio as to whether it is intended. Since there are multiple systems of audio detection circuits so that they can be connected to multiple audio lines at the same time, in addition to the main line, the operation of the actual television broadcast that is sent out through a separate auxiliary line in case of a line accident etc. By measuring the delay of the audio signal of the spare line with respect to the video signal, it is possible to immediately cope with a sudden switch of the audio line. Also, since the delay of the audio signal between the audio lines can be measured, the measuring device can be used for various purposes other than video. In the signal generator according to the present invention, the sound can be output to the outside as an electric signal, so that even if the transmitting side is a noisy site, there is no possibility that the receiving side will pick up noise other than the signal to be detected. The light-emitting surface is inclined with respect to the front of the signal generator, and a hood that can be tilted at any angle around the light-emitting surface prevents external light from being reflected on the light-emitting surface. In a studio or the like where lights are arranged, it is possible to prevent a situation in which a light-emitting surface is erroneously recognized on the receiving side due to reflection of external light or the like, and a change in luminance becomes difficult to recognize. Markers made of high-brightness colors are provided around the light-emitting surface, so that the optimal aperture setting of the television camera when the signal generator is the subject can be suggested, and the change in brightness can be reliably detected on the receiving side. Becomes possible.

[Brief description of the drawings]

FIG. 1 is a conceptual diagram of a system using a line time difference measuring device and a signal generator according to the present invention.

FIG. 2 is a front view of the line time difference measuring device of the present invention.

FIG. 3 is a block diagram of an electric circuit.

FIG. 4 is a flowchart showing an operation of the embodiment.

FIG. 5 is a flowchart showing an operation of the embodiment.

FIG. 6 is a front view of the signal generator of the present invention.

FIG. 7 is a perspective view of the same.

FIG. 8 is a block diagram of an electric circuit.

FIG. 9 is a flowchart showing an operation of the embodiment.

FIG. 10 is a conceptual diagram of a system using the line time difference measuring device of the present invention.

[Explanation of symbols]

 T line time difference measuring device 1 measuring device main body 50 probe 60 signal generator 68 light emitting surface

Continued on the front page (72) Inventor Yuki Fukada 3-5-2 Okubo, Shinjuku-ku, Tokyo F-term in Sigma System Engineering Co., Ltd. 5C061 BB03 CC03

Claims (13)

[Claims] 1. A measuring apparatus for detecting a change in video and audio synchronously generated on a transmission side of a line from a video and an audio signal arriving at a reception side, wherein a change in luminance of the video displayed on a display of the reception side is measured. Detection by the detection unit of a hand-held probe separated from the display and measuring device main body, and by detecting a change in the volume of the audio signal on the receiving side, the arrival time difference between the audio signal and the video signal transmitted on the line. And a line time difference measuring device for measuring the context. 2. The line time difference measuring apparatus according to claim 1, wherein the probe is provided with a display unit for notifying that a change in the luminance of the image is detected, and a measurement start switch. 3. The line time difference measuring apparatus according to claim 1, wherein a change in the luminance of the video can be detected in any of the cases of light to dark and dark to light. 4. The apparatus according to claim 1, further comprising means for directly detecting a change in the volume of the audio signal on the receiving side from the electric signal on the line.
The line time difference measuring device according to any one of the above. 5. A device according to claim 1, further comprising means for detecting a change in the volume of the audio signal on the receiving side via the reproduced sound on the receiving side.
The line time difference measuring device according to any one of the above. 6. A plurality of means for detecting a change in volume of an audio signal are provided, so that the arrival time difference and the context of the audio signals transmitted via a plurality of different lines, the arrival time difference between these and the video signal, and The line time difference measuring device according to claim 1, wherein the line time difference can be measured. 7. The line time difference measuring apparatus according to claim 1, further comprising means for displaying a measurement result on a display unit of the measuring apparatus. 8. The line time difference measuring apparatus according to claim 1, further comprising means for outputting a measurement result to the outside as data. 9. The line time difference measuring apparatus according to claim 1, further comprising means for reproducing the detected audio signal by a speaker. 10. For a measuring device that detects a change in video and audio synchronously generated on the transmission side of the line from the video and audio arriving on the reception side, emits light and audio synchronously on the transmission side. A signal generator, comprising: means for outputting sound as an electric signal to the outside. 11. The signal generator according to claim 10, wherein a hood that can be inclined at an arbitrary angle is provided on four sides of a light emitting surface provided in front of the signal generator. 12. The signal generator according to claim 10, further comprising a marker having a high brightness color for setting a diaphragm of the television camera around the light emitting surface. 13. The signal generator according to claim 10, wherein the light emitting surface is inclined with respect to the front of the signal generator.