Electrochromic device, lens unit, imaging device, window member, and method of driving electrochromic element

1 . An electrochromic device comprising:

an electrochromic element including a pair of electrodes, an electrochromic layer disposed between the pair of electrodes, and interconnections connected to the pair of electrodes; and

a driving circuit that is connected to the pair of electrodes and supplies voltages to the pair of electrodes via the interconnections,

wherein the electrochromic element is an electrochromic element that forms a gradation of transmittance in a transmittance changing portion where the electrochromic layer is disposed, by resistance of the electrodes,

wherein the transmittance changing portion has a first region for forming a first light transmissive state at a position in the electrodes close to the interconnections in the transmittance changing portion, and a second region for forming a second light transmissive state at a position in the electrodes farther from the interconnections than the first region,

wherein, the driving circuit repeatedly supplies, when controlling the gradation of the transmittance, a first voltage for advancing an electrochemical reaction for decreasing transmittance of the electrochromic layer and a second voltage for advancing an electrochemical reaction for increasing the transmittance of the electrochromic layer, in a frequency in which the electrochemical reaction of the electrochromic layer in the electrodes progresses in the first region and transmittance change of the first region is not visible, and

wherein the frequency at which the driving circuit repeatedly supplies the first voltage and the second voltage is 24 Hz or more.

2 . The electrochromic device according to claim 1 , wherein the second voltage is a voltage having a polarity opposite to a voltage for advancing an electrochemical reaction for decreasing the transmittance of the electrochromic layer.

3 . The electrochromic device according to claim 1 , wherein the first light transmissive state has a lower light transmittance than the second light transmissive state.

4 . The electrochromic device according to claim 1 , wherein, at a time of formation of the gradation of the transmittance, difference in light transmittance between the first light transmissive state and the second light transmissive state is two times or more between a highest value and a lowest value.

5 . The electrochromic device according to claim 1 , wherein the driving circuit controls the gradation of the transmittance by varying a ratio of time for supplying the first voltage and the second voltage.

6 . The electrochromic device according to claim 1 , wherein the frequency is 60 Hz or more.

7 . The electrochromic device according to claim 6 , wherein the frequency is 60 Hz to 300 Hz.

8 . The electrochromic device according to claim 1 , wherein the driving circuit supplies, when controlling the gradation of the transmittance, the first voltage and the second voltage in one cycle of pulse width modulation driving.

9 . The electrochromic device according to claim 1 , wherein the electrochromic element is a complementary electrochromic element in which the electrochromic layer has at least one of an anodic electrochromic compound and a cathodic electrochromic compound.

10 . The electrochromic device according to claim 9 , wherein the electrochromic element is a self-decoloration type electrochromic element.

11 . The electrochromic device according to claim 9 , wherein the anodic electrochromic compound is a dihydrophenazine derivative.

12 . The electrochromic device according to claim 9 , wherein the anodic electrochromic compound is a derivative of a pyridine salt.

13 . A lens unit comprising:

the electrochromic device according to claim 1 ; and

an imaging optical system having a plurality of lenses.

14 . An imaging device comprising:

the electrochromic device according to claim 1 ; and

an imaging element configured to receive a light transmitted through the electrochromic element of the electrochromic device.

15 . A window member comprising:

the electrochromic device according to claim 1 ; and

substrates that sandwich the electrochromic element of the electrochromic device.

16 . A driving method of an electrochromic element including a pair of electrodes, an electrochromic layer disposed between the pair of electrodes, and interconnections connected to the pair of electrodes,

wherein the electrochromic element is an electrochromic element that forms a gradation of transmittance in a transmittance changing portion where the electrochromic layer is disposed, by resistance of the electrodes, and

wherein the transmittance changing portion has a first region for forming a first light transmissive state at a position in the electrodes close to the interconnections in the transmittance changing portion, and a second region for forming a second light transmissive state at a position in the electrodes farther from the interconnections than the first region, the driving method comprising:

repeatedly supplying, when supplying voltages to the pair of electrodes via the interconnections and controlling the gradation of the transmittance, a first voltage for advancing an electrochemical reaction for decreasing transmittance of the electrochromic layer and a second voltage for advancing an electrochemical reaction for increasing the transmittance of the electrochromic layer, in a frequency in which the electrochemical reaction of the electrochromic layer in the electrodes progresses in the first region and transmittance change of the first region is not visible,

wherein the frequency at which the first voltage and the second voltage are repeatedly supplied is 24 Hz or more.