JP3368596B2 - Playback device - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a reproducing apparatus for reproducing an information signal recorded as a diagonal track on a magnetic tape by a rotary head.

[0002]

2. Description of the Related Art In a reproducing apparatus for reproducing an information signal recorded as an oblique track on a tape, a rotary head normally performs a helical scan. On the other hand, the signal recorded on the tape is divided into tracks for the convenience of this reproducing system.

At this time, there are cases where there is a reference signal with which the reproduced signal should be synchronized, such as in the run-up section of joint recording. In such a case, synchronization can be achieved by directly or indirectly comparing the phases of the reference signal and the signal reproduced from the tape and reflecting the result in the tracking control.

In the case of a consumer VTR (such as VHS), 1
A field is recorded as one track and one frame is recorded as two tracks. When reproducing this, a control signal (usually one pulse per frame) is recorded on a linear track provided separately from the diagonal track,
Tracking control is performed so as to synchronize this with the reference signal.

There is also an example in which one frame is divided into 20 to 24 tracks such as a commercial digital VTR (D1). Also in this case, there is a control track, and a servo signal of 1 pulse per one rotation of the drum (4 tracks) and a frame signal of 1 pulse per frame are recorded. When external synchronization is performed, the consumer VT is used.
The same control as in R was performed using a frame signal (for example, magazine "Broadcasting Technology" 1990, Vol.
See 12).

In either case, due to the characteristics of the linear track,
The tape position cannot be detected when the tape is stopped. By the way, at the start of reproduction, it becomes necessary to synchronize with the reference as described above. However, since the synchronization pulling speed is limited by the frame frequency, the frame frequency is N
In some cases, a sufficient pull-in speed may not be achieved with a VTR or the like that has a TSC of 30 Hz. In particular, during joint shooting, the operator issues a recording start instruction at the time when the operator confirms the image to be recorded, so the time required for start-up and frame synchronization is directly linked to the missing shot. Therefore, in order to speed up frame synchronization from the tape running stop state, a method of storing the position when the tape is stopped and adjusting the start timing with respect to the reference signal by this is also devised (for example, Japanese Patent Application No. Hei 10 (1999) -135242). No. 3-317665).

Further, regarding the reproducing apparatus of the system (ATF) which directly controls the tracking by the information from the oblique track without using the linear track, the frame to be synchronized and the tracking unit are made to coincide with each other. 8mmV which is synchronized like the linear track
In addition to the TR example, in the case of multi-segment recording, a method has been devised in which a track number for identifying the track is recorded in the track on the tape, and this is detected and synchronized (for example, Japanese Patent Application (See No. 3-50990).

In order to speed up the frame synchronization pull-in from the tape running stop state in the case of multi-segment recording, in Japanese Patent Application No. 4-81772, the stop position is within the track on the tape when the tape running is stopped. A method has been proposed in which frame synchronization can be achieved immediately after start-up by detecting the recorded track number and starting tape drive at a timing corresponding to this position.

[0009]

In the above example, there were the following problems regarding frame synchronization from the tape stopped state.

In the example using the above linear track, the position cannot be detected when the tape is stopped due to its nature. Therefore, when the vehicle is stopped, a preparatory operation such as detecting and storing the stop position is required. Moreover, such a high-speed start-up could not be performed when the preparatory operation could not be taken immediately after the tape loading operation.

Further, in the multi-segment example in which the tape stop position is detected by the track number recorded in the track on the tape, the scanning locus of the rotary head in the stopped state crosses a plurality of tracks, so that a plurality of tracks are formed in one scanning period. Track numbers may be detected. Normally, due to problems such as transmission and receiving side processing time limitations, 1
Generally, the number of tracks obtained as data in the scanning period is one. However, in this case, the error in the stop position detection is large, and considering the off-track amount of the rotary head that can read the track number and the variation in the load applied during tape driving, only the stop position detection information by the track number is used. If the tape drive timing is determined, the position of the head on the tape greatly varies immediately after the tape starts running, and high-speed frame synchronization may not be achieved.

[0012]

In order to solve the above-mentioned problems, the reproducing apparatus of the present invention sets data of a predetermined length as one frame, and the data of one frame is divided and recorded on a plurality of diagonal tracks, and At least 1 for each track
Tape drive means for running in the longitudinal direction a tape including a track number capable of identifying a track position within a frame, and in each of the tracks, a tape on which a pilot signal for tracking is recorded together with the data;
A drum for rotating the head to output a reproduction signal to the tape, outputting a reproduction signal, a reference generating means for generating a reference rotation signal and a reference frame signal which are rotation references of the drum, and a track number included in the reproduction signal. A reproducing track number detecting means for detecting, a tracking error signal detecting means for generating a tracking error signal from the pilot signal contained in the reproducing signal, and a reproducing track number detecting means for stopping the running of the tape. And a reference frame signal and a tracking error signal from the tracking error signal detecting means, the timing control means controlling the tape running start timing of the tape driving means. ing.

[0013]

With the above construction, the present invention can accurately detect the track position in the tape upper frame when the tape running is stopped and set the start of the tape drive means at an optimum timing in accordance with this.

[0014]

DESCRIPTION OF THE PREFERRED EMBODIMENTS A reproducing apparatus according to an embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram of a reproducing apparatus according to an embodiment of the present invention. In the figure, 1 is a tape, 2 is a tape driver, 3 is a drum, 4 is a reference signal generator, 5 is a reproduction track number detector, 6 is a tracking error signal detector, and 7 is a timing controller. The operation of the reproducing apparatus configured as above will be described below with reference to the time chart of FIG. In FIG. 2, a, b, d, e, f, and g indicate signal waveforms or data of the signal lines indicated by the same symbols in FIG. Also,
In this embodiment, one frame of data is divided into 12 diagonal tracks and recorded.

The drum 3 includes, as necessary, a drum main body, a motor and a driving circuit for driving the drum main body, a rotation control circuit, a head mounted on the drum, an amplifier circuit for amplifying a read signal from the head, and the like. The drum body 33 is shown in FIG.
The layout of the head mounted above is shown. Reference numerals 31 and 32 are heads, and this embodiment is an example in which the heads 31 and 32 record and reproduce two tracks substantially at the same time. Drum 3
Is rotating in synchronization with the reference rotation signal a generated by the reference signal generator 4, and the tape 1 wound around the drum 3
Data is read by a head mounted on the drum 3 and a reproduction signal d is output. Assuming that the tape running is stopped in the initial state, the head scanning by the drum 3 is performed across the tracks on the tape. Since azimuth recording is assumed, the signals of adjacent tracks cannot be read, and the reproduction signal amplitude fluctuates as shown in the figure. In FIG. 2, d is a reproduction signal read by the head 31, and the numerical value described in the reproduction signal d represents the track number recorded on the track being reproduced.

The reproduction track number detector 5 extracts the track number from the reproduction signal d and outputs the reproduction track number e. The tracking error signal detector 6 detects the tracking error signal f from the input reproduction signal. In the timing controller 7 from the reproduction signal, the reference signal generator 4
The reference track number c is internally created from the reference frame signal b and the reference rotation signal a given by This reference track number c is shown in FIG. This reference track number indicates the track number to be reproduced at that time. In this case, it is a series of numerical values that are simply counted up from 0 at the beginning of the reference frame signal to the end of the frame. Then, this is compared with the reproduction track number e indicating the tape stop position at that time, and further, based on the tracking error signal f sampled at a predetermined timing in one head scan during stop, as described later, The start timing is calculated to enable on-track time and establish frame synchronization at the same time. When an activation command is given to the terminal i from the outside, the drive start command g is given to the tape drive 2 at the calculated activation timing, in this case t1 in FIG.

Next, the tracking method will be described. Here, it is assumed that pilot signals of two different frequencies f1 and f2 are recorded every other track as shown in FIG. 4 (a). Further, it is assumed that f0 track, f1 track, f0 track, f2 track, f0 track, f1 track, ... Are recorded in order from track number 0. Here, no pilot signal is recorded on the f0 track. Frequency f1 for f1 track
The pilot signal of is recorded. A pilot signal of frequency f2 is recorded on the f2 track. Here, the pilot signal is recorded by a frequency multiplexing method or a digital pilot method by bit modulation in digital recording. The tracking is controlled so that the head 31 always scans the f0 track.
Now, assuming that the head 31 scans the track of track number 0, the leakage components of different pilot signal components f1 and f2 recorded on both adjacent tracks (here, tracks of track numbers 11 and 1) are detected. Included and detected. Tracking error signal detector 6 from this signal
The tracking error signal f is detected by, and the tape drive 2 controls the capstan motor by the input tracking error signal f. Here, as the tracking error signal detector 6, a known detector that compares the magnitudes of the f1 component and the f2 component and outputs a tracking error signal proportional to the difference is used. Here, as the tracking error signal f of the tracking error signal detector 6, a value proportional to the result of subtracting the f2 component from the f1 component is always output. Further, since the head 32 is arranged very close to the head 31 and the relative positional relationship with the head 31 can be accurately ensured, the head 32 and the track number 3 are tracked by performing the tracking between the head 31 and the track number 2. Tracking with the track can be achieved at the same time.

Upon receipt of the drive start command, the tape drive 2 starts tape drive and performs tracking control so that the head traces a track on the tape. However,
When used for tracking, the polarity of the tracking error signal of the tracking error signal detector 6 must be switched by the reproduction track number e of the reproduction track number detector 5. That is, a value proportional to the result of subtracting the magnitude of the pilot component of the rear track from the magnitude of the pilot component of the preceding track must be used. Further, the tape driver 2 includes a motor and a capstan for transmitting the rotation of the motor to the tape, a motor drive circuit, a rotation control circuit, and the like, if necessary. The switching of the polarity of the tracking error signal described above is also generally performed in the tape drive 2.

Here, since the start timing is properly measured, the reference track number and the reproduction track number match immediately after the start. That is, the synchronization between the reference frame and the playback frame is achieved without any auxiliary movement.

When a frame reference exists outside the apparatus, such as when performing joint recording, a reference frame signal is input to the input end h from the outside. In the reference generator 4, the internal clock is phase-locked with the external reference signal by a PLL or the like. As a result, the reference generator 4 generates each signal in synchronization with the external reference signal, and external synchronization becomes possible.

Next, the operations of the reproduction track number detector 5 and the tracking error signal detector 6 will be described with reference to FIG. First, regarding the portion for detecting the reproduction track number of the reproduction track number detector 5, this specific configuration method depends on the recording method of the track number on the track, and therefore its details are not mentioned here. In general, the configuration is such that clock number extraction, data reproduction (binarization), sync detection, and the like from a reproduction signal are performed to extract track number information embedded in a specific portion of data.

FIG. 4 schematically shows the locus of the head with respect to the tape position, the input / output of the reproduction track number detector 5 at that time, and the tracking error signal of the tracking error signal detector 6 at that time for some different stop positions. It is a figure. In the figure, a _{1 to} a ₅ show head loci on the tape 1. However, in order to make it easier to understand, the head locus is deformed and drawn vertically. On the other hand, the reproduced signals are b1 to b5. Subscript 1 after b
~ 5 correspond to that of a. The track number is detected using this reproduction signal as an input, but various forms are possible for its output. In addition, here, the case where the track number is detected by the head 31 is shown. That is, the track number that can be detected is always an even number. Now,
c1 to c5 are examples in which the detected values are output as they are, and the period marked with X is a period in which the input amplitude is small and the track number cannot be detected. In this case, the amount of output information is the largest, but since the timing controller 7 is optimally configured by software such as a microprocessor, as will be described later, there are drawbacks such as the limitation of processing time on the transmission side and the receiving side. Generally, as indicated by d1 to d5, the last detected track number in one scanning period is output in the next scanning period. In this case, one scan is used as data, which is advantageous in terms of processing by the timing controller.

Reference numerals e1 to e5 indicate the tracking error signal output at each stop position. Here, a value proportional to the result of subtracting the magnitude of the f2 component from the magnitude of the f1 component of the pilot signal is output. The output when the head is completely on-track is 0 (on the broken line).

FIG. 4C shows a tracking error signal TRE1 sampled at the timing after one-section scanning when the one scanning period is divided into four sections and a tracking error signal TR sampled at the timing after three-section scanning.
The stop position of E2 is changed (a1 in FIG. 4A).
-A7) It is the plotted figure.

Regarding TRE1, it can be seen that the polarity is positive in the stop position where the head locus on the tape is a1 to a5. Further, it can be seen that the polarity of TRE1 is always negative at the stop positions a5 to a7.
Therefore, in the case of the stop position where the detected track numbers are 0, 4, and 8, the polarity of TRE1 is always positive even if the stop position changes within that range. Similarly, when the stop positions are such that the detected track numbers are 2, 6 and 10, even if the stop positions change within the range, TR
The polarity of E1 is always negative.

Regarding TRE2, it can be seen that the polarity is negative when the head locus on the tape is a1 to a3 and is positive when the head locus is a3 to a5. It can be seen that even at the stop position between a5 and a7, the polarity is reversed at the intermediate point a6.

Therefore, by checking the combination of the polarities of TRE1 and TRE2, the stop position within 4 tracks corresponding to the recording period of the pilot signal can be detected with an accuracy of ± 0.5 track. In the example shown in FIG. 4, if (1) TRE1: +, TRE2:-, then a1
A2, (2) TRE1: +, TRE2: +, then a
3 to a5, (3) TRE1:-, TRE2: +
If a5 to a6 and (4) TRE1:-, TRE2:-, it can be detected that the operation is stopped at a6 to a7.

As described above, the stop position within the recording period of the pilot signal can be detected by checking the polarity of the tracking error sampled at the specific timing. Of course here, the above TRE
If a tracking error sampled at a timing different from 1 and TRE2 is used, each boundary at the time of detection can be set arbitrarily.

If the polarity of TRE2 is used for detecting the stop position together with the detected track number, the stop position in the frame can be detected with an accuracy of ± 1 track by detecting the track number, and the TRE2 at that time can be detected. The detection accuracy can be doubled (± 1 → ± 0.5 track) depending on the polarity of. In the example shown in FIG. 4, when the track number 4 is detected, the stop position becomes a
Can be detected in the range of ₁ ~a _5, it can be detected to have stopped in the range of a ₁ ~a ₃ or a ₃ ~a ₅ by detecting the polarity of TRE2.

Although the method of detecting the position by using the polarity of the tracking error signal sampled at a predetermined timing has been described above, it is assumed that the gain of the tracking error signal, that is, the signal level with respect to the off-track amount is substantially constant. Then, it is possible to further improve the position detection accuracy. In the example shown in FIG. 4,
According to the polarity of TRE2, a _{1 to} a ₃ or a _{3 to} a _{5 is used.}
Although it can be detected that it is stopped within the range of,
By comparing E2 with a given level, a ₁ ~
It is also possible to further distinguish the range of a ₃ into a _{1 to} a ₂ and a _{2 to} a ₃ .

However, since the gain of the tracking error signal generally has a large variation, the method of detecting the position by comparing with a predetermined level cannot be said to have reliability problems. On the contrary, the method of detecting the position based on the polarity of the tracking error described above is not affected by the variation in the gain of the tracking error signal and has high reliability.

Further, when the tracking error is sampled, the adverse effect of noise included in the tracking error can be reduced by performing the sampling a plurality of times near the desired timing. For example,
There is a method of using an average value of tracking error levels sampled multiple times for position detection. Further, in the case of detecting the position based on the polarity, there is also a method of detecting the position by determining the polarity by a majority decision among a plurality of samplings. In any case, the tracking error is sampled multiple times in the vicinity of a desired timing and used for position detection, so that the detection error due to noise can be reduced.

Next, of the operation of the timing controller 7, the start timing determination process will be described in more detail with reference to FIG. The operation of generating the reference track number is as described with reference to FIG. 2, and the description is omitted here. In FIG. 5A, 1 is a tape, 31 is a head, a and b are head loci, and c and d are in FIG. 5B.
Is a reproduction signal and a reproduction track number detection signal. Further, e is a tracking error signal. Although the timing controller 7 can be easily configured by hardware, its operation will be described as a series of procedures here as an example realized in software. The timing controller 7 executes the following four steps. The tape running is assumed to be stopped in the initial state. [Step 1]: The last detected track number (n) in the track numbers detected from the reproduction signal is determined to be the track to be on-tracked, and the scan cycle at which the reference track number becomes (n) is roughly started. Timing. [Step 2]: In the head scanning while stopped, the tracking error is sampled at the time corresponding to 3/4 of the scanning cycle (TRE2 described above), and the activation start timing is set according to the polarity. Even if the track is stopped at the position where the same track number (n) is detected depending on the polarity of TRE2, whether the stop position is from the track number (n + 1) or
The stop position from (n-1) is known. Since the on-track timing differs depending on this stop position, the start-start timing is changed. Here, since the pilot signal pattern can be known from the track number detected in (step 1), the relationship between the polarity of TRE2 and the stop position can also be known. The detailed relationship is as shown in FIG. [Step 3]: The timing at which a margin for the predetermined time required to activate the tape drive 2 from the on-track timing is taken into consideration is the final activation timing. [Step 4]: Wait for the start command to be given and output the drive start command at the timing determined in (step 3).

Next, these steps will be described with reference to the example of FIG. [Step 1]: When the tape running is stopped, the head 31
Scans the tape 1 across a track as indicated by a locus a indicated by a chain line. In this case, since 2ch reproduction is assumed, exactly 2 tracks are crossed. The envelope of the reproduction signal at this time is as shown by c, and the track number detected by the reproduction track number detector 5 from now on is as shown by d. The area marked with x in d is an area where the error rate is high and the track number cannot be detected because the level of the reproduction signal is low. In this case, since the detected track number is 1, the track indicated by the thick line is the head 31.
Is a track that should be on-track. Therefore, the scanning cycle in which the reference track number is (n) is the approximate timing for outputting the drive start command.

[Step 2]: If it is known that the track number and the recorded pilot signal pattern correspond to each other as shown in the figure, the locus a.
The tracking error when stopped at the position is as shown by e in the figure. Therefore, the polarity of the tracking error TRE2 sampled at the timing of 3/4 of the scanning cycle is negative (-), and the tracking error TRE2 is stopped at the track (n-1) as compared with the stop position in the case of FIG. 6 described later. I understand.

The position where the head is completely on-tracked to the track (n) is p0 on the track pattern of FIG. 5, and the timing is t0 on the time axis. This is determined from the reproduction track number and TRE2. It is difficult to detect it directly. However, the start timing can be determined more accurately than the timing determined only by the track number.

[Step 3]: If the tape drive 2 can instantly raise the tape to a constant speed,
If the start-up is performed at the timing determined in [Step 2], the on-track can be performed as it is. However, due to the inertia of the tape drive 2, some time is always required for the tape to reach a steady speed. Therefore, the timing t1 in consideration of the margin Δt is the final start timing.

[Step 4]: Waits for a start command from the outside and outputs a drive start command at the timing of [Step 3].

As a result, the head locus after starting is broken line b.
As soon as you start it, you can put it on the intended truck.

FIG. 6 shows the operation of the timing controller 7 at another stop position. In this case, since the stop position extends over two tracks, different values of (n + 2) and (n) are obtained as the reproduction track number in the first half and the second half of the scanning period. If the last detected track number is the track to be turned on, the track (n) is the track to be turned on. Therefore, the scan cycle at which the reference track number is (n) is the approximate start timing. Further, if the recording pattern of the pilot signal is the same as in the case of FIG. 5, the polarity of TRE2 is positive (+), and the track number is close to the track (n + 1) in the stop range determined to be (n). You can see that it has stopped. A point p2 (t on the time axis) farther from the start end of the scanning period than the point p0 described above.
In 2), since the head is almost on-track to the track (n), this is set as the ideal starting position, and the timing t3 traced back by the starting time from this is set as the actual starting timing.

As described above, even when the same track number (n) is detected, by checking the polarity of the tracking error signal TRE2 sampled at a specific timing, the detection accuracy of the stop position can be further improved. . If the start timing is changed according to the detected position (t1 or t3 in this embodiment), the start timing can be brought closer to the ideal start timing, and the time until completion of tracking can be shortened. .

Here, an example has been shown in which the position detection accuracy is improved by detecting the polarity of TRE2 and the start timing is changed according to the detected stop position. However, as described above, tracking sampled at a predetermined timing is performed. It is also possible to further improve the stop position detection accuracy by detecting the level of the error signal and change the start timing according to the stop position. In this case, it goes without saying that the time required to complete tracking can be further shortened.

The embodiment is an example of the realization of the present invention, and various applications are possible. Although the description of the tracks with different azimuths is omitted in the examples, obvious modifications for including the head configurations on the drum, the tape winding angle, etc. are included in the present invention. For example, in the case of the 2ch reproduction shown in the embodiment, the track number information from the head of one channel is sufficient as the position information, and the lower 1 bit of the track number actually recorded on the tape is deleted. May be

The track number is generally address information for identifying a data block unit obtained by subdividing a frame, and often includes a frame number, a block number, etc. in addition to the intra-frame track number shown in the embodiment. .
The reproduction track number detector may use such information as needed. The information necessary for tracking described in the embodiment is required not only for the in-frame track number but also for the frame number when the frame period is not an integral multiple of the tracking error signal period.

There is no particular limitation on the specific transmission form of the output of the reproduction track number detector. It may be serial, parallel, or multilevel signal.

The step for determining the start timing in the timing controller is also an example, as long as it determines the start timing according to the tape position indicated by the reproduction track number, the process itself is not particularly limited. . When it is desired to reproduce a track to be on-track by the same head as that for recording the track, it is possible to wait for the timing when the head comes around to scan.

Further, the frame of data to be recorded may be a frame corresponding to one image when recording a video signal, for example, or a color frame allows color framing. Although the method of realizing the timing controller is a software method, it may be realized by equivalent hardware.

[0048]

As described above, according to the present invention, when the tape running is stopped, the stop position is detected by the track number recorded on the tape and the tracking error signal, and the optimum position corresponding to this position is detected. Since the tape drive is started at the timing, the reproduction signal can be synchronized with the reference signal immediately after the start-up, and the state transition from the stop to the reproduction can be performed at high speed.

[Brief description of drawings]

FIG. 1 is a block diagram of a playback device according to an embodiment of the present invention.

FIG. 2 is a time chart showing signals of respective parts in FIG.

FIG. 3 is a layout view of heads mounted on the drum body.

FIG. 4 is an operation explanatory diagram of a reproduction track number detector and a tracking error signal detector.

FIG. 5 is an operation explanatory diagram of the timing controller.

FIG. 6 is an operation explanatory diagram of the timing controller.

[Explanation of symbols]

1 tape 2 tape drive 3 drums 4 Reference generator 5 Playback track number detector 6 Tracking error signal detector 7 Timing controller

─────────────────────────────────────────────────── ─── Continuation of the front page (72) Haruo Isaka Haruo Isaka 1006 Kadoma, Kadoma City, Osaka Prefecture Matsushita Electric Industrial Co., Ltd. (72) Kazuhiko Kobayashi 1006 Kadoma, Kadoma City, Osaka Matsushita Electric Industrial Co., Ltd. (56) Reference JP-A-4-285746 (JP, A) JP-A-5-159422 (JP, A) JP-A-5-290454 (JP, A) JP-A-5-290455 (JP, A) JP-A-59-36360 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) H04N 5/782-5/783 G11B 15/467

Claims (3)

(57) [Claims] 1. A predetermined length of data is defined as one frame, and one frame of data is divided and recorded in a plurality of diagonal tracks, and each track includes a track number capable of identifying a track position within at least one frame, Further, in each of the tracks, tape drive means for running a tape on which a pilot signal for tracking is recorded together with the data in the longitudinal direction thereof, and a drum for rotating and scanning the head with respect to the tape to output a reproduction signal,
Reference signal generating means for generating a reference rotation signal and a reference frame signal which are the rotation reference of the drum, a reproduction track number detecting means for detecting a track number included in the reproduction signal, and the reproduction signal included in the reproduction signal. Tracking error signal detecting means for generating a tracking error signal from a pilot signal, track number obtained from the reproducing track number detecting means with the tape running stopped, the reference frame signal, and tracking of the tracking error signal detecting means And a timing control means for controlling the tape running start timing of the tape driving means based on an error signal. 2. The timing control means controls rotation of the drum.
Tracked data sampled at a synchronized, predetermined timing
Depending on the tracking error signal of the tracking error detection means
Control the tape running start timing of the tape running means
The reproducing apparatus according to claim 1, wherein 3. The tape of the tape running means according to whether or not the tracking error signal of the tracking error signal detecting means sampled at a predetermined timing synchronized with the rotation of the drum is equal to or higher than a predetermined level. The reproduction apparatus according to claim 1, wherein the traveling start timing is controlled.