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test bridge rectifier

来源:LM317 Electronics Components编辑:Adpower时间:2021-06-15 13:43:50

With PC-processor supply problems easing, we expect to see sales momentum continue to build as we head into thestrong portion of the Christmas build cycle,” Boucher said.

According to Tahon, New conductive polymer layers such as Pedot-on-PES or on high-Tg polycarbonate, which are applied by a non-vacuum coating technique, can replace ITO and are a necessity to produce electro-optical devices in a continuous way.”

The test liquid-crystal cells illustrate that a number of process steps can be eliminated or made reel-to-reel compatible” — continuously applying Pedot (vs. ITO sputtering and annealing), continuously applying resist (vs. spin coating), very fast Pedot patterning (vs. ITO etching), and directly rubbing of the patterned Pedot layer (as opposed to application and curing of a separate alignment layer).

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Thanks for the memory

Over at the Display Materials and Devices Laboratory of Toshiba's Corporate R&D Center, meanwhile, a team is working on an LCD that has its own built-in memory, eliminating the need to continually refresh the image and therefore saving power. The memory device in question is a thin-film ferroelectric capacitor, and Toshiba has developed a novel low-temperature process for building the devices into LCDs that become capable of high speed and gray scale.

Inorganic ferroelectric materials, such as PZT (Pb(Ti,Zr)03 ) and perovskite film, are promising for displaying contents in the range from paperlike still pictures to multimedia moving images, because both the durability of polarization inversion and the polarization response speed are expected to be sufficiently high,” the Lab's Akiyama will explain.

test bridge rectifier

However, a process temperature problem pops up again: The process temperature of these materials formed by conventional formation methods is too high (> 600 degrees C) to form ferroelectric film on the LC cell glass substrate,” he will report. Therefore, low-temperature formation technology for the ferroelectric film with good characteristics” is needed.

Akiyama and his co-authors first discussed the project, which the company is calling the image memory LCD,” in the technical literature in 1998, and in 1999 the company demonstrated the scheme using discrete ferroelectric capacitors. This year, they will report that memory operation for ultralow-power consumption as well as a high addressing speed suitable for displaying moving images has been demonstrated” for devices using thin-film capacitors.

test bridge rectifier

The particular structure chosen — connecting the PZT capacitor to the pixel electrode — has the advantage of optimization of the ferroelectric capacitance against the liquid-crystal capacitance,” the team will report.

As for the sputtering process, it's called ICP for inductive-coupled, plasma-assisted sputtering. The novel apparatus” used in the process includes, according to Akiyama, a coil antenna placed between the substrate and the target that generates extra plasma in order to ionize the sputtering particles and control their energy. The authors have obtained, for the first time, a PZT film with a perovskite phase on a non-alkali glass substrate, when a certain ICP power was applied. The PZT film has a good hysteresis loop,” he said.

If the device can accept data the host begins a standard USB 1.1-type transfer: an out” token packet followed by a data packet. The device then responds with a handshake packet indicating whether or not the packet was accepted. In a nonerror case this should always be true. The device also can respond with the Nyet handshake packet, which indicates that the data packet was received, but the device temporarily cannot accept any additional data. This tells the host to use the new Ping token at the start of the next transfer attempt, to again determine whether or not the device can accept new data. This protocol almost guarantees that a lengthy data packet will be transmitted only once, when the device can accept it.

USB 2.0 devices, which are expected to be available at the end of 2000, will be compatible with 12-Mbit/s USB 1.1 devices-it is designed to work with both new and old devices. In fact, not only is USB 2.0 backwards compatible with USB 1.1, this compatibility is completely transparent to users.

As most USB 1.1 PCs in use today are equipped with two USB ports (desktop) or one or two USB ports (portable), a hub is often used to connect more than two devices to a single PC. Much like the ac power expansion outlet, the USB hub allows multiple devices to connect to a PC. The popular standalone hub has four to six ports.

Each individual port on the USB host/hub detects and adapts to the speed of the connected device. If the device is high-speed (480 Mbits/s), the host/hub will adjust to that speed. If the device is full-speed (12 Mbits/s) or low-speed (1.5 Mbits/s) the host/hub will slow to those speeds. But if a 12-Mbit/s host is connected to a high-speed device, the device will appear as a full-speed one to the host and the transaction will run at full speed (12 Mbits/s). Naturally, a high-speed host can support both 480 Mbits/s and 12 Mbits/s while a full-speed host will support both types of devices, but will run only at 12 Mbits/s.

A USB 2.0 system performs transfers at the high-speed rate whenever possible to maximize bandwidth utilization. When communicating with a full- or low-speed host through a high-speed hub, the USB 2.0 host splits transactions to isolate the full- or low-speed traffic from other high-speed devices. A split transaction causes a high-speed hub to cache data being transferred between a high-speed host and a full- or low-speed device. This maximizes the amount of time the host can spend communicating with other high-speed devices. In a system with a USB 2.0 host controller, only direct connections between a device and its upstream host/hub port operate at full or low speed.

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