J003 BTZK-I Concave handwriting electrostatic developing instrument

Purpose

A. Indented writing restoration

When writing on multiple sheets of paper, in addition to the ink marks on the first page, there will be impression on sheets of paper below the one that contains the original writing. By coloring these indented marks, the writing content on the first sheet of paper can appear on pages below the original writing. ESDA is a special instrument to reveal indented writing.

B. Lift dust footprint

Dust footprint left on the paper can be transferred to a plastic film using the ESDA. Place the transparent plastic film on a black background, illuminate the plastic film with low-angle incident light, then the dust and the black background will form a distinct contrast.

Content

Technical parameter

Structural features

A. The ESDA consists of vacuum pump, perforated plate, high voltage generator, corona wand, charging film reel, toner pad, electrostatic powders chamber and humidifier.

B. The charging film reel is inside the unit, and the charging film is output from the discharge port.

C. To produce electrostatic charge in the air above the surface of the paper, wave the corona wand over the paper.

Working principle

Under the negative pressure generated by the vacuum pump, both the charging film and the paper adhere to the perforated plate.The high-voltage generator outputs high-voltage static to the corona wand, and an electrostatic field is generated around the exposed electrodes of the corona wand. While the corona wand moves slowly over the perforated plate, the electrostatic field generated by the corona wand drives the charge in the paper to move and accumulate at areas where there are indentations in the paper surface, thus the latent indentations can be developed. Spray the electrostatic powders on the surface of the charging film, and the charge in the indentations in the paper surface will attract the powder particles, thus revealing indented writing in black.

Method of use

A. Place the questioned document on the perforated plate, and cover the questioned document evenly with the plastic charging film.

B. Turn on the power switch to start the vacuum pump, which then sucks air through small holes on the perforated plate. Both the charging film and the document should adhere to the perforated plate tightly.

C. Turn on the high voltage switch, then the corona wand generates an electric field. Hold the corona wand and wave it 1~3cm over the entire surface of the document back and forth for 2~3 times, then turn off the high voltage switch.

D. Place the toner pad on the perforated plate and press the powder spray switch several times until writing with suitable color appears on the plastic electrostatic film.

E. The optimum ambient humidity of ESDA is 50%~75% relative humidity. When the environment humidity exceeds 75%, the testing environment should be dehumidified. When the environment humidity is lower than 50%, the electrical conductivity of the document is poor due to low water content, resulting in a poor revealing effect. In such a case, the document may need to be humidified. Add a small amount of warm water (about 5mm) to the deep tray, place the perforated tray on the deep tray, place the document on the perforated tray, then cover the perforated tray with the shallow tray. Leave it for 10 minutes to complete the humidification.

Place the questioned document on the perforated plate

Cover the questioned document evenly with the plastic charging film