Multiplex image reproducing method

Abstract

A method of reproducing multiplex images wherein an electrostatic image is formed on an image retainer by using a common electrostatic image forming device, the electrostatic image formed on the image retainer is developed, the steps of the above are repeated to superpose a plurality of toner images on the image retainer, and the toner images is transferred on a recording paper by one step. The developings other than the first time developing are carried out in such a manner that the surface of a developer layer on a developer feeding carrier does not contact with the surface of the toner image on the image retainer.

Description

1.000the developmentCarbon Black carbon black as the black pigment. The color image thus retained on the image retainer 61 was transferred to and fixed on the recording member P, as has been described with reference to FIG. 42. Moreover, the surface of the image retainer 61 having the color image transferred thereto had its charged eliminated by the charge eliminating means 13 and was cleared of the residual toners by the cleaning means 14.

The reproduced image thus obtained had little color toner mixing and was a remarkably clear color image.

Incidentally, in the present Example, the spot position of a subsequent writing operation may be overlapped upon that of a previous writing operation. In the writing and developing operations, moreover, the recording current of the recording head 3, and the voltage value, frequency and time selecting period of the d.c. or a.c. component of the voltage to be applied to the developing sleeve may be so changed as to adjust to the developed densities of the respective colors. If the writing spot positions are superposed, the color mixing becomes liable to occur to invite color vagueness but not to drop the resolution. In this case, moreover, especially the sequence of the colors to be developed is important. By adjusting the developing densities of the respective colors in the aforementioned manner, on the other hand, it is possible to attain a color image which has its tones changed.

EXAMPLE 30

The same reproducing apparatus as that of the Example 29 was used. The color image reproduction was conducted under the same conditions as those of the Example 29 except: that a magnetic image was for a background potential of 0 V by a first writing operation without any of the charging operation of the Example 29 by the pre-writing charger 2 before the first writing operation, after the charge elimination for demagnetization by the charge eliminating means 13; that a superposed voltage composed of a d.c. voltage of -50 V and an a.c. voltage of 3 kHz and 2,000 V was applied as the bias voltage before development to the developing sleeve 31; and that charge elimination and demagnetization were effected by the charge eliminating means 13 before second and later writing operations so that a magnetic image was retained for the background potential of 0 V even during the second and later writing operations.

The reproduced image which is excellent in clearness like that of the Example 29 was thus obtained.

EXAMPLE 31

The color image reproduction was conducted by the use of the same reproducing apparatus as that of the Example 29 and under the same conditions as those of the Example 29 except: that a charging operation is conducted to +300 V before a first writing operation by the pre-writing charger 2 so that a magnetic image was retained for the background potential of +300 V by the first writing operation after it had been demagnetized; that a superposed voltage composed of a d.c. voltage of +300 V and an a.c. voltage of 2 kHz and 1 KV was applied as the bias before the development to the developing sleeve 31; and that the pre-writing charger 2 was used before the demagetization and the second and later writing operations. The reproduced image obtained was a color image which was excellent in cleaness like that of the Example 29.

According to the Examples of the present invention, there can be attained an excellent effect that the tone or the like of the color image can be easily changed thanks to the use of the image retaining means having its image retainability and toner image formability separated so that a color image having excellent clearness and a high tone can be reproduced while stabilizing the reproduction.

Incidentally, the present invention can be applied not only to an image retainer having a belt or sheet shape, but also to an image retainer such as electrofax paper, which is placed on a base so that the color image formed thereon by the toners is fixed without being transferred. In this case, the sequence of superposing the color toner images has to be taken into consideration, but the transfer means, the cleaning means and so on can be omitted. It is true, but the charge eliminating means can be omitted, too, in case the toners are transferred with a predetermined polarity and a charge quantity. On the other hand, the transfer should not be limited to the corona type but may be exemplified by the bias roller type, the adhesion type, the direct pressure type or other means using an intermediate transfer member, and the fixture is not limited to the heat roller type.

In the foregoing embodiments of the present invention, moreover, the magnetic recording head is used as the writing means, but another means may be likewise used if the magnetic image is to be retained on the magnetic layer. More specifically, the present invention can be applied to the method, in which the magnetic image is retained by heating imagewise a demagnetized magnetic layer, while passing through a unidorm magnetic field, by the heating means such as a laser and by cooling the heated magnetic layer in a magnetic field.

Although the foregoing description has been directed only to the reproduction of the color image, furthermore, the method of the present invention can also be applied to the superposition of an image of identical colors. In addition, the electrophotographic image and the magnetic image can be reproduced in combination if an electrophotographic photosensitive layer is provided on the magnetic layer.