JPH06270457A - Ion printer - Google Patents

Abstract

PURPOSE:To always enable gradation image recording of high quality by always performing highly accurate correction even when ion emitting characteristics are changed after the start of use and forming correction data reduced in the error with actual ion emitting characteristics. CONSTITUTION:An ion current measuring part 8 is preliminarily incorporated in an apparatus and two measuring modulation data DMD are supplied to a printing head driving circuit 3 from an ion current measuring part 8 at every ion hole at a time of non-printing operation in such a state that a data changeover part 7 is changed over to the ion current measuring part 8 to generate an ion current I from the ion hole of a printing head 2. This ion current value is detected through a detection resistor 9 and, on the basis of the detected ion current value, linear approximate operation is performed to calculate the constant group showing the characteristics of the ion hole and the constant group is stored in a characteristic data memory part 6 to be subjected to the correction operation of gradation data at a time of subsequent printing operation.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to improvements in ion printers.

[0002]

2. Description of the Related Art An ion printer has been conventionally known as one of devices for making a hard copy of image information. The ion printer forms ions by, for example, corona discharge, and irradiates the dielectric drum while controlling the flow rate of the ions with a pair of aperture electrodes to form an electrostatic latent image corresponding to one dot. Then, the electrostatic latent image is transferred and fixed on a recording sheet in the same process as in the ordinary electrostatic electrophotographic recording.

In order to perform high quality gradation image recording in such an ion printer, it is necessary to control the amount of ions passing through the aperture electrodes forming the ion holes with high accuracy. However, each ion hole that emits ions generally has variations in ion emission characteristics. Therefore, in the prior art, for example, Japanese Patent Laid-Open No. 1-105
As disclosed in Japanese Patent No. 754, the ion emission characteristic of each ion hole is measured in advance at the manufacturing stage before the recording head is incorporated into the apparatus, and a correction coefficient is calculated based on the measurement result and stored in a memory. After the start of use, the gradation data is corrected based on the correction coefficient stored in this memory to drive the recording head.

Further, as a method for obtaining the above-mentioned correction coefficient, as shown in, for example, Japanese Patent Laid-Open No. 4-303667, an ion when the recording head is driven based on one modulation data whose value is fixed. A method has been proposed in which a current value is measured, and a characteristic is approximated by one measured value and an empirically determined slope to obtain a correction coefficient.

[0005]

However, in the above-described conventional apparatus, since the recording head is driven by correcting the gradation data based on the correction coefficient measured and created in the manufacturing stage, the recording head is used after the start of use. When the ion emission characteristic of the ion hole changes due to the change over time, the correction coefficient does not match the actual characteristic, and the correction accuracy deteriorates, which causes the deterioration of the quality of the recorded image.

Also in the above method for obtaining the correction coefficient, since the correction characteristic is approximated based on the measured value at only one point, the error from the actual ion emission characteristic tends to be large, Therefore, it was difficult to realize high-quality gradation image recording.

The present invention has been made in view of the above circumstances, and its purpose is to make it possible to perform highly accurate correction at all times even if the ion emission characteristics change after the start of use, and to make actual ion It is an object of the present invention to provide an ion printer capable of generating correction data with a small error from the radiation characteristic, and thereby always performing high-quality gradation image recording.

[0008]

In order to achieve the above object, the ion printer of the present invention incorporates an ion current measuring means in the apparatus, and the ion current measuring means allows the ion current measuring means to perform an arbitrary period during which a recording operation is not performed. , The recording head drive unit is supplied with a plurality of modulation data for measurement corresponding to each ion hole to generate an ion current from the recording head, and these ion current values are detected and the detected values are detected. The characteristic data of each ion hole is generated on the basis of the generated characteristic data, and the generated characteristic data is stored in the storage means and used for the correction of the gradation data.

[0009]

As a result, according to the present invention, the ion current is measured and the ion hole characteristic data is regenerated by the ion current measuring means incorporated in the apparatus, for example, during warm-up before the start of recording or at the recording interval. ,
The storage data of the storage means is updated to this characteristic data. Therefore, even if the ion emission characteristic of the ion hole changes due to aging of the recording head or the like, the optimum characteristic data is always stored in the storage unit in accordance with this change, which ensures that high accuracy is maintained. High-quality gradation image recording can be performed by enabling correction. Also,
Since the ion current value is measured using a plurality of measurement modulation data for each ion hole, and characteristic data is generated based on the plurality of ion current values,
It is possible to generate characteristic data with a small error corresponding to the actual ion emission characteristic, and this enables highly accurate correction.

[0010]

【Example】

(First Embodiment) FIG. 1 is a block diagram of an ion printer according to the first embodiment of the present invention.

The ion printer of the present embodiment comprises a dielectric drum 1 as a recording medium, a print head 2 arranged to face the peripheral surface of the dielectric drum 1, and a drive circuit 3 for the print head 2. The print control circuit 4, the modulation data generation unit 5, the characteristic data storage unit 6, the data switching unit 7, the ion current measurement unit 8, and the ion current detection resistor 9 are provided.
It has and.

The print head 2 is provided with a large number of ion holes each corresponding to one dot of a recorded image. These ion holes are composed of, for example, an ion generator that generates ions by corona discharge, and a pair of aperture electrodes that control the passage amount of the ion current generated from the ion generator.

The print head drive circuit 3 includes a data switching section 7
For driving the print head 2 in accordance with the modulation data MD and the hole address AD input via
The electrode drive voltage DV having the magnitude represented by the modulation data MD is supplied to the aperture electrode of the ion hole designated by the hole address AD. The passing amount of the ionic current corresponds to the magnitude of the electrode driving voltage DV.

The print control circuit 4 generates gradation data KD for each page based on the print data GD transferred from the host computer 10 which is a print data source, and the gradation data KD is used as a modulation data generation unit. Supply to 5. The gradation data KD includes data for instructing a target ion current value to be generated in each ion hole of the print head 2.

When the gradation data KD is supplied from the print control circuit 4, the modulation data generator 5 gives a hole address AD indicating the position of the ion hole to the characteristic data memory 6, and the hole address AD is given. Read out the characteristic data TD, and based on the characteristic data TD, the gradation data KD is corrected and calculated to obtain the print modulation data IMD.
To generate. Then, the print modulation data IMD is supplied to the print head drive circuit 3 via the data switching unit 7 together with the hole address AD for designating the position of the ion hole.

The ion current measuring unit 8 has a measuring function of measuring the ion current I of each ion hole of the print head 2 during non-recording operation to calculate data representing the ion emission characteristic.
It has a function of judging the life of the print head according to a predetermined life judgment algorithm based on the calculated data.

Among these, the measuring function is as follows. That is, for example, the data switching unit 7 is switched from the modulation data generation unit 5 side to the ion current measurement unit 8 side during the warm-up period after the power is turned on. In this state, first, the measurement modulation data DMD stored in advance in association with each ion hole from the built-in ROM is read out together with the hole address AD, and the measurement modulation data DMD and the hole address AD are read as the above data. It is supplied to the print head drive circuit 3 via the switching unit 7. And
Every time one measurement modulation data is supplied, the value of the ion current I emitted from the corresponding ion hole of the print head 2 is detected as the voltage value ID appearing across the detection resistor 9,
A constant group representing the ion emission characteristics of the ion hole is calculated based on the detected voltage value ID, and the old constant group of the corresponding ion hole stored in the characteristic data storage unit 6 is calculated as the newly calculated constant. Rewrite as a group.

By the way, as a method of measuring and calculating the constant group, for example, a method called a two-point method is used. In the two-point method, two measurement modulation data D1 and D2 having different values are supplied to each ion hole, and the ion current values I1 and I2 generated according to the measurement modulation data D1 and D2 are respectively supplied. To detect. Then, the ion current values I1 and I2 and the measurement modulation data D1,
Based on D2, a linear approximation operation is performed to obtain constant groups K (i), C
(i) is calculated. This constant group K (i), C (i)
The calculation formula for calculating is shown below. In addition, i has shown that it is the i-th ion hole. K (i) = (D2-D1) / (I2 (i) -I1 (i)) C (i) = D1-K (i) * I1 (i) (1) FIG. 2 shows this two-point method. It is an example of a linear approximation characteristic obtained by.

Further, as the life judgment algorithm of the print head 2 when the two-point method is used, the following one is used. That is, as shown in FIG. 2, the maximum value of the modulation data DMD for measurement is set to Dmax and the grayscale data KD
When the range of Imin to Imax is set and the following two expressions are no longer satisfied, the print head 2
Determines that it has reached the end of its life. 0 ≦ K (i) * Imax + C (i) ≦ Dmax 0 ≦ K (i) * Imin + C (i) ≦ Dmax (2)

Next, the ion current measuring operation of the ion printer constructed as described above and the normal printing operation using the characteristic data (constant group) calculated by this measurement will be described.

When the power is turned on, the apparatus first starts warming up, and the ion current measuring operation is executed using this warming up period. That is, first, the switching signal SW is output from the ionic current measuring unit 8, and the data switching unit 7 switches from the modulation data generating unit 5 side to the ionic current measuring unit 8 side.

In this state, the ion current measuring section 8 corresponds to each ion hole of the print head 2 based on the two-point method, and a hole address AD for designating the ion hole and two measurements. Modulation data D1 and D2 are output respectively. The hole address AD and the two measurement modulation data D1 and D2 are supplied to the print head drive circuit 3 via the data switching unit 7. Then, from the print head drive circuit 3, the electrode drive voltages DV1 and DV2 whose values are designated by the modulation data D1 and D2 are supplied to the ion holes (opening electrodes) designated by the hole address AD of the print head 2. Is applied. Therefore, the ion currents I1 and I2 corresponding to the values of the electrode drive voltages DV1 and DV2 are emitted from the ion holes of the print head 2, and the ion currents I1 and I2 are detected via the dielectric drum 1. The voltage flows to the resistor 9, is converted into voltage values ID1 and ID2 by the detection resistor 9, and is input to the ion current measuring unit 8.

In the ionic current measuring unit 8, linear approximation calculation is performed according to the equation (1) based on the voltage values ID1 and ID2 corresponding to the ionic currents I1 and I2 and the modulation data D1 and D2. As a result, a group of constants K (i), C representing the ion emission characteristics of the ion hole to be measured is obtained.
(i) is calculated. Then, this constant group K (i), C (i)
Is stored in the corresponding storage area of the characteristic data storage unit 6 in place of the old constant group stored until then.

Similarly, for all remaining ion holes, two pieces of measurement modulation data D1 and D2 are output from the ion current measuring section 8, and the ion current value I1 corresponding to these modulation data D1 and D2 is output. , I2 is detected. Then, the detected two ion current values I
Based on 1 and I2, a group of constants K (i) and C (i) representing the ion radiation characteristics by the linear approximation calculation formula shown in the above formula (1).
Is calculated and stored in the corresponding storage area of the characteristic data storage unit 6.

When the constant groups K (i) and C (i) are calculated, the ion current measuring unit 8 also determines the life of the print head 2. That is, the above constant groups K (i), C
Based on (i), it is determined whether or not the condition shown in the equation (2) is satisfied. If satisfied, it is determined that the print head 2 has not reached the end of its life. On the other hand, if not satisfied, it is determined that the print head 2 has reached the end of its life. The fact is displayed on the provided liquid crystal display or the like. Therefore, the operator can know the replacement time of the print head by visually recognizing this display.

When the ion current measurement and the life determination are completed, the ion current measuring unit 8 outputs a switching control signal SW, which causes the data switching unit 7 to generate modulation data from the ion current measuring unit 8 side. Return to the part 5 side. Then, the apparatus enters the printing operation mode.

That is, when the grayscale data KS is supplied from the print control circuit 4, the modulation data generating section 5 first gives a hole address AD to the characteristic data storing section 6, and thereby the corresponding constant group K (i). , C (i) are read. Then, an operation of D (i) = K (i) * I (i) + C (i) is performed using this constant group, thereby generating D (i) as the modulation data IMD.

This modulated data D (i) is supplied to the print head drive circuit 3 through the data switching section 7 together with the hole address AD. When the modulation data D (i) and the hole address AD are supplied to the print head driving circuit 3, the modulation data D (i) is supplied to the ion hole (opening electrode) of the print head 2 designated by the hole address AD. The electrode drive voltage DV represented by i) is generated and applied. Therefore, the ion current I (i) corresponding to the electrode driving voltage value is radiated from the corresponding ion hole of the print head 2, and as a result, an electrostatic latent image is formed on the dielectric drum 1.

As described above, in this embodiment, the ion current measuring section 8 is incorporated in the apparatus, and the ion current measuring section 8 is switched to the ion current measuring section 8 side during the non-printing operation. Two modulation data D1 and D2 for measurement are supplied from the unit 8 to the print head drive circuit 3 for each ion hole, and ion currents I1 and I2 are generated from the corresponding ion holes of the print head 2. Then, this ion current is detected as a voltage value via the detection resistor 9, and a linear approximation calculation is performed based on the detected ion current value to express a group of constants K (i) and C (i) representing the characteristics of the ion hole. ) Is calculated and the constant groups K (i) and C (i) are stored in the characteristic data storage unit 6 so as to be used for correction calculation of gradation data during the subsequent printing operation.

Therefore, according to the present embodiment, even after the use of the apparatus is started, the ion current is measured periodically or at an arbitrary timing and the constant group K based on the measured value.
(i) and C (i) are calculated, and the contents stored in the characteristic data storage unit 6 are updated accordingly. Therefore, even if the ion emission characteristic of the ion hole changes due to aging of the print head 2 during use, the optimum constant groups K (i) and C (i) are always stored in the characteristic data storage following this change. Since it is stored in the unit 6, high-accuracy correction can always be performed and high-quality gradation image recording can be performed.

The ion current values I1 and I2 are calculated by using the two measurement modulation data D1 and D2 for each ion hole.
Is measured and characteristic data (constant group) is generated based on these ion current values I1 and I2. Therefore, when estimating characteristic data from one conventional measurement point and an empirical slope, In comparison, it is possible to generate characteristic data with less error corresponding to the actual ion emission characteristics,
As a result, highly accurate correction can be performed.

Further, in the ion current measuring unit 8, the life of the print head 2 is judged based on the calculated constant groups K (i) and C (i), and when it is judged that the life has been reached, the fact is judged. Since the information is displayed on the console to notify the operator, the operator can clearly know when to replace the print head 2 and can use a good quality print head 2 whose life is not always reached. . (Second embodiment)

This embodiment shows a case where a multipoint method is adopted as a method of measuring and calculating a constant group. In the multipoint method, a large number of measurement modulation data D1, D2, D3, ..., Dn having different values are supplied to each ion hole, and these measurement modulation data D1, D2, D3 ,.
Ion current values I1, I2, I3 generated according to Dn
..., In are detected respectively. Then, based on these ion current values I1, I2, I3, ..., In and the measurement modulation data D1, D2, D3, ..., Dn, a polygonal line approximation calculation is performed to obtain constant groups Kj (i), Cj ( i) is calculated. A calculation formula for calculating the constant groups Kj (i) and Cj (i) is shown below. Note that j is 1 to n-1. Kj (i) = (D (j + 1) -Dj) / (I (j + 1) (i) -Ij (i)) Cj (i) = Dj-Kj (i) * Ij (i) (3) FIG. Shows an example of a polygonal line approximation characteristic obtained by this multipoint method.

The following is used as the life judgment algorithm of the print head 2 when the multipoint method is used. That is, as shown in FIG. 3, the maximum value of the measurement modulation data DMD is set to Dmax and the grayscale data KD
Setting the range of Imin to Imax, Imax and Imax
When min is in the range of In (i) to I1 (i), it is determined that the print head 2 has not reached the end of its life. On the other hand, when Imax ≧ I1 (i) and 0 <K1 (i) * Imax + C1 (i) are no longer satisfied, it is determined that the print head 2 has reached the end of its life. Further, when Imin ≤ In (i), if K (n-1) (i) * Imin + C (n-1) (i) ≤ Dmax is not satisfied, it is determined that the print head 2 has reached the end of its life. .

Now, the constant group K calculated by the above multipoint method
When j (i) and Cj (i) are stored in the characteristic data storage unit 6, the apparatus prints gradation data as follows. That is, when the grayscale data KD corresponding to the ion hole i is input from the print control circuit 4, the modulation data generation unit 5 supplies the hole address AD representing the ion hole i to the characteristic data storage unit 6, and First, the ion current values I2 (i), ..., In-1 (i) are read out. Then, k is calculated using the following equation. If I2 (i) <= I (i) then k = 1 Ij (i) <I (i) <= I (j-1) (i) if k = j I (i) <I (n-1) ) Then k = n-1

Next, the modulation data generator 5 reads the constant groups Kk (i) and Ck (i) for k from the characteristic data memory 6 and performs the following calculation to obtain the modulation data I.
D (i) as MD is generated. D (i) = Kk (i) * I (i) + Ck (i) This modulation data IMD is supplied to the print head drive circuit 3 via the data switching section 7, and thereby the print head 2
Is driven.

In this embodiment employing the multi-point method, the ion radiation characteristic data (constant group) of the ion hole is generated by the polygonal line approximation calculation based on the multi-point modulation data,
Since the gradation data is corrected based on this characteristic data, it is possible to perform the correction with higher accuracy than in the case where the two-point method is used, and thereby the gradation image can be printed with higher quality. You can In addition, the life of the print head 2 can be reliably determined. (Third
Example)

This embodiment shows the case where the three-point method is adopted as the method of measuring and calculating the constant group. In the three-point method, three measurement modulation data D1, D2, D3 having different values are supplied to each ion hole, and an ion current value I1 generated according to the measurement modulation data D1, D2, D3 is supplied. , I2, I3 are detected respectively. Then, based on these ion current values I1, I2, I3 and the measurement modulation data D1, D2, D3, a quadratic curve approximation operation is performed to obtain a group of constants K (i), C1 (i), C2 (i. ) Is calculated. This constant group K (i), C1 (i), C
The calculation formula for calculating 2 (i) is shown below.

[0039]

[Equation 1]

From this, C1 (i) =-b (i) / 2 / a (i) C2 (i) = (b (i) ^ 2-4 * a (i) * C (i)) / (2 * A (i)) ^ 2 K (i) = 1 / a (i) (4) FIG. 4 shows an example of a quadratic curve approximation characteristic obtained by the three-point method.

The following is used for the life judgment algorithm of the print head 2 when the three-point method is used. That is, as shown in FIG. 4, the maximum value of the measurement modulation data DMD is set to Dmax and the grayscale data KD
When the range of Imin to Imax is set and the following two expressions are no longer satisfied, the print head 2
Determines that it has reached the end of its life. 0 ≦ C1 (i) −sqrt (C2 (i) + K (i) * Imax)
≤Dmax 0 ≤C1 (i) -sqrt (C2 (i) + K (i) * Imin)
≤Dmax

When the constant groups Kj (i) and Cj (i) calculated by the above three-point method are stored in the characteristic data storage section 6, the apparatus prints gradation data as follows. Be done. That is, when the gradation data I (i) corresponding to the ion hole i is input from the print control circuit 4, the modulation data generation unit 5 supplies the hole address AD representing the ion hole i to the characteristic data storage unit 6. Then, the constant groups C1 (i), C2 (i) and K (i) are read from the characteristic data storage unit 6. Then, using this constant group, D (i) = C1 (i) -sqrt (C2 (i) + K (i) * I
(i)) to generate D (i) as the modulation data IMD. The modulated data IMD is supplied to the print head drive circuit 3 via the data switching unit 7, and the print head 2 is driven thereby.

In this embodiment employing the three-point method, the ion radiation characteristic data (constant group) of the ion hole is generated by the quadratic curve approximation calculation based on the three modulation data. Since the gradation data is corrected on the basis of the above, the multi-point method can be used because the correction can be performed with higher accuracy than the case where the two-point method is used, and the number of measurement points is as small as three. Compared with the case, the ion current can be measured and the characteristic data can be generated easily and in a short time. In addition, the life of the print head 2 can be reliably determined.

The present invention is not limited to the above embodiments. For example, in the above-described embodiment, the life is determined based on the characteristic data obtained during the warm-up period of the apparatus. However, not only that, but also at the time when the number of printed sheets reaches a predetermined number and after that, a fixed number of sheets are printed. It may be performed every time. In addition, regarding the control procedure and control contents when measuring the ion current and calculating the characteristic data, the configuration of the ion current measuring unit, etc.
Various modifications can be implemented without departing from the scope of the present invention.

[0045]

As described above in detail, in the present invention, the ion current measuring means is incorporated in the apparatus, and by the ion current measuring means, during an arbitrary period in which the recording operation is not performed,
The recording head drive unit is supplied with a plurality of modulation data for each measurement for each ion hole to generate an ion current from the recording head, and these ion current values are detected and each ion hole is detected based on these detected values. Characteristic data is generated, and the generated characteristic data is stored in the storage means and used for correction of gradation data.

Therefore, according to the present invention, even if the ion emission characteristic changes after the start of use, it is possible to always perform highly accurate correction, and it is possible to generate correction data having a small error from the actual ion emission characteristic. Therefore, it is possible to provide an ion printer that can always perform high-quality gradation image recording.

[Brief description of drawings]

FIG. 1 is a block configuration diagram of an ion printer according to a first embodiment of the present invention.

FIG. 2 is a diagram showing a linear approximation characteristic of an ion hole i calculated based on an ion current value measured by a two-point method.

FIG. 3 is a diagram showing a polygonal line approximation characteristic of an ion hole i calculated based on an ion current value measured by a multipoint method.

FIG. 4 is a diagram showing quadratic curve approximation characteristics of an ion hole i calculated based on an ion current value measured by a three-point method.

[Explanation of Codes] 1 ... Dielectric drum 2 ... Print head 3 ... Print head drive circuit 4 ... Print control circuit 5 ... Modulation data generation unit 6 ... Characteristic data storage unit 7 ... Data switching unit 8 ... Ion current measurement unit 9 ... Ion current detection resistance 10 ... Host computer GD ... Print data KD ... Gradation data IMD ... Print modulation data AD ... Hall address TD ... Characteristic data DMD ... Measurement modulation data DV ... Electrode drive voltage I ... Ion current ID ... Ion current value Detection voltage corresponding to

Continuation of the front page (72) Inventor Masanobu Okumura 2-43-2 Hatagaya, Shibuya-ku, Tokyo Olympus Optical Co., Ltd.

Claims (1)

[Claims] 1. A recording medium made of a dielectric material, a recording head provided with a plurality of ion holes having an ion generation source and a modulation control electrode, and modulation data for each ion hole of the recording head. A recording head drive unit that controls the irradiation of an ion current onto the recording medium by applying a corresponding modulation control voltage to form an electrostatic latent image, and the recording head during an arbitrary period during which the recording operation is not performed. A plurality of modulation data for measurement corresponding to each of the ion holes is supplied to the drive unit to generate an ion current from the corresponding ion hole, and these ion current values are detected and the respective detected values are detected. To store the characteristic data generated by this ion current measuring means and the ion current measuring means for generating the characteristic data of the corresponding ion hole Characteristic data storage means, and during recording operation, the gradation data corresponding to the recorded image is corrected based on the characteristic data stored in the characteristic data storage means, and the corrected gradation data is used as recording modulation data. An ion printer, comprising: modulation data generating means for supplying the recording head drive section.