Date Visited: October 9, 1991
Report Author: W. Doane
Manager, Organic Materials Lab.
Researcher, Organic Materials Lab.
Researcher, Organic Materials Lab.
Researcher, Organic Materials Lab.
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:
- Has memory and only needs a passive matrix
- High resolution (showed a road map of a section of U.S., excellent
- Bright display; does not require polarizers
- . Long lifetime (70% transmission), no absorption
- Quality does not degrade--unlike STN, which degrades in center of picture
in overhead projection applications
- 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:
- 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.
COMMENTS ON FLC
- 30 micro sec response is needed for 1000 lines for video rates.
- Now they obtain 120 msec for 28 V drive and 70 micro sec higher drive
- There is a problem using TFT AM because the aperture is smaller; too small
for bright projection.
- 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.
- 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.
- The sequence is I - S(subscript A) - S(subscript C) monotropic
- 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.
- Their work was reported at Boulder, CO, meeting in June, 1991. The tilt
angle is temperature-dependent and maximizes at approximately 20 degrees.
- Constant layer spacing (temp-independence) causes bookshelf structure.
- Their S(subscript C) material is a naphthaline, which they add to a Merck
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
GENERAL QUESTIONS BY THE TEAM
- What are the improvements of Ch/N projection over STN?
- STN projection degrades in center - probably due to polarizer bleaching.
STN projection can have a nonuniformity problem, particularly after use.
- 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
- 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.
- What is your opinion of the new anti-ferroelectric material reported from
- 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.
- Fujitsu brochure on research & development laboratories.
- Fujitsu Limited Annual Report, March 1991.
- Brochure: "Launchpad of Tomorrow's Microtechnologies," Fujitsu's Atsugi
- "Zigzag Defect Free Alignment and Good Bistability of Surface Stabilized
Scsuperscript *) Cells," Ferroelectrics, 113, 353-359 (1991), A.
Mochizuki, M. Hirose, and M. Nakatsuka.
- "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.
- "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.
- "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.
- "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.
- "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.
- "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.
Published: June 1992; WTEC Hyper-