[Note: Machine translation from Japanese]
For example, inside the dehumidifying unit, a desiccant for absorbing moisture is provided. This desiccant is responsible for lowering the humidity inside the dry-box, but it cannot continue to absorb the humidity forever. Therefore, when the desiccant exceeds the limit of moisture absorption and the humidity inside the box exceeds the set value, a signal is sent to a heating body called a positive star to become hot. The hygroscopic power of the desiccant is restored, and the shape memory alloy coil made so that the total length changes when heated becomes longer. As the shape memory alloy coil stretches, the length of the bias spring that works with the exhaust / intake shutter changes. The exhaust / intake shutter opens and closes, and the air inside the box is discharged to the outside.
Conceptual diagram of the mechanism of the dehumidifying unit [above]. When the hygroscopicity of the desiccant in the center decreases, the orange-colored positive star (heater) becomes hot. Then, the shape of the red spring (heat extension type shape memory alloy) changes. The valve opens and steam is exhausted to the outside of the dry-box.
After a certain period of time (about 40 minutes), the shape of the shape memory alloy returned to its original shape, the exhaust shutter closed, and moisture absorption started. Although it is a surprisingly simple mechanism, it is characterized by its simplified structure and the use of highly reliable parts. The basic structure of the dehumidifying unit is [utilized by Toyo Living dry-box].
However, since last year, Toyo Living has incorporated a photocatalyst into the dehumidifying unit of the "Auto Clean Dry" series. In general, photocatalysts are known to generate a strong oxidizing action when exposed to light and promote the decomposition of harmful substances and the like. Titanium oxide is a well-known catalyst.
Titanium oxide is also used for auto clean dry, and LEDs are used as the light source. The effect is, "It can kill harmful substances in the air. I think it provides a higher level of security." ... "Leave it in the image sensor of a digital SLR camera. And dust such as gas adheres, but it can be prevented by a photocatalyst".
Since the moisture-proof cabinet is highly airtight, there is basically no air flow except when inhaling or exhausting. Unless air is applied to the catalyst, the effect of the photocatalyst should not appear. However, due to the convection effect of the heat of the Bojisutā [ボジスター], the air inside the dry-box circulates slowly, so there seems to be no problem.
By the way, the moisture-proof unit always operates with a household power supply. The electricity bill you care about is "about 30 to 50 yen a month". It's cheaper than a drink and shouldn't be a big problem in terms of running costs. By the way, the more the humidity changes, the more electricity is required, so the more frequently the camera and lens are taken in and out, the higher the maintenance cost will be.
Durability is also high. The fact that some models have a warranty period of 5 years shows that. During the interview, he showed me a dehumidifying unit that has been used for about 20 years. I was asked to do maintenance because it is broken, but when I checked it, it worked normally. It wasn't the dehumidifying unit that was broken, but the hygrometer. In addition, although the moisture-proof cabinet is always installed in a standby state, it is almost silent and no shaking is felt.