RU2733688C1 - Device and method for detecting sweat and grease deposits of hands - Google Patents

Abstract

FIELD: forensics.

SUBSTANCE: group of inventions relates to judicial and forensic science, namely to a device and method, which are intended to detect sweat and grease deposits on the analyzed objects. Described is a device for detecting hand sweat and grease deposits, comprising a chamber for analyzed samples with a door and a compartment with equipment, separated by a wall, in which holes are made. In the chamber there is a cyanoacrylate evaporator unit, and the equipment located in the compartment includes a control unit, two fans and connected to control unit of filter-evaporator, which includes water circuit consisting of series-connected reservoir with water, pump and diffuser and filter located between diffuser and reservoir with water. First fan is connected by its inlet opening to the first hole in the wall, and by the outlet hole – to the space between the filter and the water tank, the second fan is interconnected by its inlet opening with the chamber, and outlet – with atmosphere through one check valve, and space between diffuser and filter is communicated with chamber through second hole in wall, and with atmosphere – through another check valve. Also disclosed is a method of detecting the sweat and grease deposits of hands using said device.

EFFECT: higher efficiency, reliability and possibility of conducting more tests when detecting the sweat and grease deposits of hands.

10 cl, 3 dwg

Description

The group of inventions relates to the forensic and forensic field, namely to a device and method that are designed to detect sweat traces on the objects under investigation.

A method for automatic control of the fumigation process and a device for its implementation are known. The method includes placing a sample and cyanoacrylate in an enclosed space of a fumigation plant, using heat to evaporate cyanoacrylate and depositing it on the sample to display fingerprints, using an evacuation unit to remove cyanoacrylate exhaust vapors into a filtration unit, and injecting waste gas into a channel filled with liquid (TW 200740512 , class B01D 47/02; published 01.11.2007).

The disadvantage of the known solution consists in the use of an evacuation unit to remove the exhaust vapors of cyanoacrylate, which significantly complicates and increases the cost of the design, as well as in the absence of control and automatic maintenance of humidity in the enclosed space of the fumigation plant, which are necessary for optimal display of fingerprints.

A device and method for detecting fingerprints are also known. The method includes placing a test sample in a chamber, bringing humidity and temperature in it to the required values, in particular, a temperature below ambient temperature using a refrigeration unit, and humidity using a spray / humidifier using a circulating fan, ensuring uniformity of temperature, humidity and vapor content cyanoacrylate throughout the chamber after the cyanoacrylate powder was heated. After that, the spent cyanoacrylate vapors are removed by means of a ventilation system (US 2019/0329285, cl. B05D 1/00; published 10/31/2019).

The disadvantage of the known solution consists in the use of a filtration unit based on a standard filter (for example, a carbon filter), which implies its regular replacement and significantly increases the equipment operating budget. Also, the disadvantage of this solution is the lack of a system for drying the internal space of the installation after the completion of the process of detecting traces in conditions of high humidity.

In addition, the presence of refrigeration equipment in the system reduces the reliability of the product as a whole and significantly increases the cost of the product and its maintenance.

Closest to the claimed device is a device for processing fingerprints, including a sealed chamber containing a support for placing a chemical means for fixing fingerprints, such as cyanoacrylate, and a means of holding the object under test. The device also contains a filtration system connected to the chamber for removing impurities from the air in the chamber and a closed air circulation system (US 2002/0124537, cl. B01D 50/00; published 09/12/2002).

The disadvantage of the known solution is the use of fibrous and carbon filters as a filtering element. These filters require regular replacement and are quite expensive. In case of their untimely replacement, dangerous cyanoacrylate vapors enter the environment. The consequence of this is the need to use two systems for maintaining humidity and filtering the air, which leads to a decrease in the usable volume of the chamber. The specified possibility of using an ultrasonic humidifier as a moisture maintenance system seems to be unacceptable. An ultrasonic humidifier creates moisture by atomizing fine water particles. Cyanoacrylate, in accordance with its physicochemical properties, must be deposited on these particles. This process will lead to a decrease in the concentration of cyanoacrylate in the usable volume of the chamber and, as a consequence, to a decrease in the efficiency of detecting traces.

The invention solves the technical problem of creating a reliable, effective and durable means of detecting fingerprints on objects under investigation.

The technical result, which provides a solution to this problem for the "device" object, consists in ensuring the possibility of using the same elements of the device at different stages of its operation, as well as the minimum number of nodes with moving parts, and for the "method" object - in adding a drying operation the interior of the camera and equipment compartment, as well as the filter and reducing the time for previous operations to detect these prints.

The named technical result is achieved in the invention using the following set of features.

The device for detecting sweat marks of hands contains a chamber for one or more test samples with a door and a compartment with equipment, separated by a wall in which technological holes are made. The chamber contains a cyanoacrylate evaporator unit, and the equipment located in the compartment includes a control unit connected to the filter-evaporator unit and two fans. The filter-evaporator unit includes a water circuit consisting of a series-connected reservoir with water, a pump and a diffuser and a filter located between the diffuser and the water reservoir. The first fan is connected by its inlet to the first hole in the wall, and the outlet to the space between the filter and the water tank. The second fan is communicated by its inlet with the chamber, and the outlet - with the atmosphere through one of the check valves. The space between the diffuser and the filter communicates with the chamber through a second hole in the wall, and with the atmosphere through another check valve.

The second fan can be in communication with the chamber through the cavity of the first fan or through the space between the diffuser and the filter.

The evaporator unit includes a heated stage, equipped with a temperature sensor and connected to the control unit, and a cyanoacrylate bath designed to be installed on this stage.

In the chamber for the samples under study, there is a lighting device connected to the control unit and made in the form of diode lamps (light-emitting diodes) located along the perimeter of the chamber door, which is equipped with an automatic latch with a door position sensor also connected to the control unit.

In the chamber for the investigated samples there is a humidity sensor connected to a control unit, which is connected to the first fan.

The equipment includes, located on the front wall of the device case, a touch screen connected to the control unit. The latter can be made with the possibility of wireless communication with a personal computer (PC) or tablet.

The method for detecting sweat marks of hands using the above-described device consists in moistening the chamber with one or several samples, evaporating cyanoacrylate in the chamber, judging by the appearance on each sample of the presence of sweat marks of hands, then cleaning the chamber from cyanoacrylate vapors and drying the chamber and compartment with equipment including a filter-evaporator unit.

Humidification is carried out by wetting the filter installed in the equipment compartment with water, while simultaneously passing an air flow through it by means of the first fan and supplying humidified air to the sample chamber.

Evaporation is carried out by heating a cyanoacrylate bath installed in the chamber.

Cleaning the chamber from cyanoacrylate vapors is carried out by passing cyanoacrylate through a filter.

Dehumidification of the chamber and the equipment compartment is carried out with the second fan running, both check valves open and with the first fan and pump inoperative by passing humidified and purified air from the chamber and filter-evaporator unit of the equipment compartment through one of the check valves into the atmosphere.

The invention is illustrated by a drawing, where FIG. 1 schematically shows the device (front view in section); in fig. 2 is a block diagram of the device; in fig. 3 - distribution of water and air flows at various stages of the device operation.

Shown in FIG. 1-2 of the drawing, the device 1 consists of a chamber 2 with a transparent door 4, designed to accommodate the samples (objects) under study, and a compartment with equipment 3 containing most of the technical units and parts of the device and equipped with a touch screen 5.

The following elements are located in the chamber 2: the evaporator unit 6, the lighting means 7 and the automatic latch 29 with the door position sensor 30.

The evaporator unit 6 consists of a table 8, on which a tray 9 for liquid cyanoacrylate is located, a heating element 10 intended for heating the table, a temperature sensor 11 of the table, an air humidity sensor 12 and a circulating fan 13 intended for uniform distribution of cyanoacrylate vapors throughout the entire volume of this cameras.

The lighting means 7 is made on LEDs and is located around the perimeter of the chamber door 4, which allows you to create uniform illumination of the objects under study.

An automatic latch 29 with a door position sensor 30 serves to prevent unauthorized opening of the chamber door while cyanoacrylate vapors are in the chamber; emergency mechanical opening of the door is also provided.

All electrical components of the camera are connected to the control unit 14 through a sealed lead-in and are powered from a low voltage, which increases the safety of the system, especially taking into account the high humidity required to perform the work of the system.

The equipment compartment 3 contains the following elements: filter-evaporator unit 15, control unit 14, power supply unit 16, water pump 17, flow-through water heater 18.

The filter-evaporator unit 15 is intended for air humidification at the stage of humidification and evaporation, as well as for purification of cyanoaclylate vapors at the stage of purification and dehumidification. It is made as a single plastic structure and consists of the following elements:

- in the upper part of the filter 19 there is a water diffuser 20 and a second technological opening 21 through which humidified air is supplied to chamber 2;

- the filter 19 is made of foam rubber with an open structure, which allows you to create a maximum moisturized surface, which increases the efficiency of moisture evaporation, at the same time, this material has a low resistance to air flow;

- under the filter 19 there is a reservoir with water 22, in which there is a level sensor 23 connected to the control unit 14. The sensor 23 is designed to warn the user about a low water level and blocking the water heater to prevent its failure. In the lower part of the reservoir 22, on opposite sides of it, there are: a fitting or valve 24 for filling and draining water and a pump 17 that circulates water through the filter 19. Also, in the water circuit, behind the pump there is a flow heater 18, designed to increase the efficiency of water evaporation ... The pump and heater are connected to the control unit 14;

- in the upper part of the filter-evaporator unit 15 there is a second check valve 28, its inlet is connected to the atmosphere, and the outlet is connected to the space between the diffuser 20 and the upper part of the filter 19.

To pass air along the filter-chamber circuit, a first centrifugal fan 25 is used, connected through the second technological opening (first inlet) to the chamber 2, and the outlet to the space between the filter 19 and the water tank 22.

According to one variant of the device, a second fan 26 is connected to the second inlet of the first fan 25, the outlet of which is equipped with a check valve 27 connected to the atmosphere.

The power supply 16 provides all the electrical components of the device with the required voltage and current.

The control unit 14 is designed to automatically conduct all stages of research and to communicate with the user. It provides automatic execution of all steps using the touch screen 5 and allows the user to set the required parameters, for example, the evaporation time of cyanoacrylate.

A PC or tablet can be connected wirelessly to the control unit 14 for maintenance and diagnostics by an engineer (Fig. 2).

The camera body is mainly made of plastic and its dimensions can be changed in a wide range in accordance with the customer's requirements. If the required housing dimensions exceed the capacity limit of the filter-evaporator unit, then scaling can be applied by installing several filter-evaporator units and control units, while the control units are connected according to the principle of one master many slaves.

The main advantage of the solution implemented in this device is the double use of most of its elements at various stages of the device's operation, for example, the filter is used both for humidification and for cleaning the air in the chamber, the first fan, due to the change in its performance (speed), is also used on stages of humidification and purification of air in the chamber. As a result, the reliability and efficiency of the device is significantly increased, as well as the cost of the entire product is reduced. Due to the presence of passive check valves 27 and 28, the device contains a minimum number of assemblies with moving parts, which also increases reliability and increases its service life.

Due to the efficient process of humidification of the chamber for the samples under study, as well as the possibility of preheating stage 8, the time at the stage of humidification and cleaning of the chamber is reduced and, as a consequence, the total time spent on the study.

Another advantage of the solution is the ability to drain the device. This increases the corrosion resistance of the entire device and prevents contamination of all elements and especially of the filter element with microorganisms and, as a result, increases the service life of the filter.

In addition, due to the possibility of changing the rotation speed of the first fan 25, the required humidity level in the chamber 2 is maintained, which increases the accuracy of the humidity level.

One embodiment of the proposed method is illustrated in FIG. 3.

To obtain a clear pattern of sweat traces on the test sample, the following operations are performed sequentially.

After power is supplied from the unit 16, automatic diagnostics of all units of the device are performed and the water level in the water tank 22 is checked.

When an error occurs, screen 5 displays the corresponding symbol and recommended actions. So, for example, if the water level in the reservoir 22 is insufficient, the user is prompted to add water.

If there are no errors, the normal work cycle begins.

At the initial stage, the user places one or more samples in chamber 2, and a tray 9 with cyanoacrylate is installed on the heated stage 8 of the evaporator unit 6. After that, the user closes the transparent door 4, while the automatic latch 29 is activated, blocking the door and the humidification stage automatically begins.

At the stage of humidification, the following elements of the device are turned on: in chamber 2 - a circulation fan 13, and in compartment 3: a water pump 17, a water heater 18 and the first fan 25. Water enters the upper part of the filter-evaporator unit 15 and through the diffuser 20 evenly wets the foam rubber filter 19. Next, water enters the reservoir 22 and again into the pump 17.

The first fan 25 drives the air flow in a direction opposite to the water flow - up through the foam filter 19. Then the humidified air passes through the second opening 21 (Fig. 1) into the chamber 2 and enters the first inlet of the fan 25. Due to the pressure difference created by this fan , both check valves 27 and 28 are closed and the device is disconnected from the outside.

As the air humidifies, using the readings of the humidity sensor 12, the control unit 14 can turn off and on the pump 17 and the heater 18, and also regulate the speed of the fan 25. To reduce the examination time, the heater 10 of the stage 8 is turned on in advance, since the algorithm for predicting the time of turning on the heating of the stage embedded in the software. Thus, by the time the required humidity level is reached in chamber 2, the heating stage is already warmed up and the vaporization of cyanoacrylate vapors begins.

Maintaining the required humidity level in the chamber is achieved by turning on the first fan at a very low speed. Thus, taking into account the strong flow of warm water, the air is humidified, and a weak air flow through the filter evaporator does not lead to a decrease in the concentration of cyanoacrylate vapors.

During the evaporation phase, the device automatically maintains the set humidity level and temperature of the heating table. After the time set at the initial stage, the operator through the transparent door 4 of chamber 2 can assess the quality of traces detection, and, if necessary, repeat the specified stage.

In case of successful completion of the evaporation stage, the cleaning stage begins, in which pump 17 and fan 25 are turned on at maximum speed. A powerful air flow saturated with cyanoacrylate vapors from chamber 2 passes through a humidified filter 19, on which cyanoacrylate settles. Thus, there is a fast and effective air purification from cyanoacrylate vapors.

After a predetermined time has elapsed, a dehumidification step begins, in which the pump 17 and the first fan 25 are turned off and the second fan 26 is turned on.

The direction of the air flow is reversed, as a result of which the check valves 27 and 28 are opened. Atmospheric air through the check valve 28 passes simultaneously through the chamber 2 and through the filter 19, and through the first check valve 27 it is released into the atmosphere.

After the time of the drying phase has elapsed, the automatic latch 29 is unlocked and the device returns to the initial position. The user can remove samples from the chamber. The work cycle is completed.

The operation of the device is built on a closed cycle, which ensures the absence of pollution of the surrounding atmosphere, therefore the device does not require an external ventilation system or air purification.

The device is made in the form of a rigid single structure and can be operated in any room with room temperature. It requires power from a standard electrical outlet to function.

The device is easy to operate, since its operation is carried out using a microcontroller and embedded software, at the same time, its operation can be carried out using an external terminal, for example, a tablet (Fig. 2). It is also possible to wirelessly diagnose, control and change the main parameters of the device.

Claims (10)

1. A device for detecting sweat marks of hands, containing a chamber for the test samples with a door and a compartment with equipment, separated by a wall in which holes are made, a cyanoacrylate evaporator unit is located in the chamber, and the equipment located in the compartment includes a control unit, two fans and a filter-evaporator unit connected to the control unit, including a water circuit consisting of a series-connected water tank, a pump and a diffuser and a filter located between the diffuser and the water tank, the first fan is connected by its inlet to the first hole in the wall, and the outlet is with the space between the filter and the reservoir with water, the second fan is communicated by its inlet with the chamber, and the outlet - with the atmosphere through one check valve, and the space between the diffuser and the filter is communicated with the camera through the second hole in the wall, and with the atmosphere - through another return valve. 2. The device of claim. 1, in which the second fan communicates with its inlet with the chamber through the cavity of the first fan. 3. The device of claim. 1, in which the second fan communicates with its inlet with the chamber through the space between the diffuser and the filter. 4. The apparatus of claim 1, wherein the evaporator unit includes a cyanoacrylate tray and a heated stage equipped with a temperature sensor and connected to the control unit. 5. The device according to claim. 1, in which the chamber is located lighting means connected to the control unit and made in the form of diode lamps located along the perimeter of the door. 6. The device according to claim 1, wherein the chamber door is provided with an automatic latch with a door position sensor connected to the control unit. 7. The device according to claim 1, wherein a humidity sensor is located in the chamber, connected to a control unit that is connected to the first fan. 8. The apparatus of claim 1, wherein the equipment includes a touch screen associated with a control unit. 9. The device according to claim 1, wherein the control unit is configured for wireless communication with a personal computer or tablet. 10. A method for detecting sweat marks of hands using a device according to any one of paragraphs. 1-9, which consists in humidifying the chamber with one or several samples, evaporating cyanoacrylate in the chamber, judging by the appearance of a pattern on the sample, the presence of sweat marks of hands on the sample, cleaning the chamber from cyanoacrylate vapors and drying the chamber and the compartment with equipment, when this humidification is carried out by wetting the filter with water, followed by passing an air flow through it by means of the first fan and supplying humidified air to the chamber with the sample, evaporation is carried out by heating the bath with cyanoacrylate installed in the chamber, cleaning the chamber from cyanoacrylate vapors is carried out with the first fan and pump running by passing cyanoacrylate vapors through the filter, and the chamber is dehumidified when the second fan is running, both check valves are open, and when the first fan and pump are not working, by passing humidified purified air from the chamber and filter-evaporator unit of the compartment with the equipment through one of the check valves into the atmosphere.

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