In this work, a novel pulse driving method for advanced in-cell touch (AIT) panels is proposed to meet the automotive electromagnetic interference (EMI) requirements. AIT panels are usually driven by load-free driving (LFD) to overcome the large parasitic capacitances of the in-cell touch sensors. However, strong EMI is emitted from the AIT panels, by the harmonics of the driving pulses used for LFD. Thus, a novel driving pulse for LFD is necessary to resolve the EMI problems. The proposed driving pulse is created from the frequency-spread pulse chain with a duty cycle 0.46. The spread-spectrum effect is enhanced by alternating two types of pulse chains with different frequencies. Consequently, the EMI emissions of the fifth harmonic, which is the main factor associated with EMI reduction, is attenuated by 15 dB. The first and third harmonics are fitted to a frequency band without any CISPR-25 specification. Thus, the automotive EMI requirements can be satisfied. The touch performance remained unchanged. The existing circuit components, which are designed for pulse driving, can be employed without additional modification, unlike in the case of sine-wave driving. The proposed pulse chain can provide optimized pulse driving for AIT panels.
|Number of pages||8|
|Journal||IEEE Sensors Journal|
|Publication status||Published - 2021 Mar 15|
Bibliographical noteFunding Information:
Manuscript received October 4, 2020; revised November 19, 2020 and December 22, 2020; accepted January 5, 2021. Date of publication January 11, 2021; date of current version February 17, 2021. This work was supported in part by the Institute of Information & Communications Technology Planning & Evaluation (IITP) grant funded by the Korea Government (MSIT) under Grant 2020000218 and in part by LG Display Co., Ltd., under the Yonsei Incubation Program. The associate editor coordinating the review of this article and approving it for publication was Prof. Boby George. (Corresponding author: Byung-Wook Min.) Hoonbae Kim is with the Magok Laboratory, LG Display Company, Ltd., Seoul 07336, South Korea.
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All Science Journal Classification (ASJC) codes
- Electrical and Electronic Engineering