JP3883714B2 - Fingerprint image input device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a fingerprint image input device, and more particularly to a fingerprint image input device that can visually recognize the placement state of a finger.
[0002]
[Prior art]
Conventionally, various access control devices have been put into practical use. These entrance / exit management devices are installed in the vicinity of an entrance door of a room or the like, and perform control to unlock the electric lock of the door if it can be confirmed that the person is allowed to enter the room. In addition, as a means for identifying a specific person, there is an entrance / exit management apparatus that applies a fingerprint collation technique using a human fingerprint and confirms a person who enters the room based on collation of human fingerprint data.
In an entrance / exit management device to which a conventional fingerprint verification technology is applied (hereinafter sometimes referred to as a “fingerprint verification device”), the fingerprint data of a person who intends to enter the room is read, and the fingerprint data and the entrance permission stored in advance are read The person's fingerprint data is compared and collated, and if they match, it is determined that the person is allowed to enter the room. To capture fingerprint data, first, when a person who wants to enter the room places his / her finger on the mounting surface on the prism slope, infrared light is emitted from the LED, and the infrared light passes through the prism from one bottom surface side of the prism and passes through the prism. Irradiate the table. The irradiated infrared light is absorbed only in the part touched by the finger surface, and the part not touched by the finger is reflected. Therefore, the reflected light is reflected by the CCD camera provided outside the other bottom surface of the prism. Fingerprint data is read by photographing. The fingerprint data obtained by the CCD camera is compared with the fingerprint data of the person permitted to enter the room stored in advance.
Further, when the CCD receives light other than the irradiated infrared light, the contrast of the fingerprint photographed differs depending on the intensity of the light other than the infrared light. Therefore, in order to remove light components other than the infrared rays to be projected, a band pass filter for removing wavelength components other than those near the wavelength of the irradiated infrared rays is disposed in front of the CCD.
[0003]
[Problems to be solved by the invention]
However, the conventional fingerprint collation device has a problem that when it is installed in a place where sunlight is directly irradiated, for example, outdoors, a fingerprint image cannot be input stably. That is, when the fingerprint collation device is installed outdoors, sunlight enters the fingerprint input unit. This sunlight also contains an irradiating infrared component that passes through the bandpass filter described above. And since sunlight has a larger light quantity than other artificial illuminations, and the irradiation amount varies depending on the time and weather, the amount irradiated to the fingerprint verification device also varies. Therefore, fingerprint data that can be photographed by the CCD camera varies greatly between when sunlight is irradiated and when it is not irradiated, making it difficult to capture fingerprint data stably. For example, when sunlight is strongly irradiated, the amount of light incident on the CCD camera is too large, so that the saturation state occurs and the density of the fingerprint image does not appear.
In addition, when sunlight enters the fingerprint input unit, there is a problem that a residual fingerprint image due to sebum, sweat, or the like remaining on the surface of the finger placement table is incident on the CCD camera and is captured. For this reason, the conventional fingerprint collation device is required to be installed in a place where sunlight is not directly irradiated, and there is a problem that it cannot be installed outdoors or near a window.
Therefore, an object of the present invention is to provide a fingerprint image input device that can stably input a fingerprint image and can visually recognize the placement state of a finger even when installed in a place where sunlight is directly irradiated. There is.
[0004]
[Means for Solving the Problems]
The above problems are solved by the present invention.
A light projecting unit that projects light of a predetermined wavelength;
A finger placement section;
An imaging unit that receives reflected light reflected by the surface of the mounting unit, the light projected by the light projecting unit;
A first filter that selectively transmits light in a wavelength range including the wavelength of light projected by the light projecting unit;
A second filter that shields light in a wavelength range transmitted by the first filter and transmits light in a wavelength in the visible light region;
The first filter is disposed between the placement unit and the imaging unit, and the second filter is disposed to cover the placement unit from the outside. It can be solved by an input device.
In the fingerprint image input device according to the present invention, the same component as the light from the light projecting unit included in sunlight is shielded by the second filter, and the wavelength in the visible light region is transmitted. Moreover, the light of the other component contained in sunlight is shielded by the first filter. On the other hand, the light projecting portion for projecting light reflected by placed on the placing portion the finger, since the passage of only the first filter without passing through the second filter, is shielded in its being these filters Without reaching the imaging unit. Therefore, the imaging unit can acquire a fingerprint image from the reflected light by the light from the light projecting unit without being affected by sunlight, and the user can place the finger placement position via the second filter. Can be visually recognized, improving usability.
[0005]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, a fingerprint collation apparatus according to the present invention will be described in detail with reference to FIGS. FIG. 1 is a front view showing an appearance of a fingerprint collation apparatus 10 that is one embodiment of the present invention. The fingerprint collation apparatus 10 includes a fingerprint input unit 1, an information input unit 2, and a display unit 3. The fingerprint input unit 1 can read the fingerprint of the user's real finger subjected to fingerprint verification by the fingerprint verification device 10 with a camera or the like. When the user's fingerprint is registered in advance or when fingerprint verification is performed, the fingertip Includes a finger rest for placing The information input unit 2 is a device for inputting personal identification information (for example, an ID number) or a password that is predetermined for each user, and can be configured by, for example, a numeric keypad. The information input unit 2 can consist of only a numeric keypad, but it stores personal identification information (for example, an ID number) in a magnetic card or IC card, reads a recitation number with a card reader, and inputs a password. It can also be configured to be performed separately using a numeric keypad. The display unit 3 can display operation instructions such as fingerprint collation results and operation procedures. As the display unit 3, a liquid crystal (LCD) can be preferably used, but only an audio output device such as a CRT display means or a speaker, or a combination thereof can be used.
[0006]
FIG. 2 is a side view of the fingerprint collation apparatus 10 according to the present invention, and schematically shows the internal structure of the fingerprint input unit 1 with a part thereof cut away. The fingerprint input unit 1 includes a prism 41, an LED 42 that projects infrared rays, and a CCD 43 that receives reflected light from the mounting table 41a and images it. Further, the slope of the prism 41 is exposed on the lower side wall surface of the finger insertion chamber 44 provided by being recessed from the front wall surface of the fingerprint collating device 10 to form a finger placement table 41a. A waterproof sheet or the like can be provided on the mounting table 41a. The sunlight shielding filter 13 is provided above the finger insertion chamber 44 so that the mounting table 41a is not directly irradiated with sunlight. Further, an imaging light transmission filter 45 is provided between the prism 41 and the CCD 43.
[0007]
FIG. 3 is a block diagram of the fingerprint collation apparatus 10 according to the present invention. As shown in FIG. 3, the fingerprint input unit 1 can be composed of, for example, a sensor unit 11 and an A / D conversion unit 12. The sensor unit 11 includes a prism 41 that provides a finger placement table, an LED 42 for irradiating light on the finger, a CCD 43 that captures image data, and the A / D conversion unit 12 is configured as described above. The image data captured from the sensor 11 can be quantized. The fingerprint input unit 1 is connected to the control unit 6 through an interface (I / F) 5 together with the information input unit 2 and the display unit 3. The control unit 6 is a CPU 61 including peripheral circuits, a ROM 62 for storing a program for realizing the functions of the fingerprint collation device 10, and personal identification information and collation standards for each user registered in advance. The microprocessor has a basic configuration including a RAM 63 in which personal information such as fingerprint information is stored. As described above, the fingerprint input unit 1, the information input unit 2, and the like via the interface (I / F) 5; It is connected to each part of the display unit 3 so that signals can be exchanged electrically.
[0008]
Next, a fingerprint collation operation by the fingerprint collation apparatus of the present invention will be described with reference to the attached drawings.
When an operator inserts a fingertip in which a fingerprint is registered in advance into the finger insertion chamber 44 and places it on the mounting table 41a, the infrared LED 42 responds in advance to a signal from a sensor (not shown) that senses it. Infrared light having a predetermined wavelength (for example, infrared light having a wavelength of 660 nm) is projected. Infrared light can be always projected without providing a finger placement sensor. Moreover, the wavelength of the light to project is not limited, For example, it can project green light using green LED instead of infrared LED. The projected infrared light penetrates into the prism 41 from one bottom surface 41b of the prism 41, and the infrared light is absorbed only in the part touched by the mounting table 41a which is the slope of the prism 41 on which the finger is mounted. The part touching is reflected. The reflected light travels in the prism 41 in the direction of the other bottom surface 41 c, exits the prism 41, passes through the imaging light transmission filter 45, and is received by the CCD 43. The imaging light transmission filter 45 selectively transmits only the light of the light emitted by the infrared LED 42 and the light in the wavelength range near the wavelength, and does not transmit the light of other wavelengths. Accordingly, the infrared rays projected by the infrared LED 42 reach the CCD 43, but light of other wavelengths does not substantially reach the CCD 43. Therefore, the CCD 43 is an imager having sensitivity to a wide range of wavelengths. be able to.
[0009]
In the fingerprint collation device of the present invention, the sunlight shielding filter 13 is provided as the second filter outside the finger insertion chamber 44, and sunlight is not directly passed through the sunlight shielding filter 13, but the mounting table. 41a is not irradiated. The finger insertion chamber 44 has an opening for inserting a finger. However, when a finger is inserted into the finger insertion chamber, the insertion port is almost closed, so that the diffuse reflected light of sunlight is also substantially reduced. Specifically, the mounting table 41a is not irradiated. The sunlight shielding filter 13 can transmit light in the wavelength range other than that if the light in the wavelength range transmitted by the imaging light transmission filter 45 is blocked. Thus, in the sunlight, the light in the wavelength range transmitted by the imaging light transmission filter 45 is blocked by the filtering of the sunlight shielding filter 13, and the other components of sunlight transmitted through the sunlight shielding filter 13 continue. Therefore, sunlight basically does not reach the CCD camera because it is blocked by the filtering of the imaging light transmission filter 45.
[0010]
Next, along FIG.4 and FIG.5, the transmission characteristic of a 1st filter (for example, imaging light transmission filter 45) and a 2nd filter (for example, sunlight shielding filter 13) is demonstrated concretely.
In the case of using an infrared LED, the transmission characteristics of the imaging light transmission filter 45 need only transmit light having a wavelength of at least 660 nm, and generally a wavelength range including 660 nm (for example, 600 nm to 720 nm). ) Is used. When a light projecting unit such as a green LED is used, filters having different wavelengths to be transmitted according to the light projecting wavelength are used.
[0011]
The sunlight shielding filter 13 is at least required to shield light having a wavelength that the imaging light transmission filter 45 transmits. For example, when the sunlight shielding filter 13 transmits light having a wavelength of 600 nm to 720 nm, it is necessary to shield light having a wavelength in this range at least. For example, as illustrated in FIG. 4, a filter that transmits light having a wavelength of 599 nm or less and shields light having other wavelengths is used as the sunlight shielding filter 13, and the imaging light transmission filter 45 is 660 nm to 720 nm. It is possible to employ a filter that blocks light having a wavelength of.
Further, as shown in FIG. 5, as sunshield filter 13, is transmitted through the optical light and 721nm or more wavelengths having a wavelength of not more than 599 nm, employing a filter that blocks light of other wavelengths, the imaging light transmitted through As the filter 45, a filter that shields light having a wavelength of 660 nm to 720 nm can be employed.
[0012]
The region that can be recognized by the human eye, that is, the visible region is about 500 nm to about 700 nm. Therefore, as the sunlight shielding filter 13, it is preferable to use a filter that transmits as much light as possible except for the light projecting wavelength of the light projecting LED 42 in the visible region. The reason for this is to allow the operator to confirm the position of the mounting table 41 a through the sunlight shielding filter 13. Since the fingerprint data may be different if the placement of the finger on the mounting table 41a is different, it is important for the operator to confirm the position of the mounting table 41a. Therefore, the sunlight shielding filter 13 is translucent.
[0013]
【The invention's effect】
In the fingerprint verification device according to the invention, the mounting of the finger put stand (prism) is disposed between the first filter and the (imaging light transmission filter) second filter (sunshield filter), further, the Since an imaging unit (CCD camera) is provided behind one filter (imaging light transmission filter), light in the wavelength range transmitted by the imaging light transmission filter among sunlight is filtered by the sunlight shielding filter. Other components of sunlight that are blocked and transmitted through the sunlight shielding filter are subsequently blocked by the filtering of the imaging light transmission filter, so that each component of sunlight basically does not reach the CCD camera. Since the imaging light transmission filter transmits light having a wavelength in the visible light region, it can stably input a fingerprint image even if it is installed in a place where sunlight is directly irradiated. The mounting position can be visually confirmed, and the usability is improved.
[Brief description of the drawings]
FIG. 1 is a front view of a fingerprint collation apparatus according to an embodiment of the present invention.
FIG. 2 is a side view showing a part of the fingerprint collating apparatus of FIG.
FIG. 3 is a block diagram of a fingerprint collation apparatus.
FIG. 4 is an explanatory diagram showing an example of transmission characteristics of a first filter and a second filter.
FIG. 5 is an explanatory diagram showing another example of transmission characteristics of the first filter and the second filter.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Fingerprint input part; 2 ... Information input part; 3 ... Display part;
5 ... interface; 6 ... control unit; 10 ... fingerprint collation device;
DESCRIPTION OF SYMBOLS 11 ... Sensor; 12 ... A / D conversion part; 13 ... Sunlight shielding filter;
41 ... Prism; 41a ... Mounting table (prism slope);
41b, 41c ... prism bottom; 42 ... LED; 43 ... CCD;
44 ... finger insertion chamber; 45 ... imaging light transmission filter;
61 ... CPU; 62 ... ROM; 63 ... RAM.

Claims (1)

A light projecting unit that projects light of a predetermined wavelength;
A finger placement section;
An imaging unit that receives reflected light reflected by the surface of the mounting unit, the light projected by the light projecting unit;
A first filter that selectively transmits light in a wavelength range including the wavelength of light projected by the light projecting unit;
A second filter that shields light in a wavelength range transmitted by the first filter and transmits light in a wavelength in the visible light region;
The first filter is disposed between the placement unit and the imaging unit, and the second filter is disposed to cover the placement unit from the outside. Input device.

Images