Site: Matsushita Electric Industrial Co., Ltd.
3-1-1 Yagumo-Nakamachi, Moriguchi
Osaka, 570, Japan
Date Visited: December 15, 1994
Report Author: G. Day
Matsushita Electric was founded in 1918 and has grown into a company with $64 billion in sales and over 250,000 employees. It has a broad range of products, including communications and industrial (25%), video (20%), home appliances (13%), electronic components (12%), entertainment (9%), audio (8%), and kitchen-related products and batteries (5%). It is best known through its brand names: National, Panasonic, Technics, and Quasar. Matsushita spends $3.7 billion (5.8% of sales) on R&D and has a capital investment of $2.6 billion (4% of sales). The Matsushita Electric Group comprises 318 companies, of which 150 are located overseas in 38 countries. Unfavorable economic conditions have substantially reduced Matsushita's profitability in recent years. Per share income in FY94 was about 12 yen, compared to 18 yen in FY93 and 111 yen in FY91.
Discussions with Matsushita focused on two technologies: semiconductor lasers and optical data storage.
Matsushita's work on lasers focuses on four main applications areas: optical disks (88%), printers (5%), fiber communications (4%), and bar-code scanners and pointers (3%).
Infrared lasers at a wavelength of 790 nm are the major category in mass production. They are produced in GaAlAs/GaAs by MOVPE. The power range is 3 to 5 mW for CDs and printers, and 35 mW for optical disks. A particular thrust of this program has been the development of low-current designs: this has required development of nonabsorbing blocking regions. These laser diodes are packaged in plastic flat-pack assemblies containing a laser, a 45-degree mirror, a driver circuit, and a holographic focusing element. Micrometer stability is required, so a special, high-stability plastic is used for the holographic element.
Red lasers, ranging in wavelength from 635 to 680 nm, are also mass-produced. They are strained MQW types produced in AlGaInP/GaInP by MOVPE. The power range is 3 to 5 mW for pointing and bar-code readers, 35 mW for optical disks, and up to 500 mW for some medical applications. Linear DFB lasers, MQW in InGaAsP/InP, also grown by MOVPE, are available in small production quantities for CATV and other subcarrier applications, including FTTH. Pump lasers (80 mW at 1480 nm, GaInAs/GaAs, MOVPE) are under development. Blue-green lasers are a topic of active research. The company is focusing on ZnMgSSe/GaAs strained MQW, grown by MBE. The target wavelength is less than 500 nm.
In addition to semiconductor lasers, the company produces optical amplifiers in small production quantities for FTTH applications, and there is research on bidirectional amplifiers. Amplifiers are pumped at 1480 nm and have low distortion, noise figures <7 dB, 11 dB gains, and +17 dBm output power.
Matsushita is studying OEICs for optical interconnection, and there is work on fiber lasers, specifically up-conversion designs for optical storage and medical applications. An important related area is the development of holographic read/write heads for optical data storage.
Matsushita has made very large strides in the development of phase change rewritable technology for optical data storage. This technology involves the conversion of spots on a thin film between a crystalline state and an amorphous state with a pulsed laser. Melting and cooling of the material leads to the low reflectivity (<5% R) amorphous state. Annealing restores a high reflectivity (25% R) crystalline state. This phase change occurs in about 100 ns. The materials are mixtures of GeTe-Sb2Te3-Sb, sandwiched between ZnS-SiO2 layers with an Al film backing, resulting in a four-layer structure. The films are sputtered on a polycarbonate substrate and overcoated with resin. At present the company uses 780 nm lasers, but the films (and structure) are not strongly sensitive to wavelength, and wavelengths between 770 and 790 nm work well.
Early work (1981) on PCR at Matsushita resulted in the demonstration of a 200 mm diameter WORM disk with a capacity of 15,000 still pictures, followed by a 200 MB 130 mm WORM data disk in 1987 and a 300 mm WORM disk with 60 minutes of video in 1989. Read/write (R/W) products were first introduced in 1991 with a 1 GB 130 mm disk, increased in capacity in 1993 to 1.5 GB. A 300 mm R/W disk holding 40 minutes of digital NTSC video was planned to be introduced in 1995, along with a 120 mm system called PD/CD-ROM, capable of handling both PCR media and conventional CD (audio) and CD-ROM disks.
A particular advantage of PCR technology is this compatibility with present CD and CD-ROM technology. Matsushita envisions a single drive on a personal computer that would accept both kinds of media. This is essentially the PD/CD-ROM system that was announced in September of 1994 and was planned for sale beginning in 1995. Video capability will eventually be added to this system, with the incorporation of video compression such as MPEG-2.
Matsushita believes that the major problem to be solved in this technology is reduction in the cost of the media. At present, manufacturing, which includes sputtering of the films, is done in an automated facility that requires 25 seconds per disk. A new facility, under construction in 1994, will reduce manufacturing time to 5 seconds/disk. At the time of the JTEC visit, the cost of a 1.5 GB PCR disk was $150 (SRP). The cost of a 650 MB PCR disk was expected to be $60 (SRP) in the near future.
Matsushita staff members indicated that the media has been criticized for its poor "cycleability" compared to magneto-optic media. They asserted that they were then able to achieve more than 500 thousand cycles with PCR media. MO media achieve more than a million cycles.
[Another company claimed that PCR media require 50% more laser power (60 mW compared to 40 mW for MO), and that this would be a serious limitation. Matsushita does not agree with this analysis and believes the power requirements are about the same.] Access times for PCR and MO are about the same, because the drive is the limit in both cases.
Matsushita representatives noted that since disk capacity quadruples about every 6 years, a 3 GB capacity might be available in 2 to 3 years.
Matsushita claims to have 188 Japanese and 65 overseas patents on PCR technology registered or applied for.
Matsushita Electric. 1994. Annual Report.
_____. Overview of Matsushita (viewgraph copies)
_____. Copies of viewgraphs describing activities on Opto-electronic Devices
_____. Copies of viewgraphs describing PCR technology
_____. Press release on PD optical disk system
_____. Product literature: