Application of moiré technique to the measurement of modulation transfer functions (MTF) of printing systems

It is shown theoretically and verified experimentally that by writing a low spatial frequency Ronchi grating by a computer and printing two copies of it on two transparencies by a printer, the modulation transfer function (MTF) of the printed image can be evaluated by measuring the transmittance of the superimposed gratings in a moiré fringe spacing. Application of the technique is quite simple and the results are reasonably reproducible. The technique does not require a high sensitive intensity detector and a very narrow slit for transmission scanning. Also, the presented technique can be applied to other imaging systems.     

Analysis of banding problem in multiple beam scanning system of laser printer

In the slant scanning method of multiple beams a misalignment of the slant angle causes a beam spacing error and pitch irregularities of scan lines called “banding”. This paper evaluates the pitch irregularities and tries to clarify the allowable beam spacing error. The following results are obtained: (1) The maximum spacing error of print lines is proportional to m/(dpi), where m is the number of multiple beams and dpi print dot density. (2) The noticeable limit of periodic variations of print density at low spatial frequency was presumed to be a visibility between 1 and 2% in experiments. (3) The allowable beam spacing error was calculated introducing the human eye spatial frequency response. (4) The banding simulation experiments by laser recording on the photographic paper on the XY stage showed good coincidence with the theoretical evaluations.     

彩色打印机特性化多元回归模型的研究

多元回归法是彩色打印机特性化普遍采用的方法,实验对影响多元回归精度的阶数、色空间选择、以及训练样本选取进行了研究.研究结果表明:(1)二、三、四阶的特性化精度分别在10.9±0.3、6.6±0.2、6.0±0.2个CIELAB色差单位;(2)回归模型采用RGB到CIELAB或CIEXYZ的预测精度基本相同,大概相差1个...     

Modified Spectral Neugebauer Model for Printer Characterization

Spectral Neugebauer model is widely used for spectral reflectance prediction during printer characterization. However, several factors reduce the predication precision. Thus, an improved cellular Yule-Nielson spectral Neugebauer (CYNSN) model is proposed, which modifies the traditional spectral Neugebauer model in three main aspects: (1) First, in order to adjust the nonlinearities between the predicated and measured spectral reflectance, an iteratively calculated Yule-Nielson exponent is added to the reflectance values within the Neugebauer equations. (2) Second, the quantity of Neugebauer primaries is increased by dividing the CMY colorant space into 4³ uniform cellular subdomains. (3) Third, the mapping functions are developed to map the area coverages' theoretical values to their effective values within the subdomains, and the mapped values highly improve the matching degree of the predicated and measured reflectance values. In the experiment, four related spectral Neugebauer models are employed during printer characterization, which are the traditional spectral Neugebauer model, Yule-Nielson spectral Neugebauer (YNSN) model, traditional CYNSN model, and the modified CYNSN model, respectively. And the experimental results show the modified CYNSN model yields a significant improvement over the other spectral Neugebauer models, by comparing the characterization errors in the form of colorimetry and spectroscopy.     

Holographic Three Dimensional Printer Using Galvanometer Scanners

To make holograms from computer graphic (CG) in a short time, a new holographic three dimensional (3D) printer is proposed here. This printer consists of galvanometer scanners, a micro computer and a laser, and uses a holographic contact duplicating method. Experiments have shown that a hologram of 39 × 41 mm can be obtained in 4 min.Presented at the International Commission for Optics Topical Meeting, Kyoto, 1994.     

Shear Viscosity Measurements in CBOOA

The anisotropic shear viscosity of the liquid crystal CBOOA has been measured by observing the flow through a flat capillary. Uniform alignment was maintained by application of magnetic fields up to 85 kOe. In the nematic phase, five different measurements were made to determine the five independent coefficients. In the smectic phase, when the smectic planes were parallel to the capillary plates, the flow was nearly Newtonian and the temperature dependence had an Arrhenius behavior. When the smectic planes were parallel to the velocity and to the velocity gradient. The flow was non-Newtonian and rheopectic. This non-ideal behavior is attributed to the existence of nucleation of dislocations that can become pinned at the capillary walls.     

Sustainable feasibility of waste printer ink to magnetically separable iron oxide–doped nanocarbons for styrene oxidation

A simpler cost-effective method for the isolation of magnetically separable ‘self-doped iron oxide nanocarbons’ (FeO-NC) from waste printer ink (used as a carbon source material which is available free of cost) is discussed here. The process involves carbonization of waste printer ink in a muffle furnace at ~600 °C to obtain FeO-NC. The as-prepared FeO-NC has been investigated as an efficient heterogeneous catalyst for the long-known important organic reaction involving transformation of styrene to benzaldehyde in a quantitative yield (~70%). Importantly, FeO-NC were magnetically separable along with good recyclability, which supports the sustainability of reported process.     

A model of a homogenized cavity corresponding to a multinozzle droplet generator for continuous ink-jet printers

We modelize the behavior of a vibrating fluid cavity. Small nozzles are uniformly distributed in one direction on a side of the cavity. By means of asymptotic expansion in powers of the smallest dimension of the cavity, including boundary layer terms, we get the convergence of the solution of the three-dimensional problem, as well as the convergence of the solution of the “homogenized” three-dimensional problem towards the solution of the same two-dimensional problem. Numerical experiments have been carried out in order to illustrate the previous theoretical results. © 1998 John Wiley & Sons, Inc. Numer Methods Partial Differential Eq 14: 821–842, 1998     

A modified tonality and its application to objective evaluation of laser printers noise

Noise in a laser printer is affected by many components, such as spring force, spring constant, and friction coefficient. Objective evaluation of pick up noise is difficult because of background noises, such as operating sound. In particular, pick up noise generated between the friction pad and paper in the process of printing has become an essential aspect of quality evaluation. However, the existing criteria for evaluating pick-up noise have solely relied on subjective human judgments; therefore, there is a need to objectify these criteria. In this paper, the noise index for determining the existence of pick-up noise is established using a modified tonality at just noticeable sound level limit. The study has investigated factors that cause pick-up noise and suggests the substitution of printer components that determine spring constants, spring force, and the quality of friction pads. The proposed noise index is successfully applied to classifying the pick-up noise and mitigating the noise through the optimized design combination of laser printer components.     

3D打印机控制系统的设计

设计了一种3D打印机控制系统,采用微控制器ATmega2560为主控制器,集成了USB通信接口模块、打印头温度检测模块、LCD控制器模块以及电机驱动模块等;利用计算机切片软件将3D模型切片产生G代码,通过串口送到主控制器,主控制器处理G 代码并对电机驱动模块发送控制信号,采用PWM脉冲宽度调制技术控制3D打印机的XYZ三轴电机及挤出机电机进行3D打印,为了保证打印头快速达到打印温度并保持温度恒定,采用增量式PID算法实现对温度的精确控制;测试结果表明,采用增量式PID算法后,挤出头温度控制在245℃,控制精度为1℃,将原来的300 s左右进入恒温状态提高到75 s左右进入恒温状态,提高了三维打印恒温控制的性能,减少了打印过程中打印材料断丝、粗细不均匀等现象,满足了对打印质量的要求。