Printer that facilitates detection of deteriorated component

Abstract
An evaluation method and printer in which a maintenance man may easily identify a deteriorated component in addition to a component that is broken down or is remarkably hard to operate without the need for any additional complex detecting device. A printer has a control part which controls a mechanical part and judges quantitatively in which state among normal, deteriorated, and abnormal states each mechanical part component is located. This judgment will change in accordance with whether the printer is in a maintenance or a normal mode. Further, a deteriorated component can be determined by visually inspecting a copy after one or a combination of electric parameters have been set to printable upper and lower limits.
Description




BACKGROUND OF THE INVENTION




1. Field of the Invention




The present invention generally relates to judgment methods, and more particularly to a method for detecting. when an image-forming device is inspected for maintenance purposes, deterioration in each device component. The method of the present invention is suitable, for example, for maintenance inspection of an electrophotographic printing device, such as a copier.




2. Description of the Related Art




A conventional maintenance inspection for an electrophotographic printer has required a maintenance man to use a manual operation and consider each component to be normal if it is currently working, except for components that may be inspected with eyes such as toner in a transparent plastic vessel. A maintenance man would consider a component to be abnormal and exchange/repair it only when it is completely inoperable or very hard to operate. In other words, the conventional maintenance inspection has only judged whether a target component is normal or abnormal, and considered the component to be normal if judging it not to be abnormal.




The conventional maintenance inspection cannot help considering a component to be normal which is not completely normal but it has not reached the apparently abnormal state (referred to as “a deteriorated state” hereinafter). However, the subsequent continuous use of the deteriorated state is likely to bring about a near-future failure or very bad operation. Therefore, the conventional maintenance inspection would often result in inoperativeness shortly after the maintenance inspection, annoying customers. In addition, it has been disadvantageously difficult for the conventional maintenance inspection to easily judge whether a component is in the deteriorated state.




The deterioration in a printer component may disable printing in the near future as well as gradually lower the print quality. A print operation depends upon components having various print functions as a whole. One deteriorated component would possibly lower the entire print quality. However, the conventional maintenance inspection has a difficulty in quantitatively evaluating the print quality. Even a detection of the image-quality deterioration cannot easily trace the causative component.




SUMMARY OF THE INVENTION




Therefore, it is an exemplified general object of the present invention to provide a novel and useful evaluation method and printer in which the above disadvantages are eliminated.




Another exemplified and more specific object of the present invention is to provide an evaluation method and printer without additional complex detecting means that may enable a maintenance mall to easily identify a deteriorated component in addition to a component that is broken down or is remarkably hard to operate.




Still another exemplified object of the present invention is to provide an evaluation method and printer that enable a maintenance man to quantitatively evaluate the current print quality.




Another exemplified object of the present invention is to provide a judgment method and printer that may easily localize a causative component after the image quality is considered deteriorated.




In order to achieve the above objects, a printer of a first aspect of the present invention comprises a mechanical part which feeds a printing paper and in order to print predetermined information on the printing paper, a mode switch which switches plural modes, and a control part which controls the mechanical part and determines quantitatively in each mode which state among normal, deteriorated, and abnormal states each component in said mechanical part is located in.




A printer of a second aspect of the present invention comprises a photosensitive body, a pre-charger which charges the photosensitive body, an optical part which exposes the charged photosensitive body, a developer which applies a bias voltage to toner and develops the exposed photosensitive body, forming a toner image with a desired concentration, a transfer unit which transfers the toner image onto a printing paper by applying a transfer current to the printing paper, and a control part which enable printing by setting to a printable upper and lower limits one or more set values among electric parameters including a surface potential in the photosensitive body, an exposure power in the optical part, the bias voltage in the developer, and the transfer current in the transfer unit.




An evaluation method of the present invention comprises the steps of setting a mode used to test a print quality margin, setting to an upper or lower value one or more set values among electric parameters including a surface potential in said photosensitive body, an exposure power in the optical part, a bias voltage in the developer, and a transfer current in the transfer unit, printing a predetermined pattern in accordance with the set electric parameters.




Other objects and further features of the present invention will become readily apparent from the following description of the embodiments with reference to accompanying drawings.











BRIEF DESCRIPTION OF DRAWINGS





FIG. 1

is a block diagram of a printer of a first embodiment according to the present invention.





FIG. 2

is an enlarged section showing an exemplified paper feed system that is applicable to mechanical part


10


shown in FIG.


1


.





FIG. 3

is a timing chart for detecting that something is wrong with the paper feed motor shown in FIG.


2


.





FIG. 4

is a flowchart showing an exemplified evaluation method of the present invention that is applicable to the paper feed system, shown in FIG.


2


.





FIG. 5

is a rear view of a motor in an exemplified device applicable to the printer shown in FIG.


1


.





FIG. 6

is a timing chart for detecting that something is wrong with an Mg roller and/or Mg roller detector shown in FIG.


5


.





FIG. 7

is a front view of the motor in the device shown in FIG.


5


.





FIG. 8

is a rear view of a sensor and a photo-interrupter in the device shown in FIG.


5


.





FIG. 9

is a timing chart for detecting that something is wrong with a pinch-roller adhesion motor, a pinch roller UP position detector a separation tab set position detector, a pinch-roller position down


1


detector and/or a pinch-roller position down


2


detector.





FIG. 10

is a partial block diagram of the printer mechanical part shown in FIG.


1


.





FIG. 11

is a detailed block diagram of a control part shown in FIG.


1


.





FIG. 12

is a relationship between a grid voltage and toner concentration that affect the print quality.





FIG. 13

is an exemplified flowchart of an evaluation method of the present invention.





FIG. 14

is a block diagram showing an exemplified high-voltage power unit shown in FIG.


11


.











DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS




A description will now be give of printer


100


of a first embodiment according to the present invention, with reference to the accompanying drawings. Those elements in each drawing which are designated by the same reference numerals denote the same elements, and a duplicate description thereof will be omitted.




The printer


100


of the present invention includes. as shown in

FIG. 1

, mechanical part


10


, control part


20


, monde switch


30


, detection level input part


40


, and display part


50


.

FIG. 1

is a block diagram of a printer of the first embodiment according to the present invention.




The mechanical part


10


generalizes components in the printer


100


, and thus includes paper feed, print, and other systems. The control part


20


controls the mechanical part


10


, and includes RAM


22


and ROM


24


. The RAM


22


stores a detection level entered from the detection level input part


40


, and the ROM


24


stores a control program by which the control part


20


controls the mechanical part


10


.




The mode switch


30


switches an operation mode of the printer


100


between a normal mode and a maintenance mode, by a manual operation or an automatic operation in accordance with a host device connected to the control part


20


. In the manual input, the mode switch


30


would be equipped with an input device having various types of keys. As described later, the mode switch


30


may be comprised of display part


50


and a touch-key operation panel. The normal mode allows the printer


100


to conduct a normal operation and print predetermined information on a printing paper. The maintenance mode is used for a maintenance man to inspect each component in the printer


100


. The printer


100


of the present invention displays its unique effects when the mode switch


30


is set to the maintenance mode and works similar to known printers when the mode switch


30


is set to the normal mode.




The detection level input part


40


may store detection levels corresponding to a completely normal state. a deteriorated state, and an abnormal (or unusual) state. The detection level input part


40


may be used for both the normal and maintenance modes.




The display part


50


indicates various messages to a maintenance man and an operational status of the printer


100


, such as “no paper”, “replace toner”, etc. The display part


50


may use both the normal and maintenance modes.




With reference to

FIG. 2

, a description will be given of exemplified concrete components of paper feed motor


66


and paper sensor


69


in the mechanical part


10


that is applicable to the evaluation method of the present invention.

FIG. 2

is an enlarged section showing the exemplified paper feed system in the mechanical part


10


. As illustrated, the paper feed system in the mechanical part


10


includes height sensor


61


, “no paper” detecting sensor


62


, pick roller


64


, paper feed motor


66


, feed roller


67


, reverse roller


68


, paper sensors


69


and


71


, central rollers


70


, and eject rollers


72


.




The amount of printing paper stock is detected by the height sensor


61


that detects the height of a printing paper. The “no paper” detecting sensor


62


detects that stacker


63


has no printing papers. The height sensor


61


and the “no paper” detecting sensor


62


are connected to the controller


20


shown in

FIG. 1

, and the display part


50


indicates the information on “no paper”. However, these components are known in the art, and a description of their detailed structures and operations will be omitted.




The pick roller


64


is engaged with motor shaft


65


in the paper feed motor


66


, and the paper feed motor


66


is controlled by the controller


20


. The pick roller


64


serves to pick up a printing paper. Other rollers, such as the roller


67


, are connected to motors (not shown) by a well-known method and controlled by the control part


20


, and a detailed description of their structures and operations will be omitted.




The reverse roller


68


rotates revere to the feed roller (


67


, and separates, if two sheets of papers are erroneously fed, the uppermost paper from the remaining papers so as to feed this to feed path


73


. The sensors


69


and


71


may each use a light-emitting element and a light-receiving element, for example. The ejected paper from the eject roller


72


is fed to the print system (not shown).




A fault associated with the pick roller


64


, such as a paper jam, is detectable by measuring a paper feed period (“t1”) from time when an ON signal for starting the pick roller


64


is supplied to time when the paper sensor


69


detects a paper edge, and comparing t1 with a reference value. A fault associated with the central rollers


70


at both sides of the feed path


73


is detectable by measuring a paper feed period (“t2”) between the sensors


69


and


71


, and comparing t2 with a reference value.




With reference to

FIGS. 3 and 4

, a description will now be given of the evaluation method of the present invention that is applied to the paper feed system.

FIG. 3

is a timing chart showing the paper feed period t1.

FIG. 4

is a flowchart that the controller


20


performs and is stored, for example, as a control program in the ROM


24


. Alternatively, the evaluation method of the present invention may be loaded as a printer driver onto a general-purpose personal computer connected to the printer


100


. In that case, the personal computer CPU may perform the following operation of the control part


20


.




Advantageously, the evaluation method of the present invention classifies t1 into three groups of “normal state”, “deteriorated state”, and “abnormal state”, and assigns “100 ms or shorter”, “101 ms to


119


ms”, and “120 ms or longer”, to them respectively.




The control part


20


initiates the feed motor


60


by supplying a drive circuit in the feed motor


66


(not shown) with an ON signal (step


1001


), and clears, by setting this time to be time 0, a timer (not shown) which measures the paper feed period t1 (step


1002


). The timer is provided in the controller


20


, and may employ any structure known in the art. For example, the timer includes a pulse generator that provides a pulse having a 1 ms period, and a counter that counts the number of pulses. Alternatively, the timer may use an electronic clock in a personal computer when the evaluation method of the present invention is loaded as a printer driver onto a general-purpose personal computer connected to the printer


100


. The leading edge time of the feed motor


66


in

FIG. 3

is the time when the ON signal is supplied. Thereby, the paper feed motor


66


picks up a printing paper and feeds it to the feed path


73


. When this feeding paper reaches the sensor


69


through the feed roller


67


, a detection signal of the sensor


69


is fed to the control part


20


and consequently the control part


20


may know, using the timer, the detection time by the sensor


69


. The leading edge time of the paper sensor


69


in

FIG. 3

is the time when the paper reaches the sensor


69


.




The control part


20


thus obtains the paper feed period t1 (steps


1003


and (


1004


). When the paper feed period t1 is between 0 and 100 ms, it is normal. The control part


20


then considers the current operational mode to be normal whether it is set to a normal mode or a maintenance mode (steps


1006


and


1007


), and will or will not display that fact and/or a value of t1 on the display part


50


.




When the paper feed period t1 is between 101 and 109 ms, it is deteriorated. The control part


20


then considers the current operational mode to be normal when it is set to the normal mode (steps


1009


,


1006


, and


1007


), and considers it to be abnormal when it is set to the maintenance mode (steps


1009


,


1010


, and


1011


). The display part


50


indicates the resultant judgment by the control part


20


.




According to this embodiment, the control part


20


considers the deteriorated stated to be normal in the normal mode. This is because in the normal mode in the instant embodiment the longer paper feed than the usual does not deteriorate the image quality and a user in general is presumed to be satisfied with the obtained result. On the contrary, the deterioration in a print system component disadvantageously lowers the image quality, as described later, and may be considered to be abnormal even in the normal mode. Optionally, the control part


20


may consider a component to be abnormal in the normal mode when the component belongs to a system other than the print system. Such setting may be preinstalled as a program in the ROM


24


in the factory before the printer


100


is shipped, or may be input by a provider as a result of conference with a customer at an initial setup when he/she provides the customer with the printer


100


.




When the paper feed period t1 exceed 120 ms, it is abnormal. The control part


20


then considers the current operational mode to be abnormal (steps


1012


and


1013


), and displays the fact and/or a value of t1 on the display part


50


.




The control part


20


may indicate a conceivable countermeasure instead of or in addition to displaying the normality or abnormity. For example, it is a letter or symbol that recommends an adjustment of the paper feed motor


66


, the paper sensor


69


and/or an engagement state between the pick roller


64


and the motor shaft


65


, or that identifies a component that should be replaced. Needless to say, a deteriorated component might possibly be the sensor


69


or the like rather than tile feed motor


66


.




Optionally, the control part


20


may recognize and display the deteriorated state as an independent state, instead of assigning it to the normal or abnormal state. In this case, a maintenance man may inform a customer that something will possibly be wrong with the feed motor


66


etc. in the near future, and give a spare to the customer without replacing the feed motor


66


etc. if the replacement is easy for the customer. Instead, the maintenance man leaves the conclusion to customer's decision. If the customer would like the maintenance man to come again and replace it when the breakdown occurs, the maintenance man may avoid making repairs this time. Such a measurement may take into consideration the frequency of customer's use and a deterioration level, e.g., a case where t1 is close to the normal state, such as 101 ms. Such options are common to the following embodiments.




The evaluation method of the feed system in this embodiment considers the deteriorated state to be abnormal or at least informs a customer of the deterioration, whereas the deteriorated state has been considered to be normal in the conventional maintenance mode. As a consequence, the instant evaluation method may prevent a breakdown shortly after the maintenance inspection or evade customer's disgust even if a breakdown occurs shortly after the maintenance inspection. Therefore, the evaluation method of this embodiment may improve the maintenance service.




The evaluation method of the present invention changes a detection level between the normal and maintenance modes, but does not change its operation, facilitating easy and inexpensive maintenance inspection. For example, a method that requires the maintenance mode to increase a printing-paper feed speed for a test mode needs an independent drive unit etc., making the entire device expensive. The evaluation method of the present invention eliminates such a problem.




The evaluation method of the present invention is applicable to Mg motor


80


and Mg roller rotation detector


81


when the mechanical part


10


is designed as shown in FIG.


5


. The structure shown in

FIG. 5

is known as a rear view of a motor in Fujitsu F6760 page printer, and a description of detailed structures and operations of components will be omitted.




The control part


20


in

FIG. 5

is set so that it considers abnormal a case where 2 seconds after the developer Mg motor


80


starts no output changes from the Mg roller station detector


81


continues for 300 ms or longer. Referring to

FIG. 6

, according to the evaluation method of the present invention the control part


20


considers t1 to be abnormal when t1 is 300 ms or longer, and t1 to be normal when t1 is less than 300 ms.

FIG. 6

is a timing chart for use with the Mg roller rotation detector


81


to detect that something is wrong with the Mg roller motor


80


and Mg roller rotation detector


81


, but the timing chart is usually used to detect that something is wrong with the Mg roller motor


80


. Illustrated t1 is expected to be about 150 ms in the normal state, and thus is classified into three groups of “normal state”, “deteriorated state”, and “abnormal state” which are assigned “shorter than 225 ms”, “225 ms or longer but shorter than 300 ms”, and “300 ms or longer”. The control part


20


considers the deteriorated state to be normal in the normal mode, and considers it to be abnormal in the maintenance mode.




It is understood that such an evaluation method requires the step


1005


in

FIG. 4

to be replaced with 0 through 224 ms, the step


1008


with 225 through 300 ms, the step


1012


with 300 ms or longer, and these steps


1006


and


1010


with output changes from the Mg roller rotation detector


81


.




As described, the evaluation method of the present invention quantitatively detects, using a detector in the printer


100


, which status among the normal, deteriorated and abnormal states each component is located in. The present invention is thus clearly applicable to other detectors. For example, the present invention is applicable to pinch-roller adhesion motor


82


, pinch-roller UP position detector


83


, separation tab set position detector


84


, pinch-roller position down


1


detector


85


, and pinch-roller position down


2


detector


86


shown in

FIGS. 7 and 8

. Hereupon,

FIG. 7

is a front view of a motor in Fujitsu F6760 page printer shown in

FIG. 5

, and

FIG. 8

is a rear view of a sensor and a photo-interrupter in the printer.




The control part


20


in

FIGS. 7 and 8

is set so that it may considers abnormal a case where no outputs from the separation tab set position detector


84


are generated within 1 sec after the pinch-roller adhesion motor


82


is started. Referring to

FIG. 9

, the evaluation method of this embodiment makes the control part


20


consider t1 that is 1 sec or longer, to be abnormal and evaluate t1 that is less than 1 sec, to be normal in the normal mode.

FIG. 9

is a timing chart for detecting that something is wrong with the pinch-roller adhesion motor


82


and/or detector


83


etc., but is usually used to detect that something is wrong with the pinch-roller adhesion motor


82


(and its engagement with another component). Illustrated t1 is expected to be about 260 ms if normal, and is classified in the maintenance mode into three groups of “normal state”, “deteriorated state”, and “abnormal state” which are assigned “shorter than 630 ms”, “630 ms through 1 sec” and “longer than 1 sec”, respectively. The control part


20


evaluates the deteriorated state to be normal in the normal mode, and to be abnormal in the maintenance mode.




The control part


20


terminates and then reactivates the pinch-roller adhesion motor


82


after detecting the separation tab set position. The control part


20


is also set so that it considers abnormal a case where no outputs are generated from either the pinch-roller position down


1


or


2


detector within 1 sec which is determined by an output of a paper thickness indicator (not shown). Referring to

FIG. 9

, the evaluation method of this embodiment makes the control part


20


consider t2 or t3 that is 1 sec or longer, to be abnormal, and t2 and t3 that are both less than 1 sec, to be normal in the normal mode. However, t2 shown in

FIG. 9

is expected to be about 280 ms in the normal state, and thus is classified in the maintenance mode into three groups of “normal state”, “deteriorated state”, and “abnormal state” which are respectively assigned “shorter than 640 ms”, “640 ms through 1 sec”, and “longer than 1 sec”. The control part


20


considers the deteriorated state to be normal in the normal mode, and to be abnormal in the maintenance mode. Similarly, t3 shown in

FIG. 9

is expected to be about 320 ms in the normal state, and thus is classified in the maintenance mode into three groups of “normal state”, “deteriorated state”, and “abnormal state” which are respectively assigned “shorter than 660 ms”, “660 ms through 1 sec”, and “longer than 1 sec”. The control part


20


considers the deteriorated state to be normal in the normal mode, and to be abnormal in the maintenance mode.




The control part


20


terminates and then reactivates the pinch-roller adhesion motor


82


after detecting the pinch-roller position down


1


or


2


. The control part


20


is also set so that it considers abnormal a case where no outputs are generated from the pinch-roller UP position detector


83


within 2 sec after reactivating the pinch-roller adhesion motor


82


. Referring to

FIG. 9

, the evaluation method of this embodiment makes the control part


20


consider t4 that is 2 sec or longer, to be abnormal, and t4 that is 2 sec or shorter, to be normal in the normal mode. However, t4 shown in

FIG. 9

is expected to be about 940 ms in the normal state, and thus is classified in the maintenance mode into three groups of “normal state”, “deteriorated state”, and “abnormal state” which are respectively assigned “shorter than 1470 ms”, “1470 ms through 2 sec”, and “longer than 2 sec”. The control part


20


evaluates the deteriorated state to be normal in the normal mode, and to be abnormal in the maintenance mode.




The evaluation method of this embodiment may be realized using

FIG. 4

, and a description thereof will be omitted.




Next follows a description of the inventive evaluation method applied to the print system. The conventional maintenance inspection cannot recognize the image quality quantitatively. The deteriorated image quality includes white printing (i.e., a phenomenon that a portion that should be colored in black becomes white), white bands, entirely pale or dark color, blotching, being unable to obtain the image quality corresponding to a desired print mode (for example, the image quality is coarse even in a fine mode), black blobs on a paper, etc. It is also difficult for the conventional inspection with eyes to identify a component that becomes deteriorated or broken down. The print operation is composed of a plurality of processes including charging, exposure, development, transferring with a photosensitive drum, and the image quality is a synthetic quality result of these processes.




The present invention has addressed, as electric parameters that affect the image quality, a photosensitive-drum surface potential, exposure power, development magnetic-brush bias voltage, and transfer current which depend upon the printer


100


's environment (such as temperature and humidity), and has intended to improve the entire image quality by changing these parameters singularly or in combination and evaluating the resultant image quality. Concretely, this embodiment judges, as a quality guarantee test at the time of manufacturing and/or maintenance inspection, whether the printer


100


may operate properly, while changing singularly or in combination up and down within a printable range, standard (or current) values of the above electric parameters which activate the printer


100


.




With reference to

FIGS. 5

,


7


,


8


and


10


, a brief description will be given of the photosensitive-drum surface potential, exposure power, development magnetic-brush bias voltage, and transfer current.




The printer


100


includes photosensitive drum


102


, transfer unit


104


, pre-charger


106


, optical part


108


, and developer


110


. A printing paper passes between the photosensitive drum


102


and the transfer unit


104


. The pre-charger (e.g., corona charger)


106


charges the photosensitive drum


102


. The photosensitive drum


102


is made, for example, of an aluminum drum onto which an about 20 im thickness of function-separation type organic photosensitive member is applied. The photosensitive drum


102


has a diameter, for example, of 30 mm and rotates in an arrow direction at a rotational speed of 70 mm/s. The corona charger is made, for example, of a Scorotron charger, and charges uniformly the photosensitive drum


102


surface by about −500 V. The corona charger


106


has a high-voltage wire (not shown) that may apply 8 through 12 kV, and applies a potential by corona discharge onto a grid screen (“grid”) spaced from this wire. The grid is connected directly or close to the photosensitive drum


102


, while the grid voltage and the drum surface potential are controlled to be equal. Surface-potential detector


120


which may employ any structure known in the art detects the surface potential of the photosensitive drum


102


.




Next, the optical part


108


exposes the uniformly charged photosensitive drum


102


by a laser and forms a latent image with −50 through −100 V on the photosensitive drum


102


. The exposure power thus determines the latent image quality.




Then, the latent image is developed by the developer


110


having development roll


112


, and thereby converted into a toner image on the photosensitive drum


102


. The development roll


112


rotates in arrow direction P in

FIG. 10

, and a fixed magnetic pole member having a plurality of magnetic poles, and a sleeve that rotates around the magnetic pole member. This sleeve rotates in the arrow direction P as illustrated, and feeds the development agent to a development area that faces the photosensitive drum


102


. Toner retains an electric charge opposite to the electric charge pattern on the photosensitive drum


102


, and is absorbed by the electrostatic force onto the photosensitive drum


102


surface for development. A bias voltage that is applied to the magnetic brush formed on the development roll


112


adjusts charging to toner, and toner concentration.




The transfer unit


104


faces the photosensitive drum


102


via the printing-paper feed path. The transfer unit


104


adopts a known transfer unit having a corona (discharge) wire, and applies the transfer current to a printing paper using the corona discharge. The current flowing from the corona (transfer) wire to the photosensitive drum


102


is transfer current. When a printing paper reaches the transfer position, the transfer unit


104


applies a voltage to the corolla wire


282


from a surface opposite to the printed surface of the printing paper. As a consequence, the toner image on the photosensitive drum


102


surface is transferred by absorbing and attaching the toner image onto the printing paper.




A description will be given of a margin test of the present invention regarding a controls over the photosensitive-drum surface potential, exposure power, development magnetic brush bias voltage, and transfer current. These are controlled by mechanical-part control circuit


150


that will be described below. Hereupon, the control part


20


shown in

FIG. 1

specifically includes, as shown in

FIG. 11

, controller


140


and mechanical-part control circuit


150


.




The controller


140


is connected via an interface (not shown) which is provided at the rear surface etc. of the printer


100


, to a computer, a network, such as a LAN, and other external devices (not shown) (hereinafter simply “host computer”).




The controller


140


converts print information sent from the host computer into, for example, bit map video data, and send it to the mechanical-part control circuit


150


. The controller


140


may employ any structure known in the art, and a description thereof will be omitted.




The mechanical-part control circuit


150


controls high-voltage power unit


160


and exposure power control part


170


, and generates a switching signal for them. The switching signal is changed by a selection of a double-side or single-side print unit or by a parameter, such as a regular paper and a thick paper. The mechanical-part control circuit


150


controls other mechanical components (units) in the body, such as a main motor. It is conceivable that the mechanical-part control circuit


150


includes pre-charger control part


162


, development magnetic brush bias control part


164


, and transfer current control part


166


shown FIG.


10


.




The mechanical-part control circuit


150


includes PROM


152


corresponding to the ROM


24


, various sensors (


120


,


122


aid


124


), RAM


154


corresponding to RAM


22


, and MPU


156


. The mechanical-part control circuit


150


is connected to the controller


140


. and receives bit map video data (print data) from the controller


140


. The display part


50


indicates an operation of the mechanical-part control circuit


150


connected to the display part


50


. The display part


50


may be comprised of the mode switch


30


and a touch-key operational panel. The mechanical-part control circuit


150


is connected to a main motor (not shown), the high-voltage power unit


160


, and the exposure power control part


170


. For illustration purposes,

FIG. 11

shows only signal lines that which supply control signals (s


1


through sN), and any desired number of signal lines may be provided depending upon the number of parameters to be changed (i.e., controlled).

FIG. 11

generalizes such other signal lines as sN.




The PROM


152


stores, as a program, an instruction to each unit and set data, and necessary data is loaded onto and executed by the RAM


154


. The MPU


156


operates in accordance with the program stored in the PROM


152


. Various sensors include or are connected to outputs of surface-potential detector


120


, temperature sensor


122


, and hygrometer sensor


124


, and their outputs are supplied to the MPU


156


in any event. Those sensors such as the temperature sensor


122


and the hygrometer sensor


124


may employ any structure known in the art, and a description of their structures and operations will be omitted.




The MPU


156


receives print data and resultant outputs from the various sensors. including information such as the paper size (width), paper type (such as a thick paper, a regular paper, or a printing paper made by other manufacturers), resolution etc., and generates a variety of control signals in accordance with the program stored in the PROM


152


. More specifically, the MPU


156


controls logic for each signal line, thereby controlling a print operation.




The signal s


1


switches a speed of the main motor (not shown), a voltage for the pre-charger in the high-voltage power unit


160


, and a resolution in the optical part


108


. The signal s


1


is branched in the mechanical-part control circuit


150


, and output to each unit. The signal sN includes a switch signal to regulate the high-voltage power unit


160


's transfer current and the development magnetic brush's bias voltage.




For example, (the pre-charger control part


162


in) the high-voltage power unit


160


in response to the signal s


1


switches the voltage in the pre-charger


106


. The pre-charger control part


162


controls the grid and photosensitive drum


102


so that their surface potentials are equal to each other. For example, in an attempt to set the grid and the photosensitive drum


102


to 500 V, the control part controls the voltage to be applied to the wire within the range from 8 to 12 kV. However, the dirty grid and other reasons often prevent the grid and the drum surface potential from being equal to each other. For example, even when the grid is 500 V, the drum surface potential may possibly be 400 V. In this case, the mechanical-part control circuit


150


controls the pre-charger control part


162


so that the drum surface potential becomes 500 V.




The exposure power control part


170


controls, using a clock and a counter (not shown), a laser emitting time in response to the signal s


1


(so that the laser emitting time becomes the time set by the clock x the control signal s


1


).




The printer


100


of the present invention advantageously has a print mode which may set one or all of the drum surface potential, the exposure power, the development bias voltage, and the transfer current, to printable upper and/or lower limits.




A description will be given of the evaluation method of the present invention applied to the printer


100


, with reference to FIG.


12


.

FIG. 12

is the image quality depending upon a relationship between the grid voltage and the toner concentration, and allows the current print status (i.e., margin) to be confirmed in

FIG. 12

by adjusting the grid voltage and the toner concentration. For example, suppose that the development carrier is adhered to a printed surface when the drum surface potential is set to the upper limit and the exposure power, the development bias, and the transfer current are set to the current values. That is, when the carrier that is black powder is adhered to the printing paper surface, graining the surface and/or blanching a portion that should be originally colored in black (while this state is referred to as “carrier leakage” in FIG.


12


), a gap between the developer


110


and the photosensitive drum


102


is not presumably proper and may become an inspection object for maintenance purposes. Similarly, when a portion that is not printed and thus should become white becomes gray or black when the drum surface potential is set to the lower limit and other set values are set to the current values (although this printing state is referred to as “fog” in FIG.


12


), the abnormally deteriorated development agent or unusual toner concentration are presumably causative and may become an object for maintenance inspections.




Next follows a description of the evaluation method of the present invention with reference to FIG.


13


. The (MPU


156


in the) mechanical-part control circuit


150


confirms whether the operational mode is transferred to the test (or maintenance) mode by switching at the mode switch


30


or a key input to the operational panel comprising the mode switch


30


and the display part


50


(step


1002


). When the test mode is set, the display part


50


then prompts a user to select either a single-set or combination-set printing. Then, the mechanical-part control circuit


150


confirms whether either the single-set or combination-set printing is selected (step


1004


). Hereupon, the “single-set printing” means a printing where one of the surface potential, the exposure power, the development bias, and the transfer current is set to an upper or lower limit and the other parameters remain to use the current (or standard) set values. The “combination-set printing” means a printing where two or more of them are set to upper and/or lower limits. When the single-set printing is selected, the display part


50


requires the user to select one of the above four objects and an upper or lower value for the selected object. The user, may input that data by any means. For example, the display part


50


may indicate an option of object selection in the order from the surface potential, and then display an option of value selection (i.e., upper or lower limit) for the selected object. Alternatively, the user may input using keys a specific object and a set value. In any event, an object and a set value are consequently selected (step


1006


).




For example, the transfer current set to the lower limit would generate a bad transferring or drum's evasion. The transfer current set to the upper limit would generate an uneven potential and dust/discoloration on the drum.




Hereupon, the “bad transferring” means that a necessary amount of a toner image on the photosensitive drum is not transferred to a paper. The “evasion” means that too much toner remains on the photosensitive drum to be completely removed by a cleaning part.




The “uneven potential” means that the photosensitive drum has an uneven potential even after a charge removal or uniform charging is performed for the photosensitive drum. The “dust” means that toner is transferred not to a desired position but to another position. The “discoloration” means that toner is not transferred to a recording paper and no toner is adhered into an image.




When the user selects a combination-set printing at step


1004


, the display part


50


prompts the user to select the combination. Similarly, the user may use any input manner. For example, the display part


50


may indicate an option of object selection in the order from the surface potential and then display an option of value selection in the order from the current value.




After the steps


1006


and


1008


. the display part


50


prompts the user to designate a print pattern, and the user in response designates the print pattern (step


1010


). Alternatively, the display part


50


may indicate a plurality of print-pattern candidates that have been previously stored in the PROM


152


etc., and prompt the user to designate one of the candidates. Optionally. such a step may be omitted by always using a fixed print pattern, or a step for confirming whether the selected value is within the actually printable range may be added. For example, when the current value of the grid voltage is 700 V and 150 V is selected to define the lower limit, i.e., the lower limit is set to 750−150=550 V, a step for confirming whether 550 V is more than the printable lower limit (for example, that is 450 V). Such a step is especially useful when the user arbitrarily sets the upper and lower limits using the operational panel. However, such a step is unnecessary if the MPU


156


automatically executes an operation, and ascertains that the set current value may always be between the printable upper and lower limits. The printable upper and lower limits associated with temperature, humidity etc. may be stored as simulation data in the ROM


24


.




Suppose that the surface potential and the development bias voltage are varied to their upper and/or lower limits. When the surface potential and the development bias voltage are set to their lower limits, the toner concentration on the photosensitive drum would decrease and fade print. The surface voltage that is set to the upper limit and the development bias voltage that is set to the lower limit would cause the carrier leakage and/or fog (charge injunction) in addition to the faded print. When the surface voltage is set to the lower limit and the development bias voltage is set to the upper limit, a bad fixation, void, (true) fog, and/or dullness occurs. When the surface voltage and the development bias voltage that are set to their upper limits, the toner concentration on the photosensitive drum increases, generating dullness and void.




The “faded print” means that the small amount of toner on the photosensitive drum lowers the toner concentration on a paper, exhibiting a pale printing. The “carrier leakage” means that the carrier in the developer is pulled out by the photosensitive-drum surface voltage, and adhered to the paper. The “fog (charge injection)” means that the photosenisitive-drum surface voltage is high enough to absorb the toner on the development roller, developing a portion that should not be originally developed on the photosensitive drum and causing an entirely dark printing. The “(true) fog” means that toner's electric charges are pulled onto the photosensitive drum and develop a portion that should not be originally developed, generating an entirely dark printing. As to the phenomenon, the (true) fog is similar to the fog (electric charge injection). The “bad fixation” means that too much toner is transferred onto a paper to fix on the paper even after the paper passes through the fixation device, causing peeling off of the toner. The “void” means that toner transferred onto a paper is popped at the fixation stage, generating an uneven toner surface. The void causes an image of unequal brilliance, and the popped toner spreads and results in collapse. This void is likely to occur in the fixation device that uses a flush fixation using light to fix toner. The “dullness” means that too much toner transferred onto a paper causes an image to be fixed outside a portion that defines the original image, causing a blurred line and a crushed letter.




Next follows a printing (step


1012


). The number of prints is preferably, for example, three on end for each kind while all the objects and their set values are printed at an upper left portion of the print pattern, thereby, improving reliability.




If necessity arises, the above operation continues for a different control object (step


1014


). When the normal mode is selected after the test (step


1016


), a set value for each control object is returned to the current value (step


1018


).




The upper and lower values of the drum surface potential, the exposure power, the development bias voltage, and the transfer current may be set by configuring the high-voltage power unit


160


with rectifier


161


, switching part


162


, transformer


163


. DC output part


164


, voltage control part


165


, and variable DC voltage part


166


. The variable DC voltage part


166


includes resistors R


1


through R


4


, analog switches


167


and


168


connected to R


2


and R


3


. As control signals sn


1


and sn


2


from the MPU


156


opens and closes switches


167


and


168


, the output voltage Vout becomes {(R


1


+R


2


+R


3


+R


4


)/(R


3


+R


4


)}Vf when the switches


167


and


168


both turn off, {(R


1


+R


3


+R


4


)/(R


3


+R


4


)}Vf when the switch


167


turns on and the switch


168


turns off, and {(R


1


+R


2


+R


4


)/R


4


}Vf when the switch


167


turns off and the switch


168


turns on. R


1


through R


4


may be adjusted so that the above values become respectively a standard value, a lower value, and an upper value. The rectifier


161


, switching part


162


. transformer


163


, DC output part


164


, and voltage control part


165


may use any structure known in the art, and a description thereof will be omitted.




The PROM


152


has previously stored upper and lower values as simulation data suitable for printer's environment (such as temperature and humidity), and the MPU


156


may preferably calculate the optimal upper and lower values using such data. Optionally, the upper and lower values may be arbitrarily set from the input means such as the operational panel. Then, the display part


50


and/or all alarm (not shown) may alarm by indication or sound in response to an input which exceeds the printable upper or lower limit.




The present invention enables a user to arbitrarily select one or more the above drum surface potential, the exposure power, the development bias voltage, and the transfer current, by means of the display part


50


etc. The printing under such dividable process conditions facilitates a margin confirmation and preventive maintenance. The image quality is commonly composed of a plurality of processes, and the prior art image-result inspection with eyes cannot identify a deteriorated component. On the other hand, the inventive printing may easily identify the deteriorated component by using the electric parameters singularly or in combination. The upper and lower values that are quantified improve simplicity and reliability in comparison with the conventional inspection with eyes.




Further, the present invention is not limited to these preferred embodiments, but various variations and modifications may be made without departing from the scope of the present invention.




A printer of a first aspect of the present invention may quantitatively recognize deterioration of a component that has not been recognized in the prior art, and predict a possible drawback that would happen in the near future by evaluating the deteriorated state to be abnormal. A printer of a second aspect of the present invention may print while setting one or more of those electric parameters which include photosensitive drum's surface potential, optical part's exposure power, developer's bias voltage, and transfer unit's transfer current, to printable upper and/or lower limits, thereby confirming the image quality margin easily and improving the reliability on a printed result. The image quality is commonly composed of a plurality of processes, and the prior art image-result inspection with eyes cannot identify a deteriorated component. On the other hand, this invention may easily identify the deteriorated component by using the electric parameters singularly or in combination. The upper and lower limits that are quantified improve simplicity and reliability in comparison with the conventional inspection with eyes. Similarly the evaluation method of the present invention enables printing by setting the electric parameters to upper and/or lower limits, thereby confirming the image quality margin easily and improving the reliability on a printed result.



Claims
  • 1. A printer comprising:a mechanical part which feeds a printing paper in order to print predetermined information on the printing paper; a mode switch which switches between plural modes; and a control part which controls said mechanical part and determines quantitatively, in each mode in which state among normal, deteriorated, and abnormal states each component in said mechanical part is located, wherein said mode switch switches an operation of said mechanical part between a normal mode and a maintenance mode, wherein said control part considers the normal and deteriorated states to be normal and the abnormal state to be abnormal when said mode switch is set to the normal mode, and wherein said control part considers the normal state to be normal and the deteriorated and abnormal states to be abnormal when said mode switch is set to the maintenance mode.
  • 2. A printer according to claim 1, further comprising a display part that indicates the normal state, the deteriorated state, and the abnormal state of said mechanical part.
  • 3. A printer according to claim 1, further comprising a display part which indicates a deterioration level when said mechanical part is in the deteriorated state.
  • 4. A printer according to claim 1, further comprising a detection level input part which sets detection values for the normal, deteriorated, and abnormal states.
  • 5. A printer comprising:a photosensitive body; a pre-charger which charges said photosensitive body; an optical part which exposes said charged photosensitive body; a developer which applied a bias voltage to toner and develops said exposed photosensitive body, forming a toner image with a desired concentration; a transfer unit which transfers the toner image onto a printing paper by applying a transfer current to the printing paper; and a control part which enables printing by setting to printable upper and lower limits one or more set values among electric parameters including an exposure power in said optical part, the bias voltage in said developer, and the transfer current in said transfer unit.
  • 6. A printer according to claim 5, further comprising an input part that may select an arbitrary combination out of the electric parameters,wherein the electric parameters further include a surface potential in said photosensitive body which is to be combined, when used by said control part, with at least one of the exposure power, the bias voltage, and the transfer current.
  • 7. A printer according to claim 5, further comprising a compensation part which compensates the upper and lower limits in accordance with an environment.
  • 8. A printer according to claim 5, further comprising an input part that may set the set values.
  • 9. A printer according to claim 8, further comprising an alarm part that notices that the set value exceeds the printable upper or lower limit.
  • 10. A printer according to claim 5, further comprising a selection part which enables the set values among the electric parameters to be printed on the printing paper.
  • 11. An evaluation method comprising the steps of:setting a mode used to test a print-quality margin; setting to an upper or lower value one or more set values among electric parameters including an exposure power in an optical part, a bias voltage in a developer, and a transfer current in a transfer unit; and printing a predetermined pattern in accordance with the set electric parameters.
Priority Claims (1)
Number Date Country Kind
11-026438 Feb 1999 JP
US Referenced Citations (12)
Number Name Date Kind
4335952 Conly et al. Jun 1982 A
4785329 Walsh Nov 1988 A
4821068 Honma et al. Apr 1989 A
4958188 Miyamoto Sep 1990 A
5012279 Nakajima et al. Apr 1991 A
5053815 Wendell Oct 1991 A
5313253 Martin et al. May 1994 A
5335043 Kluger et al. Aug 1994 A
5508787 Hasegawa et al. Apr 1996 A
5619307 Machino et al. Apr 1997 A
5839013 Murasawa et al. Nov 1998 A
5946521 Budnik et al. Aug 1999 A
Foreign Referenced Citations (15)
Number Date Country
0093242 Nov 1983 EP
0 476 681 Mar 1992 EP
0 684 526 Nov 1995 EP
0 810 484 Dec 1997 EP
0 811 890 Dec 1997 EP
56-50338 May 1981 JP
58-200250 Nov 1983 JP
61-198174 Sep 1986 JP
62-221572 Sep 1987 JP
1-311898 Dec 1989 JP
3-44730 Feb 1991 JP
3-73865 Mar 1991 JP
4-284465 Oct 1992 JP
5-31960 Feb 1993 JP
7-280889 Oct 1995 JP