Circuit arrangement for regulating light transmission of an electrochromic glass pane

• US 6,501,457 B1
• Filed: 06/02/2000
• Issued: 12/31/2002
• Est. Priority Date: 06/02/1999
• Status: Expired due to Term

• Current Assignee: Airbus Operations GmbH (Airbus SE)
• Original Assignee: Airbus Deutschland GmbH (Airbus SE)
• Inventors: Huetzen, Ulrich, Bruechmann, Gerd, Wiese, Christian
• Primary Examiner(s): Shalwala, Bipin
• Assistant Examiner(s): LEWIS, DAVID LEE
• Application Number:
  US09/586,285
• Time in Patent Office: 942 Days
• Field of Search: 345/105, 345/212, 359/265, 359/267, 359/268, 359/269, 359/275, 359/601, 359/604
• US Class Current: 345/105
• CPC Class Codes: E06B 2009/2464 featuring transparency control by applying voltage, e.g. LCD, electrochromic panels
• CPC Class Codes: E06B 9/24 Screens or other constructions affording protection against light, especially against sunshine; Similar screens for privacy or appearance; Slat blindsoperating, guiding or securing devices or arrangements for roll-type closures E06B9/56; free-hanging flexible screens A47H23/00
• CPC Class Codes: G02F 1/163 Operation of electrochromic cells, e.g. electrodeposition cells; Circuit arrangements therefor

Abstract

A circuit arrangement can carry out a method for controlling the light transmission of an electrochromic glass that involves generating a control voltage that is applied to the electrochromic glass to bring about a desired transparency or lack of transparency. The method optimizes, i.e. minimizes, the electrical energy that must be applied to the electrochromic glass, with respect to magnitude and duration, while achieving the desired degree of transparency very quickly. The actual voltage on the glass is measured at certain intervals and compared with a reference voltage that corresponds to a desired light transmission. A control voltage of positive or negative polarity is applied to the electrochromic glass for a certain charging or discharging period, depending on the deviation of the actual voltage from the reference value, and the actual voltage on the glass is again measured and compared with the reference voltage. These steps are repeated until the actual voltage on the glass is substantially equal to the reference voltage. The control voltage is then switched off or reduced such that no control current flows in the glass, until a subsequent measurement determines that the actual voltage has fallen below the reference voltage by more than an acceptable threshold difference amount, at which point the control voltage is again switched on.

Claims

1. A circuit arrangement for regulating light transmission of an electrochromic glass, said circuit arrangement comprising:

a microprocessor having a first microprocessor input, a second microprocessor input, and a microprocessor output;

a voltage follower comprising a regulated voltage source;

a voltage reversing device having two voltage reversing outputs;

a first analog-to-digital converter;

a second analog-to-digital converter;

a digital-to-analog converter;

a variable reference voltage device; and

an electrochromic glass having a first terminal and a second terminal;

wherein said variable reference voltage device is connected to said first microprocessor input of said microprocessor via said first analog-to-digital converter;

wherein said microprocessor output of said microprocessor is connected to said voltage follower via said digital-to-analog converter;

wherein said voltage reversing outputs of said voltage reversing device are electrically connected to said first and second terminals of said electrochromic glass;

. and

wherein said second terminal of said electrochromic glass and one of said voltage reversing outputs of said voltage reversing device are connected to said second microprocessor input of said microprocessor via said second analog-to-digital converter.

2. The circuit arrangement according to claim 1, wherein said voltage follower includes an operational amplifier, a MOSFET, and a current limiting resistor.

3. The circuit arrangement according to claim 1, wherein said voltage reversing device includes a relay, a MOSFET, and a diode.

4. The circuit arrangement according to claim 3, wherein said microprocessor further has a discrete output, and said MOSFET is electrically connected to said discrete output.