JPS6173274A - Device for reproducing recording disk information - Google Patents

Abstract

PURPOSE:To freely select an optional audio system without switching the connection with a reproducing device even when only one system of output device exists, by outputting audio outputs of two systems, analog system and digital system, by appropriately selecting the outputs in accordance with output mode designation. CONSTITUTION:The rotating speed for reproduction is different between a video disk (LD, LDD) and digital audio disk (CD). The rotating speed for reproduction is controlled by switching by means of a control means 82 which inputs the output of a mode designating means 81 which designates an analog-only mode and auto-digital mode and LDD/CD disk discriminating information from a disk discriminating circuit 10. The control means 82 switches a change-over switch 75 to (b) side regardless of the output of the means 81 at the time of CD reproduction. At the time of LDD reproduction, the means 82 switches the switch 75 to (a) side under the analog-only mode and to the (b) side under the auto-digital mode. Therefore, appropriate audio signals are outputted from terminals 73L, 73R, 74L, and 74R.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a recording disc information reproducing apparatus, and more particularly to a reproducing apparatus for reproducing recorded information on a recording disc on which digital signals are recorded.

BACKGROUND ART A so-called compact disk (hereinafter abbreviated as CD), which is a digital audio disk in which an audio signal is subjected to predetermined digital modulation processing and recorded as a pulse train, is known as a recording disk on which digital signals are recorded. Furthermore, recently, a method has been developed in which an audio signal is digitized using a predetermined digital modulation method and a pulse-gear 1 signal is superimposed and recorded on each Ffvl modulated signal of a video signal and an audio signal (Japanese Patent Application No. 1983-=
15780)) has been developed.

In this recording method, the audio signal is converted into two channels, 2.3 MHz and 2°8 M f-
Each of the 1z audio carriers is FM modulated by two audio chisennel signals. In addition, the video signal is 7°6 MHz for the sync chip, 8.1 MH2 for the pedestal level, and 9.3 MHz for the white beak.
The frequency is converted to Hz. And the audio A signal is historically P Cfvl (Pu1se Co
The signal is digitized and converted into a pulse train signal using a modulation method such as deNlodula.

This pulse train signal is, for example, EFM (Eightjo
The frequency spectrum is a frequency component of a pulse train having a width of 3T to 11T. Here, T indicates the bit period of the PCM signal, and the three pulses are approximately 720 KHz.

The maximum width of 117 pulses is about 200 KHz.

Such a pulse train signal is superimposed on the video main carrier at a level of about 1/10 or less, and is slice-amplified near the zero-crossing point to become a pulse-width modulated signal, which is used as a recording signal.

RF (high frequency) obtained from a recording disk on which video signals and audio signals are recorded using the above recording method.
The frequency spectrum of the signal is as shown in FIG. In Figure 1, the component indicated by A is a digitized audio signal component, the component indicated by B is an audio FM signal component, the component indicated by C is a color information component in a video FM signal, and the component indicated by D is a digitalized audio FM signal component. This is a luminance information component.

Since the dynamic range of the digitized audio signal can be approximately 90 dB or more, the sound quality can be significantly improved compared to recording and reproducing audio signals using the F~1 modulation method.

Furthermore, video disks (hereinafter abbreviated as LD) are already known, in which digital signals are not recorded, but video signals and audio signals are frequency-modulated and recorded.

It would be extremely convenient if these discs could be played back with a single playback device. In developing such a playback device, A-
When considering the audio output system, there are two audio output systems, an analog audio system and a digital audio system, and if there is only one system of output devices such as speakers, each audio output system and output device must be connected each time. This creates the hassle of having to switch connections.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned points, and provides a recording system that allows analog and digital audio output to be selected as appropriate even when there is only one output device system, without changing the connection to the playback device. The purpose is to provide a disc information reproducing device.

The recording disc information reproducing apparatus according to the present invention provides a recording disc information reproducing apparatus on which a video signal and an audio signal are frequency-modulated and recorded.
a second recording disk on which video signals and audio signals are respectively frequency-modulated and recorded with a predetermined digital signal superimposed thereon; and predetermined information is subjected to predetermined gain modulation processing and converted into a pulse train and recorded thereon. A recording disc information reproducing apparatus capable of reproducing a third recording disc that has been reproduced, comprising a switching means for outputting a demodulated output of a reproduced audio signal and a demodulated output of a reproduced digital signal in an R-type; A mode specifying means for specifying an output mode by the switching means, a disc discriminating means for discriminating the type of disc to be reproduced, and a switching control of the switching means based on the discrimination output of the disc discriminating means and the output of the mode specifying means. It is characterized by leaking control means.

Example Hereinafter, embodiments of the present invention will be described in detail based on the drawings.

FIG. 2 is a block diagram showing an embodiment of a recording disc information reproducing apparatus according to the present invention. Such a playback device is an LD.
This is a so-called compatible player that can play , CD, and LDD. As mentioned earlier, this player has different playback speeds for video discs (LD, LDD) and digital audio sub discs (CD), so LD, LDD
A spindle motor 1 for driving DD rotation and a spindle Tanabata 2 for driving CD rotation are provided. These spindle motors 1 and 21 are selected depending on the type of disc to be reproduced, and are switched by a switching mechanism 4 using the motor 3 as a driving source, for example.

In order to detect the disc size of the disc 5 to be reproduced, for example, 3UA detection sensors 6.7 and 8 detect gQ i- in the disc radial direction relative to the disc size.
I'm getting fucked. The disc size is approximately 5 inches (12 cm) on the outside for CDs, and for video discs (LDs).
, LDD), the outer diameter is 8 inches and 12 inches.
There are different types. The outputs of the three detection C fusers 6, 7 and 8 are waveform-shaped by a waveform shaping circuit and then supplied to a disk discrimination circuit 10. For example, an optical sensor is used as the sensor for detection, but it is not limited to this.
It's okay.

The disc discrimination circuit 10 determines whether the disc to be played is a CD or an LDD based on the detection outputs of the detection sensors 6.7 and 8.
It is determined which of the three types of disks, LD and LD. The specific circuit configuration of this disk discrimination circuit 10 is not shown in FIG. In this diagram, in the case of CD,
The disc size is determined to be the minimum (12 cm), and the detection output of the innermost detection sensor 6 and the inverter 79.8
A in which the inverted output of the detection sensor 7.8 that exceeds 0 is made by three people
The output of the ND gate circuit 78 becomes CD discrimination information. Of course, when the detection sensor 6 is on and the other detection sensors 7.8 are off, it is determined that it is a CD. In the case of a video disc, since the disc sizes are 8 inches and 12 inches, the detection output of the detection sensor 7 or 8 is passed through six OR gate circuits and becomes the output of each of the AND gate circuits 70 and 71. Further, a frame synchronization detection signal generated when a frame synchronization signal is detected from a frame synchronization detection circuit 21, which will be described later, becomes another input to the AND gate circuit 71, and is also inverted by an inverter 72 and sent to the AND gate circuit 71. It can also be used as another input. When the detection output from the detection sensor 7 or 8 is generated and the frame synchronization detection signal is input, the AND gate circuit 71 outputs DD discrimination information, and when the frame synchronization detection signal is not input, the A1\D gate circuit 70 outputs an LD discrimination @ report. This discrimination information is used to drive an indicator 11 that displays the type of disc, and as a switching signal for various switches to be described later.

A pickup 12 for reading recorded information from the disk 5 is carried by a slider base (not shown) that is movably provided in the radial direction of the disk 5, and the slider base consists of a slider motor, a reduction gear, etc. The drive is driven by a mechanism (not shown). The read ti'i 9) 7 read from the recording disk 5 by the pickup 12 is supplied to a digital information demodulation system 14, an analog audio demodulation system 15, and a video demodulation system 16 via an RF amplifier 13, respectively. R
The F amplifier 13 has a wide band of 5 KHz to 14 MHz, and a single amplifier can amplify a reproduced PCM audio signal, a reproduced FM audio signal, and a reproduced video signal.

In the digital information demodulation system 14, a changeover switch 17 that changes depending on the type of disc to be played back is provided.
Based on the disc information from 0, it switches to the A side in the case of an LDD, and to the B side in the case of a CD. Zunawara, LD
The signal processing system for the reproduced digital signal is switched between D playback and CD playback. When playing a CD, the playback RF output has PCM audio information C, and this PCM
The audio information is M T F (M 0dll
latiOnTransfer Function)
Compensation will be applied.

On the other hand, in the case of LDD, FM audio information and FM
PCM audio information included in the reproduced RF signal along with the video information is extracted by one LPF (low pass filter) and supplied to the de-emphasis circuit 20. PCM
Audio A' information is, for example, an EFM signal, but if the digital signal is directly superimposed on an FM-modulated video signal during recording, the digital signal component will be FM-modulated.
Since it will be disturbed by the low frequency components of the video signal, the low b5. The ingredients have been boosted and recorded. Therefore, during playback, the de-emphasis circuit 20 reduces the low-frequency components boosted during recording.
will be done. This results in record 117 and if
f S of digital signal against low frequency noise during rip
/N can be improved.

Note that instead of changing the signal processing system using the changeover switch 17, the power supply to each signal processing system circuit can be turned off.
Even if N10FF is used, the same effect can be obtained by 1q.

The reproduced EFMfg signal that has passed through the changeover switch 17 is supplied to the EFM demodulation circuit 22 via the frame 1 (Ii output circuit 21) and is also supplied to the raw lock extraction circuit 23, and this reproduced zero lock extraction circuit. The signal is demodulated into a PCM digital signal by the EFM demodulation circuit 22 using the reproduced clock extracted in step 23.

This demodulated signal is sent to a memory 24 such as a RAM (random access memory) by the DIIO of the memory controller 25.
); 9 is loaded, but this memory controller 2
5 performs programming in synchronization with the write clock which is the frequency-divided output from the frequency divider 26 of the reproduced clock.

The four outputs of stored information from the memory 24 are performed by dividing the R oscillation output of the VCO (voltage subplane oscillator) 27, which is input to a PLL (phase locked loop) circuit, by a frequency generator 28. It is now being done in synchronization with the tarot cards. The PLL circuit has the above-mentioned V
A phase comparator (P/C) 31 which is powered by two people, the frequency-divided output from the frequency divider 29 of the recovered clock and the frequency-divided output from the frequency divider 27 of the oscillation output of the VCO 27, receives this comparison output as input. PF (low pass filter 32) and a changeover switch 33 that selectively supplies the output voltage of the LPF 32 and the reference voltage Vr+J to the VCO 27.

In the PLL circuit, the changeover switch 33 changes the output voltage of the LPF 32 from C to A8III during LDDD generation based on the discrimination result of the disk discrimination circuit 10 mentioned above.
During D playback, it switches to b IIP+ and the reference voltage Vr
cr, is supplied to the VCO 27. This allows L I)
During D playback, the read clock for not reading out the ↑0 information from the memory 24 is re-phase-synchronized with the 1 clock by the PLI circuit, and during CD playback, the loop switch 59 (described later) is turned on (opened). The output of the phase comparator 31 drives the CD rotation driving spindle 2 through the PF 77, so that the reproduced clock is phase-synchronized with the fixed clock obtained by the VCO 27 whose bias is in a fixed state.

The digital signal thus read out is converted into an analog audio signal by a D/A (digital/analog) converter 34, and then sent to an LPF 35L.

35R to become left and right playback audio outputs.

The usage status in the memory 24 is constantly monitored by the memory controller 25, and when the memory 24 overflows or becomes empty (no data exists), the controller 25 indicates these conditions. Information is provided to voltage generator 36. In the LDDD generator 1, this voltage generator 36 is connected to the memory 24 from the memory controller 25.
According to the information indicating the usage status of the LPF 32, a positive v1 plane voltage is generated when the output voltage of the output voltage of the LPF 32 is increased, and a negative control voltage is generated when the output voltage of the output voltage of the LPF 32 is increased by mW. VCO 27 via switch 33
The number of cycles of the readout clock is sterilized by supplying it to the sterilizer.

In this way, the amount of data stored in the memory 24 is constantly monitored, and when there is an excess or deficiency in each city and processing capacity of the memory 24, a positive or negative control pressure is generated to control the PLL.
By asking the circuit to take appropriate measures, the memory 24 can always be maintained in a normal state.

In analog audio demodulation system 15, re(13F
2.3Mt-1z and 2.8. "VlHz's Δ-diocyria ℃ only 7 components are passed [3+)f
(Bandpass filter) The output of 37L and 37R is FM
The signal is modulated by F M +9 in the demodulator 381.38R, and becomes the left and right reproduced audio A outputs via the de-emphasis circuits 39L and 39R.

In video iu tone system 16, reproduction RF (h number is BP
Only video information is extracted by the F&notch circuit 4o.

In this BPF & notch circuit 40, the re-i
t EFM component included in RF signal and 2.3MHz
, 2.8MHz audio carrier 1) components are actively removed. This extracted information is supplied to the FM demodulator 42 via the limiter circuit 41 and is FM demodulated. This demodulated output is supplied to the dropout compensator (DQC)/1.4 via the LPF 43, and the compensator 44
Dropout compensation is provided. This dropout compensator 44 includes, for example, a dropout pincer (D
It consists of an ablog switch that is turned off by the detection output of O8) 46, and a hold capacitor provided between the output end of this switch and the star quasi-potential point. Therefore, when a dropout occurs, the level of the output of the LPF 43 facing the generation of the output of the dropout sensor 46 is held and sent to the next stage circuit, thereby performing dropout compensation. The output of this dropout compensator 44 becomes a video output.

The output of the dropout compensator 44 is sent to the horizontal sync separation circuit 4.
7, and the horizontal synchronizing signal is separated and output. This horizontal synchronizing signal is supplied to phase comparators 48 and 49, and the phase difference with the reference signal output from the reference signal generator 50 is detected. The output of the phase comparator 48 serves as an input to the adder 51, and the output of the phase comparator 49 supplies the equalizer amplifier 5.
It serves as another input to the adder 51 via 2. The output of the amplifier 51 is an equalizer amplifier 53 and a driver 5.
4, the spindle motor 1 for driving the LDD and 10 rotations is driven. This is the spindle (1-bo system. Also, the output of the equalizer amplifier 52 is connected to the loop switch 55,
An actuator (not shown) built into the pickup 12 is driven via the changeover switch 56 and the driver 57.

By driving this actuator, the light spot for reading the information 18 is moved QfQ in the tangential direction of the recording track of the disk. This is the tangential mirror lab system. The actuator may be a tangential mirror that moves the optical spot for reading information in the tangential direction of the recording track of the disk, or a tangential mirror that moves the optical spot for information reading in the tangential direction of the recording track of the disk. A configuration in which the optical spot for information reading is biased in the tangential direction of the recording track of the disk by displacing the information in the direction is advantageous.

The loop switch 55 is turned on (opened) in response to a spindle lock signal output from the spindle lock detection circuit 58 when locking of the spindle servo system is substantially completed. That is, at the time of IiE during reproduction, '
a) The spindle motor 1 is driven by the output of the phase comparator 48, and II ni! on the time axis is driven. When the spindle servo is almost completely locked, the loop switch 55 is turned on, and the actuator is driven by the output of the phase comparator 49 to finely adjust the time axis. Sharmibo) is performed. According to this, residual jitter components that cannot be removed by the spindle servo system can be removed by the tangential mebo system.

However, with regard to the high frequency component of the residual jitter due to the tangential Schalmibo basis, the mechanical system such as the actuator drive mechanism cannot sufficiently follow the jitter, so the jitter cannot be completely removed. Therefore, in the digital information demodulation system 14 mentioned above, the PL that generates the read clock is
By setting the cutoff frequency of the LPF 32 of the L circuit lower than the maximum frequency of the band of the tangential loop, the high frequency component of the residual jitter is cut.
This means that residual jitter components can be removed. More preferably, by setting the cutoff frequency of the LPF 32 lower than the disk eccentricity frequency (30 to 8H7 in the case of LDD), it is possible to completely eliminate jitter caused by disk eccentricity.

Although the spindle servo and tangential mebo are performed based on the horizontal synchronization signal, it is also possible to perform the spindle servo and tangential mebo based on the 3,58M)-1z C2DI carrier wave included in the reproduced FM video signal. 97+ Song Dynasty is mentioned.

LS[ is a servo system that provides +5 I when playing video discs (LDD, LD), but when playing CDs,
lit 1 in the digital information demodulation system 14 mentioned above
Spindle servo is performed based on the output of the mouth comparator 31. That is, the output of the phase comparator 31 drives the spindle motor 2 for driving the CD rotation via the driver 60 and five loop switches that are turned on (closed) during CD reproduction. Conventionally, when playing a CD, the above-mentioned tangential navigation was not performed, but since the spindle motor 2 cannot sufficiently follow the high frequency component of the output signal of the phase comparator 31, which is a time axis error signal, In this embodiment, the high-frequency component of the time axis error signal extracted by the l-lPF 61 drives the servo, that is, the tangential servo, which drives the actuator in the big 7 tube 12 via the changeover switch 56 and the driver 57. b. The selector switch 56 is switched to the a side when reproducing an LDD or 'LD, and to the b side when reproducing a CD, based on the determination result of the disc discriminating circuit 10.

In addition, the tangential servo during CD playback (4, the reproduction extracted by the reproduced clock extraction circuit 23) is set to ?t based on the frequency division output of 1 (frame same IUJ detection circuit 21). Frame detected in )IJ1
Even if it is based on the frequency-divided output of the signal, the same effect can be obtained because the frame synchronization signal and the reproduced clock are in a synchronous relationship.

The output of the spindle lock and detection circuit 58 is connected to the inverter 6.
It is inverted at 2 and becomes the sole power of the OR gate circuit 63 as a spindle unlock signal indicating that the spindle servo system is not in the locked state.

As the output of the OR gate circuit 63, a random access information signal generated at the time of a random access command such as scan, search, jump, etc. is supplied. Furthermore, the LDD information output from the disk discrimination circuit 10 is also input to the OR gate circuit 63.

The output of the OR gate circuit 63 is i(I III command circuit 6
4 to the recovered clock extraction circuit 23.

A specific circuit configuration of the recovered clock extraction circuit 23 is shown in FIG. In this figure, the reproduced EFM signal is transmitted to the phase comparator 6.
5, the phase difference with the oscillation output of the VC○ (voltage controlled oscillator) 66 is detected, and the phase;! jfi 1 is lPF
67 and a changeover switch 68 to the VCO 66 . As described above, a PLL circuit that generates a reproduced clock is configured.

The changeover switch 68 is normally located on the a side and supplies the output of the lPF 67 to the VCO 66, but when a command signal is output from the a+lI control command circuit 64 mentioned above, it switches to the b side in response to this command signal. Predetermined reference voltage Vre
fz is supplied to the VCO 66.

That is, when the spindle servo is not in the locked state or when the information reading optical spot jumps tracks due to a random access command such as scan, search, jump, etc., the sub-voltage Vrcr2 is applied to the VCO 66. By fixing the oscillation frequency to a frequency close to the reproduced clock frequency, it is possible to hasten the lock-in of the reproduced clock after the spindle servo is locked or after the random access command is released.

Referring again to FIG. 2, the audio output section includes a pair of left and right output terminals 73L and 73R of the analog audio output system.
A pair of left and right output terminals 74L and 74R of a digital audio output system are provided. Output terminal 73L,
The audio output from the analog audio demodulation system 14 is supplied to 73R. When playing this audio output terminal D, the output terminals 74L and 7
Supplied after 4R. The audio output from the analog audio demodulation system 14 and the audio output supplied from the digital information demodulation system 14 via the left and right mode selection switches 76L and 76R are input to the changeover switch 75. is on the a side as
The output mode of the mode specifying means 81 for specifying the output mode by this changeover switch 75), for example, analog Δ only and Δ-to-digital (digital audio is given priority), and the LDD and CD disc discrimination information from the disc discrimination circuit 10 are input. Switching 1i1 by control means 82 to
1611. This control 2i1 means 82 switches the selector switch 75 to the b side regardless of the output of the 7th mode specifying means 81 during CD playback, and switches the selector switch 75 to the b side regardless of the output of the mode specifying means 81 during LDD playback. Hold it on the a side, and in the case of auto digital, hold it on the b side.
control to switch to the side.

As a result, the output terminal 73 is output during LD playback.

Normal audio signals are output from 73R and output terminals 74L and 74R, and when playing a CD, output terminals 74L and 74R are output.
A high-quality audio signal is output from 74R, and the LDD
During playback, if the mode specified by the mode specifying means 81 is analog only, the LD is replayed, and the output terminal 7 is output in the same way as ¥.
Normal audio fffi 8 is output from both 3L and 73R and output terminals 74L and 74R, and in the case of auto digital, normal audio signals are output from output terminals 73L and 73R, and high quality A is output from output terminals 74L and 74R. -Dio (g number will be output.

The mode changeover switches 76L and 76R are provided to change over the output mode of the digital audio system audio signal B in an analog stage. In other words, if the audio output from the digital audio demodulation system 14 is stereophonic, the above-mentioned output mode will suffice, but in the case of audio multiplexing, for example, the L (left) channel may be Japanese and the R (right) channel may be the same. Outside [lf1 word, mode changeover switch 7 that operates independently of each other.
By using the output terminals 6L and 76R, the audio output from the output terminals 74L and 74R can be switched to three output modes: Japanese and foreign languages, Japanese only, and foreign languages only. The mode changeover switches 76L and 76R are driven separately according to control information from an operation section (not shown).

Relays that operate independently are used as the mode changeover switches 76L and 76R. Normally, a relay with one movable contact and two fixed contacts is sufficient for signal switching, but in this embodiment, one additional movable contact and two fixed contacts are used. A relay is used. In other words, relay 7 of 1jiX channel 11111
Taking 61 as an example, there are two sets of movable contacts Sll that are linked to each other.

Sol, and two sets of fixed contacts 512, 13., one pair provided for each of these two sets of movable contacts Sll, 821. Sn
, 23, and the two fixed contacts s+2., which are closest to each other among the two sets of fixed contacts. s23 becomes the input terminal for two signals @ (left and right A-dio signals), and one movable contact S
n is the output end. According to this, since two gaps exist between the right signal lines, crosstalk between left and right signals can be reliably prevented. Of course, crosstalk can be more reliably prevented by increasing the number of contacts and providing more gaps.

Although not shown in the figure, there is a focus servo system that controls the position of the pickup 2 in the direction perpendicular to the disk surface relative to the disk 5, and a tracking system that controls the position of the pickup 12 in the disk radial direction. Of course, a servo system is also provided.
It is preferable to switch the signal processing system of the error f bow during playback and when playing back a digital audio disc (CD), so that good servo can be performed regardless of the type of disc being played back.

Furthermore, the digital signal recorded on the CD or LDD includes not only audio information but also digitized image information or control information for computer control.

As described in detail of the invention, according to the recording disk information reproduction \RJ according to the present invention, it is possible to select and output two audio output systems, analog system and audio system, as appropriate according to the output mode designation. Therefore, even if there is only one system of output devices such as speakers, the desired audio system can be freely and easily selected without switching the connection to the playback device.

[Brief explanation of the drawing]

Figure 1 shows the frequency of the video signal and audio signal, respectively. ! ! A diagram showing an RF multiplied signal frequency spectrum obtained from a recording disk recorded by superimposing a processed signal and a pulsed signal obtained by PCM modulating an analog signal. FIG. 2 is a diagram showing the recording disk information reproduction according to the present invention. 3 is a block diagram showing a concrete circuit diagram of the disk discrimination circuit in FIG. 2, and FIG. 4 is a block diagram showing a concrete circuit diagram of the reproduced clock extraction circuit in FIG. 2. FIG. 2 is a block diagram showing a circuit configuration. Explanation of symbols of main parts 1...Swiss spindle motor 2 for LD and LDD
...CD spindle motor 5...Recording disc 10...Disc discrimination circuit 12...Pickup 14...F-internal information demodulation system 15... ...
・Analog audio demodulation system 16...Video demodulation system

Claims (1)

[Claims] A first recording disk on which a video signal and an audio signal are recorded after being modulated in a predetermined manner, and a second recording disk on which a predetermined digital signal and a video signal and an audio signal, respectively, are superimposed and recorded. , a third recording disc on which predetermined information has been subjected to a predetermined digital modulation process and pulsed and recorded, the recording disc information reproducing apparatus being capable of reproducing a third recording disc on which predetermined information has been subjected to a predetermined digital modulation process and pulsed, and which is capable of reproducing a demodulated output of a reproduced audio signal and a demodulated output of a reproduced digital signal. a mode specifying means for specifying an output mode by the switching means, a disc discriminating means for discriminating the type of disc to be played, and a discrimination output of the disc discriminating means and the mode specifying means. 1. A recording disc information reproducing apparatus comprising: control means for controlling switching of said switching means based on the output of said switching means.