Date Visited: October 9, 1991

Report Author: W. Doane

ATTENDEES

JTEC:

Doane
Thompson
Uyehara

HOST:

Toshiaki Narusawa

Akihiro Mochizuki

Shigeo Kasahara

Katsusada Motoyoshi

Scientists from flat-panel display (STN & AM) of Fujitsu were not present. Mr. Mochizuki explained that Fujitsu's STN program was very much behind others in Japan. The presentation was conducted by Mr. Mochizuki (a doctoral student of Kobayashi).

PRESENTATION OF CH/N PHASE-CHANGE HD PROJECTOR

• Mr. Mochizuki demonstrated a 5 million pixel black and white overhead projector. He explained that they were working on a 7 million pixel one and have sold some 800 x 800 ones used to sell automobiles (work well).
• They have front and rear projection types.
• Advantages of Ch/N projection:
  
  1. Has memory and only needs a passive matrix
  2. High resolution (showed a road map of a section of U.S., excellent quality)
  3. Bright display; does not require polarizers
  4. . Long lifetime (70% transmission), no absorption
  5. Quality does not degrade--unlike STN, which degrades in center of picture in overhead projection applications
  6. Writing speed - 5 seconds to write 2240 lines each with 2240 pixels (each line 2 msec), speed proportional to number of lines
• TFT AM is needed for TV rates when using Ch/N phase change display.
• Current display is good for publishing systems--editor wants full page with high resolution--also good for education.
• This is cost effective: cheaper than STN.
• The display can be manufactured on STN line using fewer steps.
• They plan to market and sell a whole overhead projection system in competition with the STN projection system.
• Memory is optimized (M, see Figure Fujitsu.1) by adjusting K(subscript 33) and K(subscript 22) and reducing cell thickness d, now d = 5- 6 microns (same as STN) hysteresis (M) depends on p/d where p = pitch approx. 1.0 = microns.
• Important feature on cost is the use of conventional drivers: Ch/N phase change device does this.
• Key to their success is temperature-independent p obtained by use of following compound (see Figure Fujitsu.2).
• Characteristics of their Ch/N demo:
  
  • 2240 x 2240
  • 85 x 85 (micron)² pixel size
  • 224 x 224 mm(suberscript 2) size overall
  • Projected on to a screen approx. 30 ft²
  • Contrast ratio 4 as compared to 5 or 6 for a normal overhead viewgraph
  • Screen Lum 800 Cd/m²
    Trans 60%; loss is primarily due to aperture ratio of pixel
  • Color chart - X : Y (.419 x .380)
  • Drive - 12 V, 4.9-sec screen rate
• Color is obtained by choice of pitch (p). Have made one with stacked R & G to give four colors: R, G, black (both on), white (both off). This was done in 1989.
  • Using R, G, yellow: 9 colors possible
  • Using color filter get 15
• They demonstrated a black-and-white photo (to obtain gray levels)--it looked very nice.
• Use homeotropic boundary layer
• Costs--cheaper than STN--Manufacture at subsidiary
• Direct-view displays using Ch/N phase-change techniques do not have good contrast at plus/minus 20 degree angles of view.

Figure Fujitsu.1.

Figure Fujitsu.2

COMMENTS ON FLC

1. 30 micro sec response is needed for 1000 lines for video rates.
2. Now they obtain 120 msec for 28 V drive and 70 micro sec higher drive voltage.
3. There is a problem using TFT AM because the aperture is smaller; too small for bright projection.
4. Fujitsu can obtain stable bookshelf surface structure, which is more stable against mechanical shock (tapping display on table does not destroy it) but bending or stress on substrate destroys surface. He believes Canon uses an air support suspension system to prevent shock damage.
5. Fujitsu has a material which has wide S(subscript A) temperature range and a temperature- independent inner layer spacing to stabilize surface alignment and create the bookshelf structure.
6. The sequence is I - S(subscript A) - S(subscript C) monotropic nematic.
7. Mochizuki claims that the key to surface stabilization is a S(subscript C) material with a large range S(subscript A) and one in which the layer spacing does not vary much with temperature.
8. Their work was reported at Boulder, CO, meeting in June, 1991. The tilt angle is temperature-dependent and maximizes at approximately 20 degrees.
9. Constant layer spacing (temp-independence) causes bookshelf structure.
10. Their S(subscript C) material is a naphthaline, which they add to a Merck mixture.

Fujitsu FLC Prototypes

• 196 x 120
• CR is 40:1
• plus/minus 70 degree view angle
• d = cell spacing = 2.1 to 0.1 microns
• 20-V drive yields 120-micro sec response
• 30-V drive yields 80-micro ec response

They showed us a photo (B & W) in memory state - nice.

They showed us a reflection display - nice. Cell has 80% transmission without polarizer/analyzer

GENERAL QUESTIONS BY THE TEAM

Q:

• What are the improvements of Ch/N projection over STN?

A:

• STN projection degrades in center - probably due to polarizer bleaching. STN projection can have a nonuniformity problem, particularly after use.

Q:

• What about VAN?

A:

• Nice but needs a negative which tends to be too small thus requiring higher drive voltage (limiting). Must reduce drive voltage to be able to use low cost commercial drive circuits.

Q:

• What about PDLC?

A:

• Good for projection and for large-area signs (public announcement) - need poly Si or a-Si AM for high resolution; poly-Si is better because cycle time can be reduced with improved stability.

Q:

• What is your opinion of the new anti-ferroelectric material reported from Europe?

A:

• Surface stability is better because of soft layers but the contrast ratio is not so good. Electro-optic properties are the same, about like Ch/N in switching between two states. Long pretransition region causes local nonuniformity, which affects driving; could use anti-FLC with TFT AM.

FINAL COMMENT BY MOCHIZUKI

Our host commented politely that the antidumping laws could hamper cooperativeness between U.S. and Japanese display developers.

REFERENCES

1. Fujitsu brochure on research & development laboratories.
2. Fujitsu Limited Annual Report, March 1991.
3. Brochure: "Launchpad of Tomorrow's Microtechnologies," Fujitsu's Atsugi Laboratories.
4. "Zigzag Defect Free Alignment and Good Bistability of Surface Stabilized Scsuperscript *) Cells," Ferroelectrics, 113, 353-359 (1991), A. Mochizuki, M. Hirose, and M. Nakatsuka.
5. "Elimination of Crosstalk in Highly Multiplexed STN-LCDs by Using Conducting Orientation Films," Proceedings of the SID, 31, 327-332 (1990), A. Mochizuki, T. Yoshihara, Y. Yoneda, K. Motoyoshi, and S. Kobayashi.
6. "Electro-Optical Switching of Bookshelf Layer Structure Sc(superscript*) Cells Aligned with a Rubber Polymer Film," Proceedings of the SID, 31, 123-128 (1990), A. Mochizuki, T. Yoshihara, M. Iwasaki, M. Nakatsuka, Y. Takanishi, Y. Ouchi, H. Takezoe, and A. Fukuda.
7. "A 1120 x 768 Pixel Four-Color Double-Layer Liquid-Crystal Projection Display," Proceedings of the SID, 31, 155-161 (1990), A. Mochizuki, T. Yoshihara, M. Iwasaki, Y. Yamagishi, Y. Koike, M. Haraguchi, and Y. Kaneko.
8. "Electro-Optical Switching of Bookshelf Layer Structure Ferroelectric Liquid- Crystal," Fujitsu Scientific and Technical Journal, 27, 233-242 (1991), A. Mochizuki, M. Nakatsuka, and Y. Takanishi.
9. "A Ferroelectric Layer in a Cell Containing a Polar Molecular Mixture in Nematic and Isotropic Phases," Japanese Journal of Applied Physics, 29, L1898-L1900 (1990), A. Mochizuki, K. Motoyoshi, and S. Kobayashi.
10. "Second-Harmonic Generation from an Interfacial Layer between Orientational Films and Liquid Crystal Layers of Nematic Liquid Crystal Cell," Japanese Journal of Applied Physics, 30, L504-L506 (1991), A. Mochizuki, W. Sotoyama, S. Tatsuura, T. Ishitsuka, K. Motoyoshi, and S. Kobayashi.