Automatic analyzer

According to one embodiment, an automatic analyzer comprises a light source, a spectroscope, a photo detection unit, a storage unit, a selection unit, and a calculation unit. The storage unit stores photo detector identifiers related to photo detectors and wavelength band identifiers in association with each other. The selection unit selects a specific photo detector from photo detectors. The specific photo detector corresponds to a specific photo detector identifier associated with a wavelength band identifier of a wavelength band according to a measurement item of a sample. The calculation unit calculates an absorbance related to the measurement item based on a signal from the selected specific photo detector.

FIELD

Embodiments described herein relate generally to an automatic analyzer.

BACKGROUND

An automatic analyzer spectrally separates light, which has been transmitted through a liquid mixture of a sample and reagent, using a spectroscope, and receives light components from the spectroscope by a photo detection unit. The light components from the spectroscope have different wavelengths depending on physical positions. The photo detection unit has a plurality of photo detectors. Respective photo detectors receive light components related to wavelengths according to their locations.

The photo detectors are often deviated from their original positions at the time of assembling or the like of the apparatus. Such deviations are called wavelength accuracy deviations. When the wavelength accuracy deviations have occurred, position adjustments of the photo detectors are executed. However, the position adjustments of the photo detectors impose a heavy load on the assembler.

It is an object to provide an automatic analyzer which can reduce a load on position adjustments of photo detectors.

DETAILED DESCRIPTION

In general, according to one embodiment, an automatic analyzer comprising a light source, a spectroscope, a photo detection unit, a storage unit, a selection unit, a calculation unit. The light source emits light. The spectroscope disperses light, which is emitted by the light source and is transmitted through a liquid mixture of a sample and a reagent, into different wavelengths. The photo detection unit includes a plurality of photo detectors which receive light from the spectroscope, each of the photo detectors receive light related to a wavelength band corresponding to a location of that photo detector, and generates a signal according to the received light. The storage unit stores a plurality of photo detector identifiers related to the plurality of photo detectors and a plurality of wavelength band identifiers in association with each other. The selection unit selects a specific photo detector from the photo detectors, the specific photo detector corresponding to a specific photo detector identifier associated with a wavelength band identifier of a wavelength band according to a measurement item of the sample. The calculation unit calculates an absorbance related to the measurement item based on a signal from the selected specific photo detector.

An automatic analyzer according to this embodiment will be described hereinafter with reference to the drawings.

FIG. 1is a schematic view showing the arrangement of an automatic analyzer100according to this embodiment. As shown inFIG. 1, a reaction disc20is arranged at nearly a central portion of a stage of the automatic analyzer100. The reaction disc20holds a plurality of reaction containers (cuvettes)22which are laid out on the circumference. The reaction disc20repetitively pivots and stops at a predetermined cycle.

A disc-shaped sample disc30is disposed in the vicinity of the reaction disc20. The sample disc30holds a plurality of sample containers32, which are laid out concentrically. Each sample container32contains a sample. The sample disc30is rotated about a rotation axis, and locates a sample container32which contains a sample to be dispensed at a sample suction position on the sample disc30.

A first reagent storage40is disposed in the vicinity of the reaction disc20. The first reagent storage40has a disc-shaped first reagent disc. The first reagent disc holds a plurality of first reagent containers42which are laid out concentrically. Each first reagent container42contains a first reagent that causes chemical reactions with components which are included in a sample and correspond to respective measurement items. The first reagent disc is rotated about a rotation axis, and locates a first reagent container42which contains a first reagent to be dispensed at a first reagent suction position on the first reagent storage40.

A second reagent storage50is disposed inside the reaction disc20. The second reagent storage50has a disc-shaped second reagent disc. The second reagent disc holds a plurality of second reagent containers52which are laid out on the circumference. Each second reagent container52contains a second reagent corresponding to the first reagent. The second reagent disc is rotated about a rotation axis, and locates a second reagent container52which contains a second reagent to be dispensed at a second reagent suction position on the second reagent storage50.

A sample arm34is disposed between the reaction disc20and sample disc30. A sample probe36is attached to the distal end of the sample arm34. The sample probe36sucks in or discharges a sample by an electrically operated pump (not shown). The sample arm34moves the sample probe36to pivot between the sample suction position on the sample disc30and the sample discharge position on the reaction disc20. The sample arm34moves the sample probe36upward and downward.

A first reagent arm44is disposed between the reaction disc20and first reagent storage40. A first reagent probe46is attached to the distal end of the first reagent arm44. The first reagent probe46sucks in or discharges a first reagent by a pump (not shown). The first reagent arm44moves the first reagent probe46to pivot between the first reagent suction position on the first reagent storage40and the first reagent discharge position on the reaction disc20. Also, the first reagent arm44moves the first reagent probe46upward and downward.

A second reagent arm54is disposed in the vicinity of the outer circumference of the reaction disc20. A second reagent probe56is attached to the distal end of the second reagent arm54. The second reagent probe56sucks in or discharges a second reagent by a pump (not shown). The second reagent arm54moves the second reagent probe56to pivot between the second reagent suction position on the second reagent storage50and the second reagent discharge position on the reaction disc20. Also, the second reagent arm54moves the second reagent probe56upward and downward.

A stirring unit arm60is disposed in the vicinity of the outer circumference of the reaction disc20. The stirring unit60stirs a liquid mixture of a sample and first reagent or that of a sample, first reagent, and second reagent in the cuvette22at a stirring position on the reaction disc20by a stirrer62.

A photometry unit1is arranged inside the stage. The photometry unit1executes photometry so as to calculate absorbance related to measurement items of an object to be measured.

FIG. 2illustrates the structure of an optical system included in the photometry unit1. As shown inFIG. 2, the photometry unit1mounts a light source2which emits light. As the light source2, a lamp such as a halogen lamp or tungsten lamp is used. Note that an LED (light emitting diode) may be used as the light source2. When the reaction disc pivots, the cuvette22passes a predetermined position (photometry position) PP in the optical system. Along an optical path between the lamp2and the photometry position PP, an infrared cut filter3, lens4, and slit5are arranged in turn from the lamp2side. The infrared cut filter3mainly moderately absorbs infrared rays unnecessary in measurements from the lamp2. The lens4condenses light transmitted through the infrared cut filter3. The slit5limits a width of the light condensed by the lens4. The light, which has passed through the slit5, is transmitted through a liquid mixture in the cuvette22.

The light transmitted through the liquid mixture is received by a photo detection unit8via some optical devices6and7. Along an optical path between the photometry position PP and photo detection unit8, a slit6and spectroscope7are arranged in turn from the photometry position PP side. The slit6limits a width of the light transmitted through the liquid mixture in the cuvette22. The spectroscope7spectrally separates the light, which has passed through the slit6. As the spectroscope7, for example, a diffraction grating is adopted. The diffraction grating is configured by, for example, a concave mirror on a mirror surface of which a plurality of grooves (grid lines) are formed at equal intervals. Light with which the diffraction grating is irradiated is diffused for respective wavelengths by the grid lines on the diffraction grating. In other words, the diffraction grating separates light into a plurality of rays (monochromatic light rays) related to a plurality of wavelengths. The plurality of rays (primary diffracted light rays) from the diffraction grating are received by the photo detection unit8.

The photo detection unit8is disposed on optical paths of the plurality of rays (primary diffracted light rays) coming from the spectroscope7so as to cover all wavelength widths which can be used in absorbance calculations. The photo detection unit8includes a plurality of photo detectors.

FIG. 3shows an example of a layout pattern of photo detectors81. As shown inFIG. 3, the plurality of photo detectors81are two-dimensionally laid out on a substrate82or the like of the photo detection unit8. As the photo detectors81, a CCD image sensor or photo diode array (PDA: photo detector array) on which photoelectric conversion elements such as CCDs (charge coupled devices) or photo detectors are two-dimensionally laid out is used. Each photo detector81to be adopted is sensitive to near-ultraviolet rays, visible rays, or near-infrared rays. Typically, all the photo detectors81to be used included in the photo detection unit8have the same performance.

One layout direction of the photo detectors81is parallel to a diffusion direction of wavelengths (a spectrum layout direction). The diffusion direction of wavelengths is specified to agree with a channel direction of the photo detectors81. For example, 125 photo detectors81(for 125 channels) are laid out along the channel direction. The other layout direction of the photo detectors81is parallel to, for example, an orthogonal direction of the channel direction and an optical axis direction of primary diffracted light from the spectroscope7. Ideally, the wavelengths of the plurality of rays from the spectroscope7do not change along this orthogonal direction. The photo detectors81belonging to a single channel receive light components having a nearly single wavelength. A plurality of photo detectors81which belong to an identical channel will be referred to as a photo detector column83hereinafter. Also, this orthogonal direction will be referred to as a column direction hereinafter. Note that the number of photo detectors81, which are laid out along the channel direction, is not limited to 125. For example, 250 elements which are equal to or larger than 125 elements or 80 elements which are equal to or smaller than 125 elements may be arranged.

A length of a photo detection surface related to the channel direction of one photo detector81is designed to be, for example, 1 to 4 nm. Since the photo detection surface of each photo detector81has a width having a physically nonnegligible length, the photo detector81cannot receive light of only a single wavelength, and receives rays within a wavelength width according to the length of the photo detection surface related to the channel direction. A wavelength range within the wavelength width having a center wavelength of light received by one photo detector81as the center will be referred to as a wavelength band hereinafter. The wavelength band is decided according to a spatial location of the photo detector81and the length of the photo detection surface in the channel direction. For example, when the center wavelength of 340 nm and the wavelength width is ±2 nm, the wavelength band ranges from 338 nm to 342 nm. Note that all the photo detectors81in the photo detection unit8have the same photo detection surface area. Therefore, the wavelength band associated with each photo detector81is decided according to its spatial location. To the photo detectors81, signal lines84via which amplifiers in a subsequent stage are electrically connected are connected.

When 125 photo detectors81are laid out along the channel direction, and a wavelength band used in absorbance calculations ranges from 330 nm to 830 nm, a wavelength width per photo detector81corresponds to 4 nm. Therefore, when the photo detectors81can be laid out without any gap, the width of the photo detection area of each photo detector81is preferably 4 nm. However, as shown inFIG. 3, the photo detectors81are laid out to have gaps85between them. The gaps85are set to have equal intervals. When the gaps85are too large, a probability of a reception failure of light of a desired wavelength unwantedly increases. In this case, in order to reduce this probability, it is desirable to lay out the photo detector81so that a photo detection area S1of each photo detector81and an area S0of each gap85along the channel direction satisfy (S1/S1+S0))<0.2. In other words, the gap85is preferably designed so that its wavelength width is smaller than 20% of that of one photo detector81.

Note that in this embodiment, the gaps85need not always be laid out so as to satisfy (S1/S1+S0))<0.2, and they may be laid out to satisfy (S1/S1+S0))<0.5. Note that the photo detectors81may be laid out without any gap.

In subsequent absorbance calculations, not only light of only a measurement wavelength but also rays for a wavelength width having the measurement wavelength as the center are used. For example, rays for a wavelength width of about ±10 nm having the measurement wavelength as the center are used. Therefore, for one measurement wavelength, outputs from the four or five photo detectors81along the channel direction are used in absorbance calculations.

The overall arrangement of the photometry unit1according to this embodiment will be described below with reference toFIG. 4. As shown inFIG. 4, the photometry unit1according to this embodiment includes a storage unit11, the photo detection unit8, amplifiers12, a selection unit13, an A/D converter14, an absorbance calculation unit15, a setting unit16, an operation unit17, and a display unit18to have a system control unit10as a core.

The storage unit11stores identifiers of the plurality of photo detectors (to be referred to as photo detector identifiers hereinafter) and those of a plurality of wavelength bands (to be referred to as wavelength band identifiers hereinafter) in association with each other. As each identifier, for example, its number or name is adopted. The storage unit11typically stores a database which associates photo detector identifiers and wavelength band identifiers with each other (to be referred to as an element/wavelength database hereinafter).

As described above, the photo detection unit8has the plurality of photo detectors81, which are laid out two-dimensionally. Each photo detector81receives rays associated with its corresponding wavelength band, and generates an electrical signal according to the intensities of the received rays. To the plurality of photo detectors81, a plurality of amplifiers12are respectively connected via the signal lines84.

The plurality of amplifiers12are arranged on, for example, a single electronic broad. The amplifiers12amplify electrical signals from the photo detectors81. To the plurality of amplifiers12, the A/D converter14is connected via the selection unit13.

The selection unit13selects photo detectors, which belong to wavelength bands used in absorbance calculations of measurement items of an object to be measured using the element/wavelength database. More specifically, the selection unit13selects, from the plurality of photo detectors81, those corresponding to photo detector identifiers, which are associated with wavelength band identifiers of wavelength bands according to measurement items of a sample on the element/wavelength database. More particularly, the selection unit13is implemented by a switching unit131and collected data control unit132. The switching unit131is arranged between the photo detection unit8and A/D converter14. The switching unit131switches electrical connections between the plurality of photo detectors81in the photo detection unit8and the A/D converter14, and can use electronic circuit elements such as multiplexers. The collected data control unit132controls the switching unit131to electrically connect the photo detectors81selected by the selection unit13to the A/D converter14.

The A/D converter14A/D-converts analog electrical signals from the amplifiers12connected to the photo detectors81selected by the selection unit13, thus generating digital electrical signals. To the A/D converter14, the absorbance calculation unit15is connected.

The absorbance calculation unit15calculates absorbance related to measurement items of an object to be measured based on the digital electrical signals supplied from the A/D converter14.

The setting unit16sets associations between the photo detector identifiers and wavelength band identifiers on the element/wavelength database according to an instruction from the user via the operation unit17. Also, the setting unit16can change the associations between the photo detector identifiers and wavelength band identifiers in accordance with an instruction from the user via the operation unit17.

The operation unit17accepts various commands and information inputs from the user. As the operation unit17, a keyboard, mouse, switches, and the like can be used as needed.

The display unit18displays a screen to create the element/wavelength database and absorbance calculation results. As the display unit18, for example, a CRT display, liquid crystal display, organic EL display, plasma display, or the like can be used as needed.

An operation example of the automatic analyzer100in the element/wavelength database generation stage will be described below with reference toFIG. 5.FIG. 5shows the typical sequence of processing in the element/wavelength database generation stage. The element/wavelength database is generated at the time of assembling of the photometry unit1or when wavelength accuracy deviations have occurred. Before the beginning of step SA1, the photo detection unit8is set at a position where it can receive rays from the spectroscope7. For example, assuming that a wavelength band from 340 nm to 804 nm is indispensable to absorbance calculations, the photo detection unit8is set at a position where it can cover at least this wavelength band. Note that in order to prevent the wavelength band indispensable to absorbance calculations from failing to be covered due to occurrence of wavelength accuracy deviations, the photo detection unit8is preferably set to cover a wavelength band broader than the indispensable wavelength band.

As shown inFIG. 5, after the photo detection unit8is set, photometry is executed using light of a given wavelength. That is, the lamp2is controlled to emit light related to the given wavelength, and the photo detection unit8is irradiated with the light emitted by the lamp2via the spectroscope7(step SA1).

At this time, signal strengths of the respective photo detectors are measured to measure photo detection sensitivities of the respective photo detectors with respect to the given wavelength, thereby specifying the photo detectors81, which received the light, from the plurality of photo detectors81(step SA2). The photo detectors81are specified by, for example, the following method. Initially, strengths of electrical signals from the plurality of photo detectors81are monitored. Then, photo detectors81, which generated electrical signals having strengths larger than a prescribed threshold, are specified as those which received the rays. Also, photo detection sensitivities with respect to the given wavelength of the specified photo detectors are stored.

The setting unit16records the photo detectors81specified in step SA2and the photo detection sensitivities with respect to the given wavelength in the element/wavelength database by associating their photo detector identifiers and a wavelength band identifier of a wavelength band, to which the given wavelength belongs, with each other (step SA3). Step SA3will be described in detail below. In the element/wavelength database generation stage, the display unit18displays a screen to create an element/wavelength database (generation screen). On the generation screen, various GUI components required to associate the photo detector identifiers and wavelength band identifiers with each other are laid out. A wavelength band of light that can be received by each photo detector is decided according to, for example, the given wavelength and the wavelength width based on the size of the photo detection surface. The user makes an operation for associating the photo detector identifiers specified in step SA1with the wavelength band identifier related to the given wavelength via the operation unit17. The setting unit16associates the photo detector identifiers and the wavelength band identifier related to the given wavelength with each other according to this operation. Then, the setting unit16sets (records) the associated contents in an element/wavelength database D1.

Typically, a single wavelength band is associated with a plurality of photo detectors81which belong to a single channel. However, this embodiment is not limited to this. For example, a plurality of wavelength bands may be associated with a plurality of photo detectors81which belong to a single channel.

FIG. 6is a view for explaining the photo detector identifiers and wavelength band identifiers, which are associated with each other by the setting unit16. As shown inFIG. 6, assume that 125 photo detectors81are laid out in the channel direction, and five photo detectors81are laid out in the column direction. For the purpose of associations, names are set for layout positions in the channel direction and those in the column direction. When a plurality of photo detector identifiers related to a plurality of photo detectors81which belong to a single channel are to be associated with a single wavelength band identifier, that is, when a wavelength band is associated with each photo detector column83, the setting unit16associates the wavelength band identifier with names (photo detector identifiers) such as C1, C2, . . . , C125. In this case, the selection unit13selects the photo detector columns83using names such as C1, C2, . . . ,

C125. When wavelength band identifiers are associated with respective photo detectors81, the setting unit16associates the wavelength band identifiers with names (photo detector identifiers) such as R1-C1, R1-C2, . . . , R5-C125. In this case, the selection unit13selects the photo detectors81using the names such as R1-C1, R1-C2, . . . , R5-C125.

Steps SA1to SA3are repetitively executed while changing a wavelength so as to associate wavelength band identifiers with all the photo detector identifiers.

For example, when a full measurement wavelength band ranges from 340 nm to 800 nm, and a wavelength width of each photo detector is ±2 nm, light of the given wavelength is repetitively measured to set a wavelength width to be ±2 nm with respect to each center wavelength while changing the center wavelength in 4-nm increments from 340 nm to 800 nm.

In this way, the element/wavelength database D1is generated. Note that photo detector identifiers and wavelength band identifiers need not be associated with each other by irradiating all the photo detectors with light of the given wavelength in practice. For example, an unknown correspondence relationship between photo detector identifiers and wavelength band identifiers may be estimated from the given correspondence relationship between them.

An operation example of the automatic analyzer100at the time of photometry will be described below with reference toFIG. 7.FIG. 7shows the typical sequence of processing of the automatic analyzer100in the photometry stage. Note that the photometry is executed each time the cuvette22passes the photometry position in the photometry unit1. In each cuvette22, measurement items are set by the system control unit10or the like according to an instruction from the user via the operation unit17.

Note that absorbance calculations according to this embodiment are applicable to both a calculation method (1-wavelength calculations) using one wavelength band and that (2-wavelength calculations) using two discrete wavelength bands. However, for the sake of simplicity of the following description, assume that the absorbance calculations are 1-wavelength calculations, unless otherwise specified. A wavelength band used in absorbance calculations is typically broader than that for one channel. Therefore, even in case of the 1-wavelength calculations, a wavelength band used in absorbance calculations includes continuous wavelength bands for a plurality of channels. For example, when a wavelength band used in absorbance calculations ranges from 360 nm to 374 nm, continuous wavelength bands for three channels of 360 nm to 364 nm, 365 nm to 369 nm, and 370 nm to 374 nm are included.

In a stage before the cuvette22to be measured passes the photometry position PP, the selection unit13selects photo detectors81(step SB1). Step SB1will be described in detail below. The collected data control unit132of the selection unit13specifies wavelength bands used in absorbance calculations. The wavelength bands used in absorbance calculations are decided according to measurement items. After the wavelength bands are specified, the collected data control unit132searches the element/wavelength database D1using identifiers of the specified wavelength bands as search keys, thereby specifying photo detector identifiers, which are associated with the search keys on the element/wavelength database D1. Next, the collected data control unit132controls the switching unit131so that only electrical signals from photo detectors81corresponding to the specified identifiers are supplied to the A/D converter14. The switching unit131electrically connects the specified photo detectors81to the A/D converter14under the control of the collected data control unit132. Thus, the photo detectors81corresponding to measurement items are automatically selected. Note that the switching unit131can instantaneously switch electrical connections.

After the photo detectors81are selected, photometry is executed (step SB2). That is, the lamp2emits light. Light emitted by the lamp2transmits through a liquid mixture in the cuvette22. The light transmitted through the liquid mixture is received by the photo detectors81via the spectroscope7. The photo detectors81, which received the light, generate electrical signals according to the received light. The generated electrical signals are supplied to the amplifiers12. The amplifiers12amplify the supplied electrical signals. Only the photo detectors81, which belong to wavelength bands used in absorbance calculations, are electrically connected to the A/D converter14via the amplifiers12. That is, the electrical signals generated by the photo detectors81, which belong to the wavelength bands used in absorbance calculations, are supplied to the A/D converter14via the amplifiers12. The photo detectors81, which belong to wavelength bands not used in absorbance calculations, are not connected to the A/D converter14via the amplifiers12. Therefore, electrical signals generated by the photo detectors81, which belong to the wavelength bands not used in absorbance calculations, are not supplied to the A/D converter14, and are, for example, deleted. The A/D converter14converts the analog electrical signals from the photo detectors81, which belong to the wavelength bands used in absorbance calculations, into digital electrical signals. The digital electrical signals are supplied to the absorbance calculation unit15.

When the digital electrical signals are supplied, the absorbance calculation unit15calculates absorbance based on the electrical signals (step SB3). When a plurality of electrical signals from a plurality of channels are used in absorbance calculations, the absorbance calculation unit15may add the plurality of electrical signals by numeric calculations. Also, as shown inFIG. 8, photo detection sensitivities with respect to a desired wavelength (band) used in photometry are normally different depending on channels. Therefore, the absorbance calculation unit15may apply weighted additions according to photo detection sensitivities of a measurement wavelength to the electrical signals of the plurality of channels. For example, when electrical signals from N channels undergo weighted additions, an absorbance Abs is calculated according to:

Abs=∑nN⁢an·xn(1)
where Xnis a strength of an electrical signal of a channel n, and anis a weighting coefficient (a photo detection sensitivity coefficient with respect to a predetermined wavelength) to the electrical signal of the channel n.

For example, a weighting coefficient assumes a larger value with increasing photo detection sensitivity with respect to the predetermined wavelength, and it assumes a smaller value with decreasing photo detection sensitivity. Alternatively, the weighting coefficient may be set according to absorption spectrum characteristics of an object to be measured (reaction solution), which are measured in advance. Alternatively, the weighting coefficient may be set by superposing both the photo detection sensitivity with respect to the predetermined wavelength and the absorption spectrum characteristics of the object to be measured (reaction solution). The calculated absorbance data are supplied to the system control unit10. The system control unit10displays absorbance corresponding to the supplied data on the display unit18.

As described above, the automatic analyzer100according to this embodiment stores the element/wavelength database which associates the photo detector identifiers with the wavelength band identifiers. Using this element/wavelength database, the automatic analyzer100selects, for respective measurement items, photo detectors81which receive light associated with wavelength bands according to the measurement items. The selected photo detectors81are electrically connected to the A/D converter14. That is, only electrical signals from the selected photo detectors81are supplied to the A/D converter14. The A/D converter14can convert only the electrical analog signals from the selected photo detectors81into the digital ones. Therefore, compared to the conventional case in which electrical analog signals from all photo detectors81are converted into the digital ones, the number of electrical signals to be A/D-converted can be reduced in this embodiment. That is, by limiting electrical signals to be supplied to the A/D converter14, the processing volume of the A/D converter14can be reduced, thus reducing a load on the A/D converter14.

Also, as described above, each of the photo detectors according to this embodiment has a small photo detection surface, and these elements are two-dimensionally and densely laid out. Therefore, each individual photo detector covers a narrower wavelength band than the conventional element. Hence, an optimal measurement wavelength band can be set for each measurement item. Therefore, according to this embodiment, the absorbance calculation precision can be improved.

Also, the automatic analyzer according to this embodiment can arbitrarily associate the photo detectors with wavelength bands, and can change correspondence between the photo detectors and wavelength bands. Therefore, according to this embodiment, even when wavelength accuracy deviations have occurred, the associations between the photo detectors and wavelength bands need only be changed without any position adjustments of the photo detectors. For this reason, the automatic analyzer according to this embodiment can correct wavelength accuracy deviations more easily than the conventional apparatus. Also, the automatic analyzer according to this embodiment can reduce cost required for position adjustments of photo detectors compared to the conventional apparatus.

As described above, the automatic analyzer according to this embodiment can reduce a load on the position adjustments of photo detectors.

An automatic analyzer according to the first modification of this embodiment will be described below. Note that in the following description, the same reference numerals denote components and steps having substantially the same functions as those of this embodiment, and a redundant description will be given only when it is necessary.

As described above, wavelength bands used in absorbance calculations are decided according to types of measurement items. The storage unit11according to the modification stores an item/wavelength database which associates identifiers of a plurality of measurement items with those of a plurality of wavelength bands. The storage unit11according to the modification may combine the element/wavelength database and the item/wavelength database. That is, the storage unit11according to the modification may store a plurality of photo detector identifiers and a plurality of identifiers related to the plurality of measurement items (to be referred to as measurement item identifiers hereinafter) in association with each other. The photo detector identifiers and measurement item identifiers are associated with each other in an element/item database. The setting unit16according to the modification can associate measurement items identifiers with photo detector identifiers at the time of generation of the aforementioned element/wavelength database. Also, the setting unit16according to the modification can change associations between the photo detector identifiers and measurement item identifiers in accordance with an instruction from the user via the operation unit17.

An operation example of the automatic analyzer according to the first modification at the time of photometry will be described below with reference toFIG. 9.FIG. 9shows the typical sequence of processing in a photometry stage of the automatic analyzer according to the first modification. Note that differences betweenFIGS. 5 and 9lie in steps SC1and SC2. Therefore, only steps SC1and SC2will be described below.

As shown inFIG. 9, the collected data control unit132of the selection unit13recognizes measurement items set in the cuvette22to be measured before this cuvette22passes the photometry position PP (step SC1). The measurement items can be recognized by referring to a measurement order managed by, for example, the system control unit10.

After the measurement items are recognized, the collected data control unit132selects photo detectors81according to the recognized measurement items (step SC2). Step SC2will be described in detail below. The selection method of the photo detectors according to measurement items includes a method using an element/item database D2and that using the element/wavelength database D1and an item/wavelength database D3.

When the element/item database D2is used, the collected data control unit132searches the element/item database D2using the measurement item identifiers of the recognized measurement items as search keys, thereby specifying photo detector identifiers associated with the search keys on the element/item database D2. After the photo detector identifiers are specified, the collected data control unit132controls the switching unit131to electrically connect the photo detectors81corresponding to the specified photo detector identifiers to the A/D converter14. Thus, the photo detectors81according to the measurement items can be selected.

When the element/wavelength database D1and item/wavelength database D3are used, the collected data control unit132searches the item/wavelength database D3using the measurement item identifiers of the recognized measurement items as search keys, thus specifying wavelength band identifiers associated with the search keys on the item/wavelength database D3. Next, the collected data control unit132searches the element/wavelength database D1using the specified wavelength band identifiers as search keys, thus specifying photo detector identifiers associated with the search keys on the element/wavelength database D1. After the photo detector identifiers are specified, the collected data control unit132controls the switching unit131to electrically connect the photo detectors81corresponding to the specified photo detector identifiers to the A/D converter14. Thus, the photo detectors81according to the measurement items can be automatically selected.

As described above, the automatic analyzer according to the first modification associates measurement items with photo detectors directly or indirectly via wavelength bands. Therefore, the automatic analyzer according to the first modification can select photo detectors more quickly than that according to this embodiment.

In the above embodiment, by selecting the photo detectors81, electrical signals to be used in absorbance calculations are selected. However, this embodiment is not limited to this. An automatic analyzer according to the second modification selects electrical signals in an absorbance calculation stage. The automatic analyzer according to the second modification will be described below. Note that in the following description, the same reference numerals denote components having substantially the same functions as those of this embodiment, and a redundant description will be given only when it is necessary.

FIG. 10shows the overall arrangement of the photometry unit1according to the second modification. As shown inFIG. 10, all photo detectors81included in the photo detection unit8are electrically connected to an A/D converter14′ via the amplifiers12. The A/D converter14′ converts analog electrical signals from all the photo detectors81into digital signals. The A/D converter14′ is electrically connected to a selection unit13′. The selection unit13′ selects electrical signals related to wavelength bands used in absorbance calculations from those of all the photo detectors. For example, the selection unit13′ selects electrical signals on software using the element/wavelength database. To the selection unit13′, the absorbance calculation unit15is connected. The absorbance calculation unit15calculates absorbance based on the electrical signals selected by the selection unit13′.

As described above, the automatic analyzer according to the second modification can select electrical signals from photo detectors, which belong to wavelength bands required for absorbance calculations, without changing the mechanical arrangement up to the A/D converter.

Some embodiments of the present invention have been explained. These embodiments are presented for the exemplary purpose only, and do not intend to limit the scope of the invention. These novel embodiments can be practiced in various other aspects, and can undergo various omissions, replacements, and changes without departing from the spirit of the invention. These embodiments and modifications are included in the scope and spirit of the invention, and are also included in the inventions described in the scope of the claims and their equivalent scopes.

For example, inFIG. 2, the optical layout of the infrared cut filter3, lens4, slit5, slit6, and the like can be changed, and the infrared cut filter3and slit5may be omitted. Also, a one-dimensional layout of the photo detectors81can be used. In this case, the photo detectors are laid out only in the channel direction.