WO2016177317A1

WO2016177317A1 - Double-sided optical disc drive

Info

Publication number: WO2016177317A1
Application number: PCT/CN2016/080940
Authority: WO
Inventors: 朱明�; 徐宏; 贾小龙
Original assignee: 苏州互盟信息存储技术有限公司
Priority date: 2015-05-04
Filing date: 2016-05-04
Publication date: 2016-11-10
Also published as: CN104934047B; CN104934047A

Abstract

Disclosed in the present invention is a double-sided optical disc drive, comprising a first optical pickup unit, a second optical pickup unit, an optical disc drive motor and a controller. The first optical pickup unit is used to read and write data on a lower bottom surface of the double-sided optical disc, and the second optical pickup unit is used to read and write data on an upper top surface of the double-sided optical disc. The optical disc drive motor is used to drive the double-sided optical disc loaded on an optical disc tray to rotate clockwise or counter-clockwise. The controller is used to control a rotation direction of the optical disc drive motor according to the to-be-read surface or the to-be-recorded surface of the double-sided optical disc. By controlling the rotation direction of the optical disc drive motor, the present invention reads or writes data with the cooperation of the first optical pickup unit and the second optical pickup unit; therefore, reading and writing of the two data surfaces of a double-sided optical disc can be achieved after one loading operation of the disc to eliminate the need of a disc turning device, thus saving space as well as improving reading efficiency. In addition, the optical drive in the present invention is simple in structure and low in cost, and has a good compatibility with a common optical drive.

Description

Double-sided optical drive

Technical field

The present invention relates to an optical disc drive, and more particularly to a double-sided optical disc drive capable of reading and writing a double-sided optical disc.

Background technique

Optical storage, abbreviated as optical disc, is a data external storage device that has received much attention in recent years, and is an indispensable device for multimedia computers. In optical storage technology, data is stored using pits or denaturation on an optical disk, and optical drives with a laser head are used to read and write data. The disc is made of a plastic polymer with a metal reflective layer that is lightweight and strong, and is magnetically resistant, waterproof and drop resistant. (Read-only) The optical disc is mainly composed of a protective layer, a metal reflective layer (aluminum, silver, gold, etc.) that reflects laser light, a grooved layer, and a (polycarbonate) plastic-based gasket. The track of the disc is a spiral with a length of about 5 kilometers. Due to the constant linear velocity, the recording density (bits per inch) of the inner and outer tracks can be made the same, so that the disc is fully utilized. It can achieve the data storage capacity it should have.

The optical drive is referred to as an optical drive and is used to read and write optical discs. The optical drive structure includes an optical pickup unit, referred to as an OPU (Optical Pick-up Unit) and a servo control system. The optical pickup unit is also called a laser head, and includes a laser, a photodetector, and an optical device. The optical pickup unit is a reading and writing system of the optical disc. When reading, the laser beam emitted by the optical pickup unit is irradiated onto the concave and convex reflective surface of the optical disc, and after being reflected by the reflective layer, the reflected laser beam is converted into an analog signal by the photodetector. After the electronic circuit processing, the signal is obtained, and the coded data is decoded to obtain the read data. When writing, the signal-modulated laser is emitted onto a blank disc to burn the disc.

In response to the growing demand for data storage, optical disc manufacturers have begun to offer double-sided discs, both of which are glossy surfaces that can record data. At the same level of technology, the data storage capacity of a single disc can be expanded. Doubled, the storage capacity of the unit's optical library is also effectively doubled. Since a normal optical disc drive (commonly referred to as an "optical drive") can only read and write one side of a disc, if you need to read and write the other side of the disc, you must eject the disc from the disc tray, and then flip it through the disc tray. The optical drive, the operation of flipping the disc can be manual or automatic. Devices that automatically turn over are often referred to as flippers. The flipper is often used as a component of the optical disc library, and is organic with other disc operators. Combine.

The use of a flipper to achieve reading and writing of double-sided discs is a traditional method. It has been proved that this method has many shortcomings. The main disadvantages are (1) mechanical action, low efficiency and slow speed. (2) The flipper is a complex electromechanical device with high failure rate and easy damage.

There are also optical drives that can read and write on double-sided discs, but they can only read and write the upper and lower sides of double-sided discs at the same time. This type of optical disc drive has the following problems: because of the optical drive, the upper and lower sides of the double-sided disc are simultaneously burned. When the upper and lower sides are simultaneously burned, whether the upper and lower sides are recorded in the order or in the reverse order, the burning direction or the reading direction of the top top data is inevitably opposite to the lower bottom surface, so that the data on the top surface of the burned disc cannot be ordinary. The CD-ROM drive can only be read by this specific double-sided optical drive, and the front and back sides of the double-sided disc must be marked when reading, otherwise it cannot be read, so that the optical drive is used to record The compatibility and versatility of double-sided discs is significantly reduced. Since the upper and lower optical pickup units are associated with each other, the accuracy of the overall hardware and software is high, and the cost is also high.

Therefore, developing a double-sided optical disc that can read a double-sided disc without using a flipper and compatible with an ordinary optical disc drive has become an urgent problem to be solved.

Summary of the invention

In order to solve the above technical problems, the present invention provides a double-sided optical disc drive capable of reading a double-sided optical disc, comprising a support frame, a first optical pickup unit, a second optical pickup unit, an optical disc drive motor, and a controller, wherein

The support frame includes a lower support frame, an upper support frame and a disc tray, and the disc tray is disposed between the lower support frame and the upper support frame for supporting the optical disc and enabling the loading of the optical disc The bottom surface can be read or burned by the first optical pickup unit, and can enable the upper top surface of the loaded optical disc to be read or recorded by the second optical pickup unit; the first optical pickup unit and the optical disc drive a motor is disposed on the lower support frame, and the second optical pickup unit is disposed on the upper support frame;

The first optical pickup unit is configured to read or write the lower bottom surface of the optical disc loaded into the optical disc tray, that is, to read information loaded on the lower bottom surface of the optical disc or to burn information to the lower bottom surface of the optical disc. The second optical pickup unit is configured to read or write the upper top surface of the optical disc loaded into the optical disc tray, that is, to read information loaded on the upper top surface of the optical disc or to burn information onto the upper top surface of the optical disc;

The optical disc drive motor is configured to drive the optical disc loaded into the optical disc tray to rotate forward or reverse, so that the first optical pickup unit reads or burns the lower bottom surface of the optical disc, and implements the second The optical pickup unit reads or burns the upper top surface of the optical disc;

The controller is configured to control a rotation direction of the optical disc drive motor according to a read surface or a recorded surface of the optical disc loaded in the optical disc tray.

Optionally, the optical disc is a single-sided optical disc or a double-sided optical disc.

If the rotation direction of the optical disc drive motor is positive when the ordinary optical disc drive reads or burns the optical disc, when the first optical pickup unit reads or burns the lower bottom surface of the optical disc, the optical disc drive motor rotates in the forward direction; When the optical pickup unit reads or writes the upper top surface of the optical disc, the optical disc drive motor rotates in the reverse direction.

Specifically, when the first optical pickup unit reads or burns the lower bottom surface of the optical disc, the rotation direction of the optical disc drive motor is the same as the rotation direction of the optical disc drive motor when the ordinary optical disc drive reads or burns the optical disc, The second optical pickup unit does not work; when the second optical pickup unit reads or burns the upper top surface of the optical disc, the rotation direction of the optical disc drive motor and the rotation direction of the optical disc drive motor when the optical disc drive reads or writes the optical disc Instead, the first optical pickup unit does not operate. If the optical disc is a single-sided optical disc, the first pick-up unit operates and the second pick-up unit does not operate.

Preferably, the number of the first optical pickup unit and the second optical pickup unit is one or more, and the number of the first optical pickup units is the same as the number of the second optical pickup units.

Preferably, the method further includes a first data interface for outputting data recorded on a lower surface of the optical disc and inputting data to be recorded on a bottom surface of the optical disc; the second data interface is used for Outputting data recorded on the top surface of the optical disc and inputting data to be recorded on the top surface of the optical disc; each first optical pickup unit corresponds to a first data interface, and each second optical pickup unit corresponds to a second data interface.

Preferably, the method further includes an interface switching device, where the interface switching device is configured to implement switching between the first data interface and the second data interface, the first data interface and the second data The interface is connected to the third data interface by using the interface switching device, where the first data interface, the second data interface, and the third data interface are both SATA interfaces, and the third data interface is used for performing with the external device. data communication.

Alternatively, the first data interface and the second data interface are SATA interfaces, and the first data interface and the second data interface are both used for data communication with an external device.

Alternatively, the first optical pickup unit is configured to convert information recorded on a lower surface of the double-sided optical disc into an analog signal, and the second optical pickup unit is configured to convert information recorded on a top surface of the double-sided optical disc into The analog signal further includes a multiplexer switch respectively connected to the controller, the first optical pickup unit and the second optical pickup unit for implementing the controller to the first optical pickup Selection of an analog signal output by the unit and the second optical pickup unit.

Also included is a total analog to digital conversion unit coupled to the controller for converting an analog signal output by the first optical pickup unit and/or the second optical pickup unit into a digital signal.

Alternatively, the first optical pickup unit includes a first information collecting unit and a first analog-to-digital conversion unit, and the first information collecting unit is configured to convert information recorded on a lower surface of the double-sided optical disk into an analog signal, The first analog to digital conversion unit is configured to convert the analog signal collected by the first information collection unit into a digital signal.

Preferably, the second optical pickup unit includes a second information acquisition unit and a second analog-to-digital conversion unit, and the second information collection unit is configured to convert information recorded on the top surface of the double-sided optical disk into an analog signal, The second analog to digital conversion unit is configured to convert the analog signal collected by the second information collection unit into a digital signal.

Applying the invention has the following beneficial effects:

1. The optical disc drive capable of reading and writing a double-sided optical disc, respectively providing a first optical pickup unit and a second optical pickup unit, and controlling the rotation direction of the optical disc drive motor to cooperate with the first optical pickup unit and the second optical pickup unit to read By taking the data, the two data planes of the double-sided disc can be respectively read and written after the disc is loaded once, so that the flipper can be directly omitted, thereby completely solving the shortcomings brought by the flipper in the disc library. Moreover, the double-sided optical disc drive of the present invention can be used as a separate optical disc drive. In this application case, the obvious advantage is that as long as the optical disc is placed once, it is possible to reduce the dirt of the optical disc data by a large amount without having to manually flip the disc back and forth. Loss, save space and improve reading efficiency.

2. Since different optical discs are used to drive the rotating direction of the motor to match the reading and writing of the upper and lower optical discs, the front and back sides of the optical disc recorded by the double-sided optical disc drive of the present invention can be read by an ordinary optical disc drive. When the double-sided optical disc recorded by the optical disc drive of the present invention is read, the data can be successfully read without marking the front and back sides of the optical disc, so that it has good compatibility and versatility with the ordinary optical disc drive. Moreover, the optical drive of the invention can read and write single-sided optical discs, and can also read and write double-sided optical discs, and has wide application range.

3. The double-sided optical disc drive of the present invention can read both single-sided optical discs and double-sided optical discs, and therefore has good compatibility. Since the two optical pickup units work independently and are not related, the stability of the system is also improved, and the assembly precision requirements of the whole machine are lowered, thereby reducing the cost.

DRAWINGS

In order to more clearly illustrate the technical solutions and advantages of the embodiments of the present invention or the prior art, the drawings used in the embodiments or the description of the prior art will be briefly described below, and obviously, the attached in the following description The drawings are only some of the embodiments of the present invention, and other drawings may be obtained from those skilled in the art without departing from the drawings.

1 is a schematic structural view of a double-sided optical disc drive according to

Embodiments

1, 2, 3, and 4 of the present invention;

2 is a schematic structural diagram of reading data of a second optical pickup unit of a double-sided optical disc drive according to

Embodiments

1, 2, 3, and 4 of the present invention;

3 is a structural block diagram of an interface portion of a double-sided optical disc drive according to Embodiment 1 of the present invention;

4 is a structural block diagram of an interface portion of a double-sided optical disc drive according to Embodiment 2 of the present invention.

In the figure: 1-second optical pickup unit, 2-disc drive motor, 3-support frame, 4-upper support frame, 5-disc tray.

detailed description

The technical solutions in the embodiments of the present invention are clearly and completely described in the following with reference to the accompanying drawings in the embodiments of the present invention. It is obvious that the described embodiments are only a part of the embodiments of the present invention, but not all embodiments. All other embodiments obtained by a person of ordinary skill in the art based on the embodiments of the present invention without creative efforts are within the scope of the present invention.

Embodiment 1:

Referring to FIG. 1 , FIG. 2 and FIG. 3 , a first embodiment of the present invention provides a double-sided optical disc drive for reading a double-sided optical disc, comprising a support frame 3 , a first optical pickup unit and a second optical pickup unit 1 . , optical disc drive motor 2 and controller, wherein

The support frame 3 includes a lower support frame, an upper support frame 4 and a disc tray, and the disc tray is disposed between the lower support frame and the upper support frame 4 for supporting the optical disc and capable of loading the The lower bottom surface of the optical disc can be read or burned by the first optical pickup unit, and the upper top surface of the loaded optical disc can be read or recorded by the second optical pickup unit 1; the first optical pickup a unit and an optical disc drive motor 2 are disposed on the lower support frame, and the second optical pickup unit 1 is disposed on the upper support frame 4;

The first optical pickup unit is configured to read or write a lower bottom surface of an optical disc loaded into the optical disc tray, and the second optical pickup unit 1 is configured to apply an upper top surface of the optical disc loaded into the optical disc tray Enter Line reading or burning;

The optical disc drive motor 2 is configured to drive the optical disc loaded into the optical disc tray to rotate forward or reverse, so that the first optical pickup unit reads or burns the lower bottom surface of the optical disc, and implements the second The optical pickup unit 1 reads or burns the upper top surface of the optical disc;

The controller is configured to control a rotational direction of the optical disc drive motor 2 in accordance with a read surface or a recorded surface of the optical disc loaded in the optical disc tray.

If the rotation direction of the optical disc drive motor is positive when the ordinary optical disc drive reads or burns the optical disc, when the first optical pickup unit reads or burns the lower bottom surface of the optical disc, the optical disc drive motor rotates in the forward direction; When the optical pickup unit 1 reads or writes the upper top surface of the optical disc, the optical disc drive motor rotates in the reverse direction.

Specifically, when the first optical pickup unit reads or burns the lower bottom surface of the optical disc, the second optical pickup unit 1 does not operate; the second optical pickup unit 1 reads the upper top surface of the optical disc. Or when burning, the first optical pickup unit does not work.

Preferably, the number of the first optical pickup unit and the second optical pickup unit 1 is one or more, and the number of the first optical pickup units is the same as the number of the second optical pickup units 1. Preferably, the plurality of first optical pickup units and the second optical pickup unit 1 are each in an array type, and the first optical pickup unit and the second optical pickup unit 1 are vertically symmetrically disposed.

Preferably, the method further includes a first data interface for outputting data recorded on a lower surface of the optical disc and inputting data to be recorded on a bottom surface of the optical disc; the second data interface is used for The data recorded on the top surface of the optical disc is output and the data to be recorded on the top surface of the optical disc is input; each of the first optical pickup units corresponds to a first data interface, and each of the second optical pickup units 1 corresponds to a second data interface.

Preferably, the method further includes an interface switching device, where the interface switching device is configured to implement switching between the first data interface and the second data interface, the first data interface and the second data The interface is connected to the third data interface by using the interface switching device, where the first data interface, the second data interface, and the third data interface are both SATA interfaces, and the third data interface is used for performing with the external device. data communication. The external device is a device with a SATA interface such as a server or a host.

If the first data interface and the second data interface are multiple, the interface switching device is configured to implement switching between the plurality of the first data interface and the plurality of the second data interfaces, and the plurality of the first data interfaces with A plurality of the second data interfaces are connected to the third data interface by the interface switching device.

When the first optical pickup unit is in operation, the first data interface is connected to the third data interface through the interface switching device; when the second optical pickup unit 1 is in operation, the second data interface and the third data interface are implemented by the interface switching device Connectivity.

Embodiment 2:

Referring to FIG. 1 , FIG. 2 and FIG. 4 , a second embodiment of the present invention provides a double-sided optical disc drive for reading a double-sided optical disc, comprising a support frame 3 , a first optical pickup unit and a second optical pickup unit 1 . , optical disc drive motor 2 and controller, wherein

The first optical pickup unit is configured to read or write a lower bottom surface of an optical disc loaded into the optical disc tray, and the second optical pickup unit 1 is configured to apply an upper top surface of the optical disc loaded into the optical disc tray Read or burn;

If the rotation direction of the optical disc drive motor is positive when the ordinary optical disc drive reads or writes the optical disc, when the first optical pickup unit reads or writes the lower bottom surface of the optical disc, the optical disc drive motor rotates in the forward direction; When the second optical pickup unit 1 reads or writes the upper top surface of the optical disk, the optical disk drive motor rotates in the reverse direction.

Preferably, the number of the first optical pickup unit and the second optical pickup unit 1 is one or more, and the number of the first optical pickup units is the same as the number of the second optical pickup units 1.

Preferably, the method further includes a first data interface and a second data interface, where the first data interface is used for inputting Data written on the bottom surface of the disc and input data to be recorded on the bottom surface of the disc; the second data interface is used to output data recorded on the top surface of the disc and input data to be recorded on the top surface of the disc; The first optical pickup unit corresponds to a first data interface, and each of the second optical pickup units 1 corresponds to a second data interface.

Alternatively, the first data interface and the second data interface are SATA interfaces, and the first data interface and the second data interface are used for data communication with an external device.

Embodiment 3:

Referring to FIG. 1 and FIG. 2, a third embodiment of the present invention provides a double-sided optical disc drive for reading a double-sided optical disc, comprising a support frame 3, a first optical pickup unit, a second optical pickup unit 1, and an optical disc drive. Motor 2 and controller, where

If the rotation direction of the optical disc drive motor is positive when the ordinary optical disc drive reads or writes the optical disc, when the first optical pickup unit reads or burns the lower bottom surface of the optical disc, the optical disc drive motor rotates forward. When the second optical pickup unit 1 reads or burns the upper top surface of the optical disc, the optical disc drive motor rotates in the reverse direction.

The controller controls reading and writing of the first optical pickup unit and the second optical pickup unit 1, respectively, and performs data transmission with the first optical pickup unit and the second optical pickup unit 1, respectively.

Specifically, the first optical pickup unit is configured to convert information recorded on a lower surface of the double-sided optical disc into an analog signal, and the second optical pickup unit 1 is configured to convert information recorded on a top surface of the double-sided optical disc into an analog signal. . A multi-way selection switch is further included, the multi-way selection switch being respectively connected to the controller, the first optical pickup unit and the second optical pickup unit 1 for implementing the controller to the first optical pickup unit and Selection of an analog signal output by the second optical pickup unit 1.

Also included is a total analog to digital conversion unit coupled to the controller for converting an analog signal output by the first optical pickup unit and/or the second optical pickup unit 1 into a digital signal.

When the first optical pickup unit reads the data, the controller controls the analog signal acquired by the first optical pickup unit to communicate with the controller through the multi-way selection switch, and sends the analog signal to the total analog-to-digital conversion unit for conversion; the second optical When the pickup unit 1 reads data, the controller controls the analog signal acquired by the second optical pickup unit 1 to communicate with the controller through the multi-way selection switch, and sends the analog signal to the total analog-to-digital conversion unit for conversion. The controller outputs the processed data to the external server through the SATA interface.

Embodiment 4:

Referring to FIG. 1 and FIG. 2, a fourth embodiment of the present invention provides a double-sided optical disc drive, including a support frame 3, a first optical pickup unit, a second optical pickup unit 1, an optical disc drive motor 2, and a controller.

The first optical pickup unit includes a first information collecting unit and a first analog-to-digital conversion unit, and the first information collecting unit is configured to convert information recorded on a lower surface of the double-sided optical disc into an analog signal, the first modulus The conversion unit is configured to convert the analog signal collected by the first information collection unit into a digital signal.

The second optical pickup unit 1 includes a second information collection unit and a second analog-to-digital conversion unit, and the second information collection unit is configured to convert information recorded on the top surface of the double-sided optical disk into an analog signal, the second The analog to digital conversion unit is configured to convert the analog signal collected by the second information collection unit into a digital signal.

Both the first analog to digital conversion unit and the second analog to digital conversion unit are in direct communication with the controller.

Applying the invention has the following beneficial effects:

2, because the different disc drive motor rotation direction to match the read and write of the upper and lower optical drive, Therefore, both the front and back sides of the optical disc recorded by the double-sided optical disc drive of the present invention can be read by an ordinary optical disc drive. When the double-sided optical disc recorded by the optical disc drive of the present invention is read, the data can be successfully read without marking the front and back sides of the optical disc, so that the optical disc drive has good compatibility with the ordinary optical disc drive.

The above is a preferred embodiment of the present invention, and it should be noted that those skilled in the art can also make several improvements and retouchings without departing from the principles of the present invention. It is the scope of protection of the present invention.

Claims

A double-sided optical disc drive, comprising: a support frame (3), a first optical pickup unit, a second optical pickup unit (1), an optical disk drive motor (2), and a controller, wherein

The support frame (3) includes a lower support frame, an upper support frame (4) and a disc tray, and the disc tray is disposed between the lower support frame and the upper support frame (4) for supporting the optical disc and capable of supporting the optical disc Enabling the lower bottom surface of the loaded optical disc to be read or burned by the first optical pickup unit, and enabling the upper top surface of the loaded optical disc to be read by the second optical pickup unit (1) or Recording; the first optical pickup unit and the optical disc drive motor (2) are disposed on the lower support frame, and the second optical pickup unit (1) is disposed on the upper support frame (4);

The first optical pickup unit is configured to read or write a lower bottom surface of an optical disc loaded into the optical disc tray, and the second optical pickup unit (1) is used to mount an optical disc loaded on the optical disc tray The top surface is read or burned;

The optical disc drive motor (2) is configured to drive a disc that is loaded into the disc tray to rotate forward or reverse;

The controller is configured to control a rotational direction of the optical disc drive motor (2) according to a read surface or a recorded surface of the optical disc loaded in the optical disc tray.
The double-sided optical disc drive according to claim 1, wherein said second optical pickup unit (1) does not operate when said first optical pickup unit reads or writes a lower bottom surface of said optical disc; When the second optical pickup unit (1) reads or burns the upper top surface of the optical disc, the first optical pickup unit does not operate.
The double-sided optical disc drive according to claim 1 or 2, wherein the number of the first optical pickup unit and the second optical pickup unit (2) is one or more, and the first optical pickup The number of units is the same as the number of the second optical pickup units (2).
The double-sided optical disc drive according to claim 3, further comprising a first data interface and a second data interface, wherein the first data interface is used for outputting the bottom surface of the optical disc The data and input need to be recorded on the bottom surface of the disc; the second data interface is used to output the data recorded on the top surface of the disc and input the data to be recorded on the top surface of the disc; each first optical pickup unit corresponds A first data interface, each second optical pickup unit corresponding to a second data interface.
The double-sided optical disc drive according to claim 4, further comprising an interface switching device and a third data interface, wherein the interface switching device is configured to implement switching between the first data interface and the second data interface The first data interface and the second data interface are connected to the third data interface by using the interface switching device, and the first data interface, the second data interface, and the third data interface are both SATA interfaces. And the third data interface is used for data communication with an external device.
The double-sided optical disc drive according to claim 4, wherein the first data interface and the second data interface are SATA interfaces, and the first data interface and the second data interface are both for performing with an external device. data communication.
The double-sided optical disc drive according to claim 3, wherein said first optical pickup unit is configured to convert information recorded on a lower surface of the double-sided optical disc into an analog signal, and said second optical pickup unit (1) Converting information recorded on the top surface of the double-sided disc into an analog signal; further comprising a multi-way selection switch, the multi-way selection switch and the controller, the first optical pickup unit and the second optical pickup unit (1) Connected for implementing selection of an analog signal output by the controller to the first optical pickup unit and the second optical pickup unit (1).
A double-sided optical disc drive according to claim 7, further comprising a total analog-to-digital conversion unit coupled to the controller for the first optical pickup unit and/or the The analog signal output by the two optical pickup unit (1) is converted into a digital signal.
The double-sided optical disc drive according to claim 3, wherein said first optical pickup unit comprises a first information collecting unit and a first analog to digital converting unit, said first information The collecting unit is configured to convert information recorded on the lower surface of the double-sided optical disc into an analog signal, and the first analog-to-digital conversion unit is configured to convert the analog signal collected by the first information collecting unit into a digital signal.
A double-sided optical disc drive according to claim 9, wherein said second optical pickup unit (1) comprises a second information acquisition unit and a second analog-to-digital conversion unit, said second information acquisition unit for The information recorded on the top surface of the double-sided disc is converted into an analog signal, and the second analog-to-digital conversion unit is configured to convert the analog signal collected by the second information collecting unit into a digital signal.